diff mbox series

[meta-oe,3/3] btop: Update fmt header to latest

Message ID 20250312081309.3413533-3-raj.khem@gmail.com
State New
Headers show
Series [meta-oe,1/3] grpc: Upgrade to 1.71.0 Release | expand

Commit Message

Khem Raj March 12, 2025, 8:13 a.m. UTC
Fixes build with newer compilers e.g. clang20+

Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 .../0001-fmt-Update-headers-from-11.1.4.patch | 19338 ++++++++++++++++
 meta-oe/recipes-support/btop/btop_1.4.0.bb    |     4 +-
 2 files changed, 19341 insertions(+), 1 deletion(-)
 create mode 100644 meta-oe/recipes-support/btop/btop/0001-fmt-Update-headers-from-11.1.4.patch
diff mbox series

Patch

diff --git a/meta-oe/recipes-support/btop/btop/0001-fmt-Update-headers-from-11.1.4.patch b/meta-oe/recipes-support/btop/btop/0001-fmt-Update-headers-from-11.1.4.patch
new file mode 100644
index 0000000000..50834e57e8
--- /dev/null
+++ b/meta-oe/recipes-support/btop/btop/0001-fmt-Update-headers-from-11.1.4.patch
@@ -0,0 +1,19338 @@ 
+From 236f243428b898e3ababb611c648ec120abd2857 Mon Sep 17 00:00:00 2001
+From: Khem Raj <raj.khem@gmail.com>
+Date: Tue, 11 Mar 2025 20:02:10 -0700
+Subject: [PATCH] fmt: Update headers from 11.1.4+
+
+Newer compilers e.g. clang-20+ are not able to compile the fmt headers
+from old snapshop, therefore bring the latest from libfmt upstream
+
+Upstream-Status: Submitted [https://github.com/aristocratos/btop/pull/1063]
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+---
+ include/fmt/args.h       |  174 +-
+ include/fmt/base.h       | 2974 +++++++++++++++++++++++++++++++
+ include/fmt/chrono.h     | 1534 ++++++++--------
+ include/fmt/color.h      |  444 ++---
+ include/fmt/compile.h    |  280 ++-
+ include/fmt/core.h       | 2908 +-----------------------------
+ include/fmt/format-inl.h |  529 ++++--
+ include/fmt/format.h     | 3617 +++++++++++++++++---------------------
+ include/fmt/os.h         |  300 ++--
+ include/fmt/ostream.h    |  189 +-
+ include/fmt/printf.h     |  426 +++--
+ include/fmt/ranges.h     |  624 ++++---
+ include/fmt/std.h        |  677 +++++--
+ include/fmt/xchar.h      |  275 ++-
+ 14 files changed, 7656 insertions(+), 7295 deletions(-)
+ create mode 100644 include/fmt/base.h
+
+diff --git a/include/fmt/args.h b/include/fmt/args.h
+index a3966d1..3ff4788 100644
+--- a/include/fmt/args.h
++++ b/include/fmt/args.h
+@@ -1,4 +1,4 @@
+-// Formatting library for C++ - dynamic format arguments
++// Formatting library for C++ - dynamic argument lists
+ //
+ // Copyright (c) 2012 - present, Victor Zverovich
+ // All rights reserved.
+@@ -8,34 +8,39 @@
+ #ifndef FMT_ARGS_H_
+ #define FMT_ARGS_H_
+ 
+-#include <functional>  // std::reference_wrapper
+-#include <memory>      // std::unique_ptr
+-#include <vector>
++#ifndef FMT_MODULE
++#  include <functional>  // std::reference_wrapper
++#  include <memory>      // std::unique_ptr
++#  include <vector>
++#endif
+ 
+-#include "core.h"
++#include "format.h"  // std_string_view
+ 
+ FMT_BEGIN_NAMESPACE
+-
+ namespace detail {
+ 
+ template <typename T> struct is_reference_wrapper : std::false_type {};
+ template <typename T>
+ struct is_reference_wrapper<std::reference_wrapper<T>> : std::true_type {};
+ 
+-template <typename T> const T& unwrap(const T& v) { return v; }
+-template <typename T> const T& unwrap(const std::reference_wrapper<T>& v) {
++template <typename T> auto unwrap(const T& v) -> const T& { return v; }
++template <typename T>
++auto unwrap(const std::reference_wrapper<T>& v) -> const T& {
+   return static_cast<const T&>(v);
+ }
+ 
+-class dynamic_arg_list {
+-  // Workaround for clang's -Wweak-vtables. Unlike for regular classes, for
+-  // templates it doesn't complain about inability to deduce single translation
+-  // unit for placing vtable. So storage_node_base is made a fake template.
+-  template <typename = void> struct node {
+-    virtual ~node() = default;
+-    std::unique_ptr<node<>> next;
+-  };
++// node is defined outside dynamic_arg_list to workaround a C2504 bug in MSVC
++// 2022 (v17.10.0).
++//
++// Workaround for clang's -Wweak-vtables. Unlike for regular classes, for
++// templates it doesn't complain about inability to deduce single translation
++// unit for placing vtable. So node is made a fake template.
++template <typename = void> struct node {
++  virtual ~node() = default;
++  std::unique_ptr<node<>> next;
++};
+ 
++class dynamic_arg_list {
+   template <typename T> struct typed_node : node<> {
+     T value;
+ 
+@@ -50,7 +55,7 @@ class dynamic_arg_list {
+   std::unique_ptr<node<>> head_;
+ 
+  public:
+-  template <typename T, typename Arg> const T& push(const Arg& arg) {
++  template <typename T, typename Arg> auto push(const Arg& arg) -> const T& {
+     auto new_node = std::unique_ptr<typed_node<T>>(new typed_node<T>(arg));
+     auto& value = new_node->value;
+     new_node->next = std::move(head_);
+@@ -61,28 +66,18 @@ class dynamic_arg_list {
+ }  // namespace detail
+ 
+ /**
+-  \rst
+-  A dynamic version of `fmt::format_arg_store`.
+-  It's equipped with a storage to potentially temporary objects which lifetimes
+-  could be shorter than the format arguments object.
+-
+-  It can be implicitly converted into `~fmt::basic_format_args` for passing
+-  into type-erased formatting functions such as `~fmt::vformat`.
+-  \endrst
++ * A dynamic list of formatting arguments with storage.
++ *
++ * It can be implicitly converted into `fmt::basic_format_args` for passing
++ * into type-erased formatting functions such as `fmt::vformat`.
+  */
+-template <typename Context>
+-class dynamic_format_arg_store
+-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+-    // Workaround a GCC template argument substitution bug.
+-    : public basic_format_args<Context>
+-#endif
+-{
++template <typename Context> class dynamic_format_arg_store {
+  private:
+   using char_type = typename Context::char_type;
+ 
+   template <typename T> struct need_copy {
+     static constexpr detail::type mapped_type =
+-        detail::mapped_type_constant<T, Context>::value;
++        detail::mapped_type_constant<T, char_type>::value;
+ 
+     enum {
+       value = !(detail::is_reference_wrapper<T>::value ||
+@@ -95,7 +90,7 @@ class dynamic_format_arg_store
+   };
+ 
+   template <typename T>
+-  using stored_type = conditional_t<
++  using stored_t = conditional_t<
+       std::is_convertible<T, std::basic_string<char_type>>::value &&
+           !detail::is_reference_wrapper<T>::value,
+       std::basic_string<char_type>, T>;
+@@ -110,80 +105,72 @@ class dynamic_format_arg_store
+ 
+   friend class basic_format_args<Context>;
+ 
+-  unsigned long long get_types() const {
+-    return detail::is_unpacked_bit | data_.size() |
+-           (named_info_.empty()
+-                ? 0ULL
+-                : static_cast<unsigned long long>(detail::has_named_args_bit));
+-  }
+-
+-  const basic_format_arg<Context>* data() const {
++  auto data() const -> const basic_format_arg<Context>* {
+     return named_info_.empty() ? data_.data() : data_.data() + 1;
+   }
+ 
+   template <typename T> void emplace_arg(const T& arg) {
+-    data_.emplace_back(detail::make_arg<Context>(arg));
++    data_.emplace_back(arg);
+   }
+ 
+   template <typename T>
+   void emplace_arg(const detail::named_arg<char_type, T>& arg) {
+-    if (named_info_.empty()) {
+-      constexpr const detail::named_arg_info<char_type>* zero_ptr{nullptr};
+-      data_.insert(data_.begin(), {zero_ptr, 0});
+-    }
+-    data_.emplace_back(detail::make_arg<Context>(detail::unwrap(arg.value)));
++    if (named_info_.empty())
++      data_.insert(data_.begin(), basic_format_arg<Context>(nullptr, 0));
++    data_.emplace_back(detail::unwrap(arg.value));
+     auto pop_one = [](std::vector<basic_format_arg<Context>>* data) {
+       data->pop_back();
+     };
+     std::unique_ptr<std::vector<basic_format_arg<Context>>, decltype(pop_one)>
+         guard{&data_, pop_one};
+     named_info_.push_back({arg.name, static_cast<int>(data_.size() - 2u)});
+-    data_[0].value_.named_args = {named_info_.data(), named_info_.size()};
++    data_[0] = {named_info_.data(), named_info_.size()};
+     guard.release();
+   }
+ 
+  public:
+   constexpr dynamic_format_arg_store() = default;
+ 
++  operator basic_format_args<Context>() const {
++    return basic_format_args<Context>(data(), static_cast<int>(data_.size()),
++                                      !named_info_.empty());
++  }
++
+   /**
+-    \rst
+-    Adds an argument into the dynamic store for later passing to a formatting
+-    function.
+-
+-    Note that custom types and string types (but not string views) are copied
+-    into the store dynamically allocating memory if necessary.
+-
+-    **Example**::
+-
+-      fmt::dynamic_format_arg_store<fmt::format_context> store;
+-      store.push_back(42);
+-      store.push_back("abc");
+-      store.push_back(1.5f);
+-      std::string result = fmt::vformat("{} and {} and {}", store);
+-    \endrst
+-  */
++   * Adds an argument into the dynamic store for later passing to a formatting
++   * function.
++   *
++   * Note that custom types and string types (but not string views) are copied
++   * into the store dynamically allocating memory if necessary.
++   *
++   * **Example**:
++   *
++   *     fmt::dynamic_format_arg_store<fmt::format_context> store;
++   *     store.push_back(42);
++   *     store.push_back("abc");
++   *     store.push_back(1.5f);
++   *     std::string result = fmt::vformat("{} and {} and {}", store);
++   */
+   template <typename T> void push_back(const T& arg) {
+     if (detail::const_check(need_copy<T>::value))
+-      emplace_arg(dynamic_args_.push<stored_type<T>>(arg));
++      emplace_arg(dynamic_args_.push<stored_t<T>>(arg));
+     else
+       emplace_arg(detail::unwrap(arg));
+   }
+ 
+   /**
+-    \rst
+-    Adds a reference to the argument into the dynamic store for later passing to
+-    a formatting function.
+-
+-    **Example**::
+-
+-      fmt::dynamic_format_arg_store<fmt::format_context> store;
+-      char band[] = "Rolling Stones";
+-      store.push_back(std::cref(band));
+-      band[9] = 'c'; // Changing str affects the output.
+-      std::string result = fmt::vformat("{}", store);
+-      // result == "Rolling Scones"
+-    \endrst
+-  */
++   * Adds a reference to the argument into the dynamic store for later passing
++   * to a formatting function.
++   *
++   * **Example**:
++   *
++   *     fmt::dynamic_format_arg_store<fmt::format_context> store;
++   *     char band[] = "Rolling Stones";
++   *     store.push_back(std::cref(band));
++   *     band[9] = 'c'; // Changing str affects the output.
++   *     std::string result = fmt::vformat("{}", store);
++   *     // result == "Rolling Scones"
++   */
+   template <typename T> void push_back(std::reference_wrapper<T> arg) {
+     static_assert(
+         need_copy<T>::value,
+@@ -192,41 +179,40 @@ class dynamic_format_arg_store
+   }
+ 
+   /**
+-    Adds named argument into the dynamic store for later passing to a formatting
+-    function. ``std::reference_wrapper`` is supported to avoid copying of the
+-    argument. The name is always copied into the store.
+-  */
++   * Adds named argument into the dynamic store for later passing to a
++   * formatting function. `std::reference_wrapper` is supported to avoid
++   * copying of the argument. The name is always copied into the store.
++   */
+   template <typename T>
+   void push_back(const detail::named_arg<char_type, T>& arg) {
+     const char_type* arg_name =
+         dynamic_args_.push<std::basic_string<char_type>>(arg.name).c_str();
+     if (detail::const_check(need_copy<T>::value)) {
+       emplace_arg(
+-          fmt::arg(arg_name, dynamic_args_.push<stored_type<T>>(arg.value)));
++          fmt::arg(arg_name, dynamic_args_.push<stored_t<T>>(arg.value)));
+     } else {
+       emplace_arg(fmt::arg(arg_name, arg.value));
+     }
+   }
+ 
+-  /** Erase all elements from the store */
++  /// Erase all elements from the store.
+   void clear() {
+     data_.clear();
+     named_info_.clear();
+-    dynamic_args_ = detail::dynamic_arg_list();
++    dynamic_args_ = {};
+   }
+ 
+-  /**
+-    \rst
+-    Reserves space to store at least *new_cap* arguments including
+-    *new_cap_named* named arguments.
+-    \endrst
+-  */
++  /// Reserves space to store at least `new_cap` arguments including
++  /// `new_cap_named` named arguments.
+   void reserve(size_t new_cap, size_t new_cap_named) {
+     FMT_ASSERT(new_cap >= new_cap_named,
+-               "Set of arguments includes set of named arguments");
++               "set of arguments includes set of named arguments");
+     data_.reserve(new_cap);
+     named_info_.reserve(new_cap_named);
+   }
++
++  /// Returns the number of elements in the store.
++  size_t size() const noexcept { return data_.size(); }
+ };
+ 
+ FMT_END_NAMESPACE
+diff --git a/include/fmt/base.h b/include/fmt/base.h
+new file mode 100644
+index 0000000..fe73e37
+--- /dev/null
++++ b/include/fmt/base.h
+@@ -0,0 +1,2974 @@
++// Formatting library for C++ - the base API for char/UTF-8
++//
++// Copyright (c) 2012 - present, Victor Zverovich
++// All rights reserved.
++//
++// For the license information refer to format.h.
++
++#ifndef FMT_BASE_H_
++#define FMT_BASE_H_
++
++#if defined(FMT_IMPORT_STD) && !defined(FMT_MODULE)
++#  define FMT_MODULE
++#endif
++
++#ifndef FMT_MODULE
++#  include <limits.h>  // CHAR_BIT
++#  include <stdio.h>   // FILE
++#  include <string.h>  // memcmp
++
++#  include <type_traits>  // std::enable_if
++#endif
++
++// The fmt library version in the form major * 10000 + minor * 100 + patch.
++#define FMT_VERSION 110104
++
++// Detect compiler versions.
++#if defined(__clang__) && !defined(__ibmxl__)
++#  define FMT_CLANG_VERSION (__clang_major__ * 100 + __clang_minor__)
++#else
++#  define FMT_CLANG_VERSION 0
++#endif
++#if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER)
++#  define FMT_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
++#else
++#  define FMT_GCC_VERSION 0
++#endif
++#if defined(__ICL)
++#  define FMT_ICC_VERSION __ICL
++#elif defined(__INTEL_COMPILER)
++#  define FMT_ICC_VERSION __INTEL_COMPILER
++#else
++#  define FMT_ICC_VERSION 0
++#endif
++#if defined(_MSC_VER)
++#  define FMT_MSC_VERSION _MSC_VER
++#else
++#  define FMT_MSC_VERSION 0
++#endif
++
++// Detect standard library versions.
++#ifdef _GLIBCXX_RELEASE
++#  define FMT_GLIBCXX_RELEASE _GLIBCXX_RELEASE
++#else
++#  define FMT_GLIBCXX_RELEASE 0
++#endif
++#ifdef _LIBCPP_VERSION
++#  define FMT_LIBCPP_VERSION _LIBCPP_VERSION
++#else
++#  define FMT_LIBCPP_VERSION 0
++#endif
++
++#ifdef _MSVC_LANG
++#  define FMT_CPLUSPLUS _MSVC_LANG
++#else
++#  define FMT_CPLUSPLUS __cplusplus
++#endif
++
++// Detect __has_*.
++#ifdef __has_feature
++#  define FMT_HAS_FEATURE(x) __has_feature(x)
++#else
++#  define FMT_HAS_FEATURE(x) 0
++#endif
++#ifdef __has_include
++#  define FMT_HAS_INCLUDE(x) __has_include(x)
++#else
++#  define FMT_HAS_INCLUDE(x) 0
++#endif
++#ifdef __has_builtin
++#  define FMT_HAS_BUILTIN(x) __has_builtin(x)
++#else
++#  define FMT_HAS_BUILTIN(x) 0
++#endif
++#ifdef __has_cpp_attribute
++#  define FMT_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
++#else
++#  define FMT_HAS_CPP_ATTRIBUTE(x) 0
++#endif
++
++#define FMT_HAS_CPP14_ATTRIBUTE(attribute) \
++  (FMT_CPLUSPLUS >= 201402L && FMT_HAS_CPP_ATTRIBUTE(attribute))
++
++#define FMT_HAS_CPP17_ATTRIBUTE(attribute) \
++  (FMT_CPLUSPLUS >= 201703L && FMT_HAS_CPP_ATTRIBUTE(attribute))
++
++// Detect C++14 relaxed constexpr.
++#ifdef FMT_USE_CONSTEXPR
++// Use the provided definition.
++#elif FMT_GCC_VERSION >= 702 && FMT_CPLUSPLUS >= 201402L
++// GCC only allows constexpr member functions in non-literal types since 7.2:
++// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66297.
++#  define FMT_USE_CONSTEXPR 1
++#elif FMT_ICC_VERSION
++#  define FMT_USE_CONSTEXPR 0  // https://github.com/fmtlib/fmt/issues/1628
++#elif FMT_HAS_FEATURE(cxx_relaxed_constexpr) || FMT_MSC_VERSION >= 1912
++#  define FMT_USE_CONSTEXPR 1
++#else
++#  define FMT_USE_CONSTEXPR 0
++#endif
++#if FMT_USE_CONSTEXPR
++#  define FMT_CONSTEXPR constexpr
++#else
++#  define FMT_CONSTEXPR
++#endif
++
++// Detect consteval, C++20 constexpr extensions and std::is_constant_evaluated.
++#if !defined(__cpp_lib_is_constant_evaluated)
++#  define FMT_USE_CONSTEVAL 0
++#elif FMT_CPLUSPLUS < 201709L
++#  define FMT_USE_CONSTEVAL 0
++#elif FMT_GLIBCXX_RELEASE && FMT_GLIBCXX_RELEASE < 10
++#  define FMT_USE_CONSTEVAL 0
++#elif FMT_LIBCPP_VERSION && FMT_LIBCPP_VERSION < 10000
++#  define FMT_USE_CONSTEVAL 0
++#elif defined(__apple_build_version__) && __apple_build_version__ < 14000029L
++#  define FMT_USE_CONSTEVAL 0  // consteval is broken in Apple clang < 14.
++#elif FMT_MSC_VERSION && FMT_MSC_VERSION < 1929
++#  define FMT_USE_CONSTEVAL 0  // consteval is broken in MSVC VS2019 < 16.10.
++#elif defined(__cpp_consteval)
++#  define FMT_USE_CONSTEVAL 1
++#elif FMT_GCC_VERSION >= 1002 || FMT_CLANG_VERSION >= 1101
++#  define FMT_USE_CONSTEVAL 1
++#else
++#  define FMT_USE_CONSTEVAL 0
++#endif
++#if FMT_USE_CONSTEVAL
++#  define FMT_CONSTEVAL consteval
++#  define FMT_CONSTEXPR20 constexpr
++#else
++#  define FMT_CONSTEVAL
++#  define FMT_CONSTEXPR20
++#endif
++
++// Check if exceptions are disabled.
++#ifdef FMT_USE_EXCEPTIONS
++// Use the provided definition.
++#elif defined(__GNUC__) && !defined(__EXCEPTIONS)
++#  define FMT_USE_EXCEPTIONS 0
++#elif defined(__clang__) && !defined(__cpp_exceptions)
++#  define FMT_USE_EXCEPTIONS 0
++#elif FMT_MSC_VERSION && !_HAS_EXCEPTIONS
++#  define FMT_USE_EXCEPTIONS 0
++#else
++#  define FMT_USE_EXCEPTIONS 1
++#endif
++#if FMT_USE_EXCEPTIONS
++#  define FMT_TRY try
++#  define FMT_CATCH(x) catch (x)
++#else
++#  define FMT_TRY if (true)
++#  define FMT_CATCH(x) if (false)
++#endif
++
++#ifdef FMT_NO_UNIQUE_ADDRESS
++// Use the provided definition.
++#elif FMT_CPLUSPLUS < 202002L
++// Not supported.
++#elif FMT_HAS_CPP_ATTRIBUTE(no_unique_address)
++#  define FMT_NO_UNIQUE_ADDRESS [[no_unique_address]]
++// VS2019 v16.10 and later except clang-cl (https://reviews.llvm.org/D110485).
++#elif FMT_MSC_VERSION >= 1929 && !FMT_CLANG_VERSION
++#  define FMT_NO_UNIQUE_ADDRESS [[msvc::no_unique_address]]
++#endif
++#ifndef FMT_NO_UNIQUE_ADDRESS
++#  define FMT_NO_UNIQUE_ADDRESS
++#endif
++
++#if FMT_HAS_CPP17_ATTRIBUTE(fallthrough)
++#  define FMT_FALLTHROUGH [[fallthrough]]
++#elif defined(__clang__)
++#  define FMT_FALLTHROUGH [[clang::fallthrough]]
++#elif FMT_GCC_VERSION >= 700 && \
++    (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= 520)
++#  define FMT_FALLTHROUGH [[gnu::fallthrough]]
++#else
++#  define FMT_FALLTHROUGH
++#endif
++
++// Disable [[noreturn]] on MSVC/NVCC because of bogus unreachable code warnings.
++#if FMT_HAS_CPP_ATTRIBUTE(noreturn) && !FMT_MSC_VERSION && !defined(__NVCC__)
++#  define FMT_NORETURN [[noreturn]]
++#else
++#  define FMT_NORETURN
++#endif
++
++#ifdef FMT_NODISCARD
++// Use the provided definition.
++#elif FMT_HAS_CPP17_ATTRIBUTE(nodiscard)
++#  define FMT_NODISCARD [[nodiscard]]
++#else
++#  define FMT_NODISCARD
++#endif
++
++#ifdef FMT_DEPRECATED
++// Use the provided definition.
++#elif FMT_HAS_CPP14_ATTRIBUTE(deprecated)
++#  define FMT_DEPRECATED [[deprecated]]
++#else
++#  define FMT_DEPRECATED /* deprecated */
++#endif
++
++#ifdef FMT_ALWAYS_INLINE
++// Use the provided definition.
++#elif FMT_GCC_VERSION || FMT_CLANG_VERSION
++#  define FMT_ALWAYS_INLINE inline __attribute__((always_inline))
++#else
++#  define FMT_ALWAYS_INLINE inline
++#endif
++// A version of FMT_ALWAYS_INLINE to prevent code bloat in debug mode.
++#ifdef NDEBUG
++#  define FMT_INLINE FMT_ALWAYS_INLINE
++#else
++#  define FMT_INLINE inline
++#endif
++
++#if FMT_GCC_VERSION || FMT_CLANG_VERSION
++#  define FMT_VISIBILITY(value) __attribute__((visibility(value)))
++#else
++#  define FMT_VISIBILITY(value)
++#endif
++
++// Detect pragmas.
++#define FMT_PRAGMA_IMPL(x) _Pragma(#x)
++#if FMT_GCC_VERSION >= 504 && !defined(__NVCOMPILER)
++// Workaround a _Pragma bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59884
++// and an nvhpc warning: https://github.com/fmtlib/fmt/pull/2582.
++#  define FMT_PRAGMA_GCC(x) FMT_PRAGMA_IMPL(GCC x)
++#else
++#  define FMT_PRAGMA_GCC(x)
++#endif
++#if FMT_CLANG_VERSION
++#  define FMT_PRAGMA_CLANG(x) FMT_PRAGMA_IMPL(clang x)
++#else
++#  define FMT_PRAGMA_CLANG(x)
++#endif
++#if FMT_MSC_VERSION
++#  define FMT_MSC_WARNING(...) __pragma(warning(__VA_ARGS__))
++#else
++#  define FMT_MSC_WARNING(...)
++#endif
++
++#ifndef FMT_BEGIN_NAMESPACE
++#  define FMT_BEGIN_NAMESPACE \
++    namespace fmt {           \
++    inline namespace v11 {
++#  define FMT_END_NAMESPACE \
++    }                       \
++    }
++#endif
++
++#ifndef FMT_EXPORT
++#  define FMT_EXPORT
++#  define FMT_BEGIN_EXPORT
++#  define FMT_END_EXPORT
++#endif
++
++#ifdef _WIN32
++#  define FMT_WIN32 1
++#else
++#  define FMT_WIN32 0
++#endif
++
++#if !defined(FMT_HEADER_ONLY) && FMT_WIN32
++#  if defined(FMT_LIB_EXPORT)
++#    define FMT_API __declspec(dllexport)
++#  elif defined(FMT_SHARED)
++#    define FMT_API __declspec(dllimport)
++#  endif
++#elif defined(FMT_LIB_EXPORT) || defined(FMT_SHARED)
++#  define FMT_API FMT_VISIBILITY("default")
++#endif
++#ifndef FMT_API
++#  define FMT_API
++#endif
++
++#ifndef FMT_OPTIMIZE_SIZE
++#  define FMT_OPTIMIZE_SIZE 0
++#endif
++
++// FMT_BUILTIN_TYPE=0 may result in smaller library size at the cost of higher
++// per-call binary size by passing built-in types through the extension API.
++#ifndef FMT_BUILTIN_TYPES
++#  define FMT_BUILTIN_TYPES 1
++#endif
++
++#define FMT_APPLY_VARIADIC(expr) \
++  using unused = int[];          \
++  (void)unused { 0, (expr, 0)... }
++
++// Enable minimal optimizations for more compact code in debug mode.
++FMT_PRAGMA_GCC(push_options)
++#if !defined(__OPTIMIZE__) && !defined(__CUDACC__) && !defined(FMT_MODULE)
++FMT_PRAGMA_GCC(optimize("Og"))
++#endif
++FMT_PRAGMA_CLANG(diagnostic push)
++
++FMT_BEGIN_NAMESPACE
++
++// Implementations of enable_if_t and other metafunctions for older systems.
++template <bool B, typename T = void>
++using enable_if_t = typename std::enable_if<B, T>::type;
++template <bool B, typename T, typename F>
++using conditional_t = typename std::conditional<B, T, F>::type;
++template <bool B> using bool_constant = std::integral_constant<bool, B>;
++template <typename T>
++using remove_reference_t = typename std::remove_reference<T>::type;
++template <typename T>
++using remove_const_t = typename std::remove_const<T>::type;
++template <typename T>
++using remove_cvref_t = typename std::remove_cv<remove_reference_t<T>>::type;
++template <typename T>
++using make_unsigned_t = typename std::make_unsigned<T>::type;
++template <typename T>
++using underlying_t = typename std::underlying_type<T>::type;
++template <typename T> using decay_t = typename std::decay<T>::type;
++using nullptr_t = decltype(nullptr);
++
++#if FMT_GCC_VERSION && FMT_GCC_VERSION < 500
++// A workaround for gcc 4.9 to make void_t work in a SFINAE context.
++template <typename...> struct void_t_impl {
++  using type = void;
++};
++template <typename... T> using void_t = typename void_t_impl<T...>::type;
++#else
++template <typename...> using void_t = void;
++#endif
++
++struct monostate {
++  constexpr monostate() {}
++};
++
++// An enable_if helper to be used in template parameters which results in much
++// shorter symbols: https://godbolt.org/z/sWw4vP. Extra parentheses are needed
++// to workaround a bug in MSVC 2019 (see #1140 and #1186).
++#ifdef FMT_DOC
++#  define FMT_ENABLE_IF(...)
++#else
++#  define FMT_ENABLE_IF(...) fmt::enable_if_t<(__VA_ARGS__), int> = 0
++#endif
++
++template <typename T> constexpr auto min_of(T a, T b) -> T {
++  return a < b ? a : b;
++}
++template <typename T> constexpr auto max_of(T a, T b) -> T {
++  return a > b ? a : b;
++}
++
++namespace detail {
++// Suppresses "unused variable" warnings with the method described in
++// https://herbsutter.com/2009/10/18/mailbag-shutting-up-compiler-warnings/.
++// (void)var does not work on many Intel compilers.
++template <typename... T> FMT_CONSTEXPR void ignore_unused(const T&...) {}
++
++constexpr auto is_constant_evaluated(bool default_value = false) noexcept
++    -> bool {
++// Workaround for incompatibility between clang 14 and libstdc++ consteval-based
++// std::is_constant_evaluated: https://github.com/fmtlib/fmt/issues/3247.
++#if FMT_CPLUSPLUS >= 202002L && FMT_GLIBCXX_RELEASE >= 12 && \
++    (FMT_CLANG_VERSION >= 1400 && FMT_CLANG_VERSION < 1500)
++  ignore_unused(default_value);
++  return __builtin_is_constant_evaluated();
++#elif defined(__cpp_lib_is_constant_evaluated)
++  ignore_unused(default_value);
++  return std::is_constant_evaluated();
++#else
++  return default_value;
++#endif
++}
++
++// Suppresses "conditional expression is constant" warnings.
++template <typename T> FMT_ALWAYS_INLINE constexpr auto const_check(T val) -> T {
++  return val;
++}
++
++FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
++                                      const char* message);
++
++#if defined(FMT_ASSERT)
++// Use the provided definition.
++#elif defined(NDEBUG)
++// FMT_ASSERT is not empty to avoid -Wempty-body.
++#  define FMT_ASSERT(condition, message) \
++    fmt::detail::ignore_unused((condition), (message))
++#else
++#  define FMT_ASSERT(condition, message)                                    \
++    ((condition) /* void() fails with -Winvalid-constexpr on clang 4.0.1 */ \
++         ? (void)0                                                          \
++         : fmt::detail::assert_fail(__FILE__, __LINE__, (message)))
++#endif
++
++#ifdef FMT_USE_INT128
++// Use the provided definition.
++#elif defined(__SIZEOF_INT128__) && !defined(__NVCC__) && \
++    !(FMT_CLANG_VERSION && FMT_MSC_VERSION)
++#  define FMT_USE_INT128 1
++using int128_opt = __int128_t;  // An optional native 128-bit integer.
++using uint128_opt = __uint128_t;
++inline auto map(int128_opt x) -> int128_opt { return x; }
++inline auto map(uint128_opt x) -> uint128_opt { return x; }
++#else
++#  define FMT_USE_INT128 0
++#endif
++#if !FMT_USE_INT128
++enum class int128_opt {};
++enum class uint128_opt {};
++// Reduce template instantiations.
++inline auto map(int128_opt) -> monostate { return {}; }
++inline auto map(uint128_opt) -> monostate { return {}; }
++#endif
++
++#ifndef FMT_USE_BITINT
++#  define FMT_USE_BITINT (FMT_CLANG_VERSION >= 1500)
++#endif
++
++#if FMT_USE_BITINT
++FMT_PRAGMA_CLANG(diagnostic ignored "-Wbit-int-extension")
++template <int N> using bitint = _BitInt(N);
++template <int N> using ubitint = unsigned _BitInt(N);
++#else
++template <int N> struct bitint {};
++template <int N> struct ubitint {};
++#endif  // FMT_USE_BITINT
++
++// Casts a nonnegative integer to unsigned.
++template <typename Int>
++FMT_CONSTEXPR auto to_unsigned(Int value) -> make_unsigned_t<Int> {
++  FMT_ASSERT(std::is_unsigned<Int>::value || value >= 0, "negative value");
++  return static_cast<make_unsigned_t<Int>>(value);
++}
++
++template <typename Char>
++using unsigned_char = conditional_t<sizeof(Char) == 1, unsigned char, unsigned>;
++
++// A heuristic to detect std::string and std::[experimental::]string_view.
++// It is mainly used to avoid dependency on <[experimental/]string_view>.
++template <typename T, typename Enable = void>
++struct is_std_string_like : std::false_type {};
++template <typename T>
++struct is_std_string_like<T, void_t<decltype(std::declval<T>().find_first_of(
++                                 typename T::value_type(), 0))>>
++    : std::is_convertible<decltype(std::declval<T>().data()),
++                          const typename T::value_type*> {};
++
++// Check if the literal encoding is UTF-8.
++enum { is_utf8_enabled = "\u00A7"[1] == '\xA7' };
++enum { use_utf8 = !FMT_WIN32 || is_utf8_enabled };
++
++#ifndef FMT_UNICODE
++#  define FMT_UNICODE 1
++#endif
++
++static_assert(!FMT_UNICODE || use_utf8,
++              "Unicode support requires compiling with /utf-8");
++
++template <typename T> constexpr const char* narrow(const T*) { return nullptr; }
++constexpr FMT_ALWAYS_INLINE const char* narrow(const char* s) { return s; }
++
++template <typename Char>
++FMT_CONSTEXPR auto compare(const Char* s1, const Char* s2, std::size_t n)
++    -> int {
++  if (!is_constant_evaluated() && sizeof(Char) == 1) return memcmp(s1, s2, n);
++  for (; n != 0; ++s1, ++s2, --n) {
++    if (*s1 < *s2) return -1;
++    if (*s1 > *s2) return 1;
++  }
++  return 0;
++}
++
++namespace adl {
++using namespace std;
++
++template <typename Container>
++auto invoke_back_inserter()
++    -> decltype(back_inserter(std::declval<Container&>()));
++}  // namespace adl
++
++template <typename It, typename Enable = std::true_type>
++struct is_back_insert_iterator : std::false_type {};
++
++template <typename It>
++struct is_back_insert_iterator<
++    It, bool_constant<std::is_same<
++            decltype(adl::invoke_back_inserter<typename It::container_type>()),
++            It>::value>> : std::true_type {};
++
++// Extracts a reference to the container from *insert_iterator.
++template <typename OutputIt>
++inline FMT_CONSTEXPR20 auto get_container(OutputIt it) ->
++    typename OutputIt::container_type& {
++  struct accessor : OutputIt {
++    FMT_CONSTEXPR20 accessor(OutputIt base) : OutputIt(base) {}
++    using OutputIt::container;
++  };
++  return *accessor(it).container;
++}
++}  // namespace detail
++
++// Parsing-related public API and forward declarations.
++FMT_BEGIN_EXPORT
++
++/**
++ * An implementation of `std::basic_string_view` for pre-C++17. It provides a
++ * subset of the API. `fmt::basic_string_view` is used for format strings even
++ * if `std::basic_string_view` is available to prevent issues when a library is
++ * compiled with a different `-std` option than the client code (which is not
++ * recommended).
++ */
++template <typename Char> class basic_string_view {
++ private:
++  const Char* data_;
++  size_t size_;
++
++ public:
++  using value_type = Char;
++  using iterator = const Char*;
++
++  constexpr basic_string_view() noexcept : data_(nullptr), size_(0) {}
++
++  /// Constructs a string reference object from a C string and a size.
++  constexpr basic_string_view(const Char* s, size_t count) noexcept
++      : data_(s), size_(count) {}
++
++  constexpr basic_string_view(nullptr_t) = delete;
++
++  /// Constructs a string reference object from a C string.
++#if FMT_GCC_VERSION
++  FMT_ALWAYS_INLINE
++#endif
++  FMT_CONSTEXPR20 basic_string_view(const Char* s) : data_(s) {
++#if FMT_HAS_BUILTIN(__builtin_strlen) || FMT_GCC_VERSION || FMT_CLANG_VERSION
++    if (std::is_same<Char, char>::value) {
++      size_ = __builtin_strlen(detail::narrow(s));
++      return;
++    }
++#endif
++    size_t len = 0;
++    while (*s++) ++len;
++    size_ = len;
++  }
++
++  /// Constructs a string reference from a `std::basic_string` or a
++  /// `std::basic_string_view` object.
++  template <typename S,
++            FMT_ENABLE_IF(detail::is_std_string_like<S>::value&& std::is_same<
++                          typename S::value_type, Char>::value)>
++  FMT_CONSTEXPR basic_string_view(const S& s) noexcept
++      : data_(s.data()), size_(s.size()) {}
++
++  /// Returns a pointer to the string data.
++  constexpr auto data() const noexcept -> const Char* { return data_; }
++
++  /// Returns the string size.
++  constexpr auto size() const noexcept -> size_t { return size_; }
++
++  constexpr auto begin() const noexcept -> iterator { return data_; }
++  constexpr auto end() const noexcept -> iterator { return data_ + size_; }
++
++  constexpr auto operator[](size_t pos) const noexcept -> const Char& {
++    return data_[pos];
++  }
++
++  FMT_CONSTEXPR void remove_prefix(size_t n) noexcept {
++    data_ += n;
++    size_ -= n;
++  }
++
++  FMT_CONSTEXPR auto starts_with(basic_string_view<Char> sv) const noexcept
++      -> bool {
++    return size_ >= sv.size_ && detail::compare(data_, sv.data_, sv.size_) == 0;
++  }
++  FMT_CONSTEXPR auto starts_with(Char c) const noexcept -> bool {
++    return size_ >= 1 && *data_ == c;
++  }
++  FMT_CONSTEXPR auto starts_with(const Char* s) const -> bool {
++    return starts_with(basic_string_view<Char>(s));
++  }
++
++  // Lexicographically compare this string reference to other.
++  FMT_CONSTEXPR auto compare(basic_string_view other) const -> int {
++    int result =
++        detail::compare(data_, other.data_, min_of(size_, other.size_));
++    if (result != 0) return result;
++    return size_ == other.size_ ? 0 : (size_ < other.size_ ? -1 : 1);
++  }
++
++  FMT_CONSTEXPR friend auto operator==(basic_string_view lhs,
++                                       basic_string_view rhs) -> bool {
++    return lhs.compare(rhs) == 0;
++  }
++  friend auto operator!=(basic_string_view lhs, basic_string_view rhs) -> bool {
++    return lhs.compare(rhs) != 0;
++  }
++  friend auto operator<(basic_string_view lhs, basic_string_view rhs) -> bool {
++    return lhs.compare(rhs) < 0;
++  }
++  friend auto operator<=(basic_string_view lhs, basic_string_view rhs) -> bool {
++    return lhs.compare(rhs) <= 0;
++  }
++  friend auto operator>(basic_string_view lhs, basic_string_view rhs) -> bool {
++    return lhs.compare(rhs) > 0;
++  }
++  friend auto operator>=(basic_string_view lhs, basic_string_view rhs) -> bool {
++    return lhs.compare(rhs) >= 0;
++  }
++};
++
++using string_view = basic_string_view<char>;
++
++/// Specifies if `T` is an extended character type. Can be specialized by users.
++template <typename T> struct is_xchar : std::false_type {};
++template <> struct is_xchar<wchar_t> : std::true_type {};
++template <> struct is_xchar<char16_t> : std::true_type {};
++template <> struct is_xchar<char32_t> : std::true_type {};
++#ifdef __cpp_char8_t
++template <> struct is_xchar<char8_t> : std::true_type {};
++#endif
++
++// DEPRECATED! Will be replaced with an alias to prevent specializations.
++template <typename T> struct is_char : is_xchar<T> {};
++template <> struct is_char<char> : std::true_type {};
++
++template <typename T> class basic_appender;
++using appender = basic_appender<char>;
++
++// Checks whether T is a container with contiguous storage.
++template <typename T> struct is_contiguous : std::false_type {};
++
++class context;
++template <typename OutputIt, typename Char> class generic_context;
++template <typename Char> class parse_context;
++
++// Longer aliases for C++20 compatibility.
++template <typename Char> using basic_format_parse_context = parse_context<Char>;
++using format_parse_context = parse_context<char>;
++template <typename OutputIt, typename Char>
++using basic_format_context =
++    conditional_t<std::is_same<OutputIt, appender>::value, context,
++                  generic_context<OutputIt, Char>>;
++using format_context = context;
++
++template <typename Char>
++using buffered_context =
++    conditional_t<std::is_same<Char, char>::value, context,
++                  generic_context<basic_appender<Char>, Char>>;
++
++template <typename Context> class basic_format_arg;
++template <typename Context> class basic_format_args;
++
++// A separate type would result in shorter symbols but break ABI compatibility
++// between clang and gcc on ARM (#1919).
++using format_args = basic_format_args<context>;
++
++// A formatter for objects of type T.
++template <typename T, typename Char = char, typename Enable = void>
++struct formatter {
++  // A deleted default constructor indicates a disabled formatter.
++  formatter() = delete;
++};
++
++/// Reports a format error at compile time or, via a `format_error` exception,
++/// at runtime.
++// This function is intentionally not constexpr to give a compile-time error.
++FMT_NORETURN FMT_API void report_error(const char* message);
++
++enum class presentation_type : unsigned char {
++  // Common specifiers:
++  none = 0,
++  debug = 1,   // '?'
++  string = 2,  // 's' (string, bool)
++
++  // Integral, bool and character specifiers:
++  dec = 3,  // 'd'
++  hex,      // 'x' or 'X'
++  oct,      // 'o'
++  bin,      // 'b' or 'B'
++  chr,      // 'c'
++
++  // String and pointer specifiers:
++  pointer = 3,  // 'p'
++
++  // Floating-point specifiers:
++  exp = 1,  // 'e' or 'E' (1 since there is no FP debug presentation)
++  fixed,    // 'f' or 'F'
++  general,  // 'g' or 'G'
++  hexfloat  // 'a' or 'A'
++};
++
++enum class align { none, left, right, center, numeric };
++enum class sign { none, minus, plus, space };
++enum class arg_id_kind { none, index, name };
++
++// Basic format specifiers for built-in and string types.
++class basic_specs {
++ private:
++  // Data is arranged as follows:
++  //
++  //  0                   1                   2                   3
++  //  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
++  // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
++  // |type |align| w | p | s |u|#|L|  f  |          unused           |
++  // +-----+-----+---+---+---+-+-+-+-----+---------------------------+
++  //
++  //   w - dynamic width info
++  //   p - dynamic precision info
++  //   s - sign
++  //   u - uppercase (e.g. 'X' for 'x')
++  //   # - alternate form ('#')
++  //   L - localized
++  //   f - fill size
++  //
++  // Bitfields are not used because of compiler bugs such as gcc bug 61414.
++  enum : unsigned {
++    type_mask = 0x00007,
++    align_mask = 0x00038,
++    width_mask = 0x000C0,
++    precision_mask = 0x00300,
++    sign_mask = 0x00C00,
++    uppercase_mask = 0x01000,
++    alternate_mask = 0x02000,
++    localized_mask = 0x04000,
++    fill_size_mask = 0x38000,
++
++    align_shift = 3,
++    width_shift = 6,
++    precision_shift = 8,
++    sign_shift = 10,
++    fill_size_shift = 15,
++
++    max_fill_size = 4
++  };
++
++  unsigned data_ = 1 << fill_size_shift;
++  static_assert(sizeof(basic_specs::data_) * CHAR_BIT >= 18, "");
++
++  // Character (code unit) type is erased to prevent template bloat.
++  char fill_data_[max_fill_size] = {' '};
++
++  FMT_CONSTEXPR void set_fill_size(size_t size) {
++    data_ = (data_ & ~fill_size_mask) |
++            (static_cast<unsigned>(size) << fill_size_shift);
++  }
++
++ public:
++  constexpr auto type() const -> presentation_type {
++    return static_cast<presentation_type>(data_ & type_mask);
++  }
++  FMT_CONSTEXPR void set_type(presentation_type t) {
++    data_ = (data_ & ~type_mask) | static_cast<unsigned>(t);
++  }
++
++  constexpr auto align() const -> align {
++    return static_cast<fmt::align>((data_ & align_mask) >> align_shift);
++  }
++  FMT_CONSTEXPR void set_align(fmt::align a) {
++    data_ = (data_ & ~align_mask) | (static_cast<unsigned>(a) << align_shift);
++  }
++
++  constexpr auto dynamic_width() const -> arg_id_kind {
++    return static_cast<arg_id_kind>((data_ & width_mask) >> width_shift);
++  }
++  FMT_CONSTEXPR void set_dynamic_width(arg_id_kind w) {
++    data_ = (data_ & ~width_mask) | (static_cast<unsigned>(w) << width_shift);
++  }
++
++  FMT_CONSTEXPR auto dynamic_precision() const -> arg_id_kind {
++    return static_cast<arg_id_kind>((data_ & precision_mask) >>
++                                    precision_shift);
++  }
++  FMT_CONSTEXPR void set_dynamic_precision(arg_id_kind p) {
++    data_ = (data_ & ~precision_mask) |
++            (static_cast<unsigned>(p) << precision_shift);
++  }
++
++  constexpr bool dynamic() const {
++    return (data_ & (width_mask | precision_mask)) != 0;
++  }
++
++  constexpr auto sign() const -> sign {
++    return static_cast<fmt::sign>((data_ & sign_mask) >> sign_shift);
++  }
++  FMT_CONSTEXPR void set_sign(fmt::sign s) {
++    data_ = (data_ & ~sign_mask) | (static_cast<unsigned>(s) << sign_shift);
++  }
++
++  constexpr auto upper() const -> bool { return (data_ & uppercase_mask) != 0; }
++  FMT_CONSTEXPR void set_upper() { data_ |= uppercase_mask; }
++
++  constexpr auto alt() const -> bool { return (data_ & alternate_mask) != 0; }
++  FMT_CONSTEXPR void set_alt() { data_ |= alternate_mask; }
++  FMT_CONSTEXPR void clear_alt() { data_ &= ~alternate_mask; }
++
++  constexpr auto localized() const -> bool {
++    return (data_ & localized_mask) != 0;
++  }
++  FMT_CONSTEXPR void set_localized() { data_ |= localized_mask; }
++
++  constexpr auto fill_size() const -> size_t {
++    return (data_ & fill_size_mask) >> fill_size_shift;
++  }
++
++  template <typename Char, FMT_ENABLE_IF(std::is_same<Char, char>::value)>
++  constexpr auto fill() const -> const Char* {
++    return fill_data_;
++  }
++  template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
++  constexpr auto fill() const -> const Char* {
++    return nullptr;
++  }
++
++  template <typename Char> constexpr auto fill_unit() const -> Char {
++    using uchar = unsigned char;
++    return static_cast<Char>(static_cast<uchar>(fill_data_[0]) |
++                             (static_cast<uchar>(fill_data_[1]) << 8) |
++                             (static_cast<uchar>(fill_data_[2]) << 16));
++  }
++
++  FMT_CONSTEXPR void set_fill(char c) {
++    fill_data_[0] = c;
++    set_fill_size(1);
++  }
++
++  template <typename Char>
++  FMT_CONSTEXPR void set_fill(basic_string_view<Char> s) {
++    auto size = s.size();
++    set_fill_size(size);
++    if (size == 1) {
++      unsigned uchar = static_cast<detail::unsigned_char<Char>>(s[0]);
++      fill_data_[0] = static_cast<char>(uchar);
++      fill_data_[1] = static_cast<char>(uchar >> 8);
++      fill_data_[2] = static_cast<char>(uchar >> 16);
++      return;
++    }
++    FMT_ASSERT(size <= max_fill_size, "invalid fill");
++    for (size_t i = 0; i < size; ++i)
++      fill_data_[i & 3] = static_cast<char>(s[i]);
++  }
++
++  FMT_CONSTEXPR void copy_fill_from(const basic_specs& specs) {
++    set_fill_size(specs.fill_size());
++    for (size_t i = 0; i < max_fill_size; ++i)
++      fill_data_[i] = specs.fill_data_[i];
++  }
++};
++
++// Format specifiers for built-in and string types.
++struct format_specs : basic_specs {
++  int width;
++  int precision;
++
++  constexpr format_specs() : width(0), precision(-1) {}
++};
++
++/**
++ * Parsing context consisting of a format string range being parsed and an
++ * argument counter for automatic indexing.
++ */
++template <typename Char = char> class parse_context {
++ private:
++  basic_string_view<Char> fmt_;
++  int next_arg_id_;
++
++  enum { use_constexpr_cast = !FMT_GCC_VERSION || FMT_GCC_VERSION >= 1200 };
++
++  FMT_CONSTEXPR void do_check_arg_id(int arg_id);
++
++ public:
++  using char_type = Char;
++  using iterator = const Char*;
++
++  constexpr explicit parse_context(basic_string_view<Char> fmt,
++                                   int next_arg_id = 0)
++      : fmt_(fmt), next_arg_id_(next_arg_id) {}
++
++  /// Returns an iterator to the beginning of the format string range being
++  /// parsed.
++  constexpr auto begin() const noexcept -> iterator { return fmt_.begin(); }
++
++  /// Returns an iterator past the end of the format string range being parsed.
++  constexpr auto end() const noexcept -> iterator { return fmt_.end(); }
++
++  /// Advances the begin iterator to `it`.
++  FMT_CONSTEXPR void advance_to(iterator it) {
++    fmt_.remove_prefix(detail::to_unsigned(it - begin()));
++  }
++
++  /// Reports an error if using the manual argument indexing; otherwise returns
++  /// the next argument index and switches to the automatic indexing.
++  FMT_CONSTEXPR auto next_arg_id() -> int {
++    if (next_arg_id_ < 0) {
++      report_error("cannot switch from manual to automatic argument indexing");
++      return 0;
++    }
++    int id = next_arg_id_++;
++    do_check_arg_id(id);
++    return id;
++  }
++
++  /// Reports an error if using the automatic argument indexing; otherwise
++  /// switches to the manual indexing.
++  FMT_CONSTEXPR void check_arg_id(int id) {
++    if (next_arg_id_ > 0) {
++      report_error("cannot switch from automatic to manual argument indexing");
++      return;
++    }
++    next_arg_id_ = -1;
++    do_check_arg_id(id);
++  }
++  FMT_CONSTEXPR void check_arg_id(basic_string_view<Char>) {
++    next_arg_id_ = -1;
++  }
++  FMT_CONSTEXPR void check_dynamic_spec(int arg_id);
++};
++
++FMT_END_EXPORT
++
++namespace detail {
++
++// Constructs fmt::basic_string_view<Char> from types implicitly convertible
++// to it, deducing Char. Explicitly convertible types such as the ones returned
++// from FMT_STRING are intentionally excluded.
++template <typename Char, FMT_ENABLE_IF(is_char<Char>::value)>
++constexpr auto to_string_view(const Char* s) -> basic_string_view<Char> {
++  return s;
++}
++template <typename T, FMT_ENABLE_IF(is_std_string_like<T>::value)>
++constexpr auto to_string_view(const T& s)
++    -> basic_string_view<typename T::value_type> {
++  return s;
++}
++template <typename Char>
++constexpr auto to_string_view(basic_string_view<Char> s)
++    -> basic_string_view<Char> {
++  return s;
++}
++
++template <typename T, typename Enable = void>
++struct has_to_string_view : std::false_type {};
++// detail:: is intentional since to_string_view is not an extension point.
++template <typename T>
++struct has_to_string_view<
++    T, void_t<decltype(detail::to_string_view(std::declval<T>()))>>
++    : std::true_type {};
++
++/// String's character (code unit) type. detail:: is intentional to prevent ADL.
++template <typename S,
++          typename V = decltype(detail::to_string_view(std::declval<S>()))>
++using char_t = typename V::value_type;
++
++enum class type {
++  none_type,
++  // Integer types should go first,
++  int_type,
++  uint_type,
++  long_long_type,
++  ulong_long_type,
++  int128_type,
++  uint128_type,
++  bool_type,
++  char_type,
++  last_integer_type = char_type,
++  // followed by floating-point types.
++  float_type,
++  double_type,
++  long_double_type,
++  last_numeric_type = long_double_type,
++  cstring_type,
++  string_type,
++  pointer_type,
++  custom_type
++};
++
++// Maps core type T to the corresponding type enum constant.
++template <typename T, typename Char>
++struct type_constant : std::integral_constant<type, type::custom_type> {};
++
++#define FMT_TYPE_CONSTANT(Type, constant) \
++  template <typename Char>                \
++  struct type_constant<Type, Char>        \
++      : std::integral_constant<type, type::constant> {}
++
++FMT_TYPE_CONSTANT(int, int_type);
++FMT_TYPE_CONSTANT(unsigned, uint_type);
++FMT_TYPE_CONSTANT(long long, long_long_type);
++FMT_TYPE_CONSTANT(unsigned long long, ulong_long_type);
++FMT_TYPE_CONSTANT(int128_opt, int128_type);
++FMT_TYPE_CONSTANT(uint128_opt, uint128_type);
++FMT_TYPE_CONSTANT(bool, bool_type);
++FMT_TYPE_CONSTANT(Char, char_type);
++FMT_TYPE_CONSTANT(float, float_type);
++FMT_TYPE_CONSTANT(double, double_type);
++FMT_TYPE_CONSTANT(long double, long_double_type);
++FMT_TYPE_CONSTANT(const Char*, cstring_type);
++FMT_TYPE_CONSTANT(basic_string_view<Char>, string_type);
++FMT_TYPE_CONSTANT(const void*, pointer_type);
++
++constexpr auto is_integral_type(type t) -> bool {
++  return t > type::none_type && t <= type::last_integer_type;
++}
++constexpr auto is_arithmetic_type(type t) -> bool {
++  return t > type::none_type && t <= type::last_numeric_type;
++}
++
++constexpr auto set(type rhs) -> int { return 1 << static_cast<int>(rhs); }
++constexpr auto in(type t, int set) -> bool {
++  return ((set >> static_cast<int>(t)) & 1) != 0;
++}
++
++// Bitsets of types.
++enum {
++  sint_set =
++      set(type::int_type) | set(type::long_long_type) | set(type::int128_type),
++  uint_set = set(type::uint_type) | set(type::ulong_long_type) |
++             set(type::uint128_type),
++  bool_set = set(type::bool_type),
++  char_set = set(type::char_type),
++  float_set = set(type::float_type) | set(type::double_type) |
++              set(type::long_double_type),
++  string_set = set(type::string_type),
++  cstring_set = set(type::cstring_type),
++  pointer_set = set(type::pointer_type)
++};
++
++struct view {};
++
++template <typename Char, typename T> struct named_arg;
++template <typename T> struct is_named_arg : std::false_type {};
++template <typename T> struct is_static_named_arg : std::false_type {};
++
++template <typename Char, typename T>
++struct is_named_arg<named_arg<Char, T>> : std::true_type {};
++
++template <typename Char, typename T> struct named_arg : view {
++  const Char* name;
++  const T& value;
++
++  named_arg(const Char* n, const T& v) : name(n), value(v) {}
++  static_assert(!is_named_arg<T>::value, "nested named arguments");
++};
++
++template <bool B = false> constexpr auto count() -> int { return B ? 1 : 0; }
++template <bool B1, bool B2, bool... Tail> constexpr auto count() -> int {
++  return (B1 ? 1 : 0) + count<B2, Tail...>();
++}
++
++template <typename... Args> constexpr auto count_named_args() -> int {
++  return count<is_named_arg<Args>::value...>();
++}
++template <typename... Args> constexpr auto count_static_named_args() -> int {
++  return count<is_static_named_arg<Args>::value...>();
++}
++
++template <typename Char> struct named_arg_info {
++  const Char* name;
++  int id;
++};
++
++// named_args is non-const to suppress a bogus -Wmaybe-uninitalized in gcc 13.
++template <typename Char>
++FMT_CONSTEXPR void check_for_duplicate(named_arg_info<Char>* named_args,
++                                       int named_arg_index,
++                                       basic_string_view<Char> arg_name) {
++  for (int i = 0; i < named_arg_index; ++i) {
++    if (named_args[i].name == arg_name) report_error("duplicate named arg");
++  }
++}
++
++template <typename Char, typename T, FMT_ENABLE_IF(!is_named_arg<T>::value)>
++void init_named_arg(named_arg_info<Char>*, int& arg_index, int&, const T&) {
++  ++arg_index;
++}
++template <typename Char, typename T, FMT_ENABLE_IF(is_named_arg<T>::value)>
++void init_named_arg(named_arg_info<Char>* named_args, int& arg_index,
++                    int& named_arg_index, const T& arg) {
++  check_for_duplicate<Char>(named_args, named_arg_index, arg.name);
++  named_args[named_arg_index++] = {arg.name, arg_index++};
++}
++
++template <typename T, typename Char,
++          FMT_ENABLE_IF(!is_static_named_arg<T>::value)>
++FMT_CONSTEXPR void init_static_named_arg(named_arg_info<Char>*, int& arg_index,
++                                         int&) {
++  ++arg_index;
++}
++template <typename T, typename Char,
++          FMT_ENABLE_IF(is_static_named_arg<T>::value)>
++FMT_CONSTEXPR void init_static_named_arg(named_arg_info<Char>* named_args,
++                                         int& arg_index, int& named_arg_index) {
++  check_for_duplicate<Char>(named_args, named_arg_index, T::name);
++  named_args[named_arg_index++] = {T::name, arg_index++};
++}
++
++// To minimize the number of types we need to deal with, long is translated
++// either to int or to long long depending on its size.
++enum { long_short = sizeof(long) == sizeof(int) };
++using long_type = conditional_t<long_short, int, long long>;
++using ulong_type = conditional_t<long_short, unsigned, unsigned long long>;
++
++template <typename T>
++using format_as_result =
++    remove_cvref_t<decltype(format_as(std::declval<const T&>()))>;
++template <typename T>
++using format_as_member_result =
++    remove_cvref_t<decltype(formatter<T>::format_as(std::declval<const T&>()))>;
++
++template <typename T, typename Enable = std::true_type>
++struct use_format_as : std::false_type {};
++// format_as member is only used to avoid injection into the std namespace.
++template <typename T, typename Enable = std::true_type>
++struct use_format_as_member : std::false_type {};
++
++// Only map owning types because mapping views can be unsafe.
++template <typename T>
++struct use_format_as<
++    T, bool_constant<std::is_arithmetic<format_as_result<T>>::value>>
++    : std::true_type {};
++template <typename T>
++struct use_format_as_member<
++    T, bool_constant<std::is_arithmetic<format_as_member_result<T>>::value>>
++    : std::true_type {};
++
++template <typename T, typename U = remove_const_t<T>>
++using use_formatter =
++    bool_constant<(std::is_class<T>::value || std::is_enum<T>::value ||
++                   std::is_union<T>::value || std::is_array<T>::value) &&
++                  !has_to_string_view<T>::value && !is_named_arg<T>::value &&
++                  !use_format_as<T>::value && !use_format_as_member<U>::value>;
++
++template <typename Char, typename T, typename U = remove_const_t<T>>
++auto has_formatter_impl(T* p, buffered_context<Char>* ctx = nullptr)
++    -> decltype(formatter<U, Char>().format(*p, *ctx), std::true_type());
++template <typename Char> auto has_formatter_impl(...) -> std::false_type;
++
++// T can be const-qualified to check if it is const-formattable.
++template <typename T, typename Char> constexpr auto has_formatter() -> bool {
++  return decltype(has_formatter_impl<Char>(static_cast<T*>(nullptr)))::value;
++}
++
++// Maps formatting argument types to natively supported types or user-defined
++// types with formatters. Returns void on errors to be SFINAE-friendly.
++template <typename Char> struct type_mapper {
++  static auto map(signed char) -> int;
++  static auto map(unsigned char) -> unsigned;
++  static auto map(short) -> int;
++  static auto map(unsigned short) -> unsigned;
++  static auto map(int) -> int;
++  static auto map(unsigned) -> unsigned;
++  static auto map(long) -> long_type;
++  static auto map(unsigned long) -> ulong_type;
++  static auto map(long long) -> long long;
++  static auto map(unsigned long long) -> unsigned long long;
++  static auto map(int128_opt) -> int128_opt;
++  static auto map(uint128_opt) -> uint128_opt;
++  static auto map(bool) -> bool;
++
++  template <int N>
++  static auto map(bitint<N>) -> conditional_t<N <= 64, long long, void>;
++  template <int N>
++  static auto map(ubitint<N>)
++      -> conditional_t<N <= 64, unsigned long long, void>;
++
++  template <typename T, FMT_ENABLE_IF(is_char<T>::value)>
++  static auto map(T) -> conditional_t<
++      std::is_same<T, char>::value || std::is_same<T, Char>::value, Char, void>;
++
++  static auto map(float) -> float;
++  static auto map(double) -> double;
++  static auto map(long double) -> long double;
++
++  static auto map(Char*) -> const Char*;
++  static auto map(const Char*) -> const Char*;
++  template <typename T, typename C = char_t<T>,
++            FMT_ENABLE_IF(!std::is_pointer<T>::value)>
++  static auto map(const T&) -> conditional_t<std::is_same<C, Char>::value,
++                                             basic_string_view<C>, void>;
++
++  static auto map(void*) -> const void*;
++  static auto map(const void*) -> const void*;
++  static auto map(volatile void*) -> const void*;
++  static auto map(const volatile void*) -> const void*;
++  static auto map(nullptr_t) -> const void*;
++  template <typename T, FMT_ENABLE_IF(std::is_pointer<T>::value ||
++                                      std::is_member_pointer<T>::value)>
++  static auto map(const T&) -> void;
++
++  template <typename T, FMT_ENABLE_IF(use_format_as<T>::value)>
++  static auto map(const T& x) -> decltype(map(format_as(x)));
++  template <typename T, FMT_ENABLE_IF(use_format_as_member<T>::value)>
++  static auto map(const T& x) -> decltype(map(formatter<T>::format_as(x)));
++
++  template <typename T, FMT_ENABLE_IF(use_formatter<T>::value)>
++  static auto map(T&) -> conditional_t<has_formatter<T, Char>(), T&, void>;
++
++  template <typename T, FMT_ENABLE_IF(is_named_arg<T>::value)>
++  static auto map(const T& named_arg) -> decltype(map(named_arg.value));
++};
++
++// detail:: is used to workaround a bug in MSVC 2017.
++template <typename T, typename Char>
++using mapped_t = decltype(detail::type_mapper<Char>::map(std::declval<T&>()));
++
++// A type constant after applying type_mapper.
++template <typename T, typename Char = char>
++using mapped_type_constant = type_constant<mapped_t<T, Char>, Char>;
++
++template <typename T, typename Context,
++          type TYPE =
++              mapped_type_constant<T, typename Context::char_type>::value>
++using stored_type_constant = std::integral_constant<
++    type, Context::builtin_types || TYPE == type::int_type ? TYPE
++                                                           : type::custom_type>;
++// A parse context with extra data used only in compile-time checks.
++template <typename Char>
++class compile_parse_context : public parse_context<Char> {
++ private:
++  int num_args_;
++  const type* types_;
++  using base = parse_context<Char>;
++
++ public:
++  FMT_CONSTEXPR explicit compile_parse_context(basic_string_view<Char> fmt,
++                                               int num_args, const type* types,
++                                               int next_arg_id = 0)
++      : base(fmt, next_arg_id), num_args_(num_args), types_(types) {}
++
++  constexpr auto num_args() const -> int { return num_args_; }
++  constexpr auto arg_type(int id) const -> type { return types_[id]; }
++
++  FMT_CONSTEXPR auto next_arg_id() -> int {
++    int id = base::next_arg_id();
++    if (id >= num_args_) report_error("argument not found");
++    return id;
++  }
++
++  FMT_CONSTEXPR void check_arg_id(int id) {
++    base::check_arg_id(id);
++    if (id >= num_args_) report_error("argument not found");
++  }
++  using base::check_arg_id;
++
++  FMT_CONSTEXPR void check_dynamic_spec(int arg_id) {
++    ignore_unused(arg_id);
++    if (arg_id < num_args_ && types_ && !is_integral_type(types_[arg_id]))
++      report_error("width/precision is not integer");
++  }
++};
++
++// An argument reference.
++template <typename Char> union arg_ref {
++  FMT_CONSTEXPR arg_ref(int idx = 0) : index(idx) {}
++  FMT_CONSTEXPR arg_ref(basic_string_view<Char> n) : name(n) {}
++
++  int index;
++  basic_string_view<Char> name;
++};
++
++// Format specifiers with width and precision resolved at formatting rather
++// than parsing time to allow reusing the same parsed specifiers with
++// different sets of arguments (precompilation of format strings).
++template <typename Char = char> struct dynamic_format_specs : format_specs {
++  arg_ref<Char> width_ref;
++  arg_ref<Char> precision_ref;
++};
++
++// Converts a character to ASCII. Returns '\0' on conversion failure.
++template <typename Char, FMT_ENABLE_IF(std::is_integral<Char>::value)>
++constexpr auto to_ascii(Char c) -> char {
++  return c <= 0xff ? static_cast<char>(c) : '\0';
++}
++
++// Returns the number of code units in a code point or 1 on error.
++template <typename Char>
++FMT_CONSTEXPR auto code_point_length(const Char* begin) -> int {
++  if (const_check(sizeof(Char) != 1)) return 1;
++  auto c = static_cast<unsigned char>(*begin);
++  return static_cast<int>((0x3a55000000000000ull >> (2 * (c >> 3))) & 3) + 1;
++}
++
++// Parses the range [begin, end) as an unsigned integer. This function assumes
++// that the range is non-empty and the first character is a digit.
++template <typename Char>
++FMT_CONSTEXPR auto parse_nonnegative_int(const Char*& begin, const Char* end,
++                                         int error_value) noexcept -> int {
++  FMT_ASSERT(begin != end && '0' <= *begin && *begin <= '9', "");
++  unsigned value = 0, prev = 0;
++  auto p = begin;
++  do {
++    prev = value;
++    value = value * 10 + unsigned(*p - '0');
++    ++p;
++  } while (p != end && '0' <= *p && *p <= '9');
++  auto num_digits = p - begin;
++  begin = p;
++  int digits10 = static_cast<int>(sizeof(int) * CHAR_BIT * 3 / 10);
++  if (num_digits <= digits10) return static_cast<int>(value);
++  // Check for overflow.
++  unsigned max = INT_MAX;
++  return num_digits == digits10 + 1 &&
++                 prev * 10ull + unsigned(p[-1] - '0') <= max
++             ? static_cast<int>(value)
++             : error_value;
++}
++
++FMT_CONSTEXPR inline auto parse_align(char c) -> align {
++  switch (c) {
++  case '<': return align::left;
++  case '>': return align::right;
++  case '^': return align::center;
++  }
++  return align::none;
++}
++
++template <typename Char> constexpr auto is_name_start(Char c) -> bool {
++  return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || c == '_';
++}
++
++template <typename Char, typename Handler>
++FMT_CONSTEXPR auto parse_arg_id(const Char* begin, const Char* end,
++                                Handler&& handler) -> const Char* {
++  Char c = *begin;
++  if (c >= '0' && c <= '9') {
++    int index = 0;
++    if (c != '0')
++      index = parse_nonnegative_int(begin, end, INT_MAX);
++    else
++      ++begin;
++    if (begin == end || (*begin != '}' && *begin != ':'))
++      report_error("invalid format string");
++    else
++      handler.on_index(index);
++    return begin;
++  }
++  if (FMT_OPTIMIZE_SIZE > 1 || !is_name_start(c)) {
++    report_error("invalid format string");
++    return begin;
++  }
++  auto it = begin;
++  do {
++    ++it;
++  } while (it != end && (is_name_start(*it) || ('0' <= *it && *it <= '9')));
++  handler.on_name({begin, to_unsigned(it - begin)});
++  return it;
++}
++
++template <typename Char> struct dynamic_spec_handler {
++  parse_context<Char>& ctx;
++  arg_ref<Char>& ref;
++  arg_id_kind& kind;
++
++  FMT_CONSTEXPR void on_index(int id) {
++    ref = id;
++    kind = arg_id_kind::index;
++    ctx.check_arg_id(id);
++    ctx.check_dynamic_spec(id);
++  }
++  FMT_CONSTEXPR void on_name(basic_string_view<Char> id) {
++    ref = id;
++    kind = arg_id_kind::name;
++    ctx.check_arg_id(id);
++  }
++};
++
++template <typename Char> struct parse_dynamic_spec_result {
++  const Char* end;
++  arg_id_kind kind;
++};
++
++// Parses integer | "{" [arg_id] "}".
++template <typename Char>
++FMT_CONSTEXPR auto parse_dynamic_spec(const Char* begin, const Char* end,
++                                      int& value, arg_ref<Char>& ref,
++                                      parse_context<Char>& ctx)
++    -> parse_dynamic_spec_result<Char> {
++  FMT_ASSERT(begin != end, "");
++  auto kind = arg_id_kind::none;
++  if ('0' <= *begin && *begin <= '9') {
++    int val = parse_nonnegative_int(begin, end, -1);
++    if (val == -1) report_error("number is too big");
++    value = val;
++  } else {
++    if (*begin == '{') {
++      ++begin;
++      if (begin != end) {
++        Char c = *begin;
++        if (c == '}' || c == ':') {
++          int id = ctx.next_arg_id();
++          ref = id;
++          kind = arg_id_kind::index;
++          ctx.check_dynamic_spec(id);
++        } else {
++          begin = parse_arg_id(begin, end,
++                               dynamic_spec_handler<Char>{ctx, ref, kind});
++        }
++      }
++      if (begin != end && *begin == '}') return {++begin, kind};
++    }
++    report_error("invalid format string");
++  }
++  return {begin, kind};
++}
++
++template <typename Char>
++FMT_CONSTEXPR auto parse_width(const Char* begin, const Char* end,
++                               format_specs& specs, arg_ref<Char>& width_ref,
++                               parse_context<Char>& ctx) -> const Char* {
++  auto result = parse_dynamic_spec(begin, end, specs.width, width_ref, ctx);
++  specs.set_dynamic_width(result.kind);
++  return result.end;
++}
++
++template <typename Char>
++FMT_CONSTEXPR auto parse_precision(const Char* begin, const Char* end,
++                                   format_specs& specs,
++                                   arg_ref<Char>& precision_ref,
++                                   parse_context<Char>& ctx) -> const Char* {
++  ++begin;
++  if (begin == end) {
++    report_error("invalid precision");
++    return begin;
++  }
++  auto result =
++      parse_dynamic_spec(begin, end, specs.precision, precision_ref, ctx);
++  specs.set_dynamic_precision(result.kind);
++  return result.end;
++}
++
++enum class state { start, align, sign, hash, zero, width, precision, locale };
++
++// Parses standard format specifiers.
++template <typename Char>
++FMT_CONSTEXPR auto parse_format_specs(const Char* begin, const Char* end,
++                                      dynamic_format_specs<Char>& specs,
++                                      parse_context<Char>& ctx, type arg_type)
++    -> const Char* {
++  auto c = '\0';
++  if (end - begin > 1) {
++    auto next = to_ascii(begin[1]);
++    c = parse_align(next) == align::none ? to_ascii(*begin) : '\0';
++  } else {
++    if (begin == end) return begin;
++    c = to_ascii(*begin);
++  }
++
++  struct {
++    state current_state = state::start;
++    FMT_CONSTEXPR void operator()(state s, bool valid = true) {
++      if (current_state >= s || !valid)
++        report_error("invalid format specifier");
++      current_state = s;
++    }
++  } enter_state;
++
++  using pres = presentation_type;
++  constexpr auto integral_set = sint_set | uint_set | bool_set | char_set;
++  struct {
++    const Char*& begin;
++    format_specs& specs;
++    type arg_type;
++
++    FMT_CONSTEXPR auto operator()(pres pres_type, int set) -> const Char* {
++      if (!in(arg_type, set)) report_error("invalid format specifier");
++      specs.set_type(pres_type);
++      return begin + 1;
++    }
++  } parse_presentation_type{begin, specs, arg_type};
++
++  for (;;) {
++    switch (c) {
++    case '<':
++    case '>':
++    case '^':
++      enter_state(state::align);
++      specs.set_align(parse_align(c));
++      ++begin;
++      break;
++    case '+':
++    case ' ':
++      specs.set_sign(c == ' ' ? sign::space : sign::plus);
++      FMT_FALLTHROUGH;
++    case '-':
++      enter_state(state::sign, in(arg_type, sint_set | float_set));
++      ++begin;
++      break;
++    case '#':
++      enter_state(state::hash, is_arithmetic_type(arg_type));
++      specs.set_alt();
++      ++begin;
++      break;
++    case '0':
++      enter_state(state::zero);
++      if (!is_arithmetic_type(arg_type))
++        report_error("format specifier requires numeric argument");
++      if (specs.align() == align::none) {
++        // Ignore 0 if align is specified for compatibility with std::format.
++        specs.set_align(align::numeric);
++        specs.set_fill('0');
++      }
++      ++begin;
++      break;
++      // clang-format off
++    case '1': case '2': case '3': case '4': case '5':
++    case '6': case '7': case '8': case '9': case '{':
++      // clang-format on
++      enter_state(state::width);
++      begin = parse_width(begin, end, specs, specs.width_ref, ctx);
++      break;
++    case '.':
++      enter_state(state::precision,
++                  in(arg_type, float_set | string_set | cstring_set));
++      begin = parse_precision(begin, end, specs, specs.precision_ref, ctx);
++      break;
++    case 'L':
++      enter_state(state::locale, is_arithmetic_type(arg_type));
++      specs.set_localized();
++      ++begin;
++      break;
++    case 'd': return parse_presentation_type(pres::dec, integral_set);
++    case 'X': specs.set_upper(); FMT_FALLTHROUGH;
++    case 'x': return parse_presentation_type(pres::hex, integral_set);
++    case 'o': return parse_presentation_type(pres::oct, integral_set);
++    case 'B': specs.set_upper(); FMT_FALLTHROUGH;
++    case 'b': return parse_presentation_type(pres::bin, integral_set);
++    case 'E': specs.set_upper(); FMT_FALLTHROUGH;
++    case 'e': return parse_presentation_type(pres::exp, float_set);
++    case 'F': specs.set_upper(); FMT_FALLTHROUGH;
++    case 'f': return parse_presentation_type(pres::fixed, float_set);
++    case 'G': specs.set_upper(); FMT_FALLTHROUGH;
++    case 'g': return parse_presentation_type(pres::general, float_set);
++    case 'A': specs.set_upper(); FMT_FALLTHROUGH;
++    case 'a': return parse_presentation_type(pres::hexfloat, float_set);
++    case 'c':
++      if (arg_type == type::bool_type) report_error("invalid format specifier");
++      return parse_presentation_type(pres::chr, integral_set);
++    case 's':
++      return parse_presentation_type(pres::string,
++                                     bool_set | string_set | cstring_set);
++    case 'p':
++      return parse_presentation_type(pres::pointer, pointer_set | cstring_set);
++    case '?':
++      return parse_presentation_type(pres::debug,
++                                     char_set | string_set | cstring_set);
++    case '}': return begin;
++    default:  {
++      if (*begin == '}') return begin;
++      // Parse fill and alignment.
++      auto fill_end = begin + code_point_length(begin);
++      if (end - fill_end <= 0) {
++        report_error("invalid format specifier");
++        return begin;
++      }
++      if (*begin == '{') {
++        report_error("invalid fill character '{'");
++        return begin;
++      }
++      auto alignment = parse_align(to_ascii(*fill_end));
++      enter_state(state::align, alignment != align::none);
++      specs.set_fill(
++          basic_string_view<Char>(begin, to_unsigned(fill_end - begin)));
++      specs.set_align(alignment);
++      begin = fill_end + 1;
++    }
++    }
++    if (begin == end) return begin;
++    c = to_ascii(*begin);
++  }
++}
++
++template <typename Char, typename Handler>
++FMT_CONSTEXPR FMT_INLINE auto parse_replacement_field(const Char* begin,
++                                                      const Char* end,
++                                                      Handler&& handler)
++    -> const Char* {
++  ++begin;
++  if (begin == end) {
++    handler.on_error("invalid format string");
++    return end;
++  }
++  int arg_id = 0;
++  switch (*begin) {
++  case '}':
++    handler.on_replacement_field(handler.on_arg_id(), begin);
++    return begin + 1;
++  case '{': handler.on_text(begin, begin + 1); return begin + 1;
++  case ':': arg_id = handler.on_arg_id(); break;
++  default:  {
++    struct id_adapter {
++      Handler& handler;
++      int arg_id;
++
++      FMT_CONSTEXPR void on_index(int id) { arg_id = handler.on_arg_id(id); }
++      FMT_CONSTEXPR void on_name(basic_string_view<Char> id) {
++        arg_id = handler.on_arg_id(id);
++      }
++    } adapter = {handler, 0};
++    begin = parse_arg_id(begin, end, adapter);
++    arg_id = adapter.arg_id;
++    Char c = begin != end ? *begin : Char();
++    if (c == '}') {
++      handler.on_replacement_field(arg_id, begin);
++      return begin + 1;
++    }
++    if (c != ':') {
++      handler.on_error("missing '}' in format string");
++      return end;
++    }
++    break;
++  }
++  }
++  begin = handler.on_format_specs(arg_id, begin + 1, end);
++  if (begin == end || *begin != '}')
++    return handler.on_error("unknown format specifier"), end;
++  return begin + 1;
++}
++
++template <typename Char, typename Handler>
++FMT_CONSTEXPR void parse_format_string(basic_string_view<Char> fmt,
++                                       Handler&& handler) {
++  auto begin = fmt.data(), end = begin + fmt.size();
++  auto p = begin;
++  while (p != end) {
++    auto c = *p++;
++    if (c == '{') {
++      handler.on_text(begin, p - 1);
++      begin = p = parse_replacement_field(p - 1, end, handler);
++    } else if (c == '}') {
++      if (p == end || *p != '}')
++        return handler.on_error("unmatched '}' in format string");
++      handler.on_text(begin, p);
++      begin = ++p;
++    }
++  }
++  handler.on_text(begin, end);
++}
++
++// Checks char specs and returns true iff the presentation type is char-like.
++FMT_CONSTEXPR inline auto check_char_specs(const format_specs& specs) -> bool {
++  auto type = specs.type();
++  if (type != presentation_type::none && type != presentation_type::chr &&
++      type != presentation_type::debug) {
++    return false;
++  }
++  if (specs.align() == align::numeric || specs.sign() != sign::none ||
++      specs.alt()) {
++    report_error("invalid format specifier for char");
++  }
++  return true;
++}
++
++// A base class for compile-time strings.
++struct compile_string {};
++
++template <typename T, typename Char>
++FMT_VISIBILITY("hidden")  // Suppress an ld warning on macOS (#3769).
++FMT_CONSTEXPR auto invoke_parse(parse_context<Char>& ctx) -> const Char* {
++  using mapped_type = remove_cvref_t<mapped_t<T, Char>>;
++  constexpr bool formattable =
++      std::is_constructible<formatter<mapped_type, Char>>::value;
++  if (!formattable) return ctx.begin();  // Error is reported in the value ctor.
++  using formatted_type = conditional_t<formattable, mapped_type, int>;
++  return formatter<formatted_type, Char>().parse(ctx);
++}
++
++template <typename... T> struct arg_pack {};
++
++template <typename Char, int NUM_ARGS, int NUM_NAMED_ARGS, bool DYNAMIC_NAMES>
++class format_string_checker {
++ private:
++  type types_[max_of(1, NUM_ARGS)];
++  named_arg_info<Char> named_args_[max_of(1, NUM_NAMED_ARGS)];
++  compile_parse_context<Char> context_;
++
++  using parse_func = auto (*)(parse_context<Char>&) -> const Char*;
++  parse_func parse_funcs_[max_of(1, NUM_ARGS)];
++
++ public:
++  template <typename... T>
++  FMT_CONSTEXPR explicit format_string_checker(basic_string_view<Char> fmt,
++                                               arg_pack<T...>)
++      : types_{mapped_type_constant<T, Char>::value...},
++        named_args_{},
++        context_(fmt, NUM_ARGS, types_),
++        parse_funcs_{&invoke_parse<T, Char>...} {
++    int arg_index = 0, named_arg_index = 0;
++    FMT_APPLY_VARIADIC(
++        init_static_named_arg<T>(named_args_, arg_index, named_arg_index));
++    ignore_unused(arg_index, named_arg_index);
++  }
++
++  FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
++
++  FMT_CONSTEXPR auto on_arg_id() -> int { return context_.next_arg_id(); }
++  FMT_CONSTEXPR auto on_arg_id(int id) -> int {
++    context_.check_arg_id(id);
++    return id;
++  }
++  FMT_CONSTEXPR auto on_arg_id(basic_string_view<Char> id) -> int {
++    for (int i = 0; i < NUM_NAMED_ARGS; ++i) {
++      if (named_args_[i].name == id) return named_args_[i].id;
++    }
++    if (!DYNAMIC_NAMES) on_error("argument not found");
++    return -1;
++  }
++
++  FMT_CONSTEXPR void on_replacement_field(int id, const Char* begin) {
++    on_format_specs(id, begin, begin);  // Call parse() on empty specs.
++  }
++
++  FMT_CONSTEXPR auto on_format_specs(int id, const Char* begin, const Char* end)
++      -> const Char* {
++    context_.advance_to(begin);
++    if (id >= 0 && id < NUM_ARGS) return parse_funcs_[id](context_);
++    while (begin != end && *begin != '}') ++begin;
++    return begin;
++  }
++
++  FMT_NORETURN FMT_CONSTEXPR void on_error(const char* message) {
++    report_error(message);
++  }
++};
++
++/// A contiguous memory buffer with an optional growing ability. It is an
++/// internal class and shouldn't be used directly, only via `memory_buffer`.
++template <typename T> class buffer {
++ private:
++  T* ptr_;
++  size_t size_;
++  size_t capacity_;
++
++  using grow_fun = void (*)(buffer& buf, size_t capacity);
++  grow_fun grow_;
++
++ protected:
++  // Don't initialize ptr_ since it is not accessed to save a few cycles.
++  FMT_MSC_WARNING(suppress : 26495)
++  FMT_CONSTEXPR buffer(grow_fun grow, size_t sz) noexcept
++      : size_(sz), capacity_(sz), grow_(grow) {}
++
++  constexpr buffer(grow_fun grow, T* p = nullptr, size_t sz = 0,
++                   size_t cap = 0) noexcept
++      : ptr_(p), size_(sz), capacity_(cap), grow_(grow) {}
++
++  FMT_CONSTEXPR20 ~buffer() = default;
++  buffer(buffer&&) = default;
++
++  /// Sets the buffer data and capacity.
++  FMT_CONSTEXPR void set(T* buf_data, size_t buf_capacity) noexcept {
++    ptr_ = buf_data;
++    capacity_ = buf_capacity;
++  }
++
++ public:
++  using value_type = T;
++  using const_reference = const T&;
++
++  buffer(const buffer&) = delete;
++  void operator=(const buffer&) = delete;
++
++  auto begin() noexcept -> T* { return ptr_; }
++  auto end() noexcept -> T* { return ptr_ + size_; }
++
++  auto begin() const noexcept -> const T* { return ptr_; }
++  auto end() const noexcept -> const T* { return ptr_ + size_; }
++
++  /// Returns the size of this buffer.
++  constexpr auto size() const noexcept -> size_t { return size_; }
++
++  /// Returns the capacity of this buffer.
++  constexpr auto capacity() const noexcept -> size_t { return capacity_; }
++
++  /// Returns a pointer to the buffer data (not null-terminated).
++  FMT_CONSTEXPR auto data() noexcept -> T* { return ptr_; }
++  FMT_CONSTEXPR auto data() const noexcept -> const T* { return ptr_; }
++
++  /// Clears this buffer.
++  FMT_CONSTEXPR void clear() { size_ = 0; }
++
++  // Tries resizing the buffer to contain `count` elements. If T is a POD type
++  // the new elements may not be initialized.
++  FMT_CONSTEXPR void try_resize(size_t count) {
++    try_reserve(count);
++    size_ = min_of(count, capacity_);
++  }
++
++  // Tries increasing the buffer capacity to `new_capacity`. It can increase the
++  // capacity by a smaller amount than requested but guarantees there is space
++  // for at least one additional element either by increasing the capacity or by
++  // flushing the buffer if it is full.
++  FMT_CONSTEXPR void try_reserve(size_t new_capacity) {
++    if (new_capacity > capacity_) grow_(*this, new_capacity);
++  }
++
++  FMT_CONSTEXPR void push_back(const T& value) {
++    try_reserve(size_ + 1);
++    ptr_[size_++] = value;
++  }
++
++  /// Appends data to the end of the buffer.
++  template <typename U>
++// Workaround for MSVC2019 to fix error C2893: Failed to specialize function
++// template 'void fmt::v11::detail::buffer<T>::append(const U *,const U *)'.
++#if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1940
++  FMT_CONSTEXPR20
++#endif
++      void
++      append(const U* begin, const U* end) {
++    while (begin != end) {
++      auto count = to_unsigned(end - begin);
++      try_reserve(size_ + count);
++      auto free_cap = capacity_ - size_;
++      if (free_cap < count) count = free_cap;
++      // A loop is faster than memcpy on small sizes.
++      T* out = ptr_ + size_;
++      for (size_t i = 0; i < count; ++i) out[i] = begin[i];
++      size_ += count;
++      begin += count;
++    }
++  }
++
++  template <typename Idx> FMT_CONSTEXPR auto operator[](Idx index) -> T& {
++    return ptr_[index];
++  }
++  template <typename Idx>
++  FMT_CONSTEXPR auto operator[](Idx index) const -> const T& {
++    return ptr_[index];
++  }
++};
++
++struct buffer_traits {
++  constexpr explicit buffer_traits(size_t) {}
++  constexpr auto count() const -> size_t { return 0; }
++  constexpr auto limit(size_t size) const -> size_t { return size; }
++};
++
++class fixed_buffer_traits {
++ private:
++  size_t count_ = 0;
++  size_t limit_;
++
++ public:
++  constexpr explicit fixed_buffer_traits(size_t limit) : limit_(limit) {}
++  constexpr auto count() const -> size_t { return count_; }
++  FMT_CONSTEXPR auto limit(size_t size) -> size_t {
++    size_t n = limit_ > count_ ? limit_ - count_ : 0;
++    count_ += size;
++    return min_of(size, n);
++  }
++};
++
++// A buffer that writes to an output iterator when flushed.
++template <typename OutputIt, typename T, typename Traits = buffer_traits>
++class iterator_buffer : public Traits, public buffer<T> {
++ private:
++  OutputIt out_;
++  enum { buffer_size = 256 };
++  T data_[buffer_size];
++
++  static FMT_CONSTEXPR void grow(buffer<T>& buf, size_t) {
++    if (buf.size() == buffer_size) static_cast<iterator_buffer&>(buf).flush();
++  }
++
++  void flush() {
++    auto size = this->size();
++    this->clear();
++    const T* begin = data_;
++    const T* end = begin + this->limit(size);
++    while (begin != end) *out_++ = *begin++;
++  }
++
++ public:
++  explicit iterator_buffer(OutputIt out, size_t n = buffer_size)
++      : Traits(n), buffer<T>(grow, data_, 0, buffer_size), out_(out) {}
++  iterator_buffer(iterator_buffer&& other) noexcept
++      : Traits(other),
++        buffer<T>(grow, data_, 0, buffer_size),
++        out_(other.out_) {}
++  ~iterator_buffer() {
++    // Don't crash if flush fails during unwinding.
++    FMT_TRY { flush(); }
++    FMT_CATCH(...) {}
++  }
++
++  auto out() -> OutputIt {
++    flush();
++    return out_;
++  }
++  auto count() const -> size_t { return Traits::count() + this->size(); }
++};
++
++template <typename T>
++class iterator_buffer<T*, T, fixed_buffer_traits> : public fixed_buffer_traits,
++                                                    public buffer<T> {
++ private:
++  T* out_;
++  enum { buffer_size = 256 };
++  T data_[buffer_size];
++
++  static FMT_CONSTEXPR void grow(buffer<T>& buf, size_t) {
++    if (buf.size() == buf.capacity())
++      static_cast<iterator_buffer&>(buf).flush();
++  }
++
++  void flush() {
++    size_t n = this->limit(this->size());
++    if (this->data() == out_) {
++      out_ += n;
++      this->set(data_, buffer_size);
++    }
++    this->clear();
++  }
++
++ public:
++  explicit iterator_buffer(T* out, size_t n = buffer_size)
++      : fixed_buffer_traits(n), buffer<T>(grow, out, 0, n), out_(out) {}
++  iterator_buffer(iterator_buffer&& other) noexcept
++      : fixed_buffer_traits(other),
++        buffer<T>(static_cast<iterator_buffer&&>(other)),
++        out_(other.out_) {
++    if (this->data() != out_) {
++      this->set(data_, buffer_size);
++      this->clear();
++    }
++  }
++  ~iterator_buffer() { flush(); }
++
++  auto out() -> T* {
++    flush();
++    return out_;
++  }
++  auto count() const -> size_t {
++    return fixed_buffer_traits::count() + this->size();
++  }
++};
++
++template <typename T> class iterator_buffer<T*, T> : public buffer<T> {
++ public:
++  explicit iterator_buffer(T* out, size_t = 0)
++      : buffer<T>([](buffer<T>&, size_t) {}, out, 0, ~size_t()) {}
++
++  auto out() -> T* { return &*this->end(); }
++};
++
++template <typename Container>
++class container_buffer : public buffer<typename Container::value_type> {
++ private:
++  using value_type = typename Container::value_type;
++
++  static FMT_CONSTEXPR void grow(buffer<value_type>& buf, size_t capacity) {
++    auto& self = static_cast<container_buffer&>(buf);
++    self.container.resize(capacity);
++    self.set(&self.container[0], capacity);
++  }
++
++ public:
++  Container& container;
++
++  explicit container_buffer(Container& c)
++      : buffer<value_type>(grow, c.size()), container(c) {}
++};
++
++// A buffer that writes to a container with the contiguous storage.
++template <typename OutputIt>
++class iterator_buffer<
++    OutputIt,
++    enable_if_t<is_back_insert_iterator<OutputIt>::value &&
++                    is_contiguous<typename OutputIt::container_type>::value,
++                typename OutputIt::container_type::value_type>>
++    : public container_buffer<typename OutputIt::container_type> {
++ private:
++  using base = container_buffer<typename OutputIt::container_type>;
++
++ public:
++  explicit iterator_buffer(typename OutputIt::container_type& c) : base(c) {}
++  explicit iterator_buffer(OutputIt out, size_t = 0)
++      : base(get_container(out)) {}
++
++  auto out() -> OutputIt { return OutputIt(this->container); }
++};
++
++// A buffer that counts the number of code units written discarding the output.
++template <typename T = char> class counting_buffer : public buffer<T> {
++ private:
++  enum { buffer_size = 256 };
++  T data_[buffer_size];
++  size_t count_ = 0;
++
++  static FMT_CONSTEXPR void grow(buffer<T>& buf, size_t) {
++    if (buf.size() != buffer_size) return;
++    static_cast<counting_buffer&>(buf).count_ += buf.size();
++    buf.clear();
++  }
++
++ public:
++  FMT_CONSTEXPR counting_buffer() : buffer<T>(grow, data_, 0, buffer_size) {}
++
++  constexpr auto count() const noexcept -> size_t {
++    return count_ + this->size();
++  }
++};
++
++template <typename T>
++struct is_back_insert_iterator<basic_appender<T>> : std::true_type {};
++
++template <typename OutputIt, typename InputIt, typename = void>
++struct has_back_insert_iterator_container_append : std::false_type {};
++template <typename OutputIt, typename InputIt>
++struct has_back_insert_iterator_container_append<
++    OutputIt, InputIt,
++    void_t<decltype(get_container(std::declval<OutputIt>())
++                        .append(std::declval<InputIt>(),
++                                std::declval<InputIt>()))>> : std::true_type {};
++
++// An optimized version of std::copy with the output value type (T).
++template <typename T, typename InputIt, typename OutputIt,
++          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value&&
++                            has_back_insert_iterator_container_append<
++                                OutputIt, InputIt>::value)>
++FMT_CONSTEXPR20 auto copy(InputIt begin, InputIt end, OutputIt out)
++    -> OutputIt {
++  get_container(out).append(begin, end);
++  return out;
++}
++
++template <typename T, typename InputIt, typename OutputIt,
++          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value &&
++                        !has_back_insert_iterator_container_append<
++                            OutputIt, InputIt>::value)>
++FMT_CONSTEXPR20 auto copy(InputIt begin, InputIt end, OutputIt out)
++    -> OutputIt {
++  auto& c = get_container(out);
++  c.insert(c.end(), begin, end);
++  return out;
++}
++
++template <typename T, typename InputIt, typename OutputIt,
++          FMT_ENABLE_IF(!is_back_insert_iterator<OutputIt>::value)>
++FMT_CONSTEXPR auto copy(InputIt begin, InputIt end, OutputIt out) -> OutputIt {
++  while (begin != end) *out++ = static_cast<T>(*begin++);
++  return out;
++}
++
++template <typename T, typename V, typename OutputIt>
++FMT_CONSTEXPR auto copy(basic_string_view<V> s, OutputIt out) -> OutputIt {
++  return copy<T>(s.begin(), s.end(), out);
++}
++
++template <typename It, typename Enable = std::true_type>
++struct is_buffer_appender : std::false_type {};
++template <typename It>
++struct is_buffer_appender<
++    It, bool_constant<
++            is_back_insert_iterator<It>::value &&
++            std::is_base_of<buffer<typename It::container_type::value_type>,
++                            typename It::container_type>::value>>
++    : std::true_type {};
++
++// Maps an output iterator to a buffer.
++template <typename T, typename OutputIt,
++          FMT_ENABLE_IF(!is_buffer_appender<OutputIt>::value)>
++auto get_buffer(OutputIt out) -> iterator_buffer<OutputIt, T> {
++  return iterator_buffer<OutputIt, T>(out);
++}
++template <typename T, typename OutputIt,
++          FMT_ENABLE_IF(is_buffer_appender<OutputIt>::value)>
++auto get_buffer(OutputIt out) -> buffer<T>& {
++  return get_container(out);
++}
++
++template <typename Buf, typename OutputIt>
++auto get_iterator(Buf& buf, OutputIt) -> decltype(buf.out()) {
++  return buf.out();
++}
++template <typename T, typename OutputIt>
++auto get_iterator(buffer<T>&, OutputIt out) -> OutputIt {
++  return out;
++}
++
++// This type is intentionally undefined, only used for errors.
++template <typename T, typename Char> struct type_is_unformattable_for;
++
++template <typename Char> struct string_value {
++  const Char* data;
++  size_t size;
++  auto str() const -> basic_string_view<Char> { return {data, size}; }
++};
++
++template <typename Context> struct custom_value {
++  using char_type = typename Context::char_type;
++  void* value;
++  void (*format)(void* arg, parse_context<char_type>& parse_ctx, Context& ctx);
++};
++
++template <typename Char> struct named_arg_value {
++  const named_arg_info<Char>* data;
++  size_t size;
++};
++
++struct custom_tag {};
++
++#if !FMT_BUILTIN_TYPES
++#  define FMT_BUILTIN , monostate
++#else
++#  define FMT_BUILTIN
++#endif
++
++// A formatting argument value.
++template <typename Context> class value {
++ public:
++  using char_type = typename Context::char_type;
++
++  union {
++    monostate no_value;
++    int int_value;
++    unsigned uint_value;
++    long long long_long_value;
++    unsigned long long ulong_long_value;
++    int128_opt int128_value;
++    uint128_opt uint128_value;
++    bool bool_value;
++    char_type char_value;
++    float float_value;
++    double double_value;
++    long double long_double_value;
++    const void* pointer;
++    string_value<char_type> string;
++    custom_value<Context> custom;
++    named_arg_value<char_type> named_args;
++  };
++
++  constexpr FMT_INLINE value() : no_value() {}
++  constexpr FMT_INLINE value(signed char x) : int_value(x) {}
++  constexpr FMT_INLINE value(unsigned char x FMT_BUILTIN) : uint_value(x) {}
++  constexpr FMT_INLINE value(signed short x) : int_value(x) {}
++  constexpr FMT_INLINE value(unsigned short x FMT_BUILTIN) : uint_value(x) {}
++  constexpr FMT_INLINE value(int x) : int_value(x) {}
++  constexpr FMT_INLINE value(unsigned x FMT_BUILTIN) : uint_value(x) {}
++  FMT_CONSTEXPR FMT_INLINE value(long x FMT_BUILTIN) : value(long_type(x)) {}
++  FMT_CONSTEXPR FMT_INLINE value(unsigned long x FMT_BUILTIN)
++      : value(ulong_type(x)) {}
++  constexpr FMT_INLINE value(long long x FMT_BUILTIN) : long_long_value(x) {}
++  constexpr FMT_INLINE value(unsigned long long x FMT_BUILTIN)
++      : ulong_long_value(x) {}
++  FMT_INLINE value(int128_opt x FMT_BUILTIN) : int128_value(x) {}
++  FMT_INLINE value(uint128_opt x FMT_BUILTIN) : uint128_value(x) {}
++  constexpr FMT_INLINE value(bool x FMT_BUILTIN) : bool_value(x) {}
++
++  template <int N>
++  constexpr FMT_INLINE value(bitint<N> x FMT_BUILTIN) : long_long_value(x) {
++    static_assert(N <= 64, "unsupported _BitInt");
++  }
++  template <int N>
++  constexpr FMT_INLINE value(ubitint<N> x FMT_BUILTIN) : ulong_long_value(x) {
++    static_assert(N <= 64, "unsupported _BitInt");
++  }
++
++  template <typename T, FMT_ENABLE_IF(is_char<T>::value)>
++  constexpr FMT_INLINE value(T x FMT_BUILTIN) : char_value(x) {
++    static_assert(
++        std::is_same<T, char>::value || std::is_same<T, char_type>::value,
++        "mixing character types is disallowed");
++  }
++
++  constexpr FMT_INLINE value(float x FMT_BUILTIN) : float_value(x) {}
++  constexpr FMT_INLINE value(double x FMT_BUILTIN) : double_value(x) {}
++  FMT_INLINE value(long double x FMT_BUILTIN) : long_double_value(x) {}
++
++  FMT_CONSTEXPR FMT_INLINE value(char_type* x FMT_BUILTIN) {
++    string.data = x;
++    if (is_constant_evaluated()) string.size = 0;
++  }
++  FMT_CONSTEXPR FMT_INLINE value(const char_type* x FMT_BUILTIN) {
++    string.data = x;
++    if (is_constant_evaluated()) string.size = 0;
++  }
++  template <typename T, typename C = char_t<T>,
++            FMT_ENABLE_IF(!std::is_pointer<T>::value)>
++  FMT_CONSTEXPR value(const T& x FMT_BUILTIN) {
++    static_assert(std::is_same<C, char_type>::value,
++                  "mixing character types is disallowed");
++    auto sv = to_string_view(x);
++    string.data = sv.data();
++    string.size = sv.size();
++  }
++  FMT_INLINE value(void* x FMT_BUILTIN) : pointer(x) {}
++  FMT_INLINE value(const void* x FMT_BUILTIN) : pointer(x) {}
++  FMT_INLINE value(volatile void* x FMT_BUILTIN)
++      : pointer(const_cast<const void*>(x)) {}
++  FMT_INLINE value(const volatile void* x FMT_BUILTIN)
++      : pointer(const_cast<const void*>(x)) {}
++  FMT_INLINE value(nullptr_t) : pointer(nullptr) {}
++
++  template <typename T, FMT_ENABLE_IF(std::is_pointer<T>::value ||
++                                      std::is_member_pointer<T>::value)>
++  value(const T&) {
++    // Formatting of arbitrary pointers is disallowed. If you want to format a
++    // pointer cast it to `void*` or `const void*`. In particular, this forbids
++    // formatting of `[const] volatile char*` printed as bool by iostreams.
++    static_assert(sizeof(T) == 0,
++                  "formatting of non-void pointers is disallowed");
++  }
++
++  template <typename T, FMT_ENABLE_IF(use_format_as<T>::value)>
++  value(const T& x) : value(format_as(x)) {}
++  template <typename T, FMT_ENABLE_IF(use_format_as_member<T>::value)>
++  value(const T& x) : value(formatter<T>::format_as(x)) {}
++
++  template <typename T, FMT_ENABLE_IF(is_named_arg<T>::value)>
++  value(const T& named_arg) : value(named_arg.value) {}
++
++  template <typename T,
++            FMT_ENABLE_IF(use_formatter<T>::value || !FMT_BUILTIN_TYPES)>
++  FMT_CONSTEXPR20 FMT_INLINE value(T& x) : value(x, custom_tag()) {}
++
++  FMT_ALWAYS_INLINE value(const named_arg_info<char_type>* args, size_t size)
++      : named_args{args, size} {}
++
++ private:
++  template <typename T, FMT_ENABLE_IF(has_formatter<T, char_type>())>
++  FMT_CONSTEXPR value(T& x, custom_tag) {
++    using value_type = remove_const_t<T>;
++    // T may overload operator& e.g. std::vector<bool>::reference in libc++.
++    if (!is_constant_evaluated()) {
++      custom.value =
++          const_cast<char*>(&reinterpret_cast<const volatile char&>(x));
++    } else {
++      custom.value = nullptr;
++#if defined(__cpp_if_constexpr)
++      if constexpr (std::is_same<decltype(&x), remove_reference_t<T>*>::value)
++        custom.value = const_cast<value_type*>(&x);
++#endif
++    }
++    custom.format = format_custom<value_type, formatter<value_type, char_type>>;
++  }
++
++  template <typename T, FMT_ENABLE_IF(!has_formatter<T, char_type>())>
++  FMT_CONSTEXPR value(const T&, custom_tag) {
++    // Cannot format an argument; to make type T formattable provide a
++    // formatter<T> specialization: https://fmt.dev/latest/api.html#udt.
++    type_is_unformattable_for<T, char_type> _;
++  }
++
++  // Formats an argument of a custom type, such as a user-defined class.
++  template <typename T, typename Formatter>
++  static void format_custom(void* arg, parse_context<char_type>& parse_ctx,
++                            Context& ctx) {
++    auto f = Formatter();
++    parse_ctx.advance_to(f.parse(parse_ctx));
++    using qualified_type =
++        conditional_t<has_formatter<const T, char_type>(), const T, T>;
++    // format must be const for compatibility with std::format and compilation.
++    const auto& cf = f;
++    ctx.advance_to(cf.format(*static_cast<qualified_type*>(arg), ctx));
++  }
++};
++
++enum { packed_arg_bits = 4 };
++// Maximum number of arguments with packed types.
++enum { max_packed_args = 62 / packed_arg_bits };
++enum : unsigned long long { is_unpacked_bit = 1ULL << 63 };
++enum : unsigned long long { has_named_args_bit = 1ULL << 62 };
++
++template <typename It, typename T, typename Enable = void>
++struct is_output_iterator : std::false_type {};
++
++template <> struct is_output_iterator<appender, char> : std::true_type {};
++
++template <typename It, typename T>
++struct is_output_iterator<
++    It, T,
++    enable_if_t<std::is_assignable<decltype(*std::declval<decay_t<It>&>()++),
++                                   T>::value>> : std::true_type {};
++
++#ifndef FMT_USE_LOCALE
++#  define FMT_USE_LOCALE (FMT_OPTIMIZE_SIZE <= 1)
++#endif
++
++// A type-erased reference to an std::locale to avoid a heavy <locale> include.
++class locale_ref {
++#if FMT_USE_LOCALE
++ private:
++  const void* locale_;  // A type-erased pointer to std::locale.
++
++ public:
++  constexpr locale_ref() : locale_(nullptr) {}
++  template <typename Locale> locale_ref(const Locale& loc);
++
++  inline explicit operator bool() const noexcept { return locale_ != nullptr; }
++#endif  // FMT_USE_LOCALE
++
++ public:
++  template <typename Locale> auto get() const -> Locale;
++};
++
++template <typename> constexpr auto encode_types() -> unsigned long long {
++  return 0;
++}
++
++template <typename Context, typename Arg, typename... Args>
++constexpr auto encode_types() -> unsigned long long {
++  return static_cast<unsigned>(stored_type_constant<Arg, Context>::value) |
++         (encode_types<Context, Args...>() << packed_arg_bits);
++}
++
++template <typename Context, typename... T, size_t NUM_ARGS = sizeof...(T)>
++constexpr auto make_descriptor() -> unsigned long long {
++  return NUM_ARGS <= max_packed_args ? encode_types<Context, T...>()
++                                     : is_unpacked_bit | NUM_ARGS;
++}
++
++template <typename Context, int NUM_ARGS>
++using arg_t = conditional_t<NUM_ARGS <= max_packed_args, value<Context>,
++                            basic_format_arg<Context>>;
++
++template <typename Context, int NUM_ARGS, int NUM_NAMED_ARGS,
++          unsigned long long DESC>
++struct named_arg_store {
++  // args_[0].named_args points to named_args to avoid bloating format_args.
++  arg_t<Context, NUM_ARGS> args[1 + NUM_ARGS];
++  named_arg_info<typename Context::char_type> named_args[NUM_NAMED_ARGS];
++
++  template <typename... T>
++  FMT_CONSTEXPR FMT_ALWAYS_INLINE named_arg_store(T&... values)
++      : args{{named_args, NUM_NAMED_ARGS}, values...} {
++    int arg_index = 0, named_arg_index = 0;
++    FMT_APPLY_VARIADIC(
++        init_named_arg(named_args, arg_index, named_arg_index, values));
++  }
++
++  named_arg_store(named_arg_store&& rhs) {
++    args[0] = {named_args, NUM_NAMED_ARGS};
++    for (size_t i = 1; i < sizeof(args) / sizeof(*args); ++i)
++      args[i] = rhs.args[i];
++    for (size_t i = 0; i < NUM_NAMED_ARGS; ++i)
++      named_args[i] = rhs.named_args[i];
++  }
++
++  named_arg_store(const named_arg_store& rhs) = delete;
++  named_arg_store& operator=(const named_arg_store& rhs) = delete;
++  named_arg_store& operator=(named_arg_store&& rhs) = delete;
++  operator const arg_t<Context, NUM_ARGS>*() const { return args + 1; }
++};
++
++// An array of references to arguments. It can be implicitly converted to
++// `basic_format_args` for passing into type-erased formatting functions
++// such as `vformat`. It is a plain struct to reduce binary size in debug mode.
++template <typename Context, int NUM_ARGS, int NUM_NAMED_ARGS,
++          unsigned long long DESC>
++struct format_arg_store {
++  // +1 to workaround a bug in gcc 7.5 that causes duplicated-branches warning.
++  using type =
++      conditional_t<NUM_NAMED_ARGS == 0,
++                    arg_t<Context, NUM_ARGS>[max_of(1, NUM_ARGS)],
++                    named_arg_store<Context, NUM_ARGS, NUM_NAMED_ARGS, DESC>>;
++  type args;
++};
++
++// TYPE can be different from type_constant<T>, e.g. for __float128.
++template <typename T, typename Char, type TYPE> struct native_formatter {
++ private:
++  dynamic_format_specs<Char> specs_;
++
++ public:
++  using nonlocking = void;
++
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    if (ctx.begin() == ctx.end() || *ctx.begin() == '}') return ctx.begin();
++    auto end = parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx, TYPE);
++    if (const_check(TYPE == type::char_type)) check_char_specs(specs_);
++    return end;
++  }
++
++  template <type U = TYPE,
++            FMT_ENABLE_IF(U == type::string_type || U == type::cstring_type ||
++                          U == type::char_type)>
++  FMT_CONSTEXPR void set_debug_format(bool set = true) {
++    specs_.set_type(set ? presentation_type::debug : presentation_type::none);
++  }
++
++  FMT_PRAGMA_CLANG(diagnostic ignored "-Wundefined-inline")
++  template <typename FormatContext>
++  FMT_CONSTEXPR auto format(const T& val, FormatContext& ctx) const
++      -> decltype(ctx.out());
++};
++
++template <typename T, typename Enable = void>
++struct locking
++    : bool_constant<mapped_type_constant<T>::value == type::custom_type> {};
++template <typename T>
++struct locking<T, void_t<typename formatter<remove_cvref_t<T>>::nonlocking>>
++    : std::false_type {};
++
++template <typename T = int> FMT_CONSTEXPR inline auto is_locking() -> bool {
++  return locking<T>::value;
++}
++template <typename T1, typename T2, typename... Tail>
++FMT_CONSTEXPR inline auto is_locking() -> bool {
++  return locking<T1>::value || is_locking<T2, Tail...>();
++}
++
++FMT_API void vformat_to(buffer<char>& buf, string_view fmt, format_args args,
++                        locale_ref loc = {});
++
++#if FMT_WIN32
++FMT_API void vprint_mojibake(FILE*, string_view, format_args, bool);
++#else  // format_args is passed by reference since it is defined later.
++inline void vprint_mojibake(FILE*, string_view, const format_args&, bool) {}
++#endif
++}  // namespace detail
++
++// The main public API.
++
++template <typename Char>
++FMT_CONSTEXPR void parse_context<Char>::do_check_arg_id(int arg_id) {
++  // Argument id is only checked at compile time during parsing because
++  // formatting has its own validation.
++  if (detail::is_constant_evaluated() && use_constexpr_cast) {
++    auto ctx = static_cast<detail::compile_parse_context<Char>*>(this);
++    if (arg_id >= ctx->num_args()) report_error("argument not found");
++  }
++}
++
++template <typename Char>
++FMT_CONSTEXPR void parse_context<Char>::check_dynamic_spec(int arg_id) {
++  using detail::compile_parse_context;
++  if (detail::is_constant_evaluated() && use_constexpr_cast)
++    static_cast<compile_parse_context<Char>*>(this)->check_dynamic_spec(arg_id);
++}
++
++FMT_BEGIN_EXPORT
++
++// An output iterator that appends to a buffer. It is used instead of
++// back_insert_iterator to reduce symbol sizes and avoid <iterator> dependency.
++template <typename T> class basic_appender {
++ protected:
++  detail::buffer<T>* container;
++
++ public:
++  using container_type = detail::buffer<T>;
++
++  FMT_CONSTEXPR basic_appender(detail::buffer<T>& buf) : container(&buf) {}
++
++  FMT_CONSTEXPR20 auto operator=(T c) -> basic_appender& {
++    container->push_back(c);
++    return *this;
++  }
++  FMT_CONSTEXPR20 auto operator*() -> basic_appender& { return *this; }
++  FMT_CONSTEXPR20 auto operator++() -> basic_appender& { return *this; }
++  FMT_CONSTEXPR20 auto operator++(int) -> basic_appender { return *this; }
++};
++
++// A formatting argument. Context is a template parameter for the compiled API
++// where output can be unbuffered.
++template <typename Context> class basic_format_arg {
++ private:
++  detail::value<Context> value_;
++  detail::type type_;
++
++  friend class basic_format_args<Context>;
++
++  using char_type = typename Context::char_type;
++
++ public:
++  class handle {
++   private:
++    detail::custom_value<Context> custom_;
++
++   public:
++    explicit handle(detail::custom_value<Context> custom) : custom_(custom) {}
++
++    void format(parse_context<char_type>& parse_ctx, Context& ctx) const {
++      custom_.format(custom_.value, parse_ctx, ctx);
++    }
++  };
++
++  constexpr basic_format_arg() : type_(detail::type::none_type) {}
++  basic_format_arg(const detail::named_arg_info<char_type>* args, size_t size)
++      : value_(args, size) {}
++  template <typename T>
++  basic_format_arg(T&& val)
++      : value_(val), type_(detail::stored_type_constant<T, Context>::value) {}
++
++  constexpr explicit operator bool() const noexcept {
++    return type_ != detail::type::none_type;
++  }
++  auto type() const -> detail::type { return type_; }
++
++  /**
++   * Visits an argument dispatching to the appropriate visit method based on
++   * the argument type. For example, if the argument type is `double` then
++   * `vis(value)` will be called with the value of type `double`.
++   */
++  template <typename Visitor>
++  FMT_CONSTEXPR FMT_INLINE auto visit(Visitor&& vis) const -> decltype(vis(0)) {
++    using detail::map;
++    switch (type_) {
++    case detail::type::none_type:        break;
++    case detail::type::int_type:         return vis(value_.int_value);
++    case detail::type::uint_type:        return vis(value_.uint_value);
++    case detail::type::long_long_type:   return vis(value_.long_long_value);
++    case detail::type::ulong_long_type:  return vis(value_.ulong_long_value);
++    case detail::type::int128_type:      return vis(map(value_.int128_value));
++    case detail::type::uint128_type:     return vis(map(value_.uint128_value));
++    case detail::type::bool_type:        return vis(value_.bool_value);
++    case detail::type::char_type:        return vis(value_.char_value);
++    case detail::type::float_type:       return vis(value_.float_value);
++    case detail::type::double_type:      return vis(value_.double_value);
++    case detail::type::long_double_type: return vis(value_.long_double_value);
++    case detail::type::cstring_type:     return vis(value_.string.data);
++    case detail::type::string_type:      return vis(value_.string.str());
++    case detail::type::pointer_type:     return vis(value_.pointer);
++    case detail::type::custom_type:      return vis(handle(value_.custom));
++    }
++    return vis(monostate());
++  }
++
++  auto format_custom(const char_type* parse_begin,
++                     parse_context<char_type>& parse_ctx, Context& ctx)
++      -> bool {
++    if (type_ != detail::type::custom_type) return false;
++    parse_ctx.advance_to(parse_begin);
++    value_.custom.format(value_.custom.value, parse_ctx, ctx);
++    return true;
++  }
++};
++
++/**
++ * A view of a collection of formatting arguments. To avoid lifetime issues it
++ * should only be used as a parameter type in type-erased functions such as
++ * `vformat`:
++ *
++ *     void vlog(fmt::string_view fmt, fmt::format_args args);  // OK
++ *     fmt::format_args args = fmt::make_format_args();  // Dangling reference
++ */
++template <typename Context> class basic_format_args {
++ private:
++  // A descriptor that contains information about formatting arguments.
++  // If the number of arguments is less or equal to max_packed_args then
++  // argument types are passed in the descriptor. This reduces binary code size
++  // per formatting function call.
++  unsigned long long desc_;
++  union {
++    // If is_packed() returns true then argument values are stored in values_;
++    // otherwise they are stored in args_. This is done to improve cache
++    // locality and reduce compiled code size since storing larger objects
++    // may require more code (at least on x86-64) even if the same amount of
++    // data is actually copied to stack. It saves ~10% on the bloat test.
++    const detail::value<Context>* values_;
++    const basic_format_arg<Context>* args_;
++  };
++
++  constexpr auto is_packed() const -> bool {
++    return (desc_ & detail::is_unpacked_bit) == 0;
++  }
++  constexpr auto has_named_args() const -> bool {
++    return (desc_ & detail::has_named_args_bit) != 0;
++  }
++
++  FMT_CONSTEXPR auto type(int index) const -> detail::type {
++    int shift = index * detail::packed_arg_bits;
++    unsigned mask = (1 << detail::packed_arg_bits) - 1;
++    return static_cast<detail::type>((desc_ >> shift) & mask);
++  }
++
++  template <int NUM_ARGS, int NUM_NAMED_ARGS, unsigned long long DESC>
++  using store =
++      detail::format_arg_store<Context, NUM_ARGS, NUM_NAMED_ARGS, DESC>;
++
++ public:
++  using format_arg = basic_format_arg<Context>;
++
++  constexpr basic_format_args() : desc_(0), args_(nullptr) {}
++
++  /// Constructs a `basic_format_args` object from `format_arg_store`.
++  template <int NUM_ARGS, int NUM_NAMED_ARGS, unsigned long long DESC,
++            FMT_ENABLE_IF(NUM_ARGS <= detail::max_packed_args)>
++  constexpr FMT_ALWAYS_INLINE basic_format_args(
++      const store<NUM_ARGS, NUM_NAMED_ARGS, DESC>& s)
++      : desc_(DESC | (NUM_NAMED_ARGS != 0 ? +detail::has_named_args_bit : 0)),
++        values_(s.args) {}
++
++  template <int NUM_ARGS, int NUM_NAMED_ARGS, unsigned long long DESC,
++            FMT_ENABLE_IF(NUM_ARGS > detail::max_packed_args)>
++  constexpr basic_format_args(const store<NUM_ARGS, NUM_NAMED_ARGS, DESC>& s)
++      : desc_(DESC | (NUM_NAMED_ARGS != 0 ? +detail::has_named_args_bit : 0)),
++        args_(s.args) {}
++
++  /// Constructs a `basic_format_args` object from a dynamic list of arguments.
++  constexpr basic_format_args(const format_arg* args, int count,
++                              bool has_named = false)
++      : desc_(detail::is_unpacked_bit | detail::to_unsigned(count) |
++              (has_named ? +detail::has_named_args_bit : 0)),
++        args_(args) {}
++
++  /// Returns the argument with the specified id.
++  FMT_CONSTEXPR auto get(int id) const -> format_arg {
++    auto arg = format_arg();
++    if (!is_packed()) {
++      if (id < max_size()) arg = args_[id];
++      return arg;
++    }
++    if (static_cast<unsigned>(id) >= detail::max_packed_args) return arg;
++    arg.type_ = type(id);
++    if (arg.type_ != detail::type::none_type) arg.value_ = values_[id];
++    return arg;
++  }
++
++  template <typename Char>
++  auto get(basic_string_view<Char> name) const -> format_arg {
++    int id = get_id(name);
++    return id >= 0 ? get(id) : format_arg();
++  }
++
++  template <typename Char>
++  FMT_CONSTEXPR auto get_id(basic_string_view<Char> name) const -> int {
++    if (!has_named_args()) return -1;
++    const auto& named_args =
++        (is_packed() ? values_[-1] : args_[-1].value_).named_args;
++    for (size_t i = 0; i < named_args.size; ++i) {
++      if (named_args.data[i].name == name) return named_args.data[i].id;
++    }
++    return -1;
++  }
++
++  auto max_size() const -> int {
++    unsigned long long max_packed = detail::max_packed_args;
++    return static_cast<int>(is_packed() ? max_packed
++                                        : desc_ & ~detail::is_unpacked_bit);
++  }
++};
++
++// A formatting context.
++class context {
++ private:
++  appender out_;
++  format_args args_;
++  FMT_NO_UNIQUE_ADDRESS detail::locale_ref loc_;
++
++ public:
++  /// The character type for the output.
++  using char_type = char;
++
++  using iterator = appender;
++  using format_arg = basic_format_arg<context>;
++  using parse_context_type FMT_DEPRECATED = parse_context<>;
++  template <typename T> using formatter_type FMT_DEPRECATED = formatter<T>;
++  enum { builtin_types = FMT_BUILTIN_TYPES };
++
++  /// Constructs a `context` object. References to the arguments are stored
++  /// in the object so make sure they have appropriate lifetimes.
++  FMT_CONSTEXPR context(iterator out, format_args args,
++                        detail::locale_ref loc = {})
++      : out_(out), args_(args), loc_(loc) {}
++  context(context&&) = default;
++  context(const context&) = delete;
++  void operator=(const context&) = delete;
++
++  FMT_CONSTEXPR auto arg(int id) const -> format_arg { return args_.get(id); }
++  inline auto arg(string_view name) const -> format_arg {
++    return args_.get(name);
++  }
++  FMT_CONSTEXPR auto arg_id(string_view name) const -> int {
++    return args_.get_id(name);
++  }
++  auto args() const -> const format_args& { return args_; }
++
++  // Returns an iterator to the beginning of the output range.
++  FMT_CONSTEXPR auto out() const -> iterator { return out_; }
++
++  // Advances the begin iterator to `it`.
++  FMT_CONSTEXPR void advance_to(iterator) {}
++
++  FMT_CONSTEXPR auto locale() const -> detail::locale_ref { return loc_; }
++};
++
++template <typename Char = char> struct runtime_format_string {
++  basic_string_view<Char> str;
++};
++
++/**
++ * Creates a runtime format string.
++ *
++ * **Example**:
++ *
++ *     // Check format string at runtime instead of compile-time.
++ *     fmt::print(fmt::runtime("{:d}"), "I am not a number");
++ */
++inline auto runtime(string_view s) -> runtime_format_string<> { return {{s}}; }
++
++/// A compile-time format string. Use `format_string` in the public API to
++/// prevent type deduction.
++template <typename... T> struct fstring {
++ private:
++  static constexpr int num_static_named_args =
++      detail::count_static_named_args<T...>();
++
++  using checker = detail::format_string_checker<
++      char, static_cast<int>(sizeof...(T)), num_static_named_args,
++      num_static_named_args != detail::count_named_args<T...>()>;
++
++  using arg_pack = detail::arg_pack<T...>;
++
++ public:
++  string_view str;
++  using t = fstring;
++
++  // Reports a compile-time error if S is not a valid format string for T.
++  template <size_t N>
++  FMT_CONSTEVAL FMT_ALWAYS_INLINE fstring(const char (&s)[N]) : str(s, N - 1) {
++    using namespace detail;
++    static_assert(count<(std::is_base_of<view, remove_reference_t<T>>::value &&
++                         std::is_reference<T>::value)...>() == 0,
++                  "passing views as lvalues is disallowed");
++    if (FMT_USE_CONSTEVAL) parse_format_string<char>(s, checker(s, arg_pack()));
++#ifdef FMT_ENFORCE_COMPILE_STRING
++    static_assert(
++        FMT_USE_CONSTEVAL && sizeof(s) != 0,
++        "FMT_ENFORCE_COMPILE_STRING requires format strings to use FMT_STRING");
++#endif
++  }
++  template <typename S,
++            FMT_ENABLE_IF(std::is_convertible<const S&, string_view>::value)>
++  FMT_CONSTEVAL FMT_ALWAYS_INLINE fstring(const S& s) : str(s) {
++    auto sv = string_view(str);
++    if (FMT_USE_CONSTEVAL)
++      detail::parse_format_string<char>(sv, checker(sv, arg_pack()));
++#ifdef FMT_ENFORCE_COMPILE_STRING
++    static_assert(
++        FMT_USE_CONSTEVAL && sizeof(s) != 0,
++        "FMT_ENFORCE_COMPILE_STRING requires format strings to use FMT_STRING");
++#endif
++  }
++  template <typename S,
++            FMT_ENABLE_IF(std::is_base_of<detail::compile_string, S>::value&&
++                              std::is_same<typename S::char_type, char>::value)>
++  FMT_ALWAYS_INLINE fstring(const S&) : str(S()) {
++    FMT_CONSTEXPR auto sv = string_view(S());
++    FMT_CONSTEXPR int unused =
++        (parse_format_string(sv, checker(sv, arg_pack())), 0);
++    detail::ignore_unused(unused);
++  }
++  fstring(runtime_format_string<> fmt) : str(fmt.str) {}
++
++  // Returning by reference generates better code in debug mode.
++  FMT_ALWAYS_INLINE operator const string_view&() const { return str; }
++  auto get() const -> string_view { return str; }
++};
++
++template <typename... T> using format_string = typename fstring<T...>::t;
++
++template <typename T, typename Char = char>
++using is_formattable = bool_constant<!std::is_same<
++    detail::mapped_t<conditional_t<std::is_void<T>::value, int*, T>, Char>,
++    void>::value>;
++#ifdef __cpp_concepts
++template <typename T, typename Char = char>
++concept formattable = is_formattable<remove_reference_t<T>, Char>::value;
++#endif
++
++template <typename T, typename Char>
++using has_formatter FMT_DEPRECATED = std::is_constructible<formatter<T, Char>>;
++
++// A formatter specialization for natively supported types.
++template <typename T, typename Char>
++struct formatter<T, Char,
++                 enable_if_t<detail::type_constant<T, Char>::value !=
++                             detail::type::custom_type>>
++    : detail::native_formatter<T, Char, detail::type_constant<T, Char>::value> {
++};
++
++/**
++ * Constructs an object that stores references to arguments and can be
++ * implicitly converted to `format_args`. `Context` can be omitted in which case
++ * it defaults to `context`. See `arg` for lifetime considerations.
++ */
++// Take arguments by lvalue references to avoid some lifetime issues, e.g.
++//   auto args = make_format_args(std::string());
++template <typename Context = context, typename... T,
++          int NUM_ARGS = sizeof...(T),
++          int NUM_NAMED_ARGS = detail::count_named_args<T...>(),
++          unsigned long long DESC = detail::make_descriptor<Context, T...>()>
++constexpr FMT_ALWAYS_INLINE auto make_format_args(T&... args)
++    -> detail::format_arg_store<Context, NUM_ARGS, NUM_NAMED_ARGS, DESC> {
++  // Suppress warnings for pathological types convertible to detail::value.
++  FMT_PRAGMA_GCC(diagnostic ignored "-Wconversion")
++  return {{args...}};
++}
++
++template <typename... T>
++using vargs =
++    detail::format_arg_store<context, sizeof...(T),
++                             detail::count_named_args<T...>(),
++                             detail::make_descriptor<context, T...>()>;
++
++/**
++ * Returns a named argument to be used in a formatting function.
++ * It should only be used in a call to a formatting function.
++ *
++ * **Example**:
++ *
++ *     fmt::print("The answer is {answer}.", fmt::arg("answer", 42));
++ */
++template <typename Char, typename T>
++inline auto arg(const Char* name, const T& arg) -> detail::named_arg<Char, T> {
++  return {name, arg};
++}
++
++/// Formats a string and writes the output to `out`.
++template <typename OutputIt,
++          FMT_ENABLE_IF(detail::is_output_iterator<remove_cvref_t<OutputIt>,
++                                                   char>::value)>
++auto vformat_to(OutputIt&& out, string_view fmt, format_args args)
++    -> remove_cvref_t<OutputIt> {
++  auto&& buf = detail::get_buffer<char>(out);
++  detail::vformat_to(buf, fmt, args, {});
++  return detail::get_iterator(buf, out);
++}
++
++/**
++ * Formats `args` according to specifications in `fmt`, writes the result to
++ * the output iterator `out` and returns the iterator past the end of the output
++ * range. `format_to` does not append a terminating null character.
++ *
++ * **Example**:
++ *
++ *     auto out = std::vector<char>();
++ *     fmt::format_to(std::back_inserter(out), "{}", 42);
++ */
++template <typename OutputIt, typename... T,
++          FMT_ENABLE_IF(detail::is_output_iterator<remove_cvref_t<OutputIt>,
++                                                   char>::value)>
++FMT_INLINE auto format_to(OutputIt&& out, format_string<T...> fmt, T&&... args)
++    -> remove_cvref_t<OutputIt> {
++  return vformat_to(out, fmt.str, vargs<T...>{{args...}});
++}
++
++template <typename OutputIt> struct format_to_n_result {
++  /// Iterator past the end of the output range.
++  OutputIt out;
++  /// Total (not truncated) output size.
++  size_t size;
++};
++
++template <typename OutputIt, typename... T,
++          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
++auto vformat_to_n(OutputIt out, size_t n, string_view fmt, format_args args)
++    -> format_to_n_result<OutputIt> {
++  using traits = detail::fixed_buffer_traits;
++  auto buf = detail::iterator_buffer<OutputIt, char, traits>(out, n);
++  detail::vformat_to(buf, fmt, args, {});
++  return {buf.out(), buf.count()};
++}
++
++/**
++ * Formats `args` according to specifications in `fmt`, writes up to `n`
++ * characters of the result to the output iterator `out` and returns the total
++ * (not truncated) output size and the iterator past the end of the output
++ * range. `format_to_n` does not append a terminating null character.
++ */
++template <typename OutputIt, typename... T,
++          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
++FMT_INLINE auto format_to_n(OutputIt out, size_t n, format_string<T...> fmt,
++                            T&&... args) -> format_to_n_result<OutputIt> {
++  return vformat_to_n(out, n, fmt.str, vargs<T...>{{args...}});
++}
++
++struct format_to_result {
++  /// Pointer to just after the last successful write in the array.
++  char* out;
++  /// Specifies if the output was truncated.
++  bool truncated;
++
++  FMT_CONSTEXPR operator char*() const {
++    // Report truncation to prevent silent data loss.
++    if (truncated) report_error("output is truncated");
++    return out;
++  }
++};
++
++template <size_t N>
++auto vformat_to(char (&out)[N], string_view fmt, format_args args)
++    -> format_to_result {
++  auto result = vformat_to_n(out, N, fmt, args);
++  return {result.out, result.size > N};
++}
++
++template <size_t N, typename... T>
++FMT_INLINE auto format_to(char (&out)[N], format_string<T...> fmt, T&&... args)
++    -> format_to_result {
++  auto result = vformat_to_n(out, N, fmt.str, vargs<T...>{{args...}});
++  return {result.out, result.size > N};
++}
++
++/// Returns the number of chars in the output of `format(fmt, args...)`.
++template <typename... T>
++FMT_NODISCARD FMT_INLINE auto formatted_size(format_string<T...> fmt,
++                                             T&&... args) -> size_t {
++  auto buf = detail::counting_buffer<>();
++  detail::vformat_to(buf, fmt.str, vargs<T...>{{args...}}, {});
++  return buf.count();
++}
++
++FMT_API void vprint(string_view fmt, format_args args);
++FMT_API void vprint(FILE* f, string_view fmt, format_args args);
++FMT_API void vprintln(FILE* f, string_view fmt, format_args args);
++FMT_API void vprint_buffered(FILE* f, string_view fmt, format_args args);
++
++/**
++ * Formats `args` according to specifications in `fmt` and writes the output
++ * to `stdout`.
++ *
++ * **Example**:
++ *
++ *     fmt::print("The answer is {}.", 42);
++ */
++template <typename... T>
++FMT_INLINE void print(format_string<T...> fmt, T&&... args) {
++  vargs<T...> va = {{args...}};
++  if (detail::const_check(!detail::use_utf8))
++    return detail::vprint_mojibake(stdout, fmt.str, va, false);
++  return detail::is_locking<T...>() ? vprint_buffered(stdout, fmt.str, va)
++                                    : vprint(fmt.str, va);
++}
++
++/**
++ * Formats `args` according to specifications in `fmt` and writes the
++ * output to the file `f`.
++ *
++ * **Example**:
++ *
++ *     fmt::print(stderr, "Don't {}!", "panic");
++ */
++template <typename... T>
++FMT_INLINE void print(FILE* f, format_string<T...> fmt, T&&... args) {
++  vargs<T...> va = {{args...}};
++  if (detail::const_check(!detail::use_utf8))
++    return detail::vprint_mojibake(f, fmt.str, va, false);
++  return detail::is_locking<T...>() ? vprint_buffered(f, fmt.str, va)
++                                    : vprint(f, fmt.str, va);
++}
++
++/// Formats `args` according to specifications in `fmt` and writes the output
++/// to the file `f` followed by a newline.
++template <typename... T>
++FMT_INLINE void println(FILE* f, format_string<T...> fmt, T&&... args) {
++  vargs<T...> va = {{args...}};
++  return detail::const_check(detail::use_utf8)
++             ? vprintln(f, fmt.str, va)
++             : detail::vprint_mojibake(f, fmt.str, va, true);
++}
++
++/// Formats `args` according to specifications in `fmt` and writes the output
++/// to `stdout` followed by a newline.
++template <typename... T>
++FMT_INLINE void println(format_string<T...> fmt, T&&... args) {
++  return fmt::println(stdout, fmt, static_cast<T&&>(args)...);
++}
++
++FMT_END_EXPORT
++FMT_PRAGMA_CLANG(diagnostic pop)
++FMT_PRAGMA_GCC(pop_options)
++FMT_END_NAMESPACE
++
++#ifdef FMT_HEADER_ONLY
++#  include "format.h"
++#endif
++#endif  // FMT_BASE_H_
+diff --git a/include/fmt/chrono.h b/include/fmt/chrono.h
+index 43daeeb..50c777c 100644
+--- a/include/fmt/chrono.h
++++ b/include/fmt/chrono.h
+@@ -8,51 +8,36 @@
+ #ifndef FMT_CHRONO_H_
+ #define FMT_CHRONO_H_
+ 
+-#include <algorithm>
+-#include <chrono>
+-#include <cmath>    // std::isfinite
+-#include <cstring>  // std::memcpy
+-#include <ctime>
+-#include <iterator>
+-#include <locale>
+-#include <ostream>
+-#include <type_traits>
++#ifndef FMT_MODULE
++#  include <algorithm>
++#  include <chrono>
++#  include <cmath>    // std::isfinite
++#  include <cstring>  // std::memcpy
++#  include <ctime>
++#  include <iterator>
++#  include <locale>
++#  include <ostream>
++#  include <type_traits>
++#endif
+ 
+ #include "format.h"
+ 
+-FMT_BEGIN_NAMESPACE
+-
+-// Check if std::chrono::local_t is available.
+-#ifndef FMT_USE_LOCAL_TIME
+-#  ifdef __cpp_lib_chrono
+-#    define FMT_USE_LOCAL_TIME (__cpp_lib_chrono >= 201907L)
+-#  else
+-#    define FMT_USE_LOCAL_TIME 0
+-#  endif
+-#endif
++namespace fmt_detail {
++struct time_zone {
++  template <typename Duration, typename T>
++  auto to_sys(T)
++      -> std::chrono::time_point<std::chrono::system_clock, Duration> {
++    return {};
++  }
++};
++template <typename... T> inline auto current_zone(T...) -> time_zone* {
++  return nullptr;
++}
+ 
+-// Check if std::chrono::utc_timestamp is available.
+-#ifndef FMT_USE_UTC_TIME
+-#  ifdef __cpp_lib_chrono
+-#    define FMT_USE_UTC_TIME (__cpp_lib_chrono >= 201907L)
+-#  else
+-#    define FMT_USE_UTC_TIME 0
+-#  endif
+-#endif
++template <typename... T> inline void _tzset(T...) {}
++}  // namespace fmt_detail
+ 
+-// Enable tzset.
+-#ifndef FMT_USE_TZSET
+-// UWP doesn't provide _tzset.
+-#  if FMT_HAS_INCLUDE("winapifamily.h")
+-#    include <winapifamily.h>
+-#  endif
+-#  if defined(_WIN32) && (!defined(WINAPI_FAMILY) || \
+-                          (WINAPI_FAMILY == WINAPI_FAMILY_DESKTOP_APP))
+-#    define FMT_USE_TZSET 1
+-#  else
+-#    define FMT_USE_TZSET 0
+-#  endif
+-#endif
++FMT_BEGIN_NAMESPACE
+ 
+ // Enable safe chrono durations, unless explicitly disabled.
+ #ifndef FMT_SAFE_DURATION_CAST
+@@ -72,7 +57,8 @@ template <typename To, typename From,
+           FMT_ENABLE_IF(!std::is_same<From, To>::value &&
+                         std::numeric_limits<From>::is_signed ==
+                             std::numeric_limits<To>::is_signed)>
+-FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
++FMT_CONSTEXPR auto lossless_integral_conversion(const From from, int& ec)
++    -> To {
+   ec = 0;
+   using F = std::numeric_limits<From>;
+   using T = std::numeric_limits<To>;
+@@ -93,15 +79,14 @@ FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
+   return static_cast<To>(from);
+ }
+ 
+-/**
+- * converts From to To, without loss. If the dynamic value of from
+- * can't be converted to To without loss, ec is set.
+- */
++/// Converts From to To, without loss. If the dynamic value of from
++/// can't be converted to To without loss, ec is set.
+ template <typename To, typename From,
+           FMT_ENABLE_IF(!std::is_same<From, To>::value &&
+                         std::numeric_limits<From>::is_signed !=
+                             std::numeric_limits<To>::is_signed)>
+-FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
++FMT_CONSTEXPR auto lossless_integral_conversion(const From from, int& ec)
++    -> To {
+   ec = 0;
+   using F = std::numeric_limits<From>;
+   using T = std::numeric_limits<To>;
+@@ -133,7 +118,8 @@ FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
+ 
+ template <typename To, typename From,
+           FMT_ENABLE_IF(std::is_same<From, To>::value)>
+-FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
++FMT_CONSTEXPR auto lossless_integral_conversion(const From from, int& ec)
++    -> To {
+   ec = 0;
+   return from;
+ }  // function
+@@ -154,7 +140,7 @@ FMT_CONSTEXPR To lossless_integral_conversion(const From from, int& ec) {
+ // clang-format on
+ template <typename To, typename From,
+           FMT_ENABLE_IF(!std::is_same<From, To>::value)>
+-FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {
++FMT_CONSTEXPR auto safe_float_conversion(const From from, int& ec) -> To {
+   ec = 0;
+   using T = std::numeric_limits<To>;
+   static_assert(std::is_floating_point<From>::value, "From must be floating");
+@@ -176,72 +162,18 @@ FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {
+ 
+ template <typename To, typename From,
+           FMT_ENABLE_IF(std::is_same<From, To>::value)>
+-FMT_CONSTEXPR To safe_float_conversion(const From from, int& ec) {
++FMT_CONSTEXPR auto safe_float_conversion(const From from, int& ec) -> To {
+   ec = 0;
+   static_assert(std::is_floating_point<From>::value, "From must be floating");
+   return from;
+ }
+ 
+-/**
+- * safe duration cast between integral durations
+- */
+-template <typename To, typename FromRep, typename FromPeriod,
+-          FMT_ENABLE_IF(std::is_integral<FromRep>::value),
+-          FMT_ENABLE_IF(std::is_integral<typename To::rep>::value)>
+-To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
+-                      int& ec) {
+-  using From = std::chrono::duration<FromRep, FromPeriod>;
+-  ec = 0;
+-  // the basic idea is that we need to convert from count() in the from type
+-  // to count() in the To type, by multiplying it with this:
+-  struct Factor
+-      : std::ratio_divide<typename From::period, typename To::period> {};
+-
+-  static_assert(Factor::num > 0, "num must be positive");
+-  static_assert(Factor::den > 0, "den must be positive");
+-
+-  // the conversion is like this: multiply from.count() with Factor::num
+-  // /Factor::den and convert it to To::rep, all this without
+-  // overflow/underflow. let's start by finding a suitable type that can hold
+-  // both To, From and Factor::num
+-  using IntermediateRep =
+-      typename std::common_type<typename From::rep, typename To::rep,
+-                                decltype(Factor::num)>::type;
+-
+-  // safe conversion to IntermediateRep
+-  IntermediateRep count =
+-      lossless_integral_conversion<IntermediateRep>(from.count(), ec);
+-  if (ec) return {};
+-  // multiply with Factor::num without overflow or underflow
+-  if (detail::const_check(Factor::num != 1)) {
+-    const auto max1 = detail::max_value<IntermediateRep>() / Factor::num;
+-    if (count > max1) {
+-      ec = 1;
+-      return {};
+-    }
+-    const auto min1 =
+-        (std::numeric_limits<IntermediateRep>::min)() / Factor::num;
+-    if (detail::const_check(!std::is_unsigned<IntermediateRep>::value) &&
+-        count < min1) {
+-      ec = 1;
+-      return {};
+-    }
+-    count *= Factor::num;
+-  }
+-
+-  if (detail::const_check(Factor::den != 1)) count /= Factor::den;
+-  auto tocount = lossless_integral_conversion<typename To::rep>(count, ec);
+-  return ec ? To() : To(tocount);
+-}
+-
+-/**
+- * safe duration_cast between floating point durations
+- */
++/// Safe duration_cast between floating point durations
+ template <typename To, typename FromRep, typename FromPeriod,
+           FMT_ENABLE_IF(std::is_floating_point<FromRep>::value),
+           FMT_ENABLE_IF(std::is_floating_point<typename To::rep>::value)>
+-To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
+-                      int& ec) {
++auto safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
++                        int& ec) -> To {
+   using From = std::chrono::duration<FromRep, FromPeriod>;
+   ec = 0;
+   if (std::isnan(from.count())) {
+@@ -315,18 +247,95 @@ To safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from,
+ }  // namespace safe_duration_cast
+ #endif
+ 
++namespace detail {
++
++// Check if std::chrono::utc_time is available.
++#ifdef FMT_USE_UTC_TIME
++// Use the provided definition.
++#elif defined(__cpp_lib_chrono)
++#  define FMT_USE_UTC_TIME (__cpp_lib_chrono >= 201907L)
++#else
++#  define FMT_USE_UTC_TIME 0
++#endif
++#if FMT_USE_UTC_TIME
++using utc_clock = std::chrono::utc_clock;
++#else
++struct utc_clock {
++  template <typename T> void to_sys(T);
++};
++#endif
++
++// Check if std::chrono::local_time is available.
++#ifdef FMT_USE_LOCAL_TIME
++// Use the provided definition.
++#elif defined(__cpp_lib_chrono)
++#  define FMT_USE_LOCAL_TIME (__cpp_lib_chrono >= 201907L)
++#else
++#  define FMT_USE_LOCAL_TIME 0
++#endif
++#if FMT_USE_LOCAL_TIME
++using local_t = std::chrono::local_t;
++#else
++struct local_t {};
++#endif
++
++}  // namespace detail
++
++template <typename Duration>
++using sys_time = std::chrono::time_point<std::chrono::system_clock, Duration>;
++
++template <typename Duration>
++using utc_time = std::chrono::time_point<detail::utc_clock, Duration>;
++
++template <class Duration>
++using local_time = std::chrono::time_point<detail::local_t, Duration>;
++
++namespace detail {
++
+ // Prevents expansion of a preceding token as a function-style macro.
+ // Usage: f FMT_NOMACRO()
+ #define FMT_NOMACRO
+ 
+-namespace detail {
+ template <typename T = void> struct null {};
+-inline null<> localtime_r FMT_NOMACRO(...) { return null<>(); }
+-inline null<> localtime_s(...) { return null<>(); }
+-inline null<> gmtime_r(...) { return null<>(); }
+-inline null<> gmtime_s(...) { return null<>(); }
++inline auto localtime_r FMT_NOMACRO(...) -> null<> { return null<>(); }
++inline auto localtime_s(...) -> null<> { return null<>(); }
++inline auto gmtime_r(...) -> null<> { return null<>(); }
++inline auto gmtime_s(...) -> null<> { return null<>(); }
++
++// It is defined here and not in ostream.h because the latter has expensive
++// includes.
++template <typename StreamBuf> class formatbuf : public StreamBuf {
++ private:
++  using char_type = typename StreamBuf::char_type;
++  using streamsize = decltype(std::declval<StreamBuf>().sputn(nullptr, 0));
++  using int_type = typename StreamBuf::int_type;
++  using traits_type = typename StreamBuf::traits_type;
+ 
+-inline const std::locale& get_classic_locale() {
++  buffer<char_type>& buffer_;
++
++ public:
++  explicit formatbuf(buffer<char_type>& buf) : buffer_(buf) {}
++
++ protected:
++  // The put area is always empty. This makes the implementation simpler and has
++  // the advantage that the streambuf and the buffer are always in sync and
++  // sputc never writes into uninitialized memory. A disadvantage is that each
++  // call to sputc always results in a (virtual) call to overflow. There is no
++  // disadvantage here for sputn since this always results in a call to xsputn.
++
++  auto overflow(int_type ch) -> int_type override {
++    if (!traits_type::eq_int_type(ch, traits_type::eof()))
++      buffer_.push_back(static_cast<char_type>(ch));
++    return ch;
++  }
++
++  auto xsputn(const char_type* s, streamsize count) -> streamsize override {
++    buffer_.append(s, s + count);
++    return count;
++  }
++};
++
++inline auto get_classic_locale() -> const std::locale& {
+   static const auto& locale = std::locale::classic();
+   return locale;
+ }
+@@ -336,24 +345,18 @@ template <typename CodeUnit> struct codecvt_result {
+   CodeUnit buf[max_size];
+   CodeUnit* end;
+ };
+-template <typename CodeUnit>
+-constexpr const size_t codecvt_result<CodeUnit>::max_size;
+ 
+ template <typename CodeUnit>
+-void write_codecvt(codecvt_result<CodeUnit>& out, string_view in_buf,
++void write_codecvt(codecvt_result<CodeUnit>& out, string_view in,
+                    const std::locale& loc) {
+-#if FMT_CLANG_VERSION
+-#  pragma clang diagnostic push
+-#  pragma clang diagnostic ignored "-Wdeprecated"
++  FMT_PRAGMA_CLANG(diagnostic push)
++  FMT_PRAGMA_CLANG(diagnostic ignored "-Wdeprecated")
+   auto& f = std::use_facet<std::codecvt<CodeUnit, char, std::mbstate_t>>(loc);
+-#  pragma clang diagnostic pop
+-#else
+-  auto& f = std::use_facet<std::codecvt<CodeUnit, char, std::mbstate_t>>(loc);
+-#endif
++  FMT_PRAGMA_CLANG(diagnostic pop)
+   auto mb = std::mbstate_t();
+   const char* from_next = nullptr;
+-  auto result = f.in(mb, in_buf.begin(), in_buf.end(), from_next,
+-                     std::begin(out.buf), std::end(out.buf), out.end);
++  auto result = f.in(mb, in.begin(), in.end(), from_next, std::begin(out.buf),
++                     std::end(out.buf), out.end);
+   if (result != std::codecvt_base::ok)
+     FMT_THROW(format_error("failed to format time"));
+ }
+@@ -361,11 +364,12 @@ void write_codecvt(codecvt_result<CodeUnit>& out, string_view in_buf,
+ template <typename OutputIt>
+ auto write_encoded_tm_str(OutputIt out, string_view in, const std::locale& loc)
+     -> OutputIt {
+-  if (detail::is_utf8() && loc != get_classic_locale()) {
++  if (const_check(detail::use_utf8) && loc != get_classic_locale()) {
+     // char16_t and char32_t codecvts are broken in MSVC (linkage errors) and
+     // gcc-4.
+-#if FMT_MSC_VERSION != 0 || \
+-    (defined(__GLIBCXX__) && !defined(_GLIBCXX_USE_DUAL_ABI))
++#if FMT_MSC_VERSION != 0 ||  \
++    (defined(__GLIBCXX__) && \
++     (!defined(_GLIBCXX_USE_DUAL_ABI) || _GLIBCXX_USE_DUAL_ABI == 0))
+     // The _GLIBCXX_USE_DUAL_ABI macro is always defined in libstdc++ from gcc-5
+     // and newer.
+     using code_unit = wchar_t;
+@@ -381,9 +385,9 @@ auto write_encoded_tm_str(OutputIt out, string_view in, const std::locale& loc)
+         to_utf8<code_unit, basic_memory_buffer<char, unit_t::max_size * 4>>();
+     if (!u.convert({unit.buf, to_unsigned(unit.end - unit.buf)}))
+       FMT_THROW(format_error("failed to format time"));
+-    return copy_str<char>(u.c_str(), u.c_str() + u.size(), out);
++    return copy<char>(u.c_str(), u.c_str() + u.size(), out);
+   }
+-  return copy_str<char>(in.data(), in.data() + in.size(), out);
++  return copy<char>(in.data(), in.data() + in.size(), out);
+ }
+ 
+ template <typename Char, typename OutputIt,
+@@ -392,7 +396,7 @@ auto write_tm_str(OutputIt out, string_view sv, const std::locale& loc)
+     -> OutputIt {
+   codecvt_result<Char> unit;
+   write_codecvt(unit, sv, loc);
+-  return copy_str<Char>(unit.buf, unit.end, out);
++  return copy<Char>(unit.buf, unit.end, out);
+ }
+ 
+ template <typename Char, typename OutputIt,
+@@ -408,8 +412,7 @@ inline void do_write(buffer<Char>& buf, const std::tm& time,
+   auto&& format_buf = formatbuf<std::basic_streambuf<Char>>(buf);
+   auto&& os = std::basic_ostream<Char>(&format_buf);
+   os.imbue(loc);
+-  using iterator = std::ostreambuf_iterator<Char>;
+-  const auto& facet = std::use_facet<std::time_put<Char, iterator>>(loc);
++  const auto& facet = std::use_facet<std::time_put<Char>>(loc);
+   auto end = facet.put(os, os, Char(' '), &time, format, modifier);
+   if (end.failed()) FMT_THROW(format_error("failed to format time"));
+ }
+@@ -432,38 +435,129 @@ auto write(OutputIt out, const std::tm& time, const std::locale& loc,
+   return write_encoded_tm_str(out, string_view(buf.data(), buf.size()), loc);
+ }
+ 
++template <typename Rep1, typename Rep2>
++struct is_same_arithmetic_type
++    : public std::integral_constant<bool,
++                                    (std::is_integral<Rep1>::value &&
++                                     std::is_integral<Rep2>::value) ||
++                                        (std::is_floating_point<Rep1>::value &&
++                                         std::is_floating_point<Rep2>::value)> {
++};
++
++FMT_NORETURN inline void throw_duration_error() {
++  FMT_THROW(format_error("cannot format duration"));
++}
++
++// Cast one integral duration to another with an overflow check.
++template <typename To, typename FromRep, typename FromPeriod,
++          FMT_ENABLE_IF(std::is_integral<FromRep>::value&&
++                            std::is_integral<typename To::rep>::value)>
++auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
++#if !FMT_SAFE_DURATION_CAST
++  return std::chrono::duration_cast<To>(from);
++#else
++  // The conversion factor: to.count() == factor * from.count().
++  using factor = std::ratio_divide<FromPeriod, typename To::period>;
++
++  using common_rep = typename std::common_type<FromRep, typename To::rep,
++                                               decltype(factor::num)>::type;
++
++  int ec = 0;
++  auto count = safe_duration_cast::lossless_integral_conversion<common_rep>(
++      from.count(), ec);
++  if (ec) throw_duration_error();
++
++  // Multiply from.count() by factor and check for overflow.
++  if (const_check(factor::num != 1)) {
++    if (count > max_value<common_rep>() / factor::num) throw_duration_error();
++    const auto min = (std::numeric_limits<common_rep>::min)() / factor::num;
++    if (const_check(!std::is_unsigned<common_rep>::value) && count < min)
++      throw_duration_error();
++    count *= factor::num;
++  }
++  if (const_check(factor::den != 1)) count /= factor::den;
++  auto to =
++      To(safe_duration_cast::lossless_integral_conversion<typename To::rep>(
++          count, ec));
++  if (ec) throw_duration_error();
++  return to;
++#endif
++}
++
++template <typename To, typename FromRep, typename FromPeriod,
++          FMT_ENABLE_IF(std::is_floating_point<FromRep>::value&&
++                            std::is_floating_point<typename To::rep>::value)>
++auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
++#if FMT_SAFE_DURATION_CAST
++  // Throwing version of safe_duration_cast is only available for
++  // integer to integer or float to float casts.
++  int ec;
++  To to = safe_duration_cast::safe_duration_cast<To>(from, ec);
++  if (ec) throw_duration_error();
++  return to;
++#else
++  // Standard duration cast, may overflow.
++  return std::chrono::duration_cast<To>(from);
++#endif
++}
++
++template <
++    typename To, typename FromRep, typename FromPeriod,
++    FMT_ENABLE_IF(!is_same_arithmetic_type<FromRep, typename To::rep>::value)>
++auto duration_cast(std::chrono::duration<FromRep, FromPeriod> from) -> To {
++  // Mixed integer <-> float cast is not supported by safe_duration_cast.
++  return std::chrono::duration_cast<To>(from);
++}
++
++template <typename Duration>
++auto to_time_t(sys_time<Duration> time_point) -> std::time_t {
++  // Cannot use std::chrono::system_clock::to_time_t since this would first
++  // require a cast to std::chrono::system_clock::time_point, which could
++  // overflow.
++  return detail::duration_cast<std::chrono::duration<std::time_t>>(
++             time_point.time_since_epoch())
++      .count();
++}
++
++// Workaround a bug in libstdc++ which sets __cpp_lib_chrono to 201907 without
++// providing current_zone(): https://github.com/fmtlib/fmt/issues/4160.
++template <typename T> FMT_CONSTEXPR auto has_current_zone() -> bool {
++  using namespace std::chrono;
++  using namespace fmt_detail;
++  return !std::is_same<decltype(current_zone()), fmt_detail::time_zone*>::value;
++}
+ }  // namespace detail
+ 
+ FMT_BEGIN_EXPORT
+ 
+ /**
+-  Converts given time since epoch as ``std::time_t`` value into calendar time,
+-  expressed in local time. Unlike ``std::localtime``, this function is
+-  thread-safe on most platforms.
++ * Converts given time since epoch as `std::time_t` value into calendar time,
++ * expressed in local time. Unlike `std::localtime`, this function is
++ * thread-safe on most platforms.
+  */
+-inline std::tm localtime(std::time_t time) {
++inline auto localtime(std::time_t time) -> std::tm {
+   struct dispatcher {
+     std::time_t time_;
+     std::tm tm_;
+ 
+-    dispatcher(std::time_t t) : time_(t) {}
++    inline dispatcher(std::time_t t) : time_(t) {}
+ 
+-    bool run() {
++    inline auto run() -> bool {
+       using namespace fmt::detail;
+       return handle(localtime_r(&time_, &tm_));
+     }
+ 
+-    bool handle(std::tm* tm) { return tm != nullptr; }
++    inline auto handle(std::tm* tm) -> bool { return tm != nullptr; }
+ 
+-    bool handle(detail::null<>) {
++    inline auto handle(detail::null<>) -> bool {
+       using namespace fmt::detail;
+       return fallback(localtime_s(&tm_, &time_));
+     }
+ 
+-    bool fallback(int res) { return res == 0; }
++    inline auto fallback(int res) -> bool { return res == 0; }
+ 
+ #if !FMT_MSC_VERSION
+-    bool fallback(detail::null<>) {
++    inline auto fallback(detail::null<>) -> bool {
+       using namespace fmt::detail;
+       std::tm* tm = std::localtime(&time_);
+       if (tm) tm_ = *tm;
+@@ -478,102 +572,61 @@ inline std::tm localtime(std::time_t time) {
+ }
+ 
+ #if FMT_USE_LOCAL_TIME
+-template <typename Duration>
++template <typename Duration,
++          FMT_ENABLE_IF(detail::has_current_zone<Duration>())>
+ inline auto localtime(std::chrono::local_time<Duration> time) -> std::tm {
+-  return localtime(std::chrono::system_clock::to_time_t(
+-      std::chrono::current_zone()->to_sys(time)));
++  using namespace std::chrono;
++  using namespace fmt_detail;
++  return localtime(detail::to_time_t(current_zone()->to_sys<Duration>(time)));
+ }
+ #endif
+ 
+ /**
+-  Converts given time since epoch as ``std::time_t`` value into calendar time,
+-  expressed in Coordinated Universal Time (UTC). Unlike ``std::gmtime``, this
+-  function is thread-safe on most platforms.
++ * Converts given time since epoch as `std::time_t` value into calendar time,
++ * expressed in Coordinated Universal Time (UTC). Unlike `std::gmtime`, this
++ * function is thread-safe on most platforms.
+  */
+-inline std::tm gmtime(std::time_t time) {
++inline auto gmtime(std::time_t time) -> std::tm {
+   struct dispatcher {
+     std::time_t time_;
+     std::tm tm_;
+ 
+-    dispatcher(std::time_t t) : time_(t) {}
++    inline dispatcher(std::time_t t) : time_(t) {}
+ 
+-    bool run() {
++    inline auto run() -> bool {
+       using namespace fmt::detail;
+       return handle(gmtime_r(&time_, &tm_));
+     }
+ 
+-    bool handle(std::tm* tm) { return tm != nullptr; }
++    inline auto handle(std::tm* tm) -> bool { return tm != nullptr; }
+ 
+-    bool handle(detail::null<>) {
++    inline auto handle(detail::null<>) -> bool {
+       using namespace fmt::detail;
+       return fallback(gmtime_s(&tm_, &time_));
+     }
+ 
+-    bool fallback(int res) { return res == 0; }
++    inline auto fallback(int res) -> bool { return res == 0; }
+ 
+ #if !FMT_MSC_VERSION
+-    bool fallback(detail::null<>) {
++    inline auto fallback(detail::null<>) -> bool {
+       std::tm* tm = std::gmtime(&time_);
+       if (tm) tm_ = *tm;
+       return tm != nullptr;
+     }
+ #endif
+   };
+-  dispatcher gt(time);
++  auto gt = dispatcher(time);
+   // Too big time values may be unsupported.
+   if (!gt.run()) FMT_THROW(format_error("time_t value out of range"));
+   return gt.tm_;
+ }
+ 
+-inline std::tm gmtime(
+-    std::chrono::time_point<std::chrono::system_clock> time_point) {
+-  return gmtime(std::chrono::system_clock::to_time_t(time_point));
++template <typename Duration>
++inline auto gmtime(sys_time<Duration> time_point) -> std::tm {
++  return gmtime(detail::to_time_t(time_point));
+ }
+ 
+-FMT_BEGIN_DETAIL_NAMESPACE
+-
+-// DEPRECATED!
+-template <typename Char>
+-FMT_CONSTEXPR auto parse_align(const Char* begin, const Char* end,
+-                               format_specs<Char>& specs) -> const Char* {
+-  FMT_ASSERT(begin != end, "");
+-  auto align = align::none;
+-  auto p = begin + code_point_length(begin);
+-  if (end - p <= 0) p = begin;
+-  for (;;) {
+-    switch (to_ascii(*p)) {
+-    case '<':
+-      align = align::left;
+-      break;
+-    case '>':
+-      align = align::right;
+-      break;
+-    case '^':
+-      align = align::center;
+-      break;
+-    }
+-    if (align != align::none) {
+-      if (p != begin) {
+-        auto c = *begin;
+-        if (c == '}') return begin;
+-        if (c == '{') {
+-          throw_format_error("invalid fill character '{'");
+-          return begin;
+-        }
+-        specs.fill = {begin, to_unsigned(p - begin)};
+-        begin = p + 1;
+-      } else {
+-        ++begin;
+-      }
+-      break;
+-    } else if (p == begin) {
+-      break;
+-    }
+-    p = begin;
+-  }
+-  specs.align = align;
+-  return begin;
+-}
++namespace detail {
+ 
+ // Writes two-digit numbers a, b and c separated by sep to buf.
+ // The method by Pavel Novikov based on
+@@ -609,12 +662,14 @@ inline void write_digit2_separated(char* buf, unsigned a, unsigned b,
+   }
+ }
+ 
+-template <typename Period> FMT_CONSTEXPR inline const char* get_units() {
++template <typename Period>
++FMT_CONSTEXPR inline auto get_units() -> const char* {
+   if (std::is_same<Period, std::atto>::value) return "as";
+   if (std::is_same<Period, std::femto>::value) return "fs";
+   if (std::is_same<Period, std::pico>::value) return "ps";
+   if (std::is_same<Period, std::nano>::value) return "ns";
+-  if (std::is_same<Period, std::micro>::value) return "µs";
++  if (std::is_same<Period, std::micro>::value)
++    return detail::use_utf8 ? "µs" : "us";
+   if (std::is_same<Period, std::milli>::value) return "ms";
+   if (std::is_same<Period, std::centi>::value) return "cs";
+   if (std::is_same<Period, std::deci>::value) return "ds";
+@@ -627,8 +682,9 @@ template <typename Period> FMT_CONSTEXPR inline const char* get_units() {
+   if (std::is_same<Period, std::tera>::value) return "Ts";
+   if (std::is_same<Period, std::peta>::value) return "Ps";
+   if (std::is_same<Period, std::exa>::value) return "Es";
+-  if (std::is_same<Period, std::ratio<60>>::value) return "m";
++  if (std::is_same<Period, std::ratio<60>>::value) return "min";
+   if (std::is_same<Period, std::ratio<3600>>::value) return "h";
++  if (std::is_same<Period, std::ratio<86400>>::value) return "d";
+   return nullptr;
+ }
+ 
+@@ -640,12 +696,10 @@ enum class numeric_system {
+ 
+ // Glibc extensions for formatting numeric values.
+ enum class pad_type {
+-  unspecified,
++  // Pad a numeric result string with zeros (the default).
++  zero,
+   // Do not pad a numeric result string.
+   none,
+-  // Pad a numeric result string with zeros even if the conversion specifier
+-  // character uses space-padding by default.
+-  zero,
+   // Pad a numeric result string with spaces.
+   space,
+ };
+@@ -653,7 +707,7 @@ enum class pad_type {
+ template <typename OutputIt>
+ auto write_padding(OutputIt out, pad_type pad, int width) -> OutputIt {
+   if (pad == pad_type::none) return out;
+-  return std::fill_n(out, width, pad == pad_type::space ? ' ' : '0');
++  return detail::fill_n(out, width, pad == pad_type::space ? ' ' : '0');
+ }
+ 
+ template <typename OutputIt>
+@@ -664,14 +718,13 @@ auto write_padding(OutputIt out, pad_type pad) -> OutputIt {
+ 
+ // Parses a put_time-like format string and invokes handler actions.
+ template <typename Char, typename Handler>
+-FMT_CONSTEXPR const Char* parse_chrono_format(const Char* begin,
+-                                              const Char* end,
+-                                              Handler&& handler) {
++FMT_CONSTEXPR auto parse_chrono_format(const Char* begin, const Char* end,
++                                       Handler&& handler) -> const Char* {
+   if (begin == end || *begin == '}') return begin;
+   if (*begin != '%') FMT_THROW(format_error("invalid format"));
+   auto ptr = begin;
+-  pad_type pad = pad_type::unspecified;
+   while (ptr != end) {
++    pad_type pad = pad_type::zero;
+     auto c = *ptr;
+     if (c == '}') break;
+     if (c != '%') {
+@@ -691,17 +744,11 @@ FMT_CONSTEXPR const Char* parse_chrono_format(const Char* begin,
+       pad = pad_type::none;
+       ++ptr;
+       break;
+-    case '0':
+-      pad = pad_type::zero;
+-      ++ptr;
+-      break;
+     }
+     if (ptr == end) FMT_THROW(format_error("invalid format"));
+     c = *ptr++;
+     switch (c) {
+-    case '%':
+-      handler.on_text(ptr - 1, ptr);
+-      break;
++    case '%': handler.on_text(ptr - 1, ptr); break;
+     case 'n': {
+       const Char newline[] = {'\n'};
+       handler.on_text(newline, newline + 1);
+@@ -713,145 +760,66 @@ FMT_CONSTEXPR const Char* parse_chrono_format(const Char* begin,
+       break;
+     }
+     // Year:
+-    case 'Y':
+-      handler.on_year(numeric_system::standard);
+-      break;
+-    case 'y':
+-      handler.on_short_year(numeric_system::standard);
+-      break;
+-    case 'C':
+-      handler.on_century(numeric_system::standard);
+-      break;
+-    case 'G':
+-      handler.on_iso_week_based_year();
+-      break;
+-    case 'g':
+-      handler.on_iso_week_based_short_year();
+-      break;
++    case 'Y': handler.on_year(numeric_system::standard, pad); break;
++    case 'y': handler.on_short_year(numeric_system::standard); break;
++    case 'C': handler.on_century(numeric_system::standard); break;
++    case 'G': handler.on_iso_week_based_year(); break;
++    case 'g': handler.on_iso_week_based_short_year(); break;
+     // Day of the week:
+-    case 'a':
+-      handler.on_abbr_weekday();
+-      break;
+-    case 'A':
+-      handler.on_full_weekday();
+-      break;
+-    case 'w':
+-      handler.on_dec0_weekday(numeric_system::standard);
+-      break;
+-    case 'u':
+-      handler.on_dec1_weekday(numeric_system::standard);
+-      break;
++    case 'a': handler.on_abbr_weekday(); break;
++    case 'A': handler.on_full_weekday(); break;
++    case 'w': handler.on_dec0_weekday(numeric_system::standard); break;
++    case 'u': handler.on_dec1_weekday(numeric_system::standard); break;
+     // Month:
+     case 'b':
+-    case 'h':
+-      handler.on_abbr_month();
+-      break;
+-    case 'B':
+-      handler.on_full_month();
+-      break;
+-    case 'm':
+-      handler.on_dec_month(numeric_system::standard);
+-      break;
++    case 'h': handler.on_abbr_month(); break;
++    case 'B': handler.on_full_month(); break;
++    case 'm': handler.on_dec_month(numeric_system::standard, pad); break;
+     // Day of the year/month:
+     case 'U':
+-      handler.on_dec0_week_of_year(numeric_system::standard);
++      handler.on_dec0_week_of_year(numeric_system::standard, pad);
+       break;
+     case 'W':
+-      handler.on_dec1_week_of_year(numeric_system::standard);
+-      break;
+-    case 'V':
+-      handler.on_iso_week_of_year(numeric_system::standard);
+-      break;
+-    case 'j':
+-      handler.on_day_of_year();
+-      break;
+-    case 'd':
+-      handler.on_day_of_month(numeric_system::standard);
++      handler.on_dec1_week_of_year(numeric_system::standard, pad);
+       break;
++    case 'V': handler.on_iso_week_of_year(numeric_system::standard, pad); break;
++    case 'j': handler.on_day_of_year(pad); break;
++    case 'd': handler.on_day_of_month(numeric_system::standard, pad); break;
+     case 'e':
+-      handler.on_day_of_month_space(numeric_system::standard);
++      handler.on_day_of_month(numeric_system::standard, pad_type::space);
+       break;
+     // Hour, minute, second:
+-    case 'H':
+-      handler.on_24_hour(numeric_system::standard, pad);
+-      break;
+-    case 'I':
+-      handler.on_12_hour(numeric_system::standard, pad);
+-      break;
+-    case 'M':
+-      handler.on_minute(numeric_system::standard, pad);
+-      break;
+-    case 'S':
+-      handler.on_second(numeric_system::standard, pad);
+-      break;
++    case 'H': handler.on_24_hour(numeric_system::standard, pad); break;
++    case 'I': handler.on_12_hour(numeric_system::standard, pad); break;
++    case 'M': handler.on_minute(numeric_system::standard, pad); break;
++    case 'S': handler.on_second(numeric_system::standard, pad); break;
+     // Other:
+-    case 'c':
+-      handler.on_datetime(numeric_system::standard);
+-      break;
+-    case 'x':
+-      handler.on_loc_date(numeric_system::standard);
+-      break;
+-    case 'X':
+-      handler.on_loc_time(numeric_system::standard);
+-      break;
+-    case 'D':
+-      handler.on_us_date();
+-      break;
+-    case 'F':
+-      handler.on_iso_date();
+-      break;
+-    case 'r':
+-      handler.on_12_hour_time();
+-      break;
+-    case 'R':
+-      handler.on_24_hour_time();
+-      break;
+-    case 'T':
+-      handler.on_iso_time();
+-      break;
+-    case 'p':
+-      handler.on_am_pm();
+-      break;
+-    case 'Q':
+-      handler.on_duration_value();
+-      break;
+-    case 'q':
+-      handler.on_duration_unit();
+-      break;
+-    case 'z':
+-      handler.on_utc_offset(numeric_system::standard);
+-      break;
+-    case 'Z':
+-      handler.on_tz_name();
+-      break;
++    case 'c': handler.on_datetime(numeric_system::standard); break;
++    case 'x': handler.on_loc_date(numeric_system::standard); break;
++    case 'X': handler.on_loc_time(numeric_system::standard); break;
++    case 'D': handler.on_us_date(); break;
++    case 'F': handler.on_iso_date(); break;
++    case 'r': handler.on_12_hour_time(); break;
++    case 'R': handler.on_24_hour_time(); break;
++    case 'T': handler.on_iso_time(); break;
++    case 'p': handler.on_am_pm(); break;
++    case 'Q': handler.on_duration_value(); break;
++    case 'q': handler.on_duration_unit(); break;
++    case 'z': handler.on_utc_offset(numeric_system::standard); break;
++    case 'Z': handler.on_tz_name(); break;
+     // Alternative representation:
+     case 'E': {
+       if (ptr == end) FMT_THROW(format_error("invalid format"));
+       c = *ptr++;
+       switch (c) {
+-      case 'Y':
+-        handler.on_year(numeric_system::alternative);
+-        break;
+-      case 'y':
+-        handler.on_offset_year();
+-        break;
+-      case 'C':
+-        handler.on_century(numeric_system::alternative);
+-        break;
+-      case 'c':
+-        handler.on_datetime(numeric_system::alternative);
+-        break;
+-      case 'x':
+-        handler.on_loc_date(numeric_system::alternative);
+-        break;
+-      case 'X':
+-        handler.on_loc_time(numeric_system::alternative);
+-        break;
+-      case 'z':
+-        handler.on_utc_offset(numeric_system::alternative);
+-        break;
+-      default:
+-        FMT_THROW(format_error("invalid format"));
++      case 'Y': handler.on_year(numeric_system::alternative, pad); break;
++      case 'y': handler.on_offset_year(); break;
++      case 'C': handler.on_century(numeric_system::alternative); break;
++      case 'c': handler.on_datetime(numeric_system::alternative); break;
++      case 'x': handler.on_loc_date(numeric_system::alternative); break;
++      case 'X': handler.on_loc_time(numeric_system::alternative); break;
++      case 'z': handler.on_utc_offset(numeric_system::alternative); break;
++      default:  FMT_THROW(format_error("invalid format"));
+       }
+       break;
+     }
+@@ -859,54 +827,34 @@ FMT_CONSTEXPR const Char* parse_chrono_format(const Char* begin,
+       if (ptr == end) FMT_THROW(format_error("invalid format"));
+       c = *ptr++;
+       switch (c) {
+-      case 'y':
+-        handler.on_short_year(numeric_system::alternative);
+-        break;
+-      case 'm':
+-        handler.on_dec_month(numeric_system::alternative);
+-        break;
++      case 'y': handler.on_short_year(numeric_system::alternative); break;
++      case 'm': handler.on_dec_month(numeric_system::alternative, pad); break;
+       case 'U':
+-        handler.on_dec0_week_of_year(numeric_system::alternative);
++        handler.on_dec0_week_of_year(numeric_system::alternative, pad);
+         break;
+       case 'W':
+-        handler.on_dec1_week_of_year(numeric_system::alternative);
++        handler.on_dec1_week_of_year(numeric_system::alternative, pad);
+         break;
+       case 'V':
+-        handler.on_iso_week_of_year(numeric_system::alternative);
++        handler.on_iso_week_of_year(numeric_system::alternative, pad);
+         break;
+       case 'd':
+-        handler.on_day_of_month(numeric_system::alternative);
++        handler.on_day_of_month(numeric_system::alternative, pad);
+         break;
+       case 'e':
+-        handler.on_day_of_month_space(numeric_system::alternative);
+-        break;
+-      case 'w':
+-        handler.on_dec0_weekday(numeric_system::alternative);
+-        break;
+-      case 'u':
+-        handler.on_dec1_weekday(numeric_system::alternative);
+-        break;
+-      case 'H':
+-        handler.on_24_hour(numeric_system::alternative, pad);
++        handler.on_day_of_month(numeric_system::alternative, pad_type::space);
+         break;
+-      case 'I':
+-        handler.on_12_hour(numeric_system::alternative, pad);
+-        break;
+-      case 'M':
+-        handler.on_minute(numeric_system::alternative, pad);
+-        break;
+-      case 'S':
+-        handler.on_second(numeric_system::alternative, pad);
+-        break;
+-      case 'z':
+-        handler.on_utc_offset(numeric_system::alternative);
+-        break;
+-      default:
+-        FMT_THROW(format_error("invalid format"));
++      case 'w': handler.on_dec0_weekday(numeric_system::alternative); break;
++      case 'u': handler.on_dec1_weekday(numeric_system::alternative); break;
++      case 'H': handler.on_24_hour(numeric_system::alternative, pad); break;
++      case 'I': handler.on_12_hour(numeric_system::alternative, pad); break;
++      case 'M': handler.on_minute(numeric_system::alternative, pad); break;
++      case 'S': handler.on_second(numeric_system::alternative, pad); break;
++      case 'z': handler.on_utc_offset(numeric_system::alternative); break;
++      default:  FMT_THROW(format_error("invalid format"));
+       }
+       break;
+-    default:
+-      FMT_THROW(format_error("invalid format"));
++    default: FMT_THROW(format_error("invalid format"));
+     }
+     begin = ptr;
+   }
+@@ -918,7 +866,7 @@ template <typename Derived> struct null_chrono_spec_handler {
+   FMT_CONSTEXPR void unsupported() {
+     static_cast<Derived*>(this)->unsupported();
+   }
+-  FMT_CONSTEXPR void on_year(numeric_system) { unsupported(); }
++  FMT_CONSTEXPR void on_year(numeric_system, pad_type) { unsupported(); }
+   FMT_CONSTEXPR void on_short_year(numeric_system) { unsupported(); }
+   FMT_CONSTEXPR void on_offset_year() { unsupported(); }
+   FMT_CONSTEXPR void on_century(numeric_system) { unsupported(); }
+@@ -930,13 +878,20 @@ template <typename Derived> struct null_chrono_spec_handler {
+   FMT_CONSTEXPR void on_dec1_weekday(numeric_system) { unsupported(); }
+   FMT_CONSTEXPR void on_abbr_month() { unsupported(); }
+   FMT_CONSTEXPR void on_full_month() { unsupported(); }
+-  FMT_CONSTEXPR void on_dec_month(numeric_system) { unsupported(); }
+-  FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system) { unsupported(); }
+-  FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system) { unsupported(); }
+-  FMT_CONSTEXPR void on_iso_week_of_year(numeric_system) { unsupported(); }
+-  FMT_CONSTEXPR void on_day_of_year() { unsupported(); }
+-  FMT_CONSTEXPR void on_day_of_month(numeric_system) { unsupported(); }
+-  FMT_CONSTEXPR void on_day_of_month_space(numeric_system) { unsupported(); }
++  FMT_CONSTEXPR void on_dec_month(numeric_system, pad_type) { unsupported(); }
++  FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system, pad_type) {
++    unsupported();
++  }
++  FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system, pad_type) {
++    unsupported();
++  }
++  FMT_CONSTEXPR void on_iso_week_of_year(numeric_system, pad_type) {
++    unsupported();
++  }
++  FMT_CONSTEXPR void on_day_of_year(pad_type) { unsupported(); }
++  FMT_CONSTEXPR void on_day_of_month(numeric_system, pad_type) {
++    unsupported();
++  }
+   FMT_CONSTEXPR void on_24_hour(numeric_system) { unsupported(); }
+   FMT_CONSTEXPR void on_12_hour(numeric_system) { unsupported(); }
+   FMT_CONSTEXPR void on_minute(numeric_system) { unsupported(); }
+@@ -957,11 +912,13 @@ template <typename Derived> struct null_chrono_spec_handler {
+ };
+ 
+ struct tm_format_checker : null_chrono_spec_handler<tm_format_checker> {
+-  FMT_NORETURN void unsupported() { FMT_THROW(format_error("no format")); }
++  FMT_NORETURN inline void unsupported() {
++    FMT_THROW(format_error("no format"));
++  }
+ 
+   template <typename Char>
+   FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
+-  FMT_CONSTEXPR void on_year(numeric_system) {}
++  FMT_CONSTEXPR void on_year(numeric_system, pad_type) {}
+   FMT_CONSTEXPR void on_short_year(numeric_system) {}
+   FMT_CONSTEXPR void on_offset_year() {}
+   FMT_CONSTEXPR void on_century(numeric_system) {}
+@@ -973,13 +930,12 @@ struct tm_format_checker : null_chrono_spec_handler<tm_format_checker> {
+   FMT_CONSTEXPR void on_dec1_weekday(numeric_system) {}
+   FMT_CONSTEXPR void on_abbr_month() {}
+   FMT_CONSTEXPR void on_full_month() {}
+-  FMT_CONSTEXPR void on_dec_month(numeric_system) {}
+-  FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system) {}
+-  FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system) {}
+-  FMT_CONSTEXPR void on_iso_week_of_year(numeric_system) {}
+-  FMT_CONSTEXPR void on_day_of_year() {}
+-  FMT_CONSTEXPR void on_day_of_month(numeric_system) {}
+-  FMT_CONSTEXPR void on_day_of_month_space(numeric_system) {}
++  FMT_CONSTEXPR void on_dec_month(numeric_system, pad_type) {}
++  FMT_CONSTEXPR void on_dec0_week_of_year(numeric_system, pad_type) {}
++  FMT_CONSTEXPR void on_dec1_week_of_year(numeric_system, pad_type) {}
++  FMT_CONSTEXPR void on_iso_week_of_year(numeric_system, pad_type) {}
++  FMT_CONSTEXPR void on_day_of_year(pad_type) {}
++  FMT_CONSTEXPR void on_day_of_month(numeric_system, pad_type) {}
+   FMT_CONSTEXPR void on_24_hour(numeric_system, pad_type) {}
+   FMT_CONSTEXPR void on_12_hour(numeric_system, pad_type) {}
+   FMT_CONSTEXPR void on_minute(numeric_system, pad_type) {}
+@@ -997,25 +953,25 @@ struct tm_format_checker : null_chrono_spec_handler<tm_format_checker> {
+   FMT_CONSTEXPR void on_tz_name() {}
+ };
+ 
+-inline const char* tm_wday_full_name(int wday) {
++inline auto tm_wday_full_name(int wday) -> const char* {
+   static constexpr const char* full_name_list[] = {
+       "Sunday",   "Monday", "Tuesday", "Wednesday",
+       "Thursday", "Friday", "Saturday"};
+   return wday >= 0 && wday <= 6 ? full_name_list[wday] : "?";
+ }
+-inline const char* tm_wday_short_name(int wday) {
++inline auto tm_wday_short_name(int wday) -> const char* {
+   static constexpr const char* short_name_list[] = {"Sun", "Mon", "Tue", "Wed",
+                                                     "Thu", "Fri", "Sat"};
+   return wday >= 0 && wday <= 6 ? short_name_list[wday] : "???";
+ }
+ 
+-inline const char* tm_mon_full_name(int mon) {
++inline auto tm_mon_full_name(int mon) -> const char* {
+   static constexpr const char* full_name_list[] = {
+       "January", "February", "March",     "April",   "May",      "June",
+       "July",    "August",   "September", "October", "November", "December"};
+   return mon >= 0 && mon <= 11 ? full_name_list[mon] : "?";
+ }
+-inline const char* tm_mon_short_name(int mon) {
++inline auto tm_mon_short_name(int mon) -> const char* {
+   static constexpr const char* short_name_list[] = {
+       "Jan", "Feb", "Mar", "Apr", "May", "Jun",
+       "Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
+@@ -1035,33 +991,33 @@ template <typename T>
+ struct has_member_data_tm_zone<T, void_t<decltype(T::tm_zone)>>
+     : std::true_type {};
+ 
+-#if FMT_USE_TZSET
+ inline void tzset_once() {
+-  static bool init = []() -> bool {
++  static bool init = []() {
++    using namespace fmt_detail;
+     _tzset();
+-    return true;
++    return false;
+   }();
+   ignore_unused(init);
+ }
+-#endif
+ 
+ // Converts value to Int and checks that it's in the range [0, upper).
+ template <typename T, typename Int, FMT_ENABLE_IF(std::is_integral<T>::value)>
+-inline Int to_nonnegative_int(T value, Int upper) {
+-  FMT_ASSERT(std::is_unsigned<Int>::value ||
+-                 (value >= 0 && to_unsigned(value) <= to_unsigned(upper)),
+-             "invalid value");
+-  (void)upper;
++inline auto to_nonnegative_int(T value, Int upper) -> Int {
++  if (!std::is_unsigned<Int>::value &&
++      (value < 0 || to_unsigned(value) > to_unsigned(upper))) {
++    FMT_THROW(fmt::format_error("chrono value is out of range"));
++  }
+   return static_cast<Int>(value);
+ }
+ template <typename T, typename Int, FMT_ENABLE_IF(!std::is_integral<T>::value)>
+-inline Int to_nonnegative_int(T value, Int upper) {
+-  if (value < 0 || value > static_cast<T>(upper))
++inline auto to_nonnegative_int(T value, Int upper) -> Int {
++  auto int_value = static_cast<Int>(value);
++  if (int_value < 0 || value > static_cast<T>(upper))
+     FMT_THROW(format_error("invalid value"));
+-  return static_cast<Int>(value);
++  return int_value;
+ }
+ 
+-constexpr long long pow10(std::uint32_t n) {
++constexpr auto pow10(std::uint32_t n) -> long long {
+   return n == 0 ? 1 : 10 * pow10(n - 1);
+ }
+ 
+@@ -1093,17 +1049,16 @@ void write_fractional_seconds(OutputIt& out, Duration d, int precision = -1) {
+   using subsecond_precision = std::chrono::duration<
+       typename std::common_type<typename Duration::rep,
+                                 std::chrono::seconds::rep>::type,
+-      std::ratio<1, detail::pow10(num_fractional_digits)>>;
++      std::ratio<1, pow10(num_fractional_digits)>>;
+ 
+-  const auto fractional =
+-      d - std::chrono::duration_cast<std::chrono::seconds>(d);
++  const auto fractional = d - detail::duration_cast<std::chrono::seconds>(d);
+   const auto subseconds =
+       std::chrono::treat_as_floating_point<
+           typename subsecond_precision::rep>::value
+           ? fractional.count()
+-          : std::chrono::duration_cast<subsecond_precision>(fractional).count();
++          : detail::duration_cast<subsecond_precision>(fractional).count();
+   auto n = static_cast<uint32_or_64_or_128_t<long long>>(subseconds);
+-  const int num_digits = detail::count_digits(n);
++  const int num_digits = count_digits(n);
+ 
+   int leading_zeroes = (std::max)(0, num_fractional_digits - num_digits);
+   if (precision < 0) {
+@@ -1111,22 +1066,25 @@ void write_fractional_seconds(OutputIt& out, Duration d, int precision = -1) {
+     if (std::ratio_less<typename subsecond_precision::period,
+                         std::chrono::seconds::period>::value) {
+       *out++ = '.';
+-      out = std::fill_n(out, leading_zeroes, '0');
+-      out = format_decimal<Char>(out, n, num_digits).end;
++      out = detail::fill_n(out, leading_zeroes, '0');
++      out = format_decimal<Char>(out, n, num_digits);
+     }
+-  } else {
++  } else if (precision > 0) {
+     *out++ = '.';
+-    leading_zeroes = (std::min)(leading_zeroes, precision);
+-    out = std::fill_n(out, leading_zeroes, '0');
++    leading_zeroes = min_of(leading_zeroes, precision);
+     int remaining = precision - leading_zeroes;
+-    if (remaining != 0 && remaining < num_digits) {
+-      n /= to_unsigned(detail::pow10(to_unsigned(num_digits - remaining)));
+-      out = format_decimal<Char>(out, n, remaining).end;
++    out = detail::fill_n(out, leading_zeroes, '0');
++    if (remaining < num_digits) {
++      int num_truncated_digits = num_digits - remaining;
++      n /= to_unsigned(pow10(to_unsigned(num_truncated_digits)));
++      if (n != 0) out = format_decimal<Char>(out, n, remaining);
+       return;
+     }
+-    out = format_decimal<Char>(out, n, num_digits).end;
+-    remaining -= num_digits;
+-    out = std::fill_n(out, remaining, '0');
++    if (n != 0) {
++      out = format_decimal<Char>(out, n, num_digits);
++      remaining -= num_digits;
++    }
++    out = detail::fill_n(out, remaining, '0');
+   }
+ }
+ 
+@@ -1152,11 +1110,11 @@ void write_floating_seconds(memory_buffer& buf, Duration duration,
+       num_fractional_digits = 6;
+   }
+ 
+-  format_to(std::back_inserter(buf), FMT_STRING("{:.{}f}"),
+-            std::fmod(val * static_cast<rep>(Duration::period::num) /
+-                          static_cast<rep>(Duration::period::den),
+-                      static_cast<rep>(60)),
+-            num_fractional_digits);
++  fmt::format_to(std::back_inserter(buf), FMT_STRING("{:.{}f}"),
++                 std::fmod(val * static_cast<rep>(Duration::period::num) /
++                               static_cast<rep>(Duration::period::den),
++                           static_cast<rep>(60)),
++                 num_fractional_digits);
+ }
+ 
+ template <typename OutputIt, typename Char,
+@@ -1217,8 +1175,7 @@ class tm_writer {
+     return static_cast<int>(l);
+   }
+ 
+-  // Algorithm:
+-  // https://en.wikipedia.org/wiki/ISO_week_date#Calculating_the_week_number_from_a_month_and_day_of_the_month_or_ordinal_date
++  // Algorithm: https://en.wikipedia.org/wiki/ISO_week_date.
+   auto iso_year_weeks(long long curr_year) const noexcept -> int {
+     const auto prev_year = curr_year - 1;
+     const auto curr_p =
+@@ -1268,29 +1225,28 @@ class tm_writer {
+     }
+   }
+ 
+-  void write_year_extended(long long year) {
++  void write_year_extended(long long year, pad_type pad) {
+     // At least 4 characters.
+     int width = 4;
+-    if (year < 0) {
+-      *out_++ = '-';
++    bool negative = year < 0;
++    if (negative) {
+       year = 0 - year;
+       --width;
+     }
+     uint32_or_64_or_128_t<long long> n = to_unsigned(year);
+     const int num_digits = count_digits(n);
+-    if (width > num_digits) out_ = std::fill_n(out_, width - num_digits, '0');
+-    out_ = format_decimal<Char>(out_, n, num_digits).end;
+-  }
+-  void write_year(long long year) {
+-    if (year >= 0 && year < 10000) {
+-      write2(static_cast<int>(year / 100));
+-      write2(static_cast<int>(year % 100));
+-    } else {
+-      write_year_extended(year);
++    if (negative && pad == pad_type::zero) *out_++ = '-';
++    if (width > num_digits) {
++      out_ = detail::write_padding(out_, pad, width - num_digits);
+     }
++    if (negative && pad != pad_type::zero) *out_++ = '-';
++    out_ = format_decimal<Char>(out_, n, num_digits);
++  }
++  void write_year(long long year, pad_type pad) {
++    write_year_extended(year, pad);
+   }
+ 
+-  void write_utc_offset(long offset, numeric_system ns) {
++  void write_utc_offset(long long offset, numeric_system ns) {
+     if (offset < 0) {
+       *out_++ = '-';
+       offset = -offset;
+@@ -1302,6 +1258,7 @@ class tm_writer {
+     if (ns != numeric_system::standard) *out_++ = ':';
+     write2(static_cast<int>(offset % 60));
+   }
++
+   template <typename T, FMT_ENABLE_IF(has_member_data_tm_gmtoff<T>::value)>
+   void format_utc_offset_impl(const T& tm, numeric_system ns) {
+     write_utc_offset(tm.tm_gmtoff, ns);
+@@ -1309,9 +1266,7 @@ class tm_writer {
+   template <typename T, FMT_ENABLE_IF(!has_member_data_tm_gmtoff<T>::value)>
+   void format_utc_offset_impl(const T& tm, numeric_system ns) {
+ #if defined(_WIN32) && defined(_UCRT)
+-#  if FMT_USE_TZSET
+     tzset_once();
+-#  endif
+     long offset = 0;
+     _get_timezone(&offset);
+     if (tm.tm_isdst) {
+@@ -1328,7 +1283,7 @@ class tm_writer {
+     std::time_t gt = std::mktime(&gtm);
+     std::tm ltm = gmtime(gt);
+     std::time_t lt = std::mktime(&ltm);
+-    long offset = gt - lt;
++    long long offset = gt - lt;
+     write_utc_offset(offset, ns);
+ #endif
+   }
+@@ -1358,10 +1313,10 @@ class tm_writer {
+         subsecs_(subsecs),
+         tm_(tm) {}
+ 
+-  OutputIt out() const { return out_; }
++  auto out() const -> OutputIt { return out_; }
+ 
+   FMT_CONSTEXPR void on_text(const Char* begin, const Char* end) {
+-    out_ = copy_str<Char>(begin, end, out_);
++    out_ = copy<Char>(begin, end, out_);
+   }
+ 
+   void on_abbr_weekday() {
+@@ -1408,11 +1363,11 @@ class tm_writer {
+       *out_++ = ' ';
+       on_abbr_month();
+       *out_++ = ' ';
+-      on_day_of_month_space(numeric_system::standard);
++      on_day_of_month(numeric_system::standard, pad_type::space);
+       *out_++ = ' ';
+       on_iso_time();
+       *out_++ = ' ';
+-      on_year(numeric_system::standard);
++      on_year(numeric_system::standard, pad_type::space);
+     } else {
+       format_localized('c', ns == numeric_system::standard ? '\0' : 'E');
+     }
+@@ -1434,31 +1389,31 @@ class tm_writer {
+     write_digit2_separated(buf, to_unsigned(tm_mon() + 1),
+                            to_unsigned(tm_mday()),
+                            to_unsigned(split_year_lower(tm_year())), '/');
+-    out_ = copy_str<Char>(std::begin(buf), std::end(buf), out_);
++    out_ = copy<Char>(std::begin(buf), std::end(buf), out_);
+   }
+   void on_iso_date() {
+     auto year = tm_year();
+     char buf[10];
+     size_t offset = 0;
+     if (year >= 0 && year < 10000) {
+-      copy2(buf, digits2(static_cast<size_t>(year / 100)));
++      write2digits(buf, static_cast<size_t>(year / 100));
+     } else {
+       offset = 4;
+-      write_year_extended(year);
++      write_year_extended(year, pad_type::zero);
+       year = 0;
+     }
+     write_digit2_separated(buf + 2, static_cast<unsigned>(year % 100),
+                            to_unsigned(tm_mon() + 1), to_unsigned(tm_mday()),
+                            '-');
+-    out_ = copy_str<Char>(std::begin(buf) + offset, std::end(buf), out_);
++    out_ = copy<Char>(std::begin(buf) + offset, std::end(buf), out_);
+   }
+ 
+   void on_utc_offset(numeric_system ns) { format_utc_offset_impl(tm_, ns); }
+   void on_tz_name() { format_tz_name_impl(tm_); }
+ 
+-  void on_year(numeric_system ns) {
++  void on_year(numeric_system ns, pad_type pad) {
+     if (is_classic_ || ns == numeric_system::standard)
+-      return write_year(tm_year());
++      return write_year(tm_year(), pad);
+     format_localized('Y', 'E');
+   }
+   void on_short_year(numeric_system ns) {
+@@ -1489,56 +1444,57 @@ class tm_writer {
+     }
+   }
+ 
+-  void on_dec_month(numeric_system ns) {
++  void on_dec_month(numeric_system ns, pad_type pad) {
+     if (is_classic_ || ns == numeric_system::standard)
+-      return write2(tm_mon() + 1);
++      return write2(tm_mon() + 1, pad);
+     format_localized('m', 'O');
+   }
+ 
+-  void on_dec0_week_of_year(numeric_system ns) {
++  void on_dec0_week_of_year(numeric_system ns, pad_type pad) {
+     if (is_classic_ || ns == numeric_system::standard)
+-      return write2((tm_yday() + days_per_week - tm_wday()) / days_per_week);
++      return write2((tm_yday() + days_per_week - tm_wday()) / days_per_week,
++                    pad);
+     format_localized('U', 'O');
+   }
+-  void on_dec1_week_of_year(numeric_system ns) {
++  void on_dec1_week_of_year(numeric_system ns, pad_type pad) {
+     if (is_classic_ || ns == numeric_system::standard) {
+       auto wday = tm_wday();
+       write2((tm_yday() + days_per_week -
+               (wday == 0 ? (days_per_week - 1) : (wday - 1))) /
+-             days_per_week);
++                 days_per_week,
++             pad);
+     } else {
+       format_localized('W', 'O');
+     }
+   }
+-  void on_iso_week_of_year(numeric_system ns) {
++  void on_iso_week_of_year(numeric_system ns, pad_type pad) {
+     if (is_classic_ || ns == numeric_system::standard)
+-      return write2(tm_iso_week_of_year());
++      return write2(tm_iso_week_of_year(), pad);
+     format_localized('V', 'O');
+   }
+ 
+-  void on_iso_week_based_year() { write_year(tm_iso_week_year()); }
++  void on_iso_week_based_year() {
++    write_year(tm_iso_week_year(), pad_type::zero);
++  }
+   void on_iso_week_based_short_year() {
+     write2(split_year_lower(tm_iso_week_year()));
+   }
+ 
+-  void on_day_of_year() {
++  void on_day_of_year(pad_type pad) {
+     auto yday = tm_yday() + 1;
+-    write1(yday / 100);
+-    write2(yday % 100);
+-  }
+-  void on_day_of_month(numeric_system ns) {
+-    if (is_classic_ || ns == numeric_system::standard) return write2(tm_mday());
+-    format_localized('d', 'O');
+-  }
+-  void on_day_of_month_space(numeric_system ns) {
+-    if (is_classic_ || ns == numeric_system::standard) {
+-      auto mday = to_unsigned(tm_mday()) % 100;
+-      const char* d2 = digits2(mday);
+-      *out_++ = mday < 10 ? ' ' : d2[0];
+-      *out_++ = d2[1];
++    auto digit1 = yday / 100;
++    if (digit1 != 0) {
++      write1(digit1);
+     } else {
+-      format_localized('e', 'O');
++      out_ = detail::write_padding(out_, pad);
+     }
++    write2(yday % 100, pad);
++  }
++
++  void on_day_of_month(numeric_system ns, pad_type pad) {
++    if (is_classic_ || ns == numeric_system::standard)
++      return write2(tm_mday(), pad);
++    format_localized('d', 'O');
+   }
+ 
+   void on_24_hour(numeric_system ns, pad_type pad) {
+@@ -1566,7 +1522,7 @@ class tm_writer {
+           write_floating_seconds(buf, *subsecs_);
+           if (buf.size() > 1) {
+             // Remove the leading "0", write something like ".123".
+-            out_ = std::copy(buf.begin() + 1, buf.end(), out_);
++            out_ = copy<Char>(buf.begin() + 1, buf.end(), out_);
+           }
+         } else {
+           write_fractional_seconds<Char>(out_, *subsecs_);
+@@ -1583,7 +1539,7 @@ class tm_writer {
+       char buf[8];
+       write_digit2_separated(buf, to_unsigned(tm_hour12()),
+                              to_unsigned(tm_min()), to_unsigned(tm_sec()), ':');
+-      out_ = copy_str<Char>(std::begin(buf), std::end(buf), out_);
++      out_ = copy<Char>(std::begin(buf), std::end(buf), out_);
+       *out_++ = ' ';
+       on_am_pm();
+     } else {
+@@ -1598,7 +1554,7 @@ class tm_writer {
+   void on_iso_time() {
+     on_24_hour_time();
+     *out_++ = ':';
+-    on_second(numeric_system::standard, pad_type::unspecified);
++    on_second(numeric_system::standard, pad_type::zero);
+   }
+ 
+   void on_am_pm() {
+@@ -1618,10 +1574,11 @@ class tm_writer {
+ struct chrono_format_checker : null_chrono_spec_handler<chrono_format_checker> {
+   bool has_precision_integral = false;
+ 
+-  FMT_NORETURN void unsupported() { FMT_THROW(format_error("no date")); }
++  FMT_NORETURN inline void unsupported() { FMT_THROW(format_error("no date")); }
+ 
+   template <typename Char>
+   FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
++  FMT_CONSTEXPR void on_day_of_year(pad_type) {}
+   FMT_CONSTEXPR void on_24_hour(numeric_system, pad_type) {}
+   FMT_CONSTEXPR void on_12_hour(numeric_system, pad_type) {}
+   FMT_CONSTEXPR void on_minute(numeric_system, pad_type) {}
+@@ -1631,25 +1588,24 @@ struct chrono_format_checker : null_chrono_spec_handler<chrono_format_checker> {
+   FMT_CONSTEXPR void on_iso_time() {}
+   FMT_CONSTEXPR void on_am_pm() {}
+   FMT_CONSTEXPR void on_duration_value() const {
+-    if (has_precision_integral) {
++    if (has_precision_integral)
+       FMT_THROW(format_error("precision not allowed for this argument type"));
+-    }
+   }
+   FMT_CONSTEXPR void on_duration_unit() {}
+ };
+ 
+ template <typename T,
+           FMT_ENABLE_IF(std::is_integral<T>::value&& has_isfinite<T>::value)>
+-inline bool isfinite(T) {
++inline auto isfinite(T) -> bool {
+   return true;
+ }
+ 
+ template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
+-inline T mod(T x, int y) {
++inline auto mod(T x, int y) -> T {
+   return x % static_cast<T>(y);
+ }
+ template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
+-inline T mod(T x, int y) {
++inline auto mod(T x, int y) -> T {
+   return std::fmod(x, static_cast<T>(y));
+ }
+ 
+@@ -1664,71 +1620,60 @@ template <typename T> struct make_unsigned_or_unchanged<T, true> {
+   using type = typename std::make_unsigned<T>::type;
+ };
+ 
+-#if FMT_SAFE_DURATION_CAST
+-// throwing version of safe_duration_cast
+-template <typename To, typename FromRep, typename FromPeriod>
+-To fmt_safe_duration_cast(std::chrono::duration<FromRep, FromPeriod> from) {
+-  int ec;
+-  To to = safe_duration_cast::safe_duration_cast<To>(from, ec);
+-  if (ec) FMT_THROW(format_error("cannot format duration"));
+-  return to;
+-}
+-#endif
+-
+ template <typename Rep, typename Period,
+           FMT_ENABLE_IF(std::is_integral<Rep>::value)>
+-inline std::chrono::duration<Rep, std::milli> get_milliseconds(
+-    std::chrono::duration<Rep, Period> d) {
++inline auto get_milliseconds(std::chrono::duration<Rep, Period> d)
++    -> std::chrono::duration<Rep, std::milli> {
+   // this may overflow and/or the result may not fit in the
+   // target type.
+ #if FMT_SAFE_DURATION_CAST
+   using CommonSecondsType =
+       typename std::common_type<decltype(d), std::chrono::seconds>::type;
+-  const auto d_as_common = fmt_safe_duration_cast<CommonSecondsType>(d);
++  const auto d_as_common = detail::duration_cast<CommonSecondsType>(d);
+   const auto d_as_whole_seconds =
+-      fmt_safe_duration_cast<std::chrono::seconds>(d_as_common);
++      detail::duration_cast<std::chrono::seconds>(d_as_common);
+   // this conversion should be nonproblematic
+   const auto diff = d_as_common - d_as_whole_seconds;
+   const auto ms =
+-      fmt_safe_duration_cast<std::chrono::duration<Rep, std::milli>>(diff);
++      detail::duration_cast<std::chrono::duration<Rep, std::milli>>(diff);
+   return ms;
+ #else
+-  auto s = std::chrono::duration_cast<std::chrono::seconds>(d);
+-  return std::chrono::duration_cast<std::chrono::milliseconds>(d - s);
++  auto s = detail::duration_cast<std::chrono::seconds>(d);
++  return detail::duration_cast<std::chrono::milliseconds>(d - s);
+ #endif
+ }
+ 
+ template <typename Char, typename Rep, typename OutputIt,
+           FMT_ENABLE_IF(std::is_integral<Rep>::value)>
+-OutputIt format_duration_value(OutputIt out, Rep val, int) {
++auto format_duration_value(OutputIt out, Rep val, int) -> OutputIt {
+   return write<Char>(out, val);
+ }
+ 
+ template <typename Char, typename Rep, typename OutputIt,
+           FMT_ENABLE_IF(std::is_floating_point<Rep>::value)>
+-OutputIt format_duration_value(OutputIt out, Rep val, int precision) {
+-  auto specs = format_specs<Char>();
++auto format_duration_value(OutputIt out, Rep val, int precision) -> OutputIt {
++  auto specs = format_specs();
+   specs.precision = precision;
+-  specs.type = precision >= 0 ? presentation_type::fixed_lower
+-                              : presentation_type::general_lower;
++  specs.set_type(precision >= 0 ? presentation_type::fixed
++                                : presentation_type::general);
+   return write<Char>(out, val, specs);
+ }
+ 
+ template <typename Char, typename OutputIt>
+-OutputIt copy_unit(string_view unit, OutputIt out, Char) {
+-  return std::copy(unit.begin(), unit.end(), out);
++auto copy_unit(string_view unit, OutputIt out, Char) -> OutputIt {
++  return copy<Char>(unit.begin(), unit.end(), out);
+ }
+ 
+ template <typename OutputIt>
+-OutputIt copy_unit(string_view unit, OutputIt out, wchar_t) {
++auto copy_unit(string_view unit, OutputIt out, wchar_t) -> OutputIt {
+   // This works when wchar_t is UTF-32 because units only contain characters
+   // that have the same representation in UTF-16 and UTF-32.
+   utf8_to_utf16 u(unit);
+-  return std::copy(u.c_str(), u.c_str() + u.size(), out);
++  return copy<wchar_t>(u.c_str(), u.c_str() + u.size(), out);
+ }
+ 
+ template <typename Char, typename Period, typename OutputIt>
+-OutputIt format_duration_unit(OutputIt out) {
++auto format_duration_unit(OutputIt out) -> OutputIt {
+   if (const char* unit = get_units<Period>())
+     return copy_unit(string_view(unit), out, Char());
+   *out++ = '[';
+@@ -1750,14 +1695,14 @@ class get_locale {
+   bool has_locale_ = false;
+ 
+  public:
+-  get_locale(bool localized, locale_ref loc) : has_locale_(localized) {
++  inline get_locale(bool localized, locale_ref loc) : has_locale_(localized) {
+     if (localized)
+       ::new (&locale_) std::locale(loc.template get<std::locale>());
+   }
+-  ~get_locale() {
++  inline ~get_locale() {
+     if (has_locale_) locale_.~locale();
+   }
+-  operator const std::locale&() const {
++  inline operator const std::locale&() const {
+     return has_locale_ ? locale_ : get_classic_locale();
+   }
+ };
+@@ -1795,18 +1740,12 @@ struct chrono_formatter {
+ 
+     // this may overflow and/or the result may not fit in the
+     // target type.
+-#if FMT_SAFE_DURATION_CAST
+     // might need checked conversion (rep!=Rep)
+-    auto tmpval = std::chrono::duration<rep, Period>(val);
+-    s = fmt_safe_duration_cast<seconds>(tmpval);
+-#else
+-    s = std::chrono::duration_cast<seconds>(
+-        std::chrono::duration<rep, Period>(val));
+-#endif
++    s = detail::duration_cast<seconds>(std::chrono::duration<rep, Period>(val));
+   }
+ 
+   // returns true if nan or inf, writes to out.
+-  bool handle_nan_inf() {
++  auto handle_nan_inf() -> bool {
+     if (isfinite(val)) {
+       return false;
+     }
+@@ -1823,17 +1762,22 @@ struct chrono_formatter {
+     return true;
+   }
+ 
+-  Rep hour() const { return static_cast<Rep>(mod((s.count() / 3600), 24)); }
++  auto days() const -> Rep { return static_cast<Rep>(s.count() / 86400); }
++  auto hour() const -> Rep {
++    return static_cast<Rep>(mod((s.count() / 3600), 24));
++  }
+ 
+-  Rep hour12() const {
++  auto hour12() const -> Rep {
+     Rep hour = static_cast<Rep>(mod((s.count() / 3600), 12));
+     return hour <= 0 ? 12 : hour;
+   }
+ 
+-  Rep minute() const { return static_cast<Rep>(mod((s.count() / 60), 60)); }
+-  Rep second() const { return static_cast<Rep>(mod(s.count(), 60)); }
++  auto minute() const -> Rep {
++    return static_cast<Rep>(mod((s.count() / 60), 60));
++  }
++  auto second() const -> Rep { return static_cast<Rep>(mod(s.count(), 60)); }
+ 
+-  std::tm time() const {
++  auto time() const -> std::tm {
+     auto time = std::tm();
+     time.tm_hour = to_nonnegative_int(hour(), 24);
+     time.tm_min = to_nonnegative_int(minute(), 60);
+@@ -1848,7 +1792,7 @@ struct chrono_formatter {
+     }
+   }
+ 
+-  void write(Rep value, int width, pad_type pad = pad_type::unspecified) {
++  void write(Rep value, int width, pad_type pad = pad_type::zero) {
+     write_sign();
+     if (isnan(value)) return write_nan();
+     uint32_or_64_or_128_t<int> n =
+@@ -1857,7 +1801,7 @@ struct chrono_formatter {
+     if (width > num_digits) {
+       out = detail::write_padding(out, pad, width - num_digits);
+     }
+-    out = format_decimal<char_type>(out, n, num_digits).end;
++    out = format_decimal<char_type>(out, n, num_digits);
+   }
+ 
+   void write_nan() { std::copy_n("nan", 3, out); }
+@@ -1874,7 +1818,7 @@ struct chrono_formatter {
+   }
+ 
+   void on_text(const char_type* begin, const char_type* end) {
+-    std::copy(begin, end, out);
++    copy<char_type>(begin, end, out);
+   }
+ 
+   // These are not implemented because durations don't have date information.
+@@ -1891,19 +1835,22 @@ struct chrono_formatter {
+   void on_iso_date() {}
+   void on_utc_offset(numeric_system) {}
+   void on_tz_name() {}
+-  void on_year(numeric_system) {}
++  void on_year(numeric_system, pad_type) {}
+   void on_short_year(numeric_system) {}
+   void on_offset_year() {}
+   void on_century(numeric_system) {}
+   void on_iso_week_based_year() {}
+   void on_iso_week_based_short_year() {}
+-  void on_dec_month(numeric_system) {}
+-  void on_dec0_week_of_year(numeric_system) {}
+-  void on_dec1_week_of_year(numeric_system) {}
+-  void on_iso_week_of_year(numeric_system) {}
+-  void on_day_of_year() {}
+-  void on_day_of_month(numeric_system) {}
+-  void on_day_of_month_space(numeric_system) {}
++  void on_dec_month(numeric_system, pad_type) {}
++  void on_dec0_week_of_year(numeric_system, pad_type) {}
++  void on_dec1_week_of_year(numeric_system, pad_type) {}
++  void on_iso_week_of_year(numeric_system, pad_type) {}
++  void on_day_of_month(numeric_system, pad_type) {}
++
++  void on_day_of_year(pad_type) {
++    if (handle_nan_inf()) return;
++    write(days(), 0);
++  }
+ 
+   void on_24_hour(numeric_system ns, pad_type pad) {
+     if (handle_nan_inf()) return;
+@@ -1944,7 +1891,7 @@ struct chrono_formatter {
+         if (buf.size() < 2 || buf[1] == '.') {
+           out = detail::write_padding(out, pad);
+         }
+-        out = std::copy(buf.begin(), buf.end(), out);
++        out = copy<char_type>(buf.begin(), buf.end(), out);
+       } else {
+         write(second(), 2, pad);
+         write_fractional_seconds<char_type>(
+@@ -1978,7 +1925,7 @@ struct chrono_formatter {
+     on_24_hour_time();
+     *out++ = ':';
+     if (handle_nan_inf()) return;
+-    on_second(numeric_system::standard, pad_type::unspecified);
++    on_second(numeric_system::standard, pad_type::zero);
+   }
+ 
+   void on_am_pm() {
+@@ -1997,268 +1944,391 @@ struct chrono_formatter {
+   }
+ };
+ 
+-FMT_END_DETAIL_NAMESPACE
++}  // namespace detail
+ 
+ #if defined(__cpp_lib_chrono) && __cpp_lib_chrono >= 201907
+ using weekday = std::chrono::weekday;
++using day = std::chrono::day;
++using month = std::chrono::month;
++using year = std::chrono::year;
++using year_month_day = std::chrono::year_month_day;
+ #else
+ // A fallback version of weekday.
+ class weekday {
+  private:
+-  unsigned char value;
++  unsigned char value_;
+ 
+  public:
+   weekday() = default;
+-  explicit constexpr weekday(unsigned wd) noexcept
+-      : value(static_cast<unsigned char>(wd != 7 ? wd : 0)) {}
+-  constexpr unsigned c_encoding() const noexcept { return value; }
++  constexpr explicit weekday(unsigned wd) noexcept
++      : value_(static_cast<unsigned char>(wd != 7 ? wd : 0)) {}
++  constexpr auto c_encoding() const noexcept -> unsigned { return value_; }
++};
++
++class day {
++ private:
++  unsigned char value_;
++
++ public:
++  day() = default;
++  constexpr explicit day(unsigned d) noexcept
++      : value_(static_cast<unsigned char>(d)) {}
++  constexpr explicit operator unsigned() const noexcept { return value_; }
++};
++
++class month {
++ private:
++  unsigned char value_;
++
++ public:
++  month() = default;
++  constexpr explicit month(unsigned m) noexcept
++      : value_(static_cast<unsigned char>(m)) {}
++  constexpr explicit operator unsigned() const noexcept { return value_; }
++};
++
++class year {
++ private:
++  int value_;
++
++ public:
++  year() = default;
++  constexpr explicit year(int y) noexcept : value_(y) {}
++  constexpr explicit operator int() const noexcept { return value_; }
+ };
+ 
+-class year_month_day {};
++class year_month_day {
++ private:
++  fmt::year year_;
++  fmt::month month_;
++  fmt::day day_;
++
++ public:
++  year_month_day() = default;
++  constexpr year_month_day(const year& y, const month& m, const day& d) noexcept
++      : year_(y), month_(m), day_(d) {}
++  constexpr auto year() const noexcept -> fmt::year { return year_; }
++  constexpr auto month() const noexcept -> fmt::month { return month_; }
++  constexpr auto day() const noexcept -> fmt::day { return day_; }
++};
+ #endif
+ 
+-// A rudimentary weekday formatter.
+-template <typename Char> struct formatter<weekday, Char> {
++template <typename Char>
++struct formatter<weekday, Char> : private formatter<std::tm, Char> {
+  private:
+-  bool localized = false;
++  bool localized_ = false;
++  bool use_tm_formatter_ = false;
+ 
+  public:
+-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+-      -> decltype(ctx.begin()) {
+-    auto begin = ctx.begin(), end = ctx.end();
+-    if (begin != end && *begin == 'L') {
+-      ++begin;
+-      localized = true;
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    auto it = ctx.begin(), end = ctx.end();
++    if (it != end && *it == 'L') {
++      ++it;
++      localized_ = true;
++      return it;
+     }
+-    return begin;
++    use_tm_formatter_ = it != end && *it != '}';
++    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
+   }
+ 
+   template <typename FormatContext>
+   auto format(weekday wd, FormatContext& ctx) const -> decltype(ctx.out()) {
+     auto time = std::tm();
+     time.tm_wday = static_cast<int>(wd.c_encoding());
+-    detail::get_locale loc(localized, ctx.locale());
++    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
++    detail::get_locale loc(localized_, ctx.locale());
+     auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
+     w.on_abbr_weekday();
+     return w.out();
+   }
+ };
+ 
++template <typename Char>
++struct formatter<day, Char> : private formatter<std::tm, Char> {
++ private:
++  bool use_tm_formatter_ = false;
++
++ public:
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    auto it = ctx.begin(), end = ctx.end();
++    use_tm_formatter_ = it != end && *it != '}';
++    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
++  }
++
++  template <typename FormatContext>
++  auto format(day d, FormatContext& ctx) const -> decltype(ctx.out()) {
++    auto time = std::tm();
++    time.tm_mday = static_cast<int>(static_cast<unsigned>(d));
++    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
++    detail::get_locale loc(false, ctx.locale());
++    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
++    w.on_day_of_month(detail::numeric_system::standard, detail::pad_type::zero);
++    return w.out();
++  }
++};
++
++template <typename Char>
++struct formatter<month, Char> : private formatter<std::tm, Char> {
++ private:
++  bool localized_ = false;
++  bool use_tm_formatter_ = false;
++
++ public:
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    auto it = ctx.begin(), end = ctx.end();
++    if (it != end && *it == 'L') {
++      ++it;
++      localized_ = true;
++      return it;
++    }
++    use_tm_formatter_ = it != end && *it != '}';
++    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
++  }
++
++  template <typename FormatContext>
++  auto format(month m, FormatContext& ctx) const -> decltype(ctx.out()) {
++    auto time = std::tm();
++    time.tm_mon = static_cast<int>(static_cast<unsigned>(m)) - 1;
++    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
++    detail::get_locale loc(localized_, ctx.locale());
++    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
++    w.on_abbr_month();
++    return w.out();
++  }
++};
++
++template <typename Char>
++struct formatter<year, Char> : private formatter<std::tm, Char> {
++ private:
++  bool use_tm_formatter_ = false;
++
++ public:
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    auto it = ctx.begin(), end = ctx.end();
++    use_tm_formatter_ = it != end && *it != '}';
++    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
++  }
++
++  template <typename FormatContext>
++  auto format(year y, FormatContext& ctx) const -> decltype(ctx.out()) {
++    auto time = std::tm();
++    time.tm_year = static_cast<int>(y) - 1900;
++    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
++    detail::get_locale loc(false, ctx.locale());
++    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
++    w.on_year(detail::numeric_system::standard, detail::pad_type::zero);
++    return w.out();
++  }
++};
++
++template <typename Char>
++struct formatter<year_month_day, Char> : private formatter<std::tm, Char> {
++ private:
++  bool use_tm_formatter_ = false;
++
++ public:
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    auto it = ctx.begin(), end = ctx.end();
++    use_tm_formatter_ = it != end && *it != '}';
++    return use_tm_formatter_ ? formatter<std::tm, Char>::parse(ctx) : it;
++  }
++
++  template <typename FormatContext>
++  auto format(year_month_day val, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    auto time = std::tm();
++    time.tm_year = static_cast<int>(val.year()) - 1900;
++    time.tm_mon = static_cast<int>(static_cast<unsigned>(val.month())) - 1;
++    time.tm_mday = static_cast<int>(static_cast<unsigned>(val.day()));
++    if (use_tm_formatter_) return formatter<std::tm, Char>::format(time, ctx);
++    detail::get_locale loc(true, ctx.locale());
++    auto w = detail::tm_writer<decltype(ctx.out()), Char>(loc, ctx.out(), time);
++    w.on_iso_date();
++    return w.out();
++  }
++};
++
+ template <typename Rep, typename Period, typename Char>
+ struct formatter<std::chrono::duration<Rep, Period>, Char> {
+  private:
+-  format_specs<Char> specs;
+-  int precision = -1;
+-  using arg_ref_type = detail::arg_ref<Char>;
+-  arg_ref_type width_ref;
+-  arg_ref_type precision_ref;
+-  bool localized = false;
+-  basic_string_view<Char> format_str;
+-  using duration = std::chrono::duration<Rep, Period>;
++  format_specs specs_;
++  detail::arg_ref<Char> width_ref_;
++  detail::arg_ref<Char> precision_ref_;
++  bool localized_ = false;
++  basic_string_view<Char> fmt_;
+ 
+-  using iterator = typename basic_format_parse_context<Char>::iterator;
+-  struct parse_range {
+-    iterator begin;
+-    iterator end;
+-  };
+-
+-  FMT_CONSTEXPR parse_range do_parse(basic_format_parse_context<Char>& ctx) {
+-    auto begin = ctx.begin(), end = ctx.end();
+-    if (begin == end || *begin == '}') return {begin, begin};
++ public:
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    auto it = ctx.begin(), end = ctx.end();
++    if (it == end || *it == '}') return it;
+ 
+-    begin = detail::parse_align(begin, end, specs);
+-    if (begin == end) return {begin, begin};
++    it = detail::parse_align(it, end, specs_);
++    if (it == end) return it;
+ 
+-    begin = detail::parse_dynamic_spec(begin, end, specs.width, width_ref, ctx);
+-    if (begin == end) return {begin, begin};
++    Char c = *it;
++    if ((c >= '0' && c <= '9') || c == '{') {
++      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
++      if (it == end) return it;
++    }
+ 
+     auto checker = detail::chrono_format_checker();
+-    if (*begin == '.') {
++    if (*it == '.') {
+       checker.has_precision_integral = !std::is_floating_point<Rep>::value;
+-      begin =
+-          detail::parse_precision(begin, end, precision, precision_ref, ctx);
++      it = detail::parse_precision(it, end, specs_, precision_ref_, ctx);
+     }
+-    if (begin != end && *begin == 'L') {
+-      ++begin;
+-      localized = true;
++    if (it != end && *it == 'L') {
++      localized_ = true;
++      ++it;
+     }
+-    end = detail::parse_chrono_format(begin, end, checker);
+-    return {begin, end};
+-  }
+-
+- public:
+-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+-      -> decltype(ctx.begin()) {
+-    auto range = do_parse(ctx);
+-    format_str = basic_string_view<Char>(
+-        &*range.begin, detail::to_unsigned(range.end - range.begin));
+-    return range.end;
++    end = detail::parse_chrono_format(it, end, checker);
++    fmt_ = {it, detail::to_unsigned(end - it)};
++    return end;
+   }
+ 
+   template <typename FormatContext>
+-  auto format(const duration& d, FormatContext& ctx) const
++  auto format(std::chrono::duration<Rep, Period> d, FormatContext& ctx) const
+       -> decltype(ctx.out()) {
+-    auto specs_copy = specs;
+-    auto precision_copy = precision;
+-    auto begin = format_str.begin(), end = format_str.end();
++    auto specs = specs_;
++    auto precision = specs.precision;
++    specs.precision = -1;
++    auto begin = fmt_.begin(), end = fmt_.end();
+     // As a possible future optimization, we could avoid extra copying if width
+     // is not specified.
+-    basic_memory_buffer<Char> buf;
+-    auto out = std::back_inserter(buf);
+-    detail::handle_dynamic_spec<detail::width_checker>(specs_copy.width,
+-                                                       width_ref, ctx);
+-    detail::handle_dynamic_spec<detail::precision_checker>(precision_copy,
+-                                                           precision_ref, ctx);
++    auto buf = basic_memory_buffer<Char>();
++    auto out = basic_appender<Char>(buf);
++    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
++                                ctx);
++    detail::handle_dynamic_spec(specs.dynamic_precision(), precision,
++                                precision_ref_, ctx);
+     if (begin == end || *begin == '}') {
+-      out = detail::format_duration_value<Char>(out, d.count(), precision_copy);
++      out = detail::format_duration_value<Char>(out, d.count(), precision);
+       detail::format_duration_unit<Char, Period>(out);
+     } else {
+-      detail::chrono_formatter<FormatContext, decltype(out), Rep, Period> f(
+-          ctx, out, d);
+-      f.precision = precision_copy;
+-      f.localized = localized;
++      using chrono_formatter =
++          detail::chrono_formatter<FormatContext, decltype(out), Rep, Period>;
++      auto f = chrono_formatter(ctx, out, d);
++      f.precision = precision;
++      f.localized = localized_;
+       detail::parse_chrono_format(begin, end, f);
+     }
+     return detail::write(
+-        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs_copy);
++        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs);
+   }
+ };
+ 
+-template <typename Char, typename Duration>
+-struct formatter<std::chrono::time_point<std::chrono::system_clock, Duration>,
+-                 Char> : formatter<std::tm, Char> {
+-  FMT_CONSTEXPR formatter() {
+-    this->format_str = detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>{};
++template <typename Char> struct formatter<std::tm, Char> {
++ private:
++  format_specs specs_;
++  detail::arg_ref<Char> width_ref_;
++
++ protected:
++  basic_string_view<Char> fmt_;
++
++  template <typename Duration, typename FormatContext>
++  auto do_format(const std::tm& tm, FormatContext& ctx,
++                 const Duration* subsecs) const -> decltype(ctx.out()) {
++    auto specs = specs_;
++    auto buf = basic_memory_buffer<Char>();
++    auto out = basic_appender<Char>(buf);
++    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
++                                ctx);
++
++    auto loc_ref = ctx.locale();
++    detail::get_locale loc(static_cast<bool>(loc_ref), loc_ref);
++    auto w =
++        detail::tm_writer<decltype(out), Char, Duration>(loc, out, tm, subsecs);
++    detail::parse_chrono_format(fmt_.begin(), fmt_.end(), w);
++    return detail::write(
++        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs);
+   }
+ 
+-  template <typename FormatContext>
+-  auto format(std::chrono::time_point<std::chrono::system_clock, Duration> val,
+-              FormatContext& ctx) const -> decltype(ctx.out()) {
+-    using period = typename Duration::period;
+-    if (period::num != 1 || period::den != 1 ||
+-        std::is_floating_point<typename Duration::rep>::value) {
+-      const auto epoch = val.time_since_epoch();
+-      auto subsecs = std::chrono::duration_cast<Duration>(
+-          epoch - std::chrono::duration_cast<std::chrono::seconds>(epoch));
+-
+-      if (subsecs.count() < 0) {
+-        auto second = std::chrono::duration_cast<Duration>(
+-            std::chrono::seconds(1));
+-        if (epoch.count() < ((Duration::min)() + second).count())
+-          FMT_THROW(format_error("duration is too small"));
+-        subsecs += second;
+-        val -= second;
+-      }
++ public:
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    auto it = ctx.begin(), end = ctx.end();
++    if (it == end || *it == '}') return it;
+ 
+-      return formatter<std::tm, Char>::do_format(
+-          gmtime(std::chrono::time_point_cast<std::chrono::seconds>(val)), ctx,
+-          &subsecs);
++    it = detail::parse_align(it, end, specs_);
++    if (it == end) return it;
++
++    Char c = *it;
++    if ((c >= '0' && c <= '9') || c == '{') {
++      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
++      if (it == end) return it;
+     }
+ 
+-    return formatter<std::tm, Char>::format(
+-        gmtime(std::chrono::time_point_cast<std::chrono::seconds>(val)), ctx);
++    end = detail::parse_chrono_format(it, end, detail::tm_format_checker());
++    // Replace the default format string only if the new spec is not empty.
++    if (end != it) fmt_ = {it, detail::to_unsigned(end - it)};
++    return end;
++  }
++
++  template <typename FormatContext>
++  auto format(const std::tm& tm, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    return do_format<std::chrono::seconds>(tm, ctx, nullptr);
+   }
+ };
+ 
+-#if FMT_USE_LOCAL_TIME
+ template <typename Char, typename Duration>
+-struct formatter<std::chrono::local_time<Duration>, Char>
+-    : formatter<std::tm, Char> {
++struct formatter<sys_time<Duration>, Char> : formatter<std::tm, Char> {
+   FMT_CONSTEXPR formatter() {
+-    this->format_str = detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>{};
++    this->fmt_ = detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>();
+   }
+ 
+   template <typename FormatContext>
+-  auto format(std::chrono::local_time<Duration> val, FormatContext& ctx) const
++  auto format(sys_time<Duration> val, FormatContext& ctx) const
+       -> decltype(ctx.out()) {
++    std::tm tm = gmtime(val);
+     using period = typename Duration::period;
+-    if (period::num != 1 || period::den != 1 ||
+-        std::is_floating_point<typename Duration::rep>::value) {
+-      const auto epoch = val.time_since_epoch();
+-      const auto subsecs = std::chrono::duration_cast<Duration>(
+-          epoch - std::chrono::duration_cast<std::chrono::seconds>(epoch));
+-
+-      return formatter<std::tm, Char>::do_format(
+-          localtime(std::chrono::time_point_cast<std::chrono::seconds>(val)),
+-          ctx, &subsecs);
++    if (detail::const_check(
++            period::num == 1 && period::den == 1 &&
++            !std::is_floating_point<typename Duration::rep>::value)) {
++      return formatter<std::tm, Char>::format(tm, ctx);
+     }
+-
+-    return formatter<std::tm, Char>::format(
+-        localtime(std::chrono::time_point_cast<std::chrono::seconds>(val)),
+-        ctx);
++    Duration epoch = val.time_since_epoch();
++    Duration subsecs = detail::duration_cast<Duration>(
++        epoch - detail::duration_cast<std::chrono::seconds>(epoch));
++    if (subsecs.count() < 0) {
++      auto second = detail::duration_cast<Duration>(std::chrono::seconds(1));
++      if (tm.tm_sec != 0)
++        --tm.tm_sec;
++      else
++        tm = gmtime(val - second);
++      subsecs += detail::duration_cast<Duration>(std::chrono::seconds(1));
++    }
++    return formatter<std::tm, Char>::do_format(tm, ctx, &subsecs);
+   }
+ };
+-#endif
+ 
+-#if FMT_USE_UTC_TIME
+-template <typename Char, typename Duration>
+-struct formatter<std::chrono::time_point<std::chrono::utc_clock, Duration>,
+-                 Char>
+-    : formatter<std::chrono::time_point<std::chrono::system_clock, Duration>,
+-                Char> {
++template <typename Duration, typename Char>
++struct formatter<utc_time<Duration>, Char>
++    : formatter<sys_time<Duration>, Char> {
+   template <typename FormatContext>
+-  auto format(std::chrono::time_point<std::chrono::utc_clock, Duration> val,
+-              FormatContext& ctx) const -> decltype(ctx.out()) {
+-    return formatter<
+-        std::chrono::time_point<std::chrono::system_clock, Duration>,
+-        Char>::format(std::chrono::utc_clock::to_sys(val), ctx);
++  auto format(utc_time<Duration> val, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    return formatter<sys_time<Duration>, Char>::format(
++        detail::utc_clock::to_sys(val), ctx);
+   }
+ };
+-#endif
+-
+-template <typename Char> struct formatter<std::tm, Char> {
+- private:
+-  format_specs<Char> specs;
+-  detail::arg_ref<Char> width_ref;
+-
+- protected:
+-  basic_string_view<Char> format_str;
+-
+-  FMT_CONSTEXPR auto do_parse(basic_format_parse_context<Char>& ctx)
+-      -> decltype(ctx.begin()) {
+-    auto begin = ctx.begin(), end = ctx.end();
+-    if (begin == end || *begin == '}') return begin;
+-
+-    begin = detail::parse_align(begin, end, specs);
+-    if (begin == end) return end;
+-
+-    begin = detail::parse_dynamic_spec(begin, end, specs.width, width_ref, ctx);
+-    if (begin == end) return end;
+-
+-    end = detail::parse_chrono_format(begin, end, detail::tm_format_checker());
+-    // Replace default format_str only if the new spec is not empty.
+-    if (end != begin) format_str = {begin, detail::to_unsigned(end - begin)};
+-    return end;
+-  }
+-
+-  template <typename FormatContext, typename Duration>
+-  auto do_format(const std::tm& tm, FormatContext& ctx,
+-                 const Duration* subsecs) const -> decltype(ctx.out()) {
+-    auto specs_copy = specs;
+-    basic_memory_buffer<Char> buf;
+-    auto out = std::back_inserter(buf);
+-    detail::handle_dynamic_spec<detail::width_checker>(specs_copy.width,
+-                                                       width_ref, ctx);
+ 
+-    const auto loc_ref = ctx.locale();
+-    detail::get_locale loc(static_cast<bool>(loc_ref), loc_ref);
+-    auto w =
+-        detail::tm_writer<decltype(out), Char, Duration>(loc, out, tm, subsecs);
+-    detail::parse_chrono_format(format_str.begin(), format_str.end(), w);
+-    return detail::write(
+-        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs_copy);
+-  }
+-
+- public:
+-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+-      -> decltype(ctx.begin()) {
+-    return this->do_parse(ctx);
++template <typename Duration, typename Char>
++struct formatter<local_time<Duration>, Char> : formatter<std::tm, Char> {
++  FMT_CONSTEXPR formatter() {
++    this->fmt_ = detail::string_literal<Char, '%', 'F', ' ', '%', 'T'>();
+   }
+ 
+   template <typename FormatContext>
+-  auto format(const std::tm& tm, FormatContext& ctx) const
++  auto format(local_time<Duration> val, FormatContext& ctx) const
+       -> decltype(ctx.out()) {
+-    return do_format<FormatContext, std::chrono::seconds>(tm, ctx, nullptr);
++    using period = typename Duration::period;
++    if (period::num == 1 && period::den == 1 &&
++        !std::is_floating_point<typename Duration::rep>::value) {
++      return formatter<std::tm, Char>::format(localtime(val), ctx);
++    }
++    auto epoch = val.time_since_epoch();
++    auto subsecs = detail::duration_cast<Duration>(
++        epoch - detail::duration_cast<std::chrono::seconds>(epoch));
++    return formatter<std::tm, Char>::do_format(localtime(val), ctx, &subsecs);
+   }
+ };
+ 
+diff --git a/include/fmt/color.h b/include/fmt/color.h
+index d175448..638f15b 100644
+--- a/include/fmt/color.h
++++ b/include/fmt/color.h
+@@ -190,11 +190,11 @@ enum class emphasis : uint8_t {
+ // rgb is a struct for red, green and blue colors.
+ // Using the name "rgb" makes some editors show the color in a tooltip.
+ struct rgb {
+-  FMT_CONSTEXPR rgb() : r(0), g(0), b(0) {}
+-  FMT_CONSTEXPR rgb(uint8_t r_, uint8_t g_, uint8_t b_) : r(r_), g(g_), b(b_) {}
+-  FMT_CONSTEXPR rgb(uint32_t hex)
++  constexpr rgb() : r(0), g(0), b(0) {}
++  constexpr rgb(uint8_t r_, uint8_t g_, uint8_t b_) : r(r_), g(g_), b(b_) {}
++  constexpr rgb(uint32_t hex)
+       : r((hex >> 16) & 0xFF), g((hex >> 8) & 0xFF), b(hex & 0xFF) {}
+-  FMT_CONSTEXPR rgb(color hex)
++  constexpr rgb(color hex)
+       : r((uint32_t(hex) >> 16) & 0xFF),
+         g((uint32_t(hex) >> 8) & 0xFF),
+         b(uint32_t(hex) & 0xFF) {}
+@@ -203,136 +203,174 @@ struct rgb {
+   uint8_t b;
+ };
+ 
+-FMT_BEGIN_DETAIL_NAMESPACE
++namespace detail {
+ 
+-// color is a struct of either a rgb color or a terminal color.
++// A bit-packed variant of an RGB color, a terminal color, or unset color.
++// see text_style for the bit-packing scheme.
+ struct color_type {
+-  FMT_CONSTEXPR color_type() noexcept : is_rgb(), value{} {}
+-  FMT_CONSTEXPR color_type(color rgb_color) noexcept : is_rgb(true), value{} {
+-    value.rgb_color = static_cast<uint32_t>(rgb_color);
++  constexpr color_type() noexcept = default;
++  constexpr color_type(color rgb_color) noexcept
++      : value_(static_cast<uint32_t>(rgb_color) | (1 << 24)) {}
++  constexpr color_type(rgb rgb_color) noexcept
++      : color_type(static_cast<color>(
++            (static_cast<uint32_t>(rgb_color.r) << 16) |
++            (static_cast<uint32_t>(rgb_color.g) << 8) | rgb_color.b)) {}
++  constexpr color_type(terminal_color term_color) noexcept
++      : value_(static_cast<uint32_t>(term_color) | (3 << 24)) {}
++
++  constexpr auto is_terminal_color() const noexcept -> bool {
++    return (value_ & (1 << 25)) != 0;
+   }
+-  FMT_CONSTEXPR color_type(rgb rgb_color) noexcept : is_rgb(true), value{} {
+-    value.rgb_color = (static_cast<uint32_t>(rgb_color.r) << 16) |
+-                      (static_cast<uint32_t>(rgb_color.g) << 8) | rgb_color.b;
+-  }
+-  FMT_CONSTEXPR color_type(terminal_color term_color) noexcept
+-      : is_rgb(), value{} {
+-    value.term_color = static_cast<uint8_t>(term_color);
++
++  constexpr auto value() const noexcept -> uint32_t {
++    return value_ & 0xFFFFFF;
+   }
+-  bool is_rgb;
+-  union color_union {
+-    uint8_t term_color;
+-    uint32_t rgb_color;
+-  } value;
+-};
+ 
+-FMT_END_DETAIL_NAMESPACE
++  constexpr color_type(uint32_t value) noexcept : value_(value) {}
++
++  uint32_t value_ = 0;
++};
++}  // namespace detail
+ 
+-/** A text style consisting of foreground and background colors and emphasis. */
++/// A text style consisting of foreground and background colors and emphasis.
+ class text_style {
++  // The information is packed as follows:
++  // ┌──┐
++  // │ 0│─┐
++  // │..│ ├── foreground color value
++  // │23│─┘
++  // ├──┤
++  // │24│─┬── discriminator for the above value. 00 if unset, 01 if it's
++  // │25│─┘   an RGB color, or 11 if it's a terminal color (10 is unused)
++  // ├──┤
++  // │26│──── overflow bit, always zero (see below)
++  // ├──┤
++  // │27│─┐
++  // │..│ │
++  // │50│ │
++  // ├──┤ │
++  // │51│ ├── background color (same format as the foreground color)
++  // │52│ │
++  // ├──┤ │
++  // │53│─┘
++  // ├──┤
++  // │54│─┐
++  // │..│ ├── emphases
++  // │61│─┘
++  // ├──┤
++  // │62│─┬── unused
++  // │63│─┘
++  // └──┘
++  // The overflow bits are there to make operator|= efficient.
++  // When ORing, we must throw if, for either the foreground or background,
++  // one style specifies a terminal color and the other specifies any color
++  // (terminal or RGB); in other words, if one discriminator is 11 and the
++  // other is 11 or 01.
++  //
++  // We do that check by adding the styles. Consider what adding does to each
++  // possible pair of discriminators:
++  //    00 + 00 = 000
++  //    01 + 00 = 001
++  //    11 + 00 = 011
++  //    01 + 01 = 010
++  //    11 + 01 = 100 (!!)
++  //    11 + 11 = 110 (!!)
++  // In the last two cases, the ones we want to catch, the third bit——the
++  // overflow bit——is set. Bingo.
++  //
++  // We must take into account the possible carry bit from the bits
++  // before the discriminator. The only potentially problematic case is
++  // 11 + 00 = 011 (a carry bit would make it 100, not good!), but a carry
++  // bit is impossible in that case, because 00 (unset color) means the
++  // 24 bits that precede the discriminator are all zero.
++  //
++  // This test can be applied to both colors simultaneously.
++
+  public:
+   FMT_CONSTEXPR text_style(emphasis em = emphasis()) noexcept
+-      : set_foreground_color(), set_background_color(), ems(em) {}
+-
+-  FMT_CONSTEXPR text_style& operator|=(const text_style& rhs) {
+-    if (!set_foreground_color) {
+-      set_foreground_color = rhs.set_foreground_color;
+-      foreground_color = rhs.foreground_color;
+-    } else if (rhs.set_foreground_color) {
+-      if (!foreground_color.is_rgb || !rhs.foreground_color.is_rgb)
+-        FMT_THROW(format_error("can't OR a terminal color"));
+-      foreground_color.value.rgb_color |= rhs.foreground_color.value.rgb_color;
+-    }
++      : style_(static_cast<uint64_t>(em) << 54) {}
+ 
+-    if (!set_background_color) {
+-      set_background_color = rhs.set_background_color;
+-      background_color = rhs.background_color;
+-    } else if (rhs.set_background_color) {
+-      if (!background_color.is_rgb || !rhs.background_color.is_rgb)
+-        FMT_THROW(format_error("can't OR a terminal color"));
+-      background_color.value.rgb_color |= rhs.background_color.value.rgb_color;
+-    }
+-
+-    ems = static_cast<emphasis>(static_cast<uint8_t>(ems) |
+-                                static_cast<uint8_t>(rhs.ems));
++  FMT_CONSTEXPR auto operator|=(text_style rhs) -> text_style& {
++    if (((style_ + rhs.style_) & ((1ULL << 26) | (1ULL << 53))) != 0)
++      report_error("can't OR a terminal color");
++    style_ |= rhs.style_;
+     return *this;
+   }
+ 
+-  friend FMT_CONSTEXPR text_style operator|(text_style lhs,
+-                                            const text_style& rhs) {
++  friend FMT_CONSTEXPR auto operator|(text_style lhs, text_style rhs)
++      -> text_style {
+     return lhs |= rhs;
+   }
+ 
+-  FMT_CONSTEXPR bool has_foreground() const noexcept {
+-    return set_foreground_color;
++  FMT_CONSTEXPR auto operator==(text_style rhs) const noexcept -> bool {
++    return style_ == rhs.style_;
++  }
++
++  FMT_CONSTEXPR auto operator!=(text_style rhs) const noexcept -> bool {
++    return !(*this == rhs);
+   }
+-  FMT_CONSTEXPR bool has_background() const noexcept {
+-    return set_background_color;
++
++  FMT_CONSTEXPR auto has_foreground() const noexcept -> bool {
++    return (style_ & (1 << 24)) != 0;
+   }
+-  FMT_CONSTEXPR bool has_emphasis() const noexcept {
+-    return static_cast<uint8_t>(ems) != 0;
++  FMT_CONSTEXPR auto has_background() const noexcept -> bool {
++    return (style_ & (1ULL << 51)) != 0;
+   }
+-  FMT_CONSTEXPR detail::color_type get_foreground() const noexcept {
++  FMT_CONSTEXPR auto has_emphasis() const noexcept -> bool {
++    return (style_ >> 54) != 0;
++  }
++  FMT_CONSTEXPR auto get_foreground() const noexcept -> detail::color_type {
+     FMT_ASSERT(has_foreground(), "no foreground specified for this style");
+-    return foreground_color;
++    return style_ & 0x3FFFFFF;
+   }
+-  FMT_CONSTEXPR detail::color_type get_background() const noexcept {
++  FMT_CONSTEXPR auto get_background() const noexcept -> detail::color_type {
+     FMT_ASSERT(has_background(), "no background specified for this style");
+-    return background_color;
++    return (style_ >> 27) & 0x3FFFFFF;
+   }
+-  FMT_CONSTEXPR emphasis get_emphasis() const noexcept {
++  FMT_CONSTEXPR auto get_emphasis() const noexcept -> emphasis {
+     FMT_ASSERT(has_emphasis(), "no emphasis specified for this style");
+-    return ems;
++    return static_cast<emphasis>(style_ >> 54);
+   }
+ 
+  private:
+-  FMT_CONSTEXPR text_style(bool is_foreground,
+-                           detail::color_type text_color) noexcept
+-      : set_foreground_color(), set_background_color(), ems() {
+-    if (is_foreground) {
+-      foreground_color = text_color;
+-      set_foreground_color = true;
+-    } else {
+-      background_color = text_color;
+-      set_background_color = true;
+-    }
+-  }
++  FMT_CONSTEXPR text_style(uint64_t style) noexcept : style_(style) {}
+ 
+-  friend FMT_CONSTEXPR text_style fg(detail::color_type foreground) noexcept;
++  friend FMT_CONSTEXPR auto fg(detail::color_type foreground) noexcept
++      -> text_style;
+ 
+-  friend FMT_CONSTEXPR text_style bg(detail::color_type background) noexcept;
++  friend FMT_CONSTEXPR auto bg(detail::color_type background) noexcept
++      -> text_style;
+ 
+-  detail::color_type foreground_color;
+-  detail::color_type background_color;
+-  bool set_foreground_color;
+-  bool set_background_color;
+-  emphasis ems;
++  uint64_t style_ = 0;
+ };
+ 
+-/** Creates a text style from the foreground (text) color. */
+-FMT_CONSTEXPR inline text_style fg(detail::color_type foreground) noexcept {
+-  return text_style(true, foreground);
++/// Creates a text style from the foreground (text) color.
++FMT_CONSTEXPR inline auto fg(detail::color_type foreground) noexcept
++    -> text_style {
++  return foreground.value_;
+ }
+ 
+-/** Creates a text style from the background color. */
+-FMT_CONSTEXPR inline text_style bg(detail::color_type background) noexcept {
+-  return text_style(false, background);
++/// Creates a text style from the background color.
++FMT_CONSTEXPR inline auto bg(detail::color_type background) noexcept
++    -> text_style {
++  return static_cast<uint64_t>(background.value_) << 27;
+ }
+ 
+-FMT_CONSTEXPR inline text_style operator|(emphasis lhs, emphasis rhs) noexcept {
++FMT_CONSTEXPR inline auto operator|(emphasis lhs, emphasis rhs) noexcept
++    -> text_style {
+   return text_style(lhs) | rhs;
+ }
+ 
+-FMT_BEGIN_DETAIL_NAMESPACE
++namespace detail {
+ 
+ template <typename Char> struct ansi_color_escape {
+-  FMT_CONSTEXPR ansi_color_escape(detail::color_type text_color,
++  FMT_CONSTEXPR ansi_color_escape(color_type text_color,
+                                   const char* esc) noexcept {
+     // If we have a terminal color, we need to output another escape code
+     // sequence.
+-    if (!text_color.is_rgb) {
++    if (text_color.is_terminal_color()) {
+       bool is_background = esc == string_view("\x1b[48;2;");
+-      uint32_t value = text_color.value.term_color;
++      uint32_t value = text_color.value();
+       // Background ASCII codes are the same as the foreground ones but with
+       // 10 more.
+       if (is_background) value += 10u;
+@@ -356,7 +394,7 @@ template <typename Char> struct ansi_color_escape {
+     for (int i = 0; i < 7; i++) {
+       buffer[i] = static_cast<Char>(esc[i]);
+     }
+-    rgb color(text_color.value.rgb_color);
++    rgb color(text_color.value());
+     to_esc(color.r, buffer + 7, ';');
+     to_esc(color.g, buffer + 11, ';');
+     to_esc(color.b, buffer + 15, 'm');
+@@ -385,9 +423,9 @@ template <typename Char> struct ansi_color_escape {
+   }
+   FMT_CONSTEXPR operator const Char*() const noexcept { return buffer; }
+ 
+-  FMT_CONSTEXPR const Char* begin() const noexcept { return buffer; }
+-  FMT_CONSTEXPR_CHAR_TRAITS const Char* end() const noexcept {
+-    return buffer + std::char_traits<Char>::length(buffer);
++  FMT_CONSTEXPR auto begin() const noexcept -> const Char* { return buffer; }
++  FMT_CONSTEXPR20 auto end() const noexcept -> const Char* {
++    return buffer + basic_string_view<Char>(buffer).size();
+   }
+ 
+  private:
+@@ -401,25 +439,27 @@ template <typename Char> struct ansi_color_escape {
+     out[2] = static_cast<Char>('0' + c % 10);
+     out[3] = static_cast<Char>(delimiter);
+   }
+-  static FMT_CONSTEXPR bool has_emphasis(emphasis em, emphasis mask) noexcept {
++  static FMT_CONSTEXPR auto has_emphasis(emphasis em, emphasis mask) noexcept
++      -> bool {
+     return static_cast<uint8_t>(em) & static_cast<uint8_t>(mask);
+   }
+ };
+ 
+ template <typename Char>
+-FMT_CONSTEXPR ansi_color_escape<Char> make_foreground_color(
+-    detail::color_type foreground) noexcept {
++FMT_CONSTEXPR auto make_foreground_color(color_type foreground) noexcept
++    -> ansi_color_escape<Char> {
+   return ansi_color_escape<Char>(foreground, "\x1b[38;2;");
+ }
+ 
+ template <typename Char>
+-FMT_CONSTEXPR ansi_color_escape<Char> make_background_color(
+-    detail::color_type background) noexcept {
++FMT_CONSTEXPR auto make_background_color(color_type background) noexcept
++    -> ansi_color_escape<Char> {
+   return ansi_color_escape<Char>(background, "\x1b[48;2;");
+ }
+ 
+ template <typename Char>
+-FMT_CONSTEXPR ansi_color_escape<Char> make_emphasis(emphasis em) noexcept {
++FMT_CONSTEXPR auto make_emphasis(emphasis em) noexcept
++    -> ansi_color_escape<Char> {
+   return ansi_color_escape<Char>(em);
+ }
+ 
+@@ -428,149 +468,116 @@ template <typename Char> inline void reset_color(buffer<Char>& buffer) {
+   buffer.append(reset_color.begin(), reset_color.end());
+ }
+ 
+-template <typename T> struct styled_arg {
++template <typename T> struct styled_arg : view {
+   const T& value;
+   text_style style;
++  styled_arg(const T& v, text_style s) : value(v), style(s) {}
+ };
+ 
+ template <typename Char>
+-void vformat_to(buffer<Char>& buf, const text_style& ts,
+-                basic_string_view<Char> format_str,
+-                basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+-  bool has_style = false;
++void vformat_to(buffer<Char>& buf, text_style ts, basic_string_view<Char> fmt,
++                basic_format_args<buffered_context<Char>> args) {
+   if (ts.has_emphasis()) {
+-    has_style = true;
+-    auto emphasis = detail::make_emphasis<Char>(ts.get_emphasis());
++    auto emphasis = make_emphasis<Char>(ts.get_emphasis());
+     buf.append(emphasis.begin(), emphasis.end());
+   }
+   if (ts.has_foreground()) {
+-    has_style = true;
+-    auto foreground = detail::make_foreground_color<Char>(ts.get_foreground());
++    auto foreground = make_foreground_color<Char>(ts.get_foreground());
+     buf.append(foreground.begin(), foreground.end());
+   }
+   if (ts.has_background()) {
+-    has_style = true;
+-    auto background = detail::make_background_color<Char>(ts.get_background());
++    auto background = make_background_color<Char>(ts.get_background());
+     buf.append(background.begin(), background.end());
+   }
+-  detail::vformat_to(buf, format_str, args, {});
+-  if (has_style) detail::reset_color<Char>(buf);
++  vformat_to(buf, fmt, args);
++  if (ts != text_style()) reset_color<Char>(buf);
+ }
++}  // namespace detail
+ 
+-FMT_END_DETAIL_NAMESPACE
+-
+-inline void vprint(std::FILE* f, const text_style& ts, string_view fmt,
+-                   format_args args) {
+-  // Legacy wide streams are not supported.
++inline void vprint(FILE* f, text_style ts, string_view fmt, format_args args) {
+   auto buf = memory_buffer();
+   detail::vformat_to(buf, ts, fmt, args);
+-  if (detail::is_utf8()) {
+-    detail::print(f, string_view(buf.begin(), buf.size()));
+-    return;
+-  }
+-  buf.push_back('\0');
+-  int result = std::fputs(buf.data(), f);
+-  if (result < 0)
+-    FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
++  print(f, FMT_STRING("{}"), string_view(buf.begin(), buf.size()));
+ }
+ 
+ /**
+-  \rst
+-  Formats a string and prints it to the specified file stream using ANSI
+-  escape sequences to specify text formatting.
+-
+-  **Example**::
+-
+-    fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
+-               "Elapsed time: {0:.2f} seconds", 1.23);
+-  \endrst
++ * Formats a string and prints it to the specified file stream using ANSI
++ * escape sequences to specify text formatting.
++ *
++ * **Example**:
++ *
++ *     fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
++ *                "Elapsed time: {0:.2f} seconds", 1.23);
+  */
+-template <typename S, typename... Args,
+-          FMT_ENABLE_IF(detail::is_string<S>::value)>
+-void print(std::FILE* f, const text_style& ts, const S& format_str,
+-           const Args&... args) {
+-  vprint(f, ts, format_str,
+-         fmt::make_format_args<buffer_context<char_t<S>>>(args...));
++template <typename... T>
++void print(FILE* f, text_style ts, format_string<T...> fmt, T&&... args) {
++  vprint(f, ts, fmt.str, vargs<T...>{{args...}});
+ }
+ 
+ /**
+-  \rst
+-  Formats a string and prints it to stdout using ANSI escape sequences to
+-  specify text formatting.
+-
+-  **Example**::
+-
+-    fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
+-               "Elapsed time: {0:.2f} seconds", 1.23);
+-  \endrst
++ * Formats a string and prints it to stdout using ANSI escape sequences to
++ * specify text formatting.
++ *
++ * **Example**:
++ *
++ *     fmt::print(fmt::emphasis::bold | fg(fmt::color::red),
++ *                "Elapsed time: {0:.2f} seconds", 1.23);
+  */
+-template <typename S, typename... Args,
+-          FMT_ENABLE_IF(detail::is_string<S>::value)>
+-void print(const text_style& ts, const S& format_str, const Args&... args) {
+-  return print(stdout, ts, format_str, args...);
++template <typename... T>
++void print(text_style ts, format_string<T...> fmt, T&&... args) {
++  return print(stdout, ts, fmt, std::forward<T>(args)...);
+ }
+ 
+-template <typename S, typename Char = char_t<S>>
+-inline std::basic_string<Char> vformat(
+-    const text_style& ts, const S& format_str,
+-    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+-  basic_memory_buffer<Char> buf;
+-  detail::vformat_to(buf, ts, detail::to_string_view(format_str), args);
++inline auto vformat(text_style ts, string_view fmt, format_args args)
++    -> std::string {
++  auto buf = memory_buffer();
++  detail::vformat_to(buf, ts, fmt, args);
+   return fmt::to_string(buf);
+ }
+ 
+ /**
+-  \rst
+-  Formats arguments and returns the result as a string using ANSI
+-  escape sequences to specify text formatting.
+-
+-  **Example**::
+-
+-    #include <fmt/color.h>
+-    std::string message = fmt::format(fmt::emphasis::bold | fg(fmt::color::red),
+-                                      "The answer is {}", 42);
+-  \endrst
+-*/
+-template <typename S, typename... Args, typename Char = char_t<S>>
+-inline std::basic_string<Char> format(const text_style& ts, const S& format_str,
+-                                      const Args&... args) {
+-  return fmt::vformat(ts, detail::to_string_view(format_str),
+-                      fmt::make_format_args<buffer_context<Char>>(args...));
++ * Formats arguments and returns the result as a string using ANSI escape
++ * sequences to specify text formatting.
++ *
++ * **Example**:
++ *
++ * ```
++ * #include <fmt/color.h>
++ * std::string message = fmt::format(fmt::emphasis::bold | fg(fmt::color::red),
++ *                                   "The answer is {}", 42);
++ * ```
++ */
++template <typename... T>
++inline auto format(text_style ts, format_string<T...> fmt, T&&... args)
++    -> std::string {
++  return fmt::vformat(ts, fmt.str, vargs<T...>{{args...}});
+ }
+ 
+-/**
+-  Formats a string with the given text_style and writes the output to ``out``.
+- */
+-template <typename OutputIt, typename Char,
+-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value)>
+-OutputIt vformat_to(
+-    OutputIt out, const text_style& ts, basic_string_view<Char> format_str,
+-    basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+-  auto&& buf = detail::get_buffer<Char>(out);
+-  detail::vformat_to(buf, ts, format_str, args);
++/// Formats a string with the given text_style and writes the output to `out`.
++template <typename OutputIt,
++          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
++auto vformat_to(OutputIt out, text_style ts, string_view fmt, format_args args)
++    -> OutputIt {
++  auto&& buf = detail::get_buffer<char>(out);
++  detail::vformat_to(buf, ts, fmt, args);
+   return detail::get_iterator(buf, out);
+ }
+ 
+ /**
+-  \rst
+-  Formats arguments with the given text_style, writes the result to the output
+-  iterator ``out`` and returns the iterator past the end of the output range.
+-
+-  **Example**::
+-
+-    std::vector<char> out;
+-    fmt::format_to(std::back_inserter(out),
+-                   fmt::emphasis::bold | fg(fmt::color::red), "{}", 42);
+-  \endrst
+-*/
+-template <typename OutputIt, typename S, typename... Args,
+-          bool enable = detail::is_output_iterator<OutputIt, char_t<S>>::value&&
+-              detail::is_string<S>::value>
+-inline auto format_to(OutputIt out, const text_style& ts, const S& format_str,
+-                      Args&&... args) ->
+-    typename std::enable_if<enable, OutputIt>::type {
+-  return vformat_to(out, ts, detail::to_string_view(format_str),
+-                    fmt::make_format_args<buffer_context<char_t<S>>>(args...));
++ * Formats arguments with the given text style, writes the result to the output
++ * iterator `out` and returns the iterator past the end of the output range.
++ *
++ * **Example**:
++ *
++ *     std::vector<char> out;
++ *     fmt::format_to(std::back_inserter(out),
++ *                    fmt::emphasis::bold | fg(fmt::color::red), "{}", 42);
++ */
++template <typename OutputIt, typename... T,
++          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
++inline auto format_to(OutputIt out, text_style ts, format_string<T...> fmt,
++                      T&&... args) -> OutputIt {
++  return vformat_to(out, ts, fmt.str, vargs<T...>{{args...}});
+ }
+ 
+ template <typename T, typename Char>
+@@ -579,47 +586,44 @@ struct formatter<detail::styled_arg<T>, Char> : formatter<T, Char> {
+   auto format(const detail::styled_arg<T>& arg, FormatContext& ctx) const
+       -> decltype(ctx.out()) {
+     const auto& ts = arg.style;
+-    const auto& value = arg.value;
+     auto out = ctx.out();
+ 
+     bool has_style = false;
+     if (ts.has_emphasis()) {
+       has_style = true;
+       auto emphasis = detail::make_emphasis<Char>(ts.get_emphasis());
+-      out = std::copy(emphasis.begin(), emphasis.end(), out);
++      out = detail::copy<Char>(emphasis.begin(), emphasis.end(), out);
+     }
+     if (ts.has_foreground()) {
+       has_style = true;
+       auto foreground =
+           detail::make_foreground_color<Char>(ts.get_foreground());
+-      out = std::copy(foreground.begin(), foreground.end(), out);
++      out = detail::copy<Char>(foreground.begin(), foreground.end(), out);
+     }
+     if (ts.has_background()) {
+       has_style = true;
+       auto background =
+           detail::make_background_color<Char>(ts.get_background());
+-      out = std::copy(background.begin(), background.end(), out);
++      out = detail::copy<Char>(background.begin(), background.end(), out);
+     }
+-    out = formatter<T, Char>::format(value, ctx);
++    out = formatter<T, Char>::format(arg.value, ctx);
+     if (has_style) {
+       auto reset_color = string_view("\x1b[0m");
+-      out = std::copy(reset_color.begin(), reset_color.end(), out);
++      out = detail::copy<Char>(reset_color.begin(), reset_color.end(), out);
+     }
+     return out;
+   }
+ };
+ 
+ /**
+-  \rst
+-  Returns an argument that will be formatted using ANSI escape sequences,
+-  to be used in a formatting function.
+-
+-  **Example**::
+-
+-    fmt::print("Elapsed time: {0:.2f} seconds",
+-               fmt::styled(1.23, fmt::fg(fmt::color::green) |
+-                                 fmt::bg(fmt::color::blue)));
+-  \endrst
++ * Returns an argument that will be formatted using ANSI escape sequences,
++ * to be used in a formatting function.
++ *
++ * **Example**:
++ *
++ *     fmt::print("Elapsed time: {0:.2f} seconds",
++ *                fmt::styled(1.23, fmt::fg(fmt::color::green) |
++ *                                  fmt::bg(fmt::color::blue)));
+  */
+ template <typename T>
+ FMT_CONSTEXPR auto styled(const T& value, text_style ts)
+diff --git a/include/fmt/compile.h b/include/fmt/compile.h
+index 34a581d..08d9427 100644
+--- a/include/fmt/compile.h
++++ b/include/fmt/compile.h
+@@ -8,134 +8,41 @@
+ #ifndef FMT_COMPILE_H_
+ #define FMT_COMPILE_H_
+ 
++#ifndef FMT_MODULE
++#  include <iterator>  // std::back_inserter
++#endif
++
+ #include "format.h"
+ 
+ FMT_BEGIN_NAMESPACE
+-namespace detail {
+-
+-template <typename Char, typename InputIt>
+-FMT_CONSTEXPR inline counting_iterator copy_str(InputIt begin, InputIt end,
+-                                                counting_iterator it) {
+-  return it + (end - begin);
+-}
+-
+-template <typename OutputIt> class truncating_iterator_base {
+- protected:
+-  OutputIt out_;
+-  size_t limit_;
+-  size_t count_ = 0;
+-
+-  truncating_iterator_base() : out_(), limit_(0) {}
+-
+-  truncating_iterator_base(OutputIt out, size_t limit)
+-      : out_(out), limit_(limit) {}
+-
+- public:
+-  using iterator_category = std::output_iterator_tag;
+-  using value_type = typename std::iterator_traits<OutputIt>::value_type;
+-  using difference_type = std::ptrdiff_t;
+-  using pointer = void;
+-  using reference = void;
+-  FMT_UNCHECKED_ITERATOR(truncating_iterator_base);
+-
+-  OutputIt base() const { return out_; }
+-  size_t count() const { return count_; }
+-};
+-
+-// An output iterator that truncates the output and counts the number of objects
+-// written to it.
+-template <typename OutputIt,
+-          typename Enable = typename std::is_void<
+-              typename std::iterator_traits<OutputIt>::value_type>::type>
+-class truncating_iterator;
+-
+-template <typename OutputIt>
+-class truncating_iterator<OutputIt, std::false_type>
+-    : public truncating_iterator_base<OutputIt> {
+-  mutable typename truncating_iterator_base<OutputIt>::value_type blackhole_;
+-
+- public:
+-  using value_type = typename truncating_iterator_base<OutputIt>::value_type;
+-
+-  truncating_iterator() = default;
+-
+-  truncating_iterator(OutputIt out, size_t limit)
+-      : truncating_iterator_base<OutputIt>(out, limit) {}
+-
+-  truncating_iterator& operator++() {
+-    if (this->count_++ < this->limit_) ++this->out_;
+-    return *this;
+-  }
+-
+-  truncating_iterator operator++(int) {
+-    auto it = *this;
+-    ++*this;
+-    return it;
+-  }
+-
+-  value_type& operator*() const {
+-    return this->count_ < this->limit_ ? *this->out_ : blackhole_;
+-  }
+-};
+-
+-template <typename OutputIt>
+-class truncating_iterator<OutputIt, std::true_type>
+-    : public truncating_iterator_base<OutputIt> {
+- public:
+-  truncating_iterator() = default;
+-
+-  truncating_iterator(OutputIt out, size_t limit)
+-      : truncating_iterator_base<OutputIt>(out, limit) {}
+-
+-  template <typename T> truncating_iterator& operator=(T val) {
+-    if (this->count_++ < this->limit_) *this->out_++ = val;
+-    return *this;
+-  }
+-
+-  truncating_iterator& operator++() { return *this; }
+-  truncating_iterator& operator++(int) { return *this; }
+-  truncating_iterator& operator*() { return *this; }
+-};
+ 
+ // A compile-time string which is compiled into fast formatting code.
+-class compiled_string {};
++FMT_EXPORT class compiled_string {};
+ 
+ template <typename S>
+ struct is_compiled_string : std::is_base_of<compiled_string, S> {};
+ 
+-/**
+-  \rst
+-  Converts a string literal *s* into a format string that will be parsed at
+-  compile time and converted into efficient formatting code. Requires C++17
+-  ``constexpr if`` compiler support.
+-
+-  **Example**::
++namespace detail {
+ 
+-    // Converts 42 into std::string using the most efficient method and no
+-    // runtime format string processing.
+-    std::string s = fmt::format(FMT_COMPILE("{}"), 42);
+-  \endrst
++/**
++ * Converts a string literal `s` into a format string that will be parsed at
++ * compile time and converted into efficient formatting code. Requires C++17
++ * `constexpr if` compiler support.
++ *
++ * **Example**:
++ *
++ *     // Converts 42 into std::string using the most efficient method and no
++ *     // runtime format string processing.
++ *     std::string s = fmt::format(FMT_COMPILE("{}"), 42);
+  */
+ #if defined(__cpp_if_constexpr) && defined(__cpp_return_type_deduction)
+-#  define FMT_COMPILE(s) \
+-    FMT_STRING_IMPL(s, fmt::detail::compiled_string, explicit)
++#  define FMT_COMPILE(s) FMT_STRING_IMPL(s, fmt::compiled_string)
+ #else
+ #  define FMT_COMPILE(s) FMT_STRING(s)
+ #endif
+ 
+-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
+-template <typename Char, size_t N,
+-          fmt::detail_exported::fixed_string<Char, N> Str>
+-struct udl_compiled_string : compiled_string {
+-  using char_type = Char;
+-  explicit constexpr operator basic_string_view<char_type>() const {
+-    return {Str.data, N - 1};
+-  }
+-};
+-#endif
+-
+ template <typename T, typename... Tail>
+-const T& first(const T& value, const Tail&...) {
++auto first(const T& value, const Tail&...) -> const T& {
+   return value;
+ }
+ 
+@@ -153,6 +60,29 @@ constexpr const auto& get([[maybe_unused]] const T& first,
+     return detail::get<N - 1>(rest...);
+ }
+ 
++#  if FMT_USE_NONTYPE_TEMPLATE_ARGS
++template <int N, typename T, typename... Args, typename Char>
++constexpr auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
++  if constexpr (is_static_named_arg<T>()) {
++    if (name == T::name) return N;
++  }
++  if constexpr (sizeof...(Args) > 0)
++    return get_arg_index_by_name<N + 1, Args...>(name);
++  (void)name;  // Workaround an MSVC bug about "unused" parameter.
++  return -1;
++}
++#  endif
++
++template <typename... Args, typename Char>
++FMT_CONSTEXPR auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
++#  if FMT_USE_NONTYPE_TEMPLATE_ARGS
++  if constexpr (sizeof...(Args) > 0)
++    return get_arg_index_by_name<0, Args...>(name);
++#  endif
++  (void)name;
++  return -1;
++}
++
+ template <typename Char, typename... Args>
+ constexpr int get_arg_index_by_name(basic_string_view<Char> name,
+                                     type_list<Args...>) {
+@@ -196,7 +126,8 @@ template <typename Char> struct code_unit {
+ 
+   template <typename OutputIt, typename... Args>
+   constexpr OutputIt format(OutputIt out, const Args&...) const {
+-    return write<Char>(out, value);
++    *out++ = value;
++    return out;
+   }
+ };
+ 
+@@ -220,7 +151,13 @@ template <typename Char, typename T, int N> struct field {
+ 
+   template <typename OutputIt, typename... Args>
+   constexpr OutputIt format(OutputIt out, const Args&... args) const {
+-    return write<Char>(out, get_arg_checked<T, N>(args...));
++    const T& arg = get_arg_checked<T, N>(args...);
++    if constexpr (std::is_convertible<T, basic_string_view<Char>>::value) {
++      auto s = basic_string_view<Char>(arg);
++      return copy<Char>(s.begin(), s.end(), out);
++    } else {
++      return write<Char>(out, arg);
++    }
+   }
+ };
+ 
+@@ -308,13 +245,12 @@ constexpr size_t parse_text(basic_string_view<Char> str, size_t pos) {
+ }
+ 
+ template <typename Args, size_t POS, int ID, typename S>
+-constexpr auto compile_format_string(S format_str);
++constexpr auto compile_format_string(S fmt);
+ 
+ template <typename Args, size_t POS, int ID, typename T, typename S>
+-constexpr auto parse_tail(T head, S format_str) {
+-  if constexpr (POS !=
+-                basic_string_view<typename S::char_type>(format_str).size()) {
+-    constexpr auto tail = compile_format_string<Args, POS, ID>(format_str);
++constexpr auto parse_tail(T head, S fmt) {
++  if constexpr (POS != basic_string_view<typename S::char_type>(fmt).size()) {
++    constexpr auto tail = compile_format_string<Args, POS, ID>(fmt);
+     if constexpr (std::is_same<remove_cvref_t<decltype(tail)>,
+                                unknown_format>())
+       return tail;
+@@ -346,6 +282,7 @@ constexpr parse_specs_result<T, Char> parse_specs(basic_string_view<Char> str,
+ }
+ 
+ template <typename Char> struct arg_id_handler {
++  arg_id_kind kind;
+   arg_ref<Char> arg_id;
+ 
+   constexpr int on_auto() {
+@@ -353,25 +290,28 @@ template <typename Char> struct arg_id_handler {
+     return 0;
+   }
+   constexpr int on_index(int id) {
++    kind = arg_id_kind::index;
+     arg_id = arg_ref<Char>(id);
+     return 0;
+   }
+   constexpr int on_name(basic_string_view<Char> id) {
++    kind = arg_id_kind::name;
+     arg_id = arg_ref<Char>(id);
+     return 0;
+   }
+ };
+ 
+ template <typename Char> struct parse_arg_id_result {
++  arg_id_kind kind;
+   arg_ref<Char> arg_id;
+   const Char* arg_id_end;
+ };
+ 
+ template <int ID, typename Char>
+ constexpr auto parse_arg_id(const Char* begin, const Char* end) {
+-  auto handler = arg_id_handler<Char>{arg_ref<Char>{}};
++  auto handler = arg_id_handler<Char>{arg_id_kind::none, arg_ref<Char>{}};
+   auto arg_id_end = parse_arg_id(begin, end, handler);
+-  return parse_arg_id_result<Char>{handler.arg_id, arg_id_end};
++  return parse_arg_id_result<Char>{handler.kind, handler.arg_id, arg_id_end};
+ }
+ 
+ template <typename T, typename Enable = void> struct field_type {
+@@ -385,14 +325,13 @@ struct field_type<T, enable_if_t<detail::is_named_arg<T>::value>> {
+ 
+ template <typename T, typename Args, size_t END_POS, int ARG_INDEX, int NEXT_ID,
+           typename S>
+-constexpr auto parse_replacement_field_then_tail(S format_str) {
++constexpr auto parse_replacement_field_then_tail(S fmt) {
+   using char_type = typename S::char_type;
+-  constexpr auto str = basic_string_view<char_type>(format_str);
++  constexpr auto str = basic_string_view<char_type>(fmt);
+   constexpr char_type c = END_POS != str.size() ? str[END_POS] : char_type();
+   if constexpr (c == '}') {
+     return parse_tail<Args, END_POS + 1, NEXT_ID>(
+-        field<char_type, typename field_type<T>::type, ARG_INDEX>(),
+-        format_str);
++        field<char_type, typename field_type<T>::type, ARG_INDEX>(), fmt);
+   } else if constexpr (c != ':') {
+     FMT_THROW(format_error("expected ':'"));
+   } else {
+@@ -405,7 +344,7 @@ constexpr auto parse_replacement_field_then_tail(S format_str) {
+       return parse_tail<Args, result.end + 1, result.next_arg_id>(
+           spec_field<char_type, typename field_type<T>::type, ARG_INDEX>{
+               result.fmt},
+-          format_str);
++          fmt);
+     }
+   }
+ }
+@@ -413,22 +352,21 @@ constexpr auto parse_replacement_field_then_tail(S format_str) {
+ // Compiles a non-empty format string and returns the compiled representation
+ // or unknown_format() on unrecognized input.
+ template <typename Args, size_t POS, int ID, typename S>
+-constexpr auto compile_format_string(S format_str) {
++constexpr auto compile_format_string(S fmt) {
+   using char_type = typename S::char_type;
+-  constexpr auto str = basic_string_view<char_type>(format_str);
++  constexpr auto str = basic_string_view<char_type>(fmt);
+   if constexpr (str[POS] == '{') {
+     if constexpr (POS + 1 == str.size())
+       FMT_THROW(format_error("unmatched '{' in format string"));
+     if constexpr (str[POS + 1] == '{') {
+-      return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
++      return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), fmt);
+     } else if constexpr (str[POS + 1] == '}' || str[POS + 1] == ':') {
+       static_assert(ID != manual_indexing_id,
+                     "cannot switch from manual to automatic argument indexing");
+       constexpr auto next_id =
+           ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
+       return parse_replacement_field_then_tail<get_type<ID, Args>, Args,
+-                                               POS + 1, ID, next_id>(
+-          format_str);
++                                               POS + 1, ID, next_id>(fmt);
+     } else {
+       constexpr auto arg_id_result =
+           parse_arg_id<ID>(str.data() + POS + 1, str.data() + str.size());
+@@ -436,28 +374,27 @@ constexpr auto compile_format_string(S format_str) {
+       constexpr char_type c =
+           arg_id_end_pos != str.size() ? str[arg_id_end_pos] : char_type();
+       static_assert(c == '}' || c == ':', "missing '}' in format string");
+-      if constexpr (arg_id_result.arg_id.kind == arg_id_kind::index) {
++      if constexpr (arg_id_result.kind == arg_id_kind::index) {
+         static_assert(
+             ID == manual_indexing_id || ID == 0,
+             "cannot switch from automatic to manual argument indexing");
+-        constexpr auto arg_index = arg_id_result.arg_id.val.index;
++        constexpr auto arg_index = arg_id_result.arg_id.index;
+         return parse_replacement_field_then_tail<get_type<arg_index, Args>,
+                                                  Args, arg_id_end_pos,
+                                                  arg_index, manual_indexing_id>(
+-            format_str);
+-      } else if constexpr (arg_id_result.arg_id.kind == arg_id_kind::name) {
++            fmt);
++      } else if constexpr (arg_id_result.kind == arg_id_kind::name) {
+         constexpr auto arg_index =
+-            get_arg_index_by_name(arg_id_result.arg_id.val.name, Args{});
++            get_arg_index_by_name(arg_id_result.arg_id.name, Args{});
+         if constexpr (arg_index >= 0) {
+           constexpr auto next_id =
+               ID != manual_indexing_id ? ID + 1 : manual_indexing_id;
+           return parse_replacement_field_then_tail<
+               decltype(get_type<arg_index, Args>::value), Args, arg_id_end_pos,
+-              arg_index, next_id>(format_str);
++              arg_index, next_id>(fmt);
+         } else if constexpr (c == '}') {
+           return parse_tail<Args, arg_id_end_pos + 1, ID>(
+-              runtime_named_field<char_type>{arg_id_result.arg_id.val.name},
+-              format_str);
++              runtime_named_field<char_type>{arg_id_result.arg_id.name}, fmt);
+         } else if constexpr (c == ':') {
+           return unknown_format();  // no type info for specs parsing
+         }
+@@ -466,29 +403,26 @@ constexpr auto compile_format_string(S format_str) {
+   } else if constexpr (str[POS] == '}') {
+     if constexpr (POS + 1 == str.size())
+       FMT_THROW(format_error("unmatched '}' in format string"));
+-    return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), format_str);
++    return parse_tail<Args, POS + 2, ID>(make_text(str, POS, 1), fmt);
+   } else {
+     constexpr auto end = parse_text(str, POS + 1);
+     if constexpr (end - POS > 1) {
+-      return parse_tail<Args, end, ID>(make_text(str, POS, end - POS),
+-                                       format_str);
++      return parse_tail<Args, end, ID>(make_text(str, POS, end - POS), fmt);
+     } else {
+-      return parse_tail<Args, end, ID>(code_unit<char_type>{str[POS]},
+-                                       format_str);
++      return parse_tail<Args, end, ID>(code_unit<char_type>{str[POS]}, fmt);
+     }
+   }
+ }
+ 
+ template <typename... Args, typename S,
+-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+-constexpr auto compile(S format_str) {
+-  constexpr auto str = basic_string_view<typename S::char_type>(format_str);
++          FMT_ENABLE_IF(is_compiled_string<S>::value)>
++constexpr auto compile(S fmt) {
++  constexpr auto str = basic_string_view<typename S::char_type>(fmt);
+   if constexpr (str.size() == 0) {
+     return detail::make_text(str, 0, 0);
+   } else {
+     constexpr auto result =
+-        detail::compile_format_string<detail::type_list<Args...>, 0, 0>(
+-            format_str);
++        detail::compile_format_string<detail::type_list<Args...>, 0, 0>(fmt);
+     return result;
+   }
+ }
+@@ -517,7 +451,7 @@ constexpr FMT_INLINE OutputIt format_to(OutputIt out, const CompiledFormat& cf,
+ }
+ 
+ template <typename S, typename... Args,
+-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
++          FMT_ENABLE_IF(is_compiled_string<S>::value)>
+ FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
+                                                            Args&&... args) {
+   if constexpr (std::is_same<typename S::char_type, char>::value) {
+@@ -544,7 +478,7 @@ FMT_INLINE std::basic_string<typename S::char_type> format(const S&,
+ }
+ 
+ template <typename OutputIt, typename S, typename... Args,
+-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
++          FMT_ENABLE_IF(is_compiled_string<S>::value)>
+ FMT_CONSTEXPR OutputIt format_to(OutputIt out, const S&, Args&&... args) {
+   constexpr auto compiled = detail::compile<Args...>(S());
+   if constexpr (std::is_same<remove_cvref_t<decltype(compiled)>,
+@@ -559,42 +493,42 @@ FMT_CONSTEXPR OutputIt format_to(OutputIt out, const S&, Args&&... args) {
+ #endif
+ 
+ template <typename OutputIt, typename S, typename... Args,
+-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+-format_to_n_result<OutputIt> format_to_n(OutputIt out, size_t n,
+-                                         const S& format_str, Args&&... args) {
+-  auto it = fmt::format_to(detail::truncating_iterator<OutputIt>(out, n),
+-                           format_str, std::forward<Args>(args)...);
+-  return {it.base(), it.count()};
++          FMT_ENABLE_IF(is_compiled_string<S>::value)>
++auto format_to_n(OutputIt out, size_t n, const S& fmt, Args&&... args)
++    -> format_to_n_result<OutputIt> {
++  using traits = detail::fixed_buffer_traits;
++  auto buf = detail::iterator_buffer<OutputIt, char, traits>(out, n);
++  fmt::format_to(std::back_inserter(buf), fmt, std::forward<Args>(args)...);
++  return {buf.out(), buf.count()};
+ }
+ 
+ template <typename S, typename... Args,
+-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+-FMT_CONSTEXPR20 size_t formatted_size(const S& format_str,
+-                                      const Args&... args) {
+-  return fmt::format_to(detail::counting_iterator(), format_str, args...)
+-      .count();
++          FMT_ENABLE_IF(is_compiled_string<S>::value)>
++FMT_CONSTEXPR20 auto formatted_size(const S& fmt, const Args&... args)
++    -> size_t {
++  auto buf = detail::counting_buffer<>();
++  fmt::format_to(appender(buf), fmt, args...);
++  return buf.count();
+ }
+ 
+ template <typename S, typename... Args,
+-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+-void print(std::FILE* f, const S& format_str, const Args&... args) {
+-  memory_buffer buffer;
+-  fmt::format_to(std::back_inserter(buffer), format_str, args...);
+-  detail::print(f, {buffer.data(), buffer.size()});
++          FMT_ENABLE_IF(is_compiled_string<S>::value)>
++void print(std::FILE* f, const S& fmt, const Args&... args) {
++  auto buf = memory_buffer();
++  fmt::format_to(appender(buf), fmt, args...);
++  detail::print(f, {buf.data(), buf.size()});
+ }
+ 
+ template <typename S, typename... Args,
+-          FMT_ENABLE_IF(detail::is_compiled_string<S>::value)>
+-void print(const S& format_str, const Args&... args) {
+-  print(stdout, format_str, args...);
++          FMT_ENABLE_IF(is_compiled_string<S>::value)>
++void print(const S& fmt, const Args&... args) {
++  print(stdout, fmt, args...);
+ }
+ 
+ #if FMT_USE_NONTYPE_TEMPLATE_ARGS
+ inline namespace literals {
+-template <detail_exported::fixed_string Str> constexpr auto operator""_cf() {
+-  using char_t = remove_cvref_t<decltype(Str.data[0])>;
+-  return detail::udl_compiled_string<char_t, sizeof(Str.data) / sizeof(char_t),
+-                                     Str>();
++template <detail::fixed_string Str> constexpr auto operator""_cf() {
++  return FMT_COMPILE(Str.data);
+ }
+ }  // namespace literals
+ #endif
+diff --git a/include/fmt/core.h b/include/fmt/core.h
+index 4c31964..8ca735f 100644
+--- a/include/fmt/core.h
++++ b/include/fmt/core.h
+@@ -1,2905 +1,5 @@
+-// Formatting library for C++ - the core API for char/UTF-8
+-//
+-// Copyright (c) 2012 - present, Victor Zverovich
+-// All rights reserved.
+-//
+-// For the license information refer to format.h.
++// This file is only provided for compatibility and may be removed in future
++// versions. Use fmt/base.h if you don't need fmt::format and fmt/format.h
++// otherwise.
+ 
+-#ifndef FMT_CORE_H_
+-#define FMT_CORE_H_
+-
+-#include <cstddef>  // std::byte
+-#include <cstdio>   // std::FILE
+-#include <cstring>  // std::strlen
+-#include <iterator>
+-#include <limits>
+-#include <string>
+-#include <type_traits>
+-
+-// The fmt library version in the form major * 10000 + minor * 100 + patch.
+-#define FMT_VERSION 100001
+-
+-#if defined(__clang__) && !defined(__ibmxl__)
+-#  define FMT_CLANG_VERSION (__clang_major__ * 100 + __clang_minor__)
+-#else
+-#  define FMT_CLANG_VERSION 0
+-#endif
+-
+-#if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER) && \
+-    !defined(__NVCOMPILER)
+-#  define FMT_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
+-#else
+-#  define FMT_GCC_VERSION 0
+-#endif
+-
+-#ifndef FMT_GCC_PRAGMA
+-// Workaround _Pragma bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59884.
+-#  if FMT_GCC_VERSION >= 504
+-#    define FMT_GCC_PRAGMA(arg) _Pragma(arg)
+-#  else
+-#    define FMT_GCC_PRAGMA(arg)
+-#  endif
+-#endif
+-
+-#ifdef __ICL
+-#  define FMT_ICC_VERSION __ICL
+-#elif defined(__INTEL_COMPILER)
+-#  define FMT_ICC_VERSION __INTEL_COMPILER
+-#else
+-#  define FMT_ICC_VERSION 0
+-#endif
+-
+-#ifdef _MSC_VER
+-#  define FMT_MSC_VERSION _MSC_VER
+-#  define FMT_MSC_WARNING(...) __pragma(warning(__VA_ARGS__))
+-#else
+-#  define FMT_MSC_VERSION 0
+-#  define FMT_MSC_WARNING(...)
+-#endif
+-
+-#ifdef _MSVC_LANG
+-#  define FMT_CPLUSPLUS _MSVC_LANG
+-#else
+-#  define FMT_CPLUSPLUS __cplusplus
+-#endif
+-
+-#ifdef __has_feature
+-#  define FMT_HAS_FEATURE(x) __has_feature(x)
+-#else
+-#  define FMT_HAS_FEATURE(x) 0
+-#endif
+-
+-#if defined(__has_include) || FMT_ICC_VERSION >= 1600 || FMT_MSC_VERSION > 1900
+-#  define FMT_HAS_INCLUDE(x) __has_include(x)
+-#else
+-#  define FMT_HAS_INCLUDE(x) 0
+-#endif
+-
+-#ifdef __has_cpp_attribute
+-#  define FMT_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
+-#else
+-#  define FMT_HAS_CPP_ATTRIBUTE(x) 0
+-#endif
+-
+-#define FMT_HAS_CPP14_ATTRIBUTE(attribute) \
+-  (FMT_CPLUSPLUS >= 201402L && FMT_HAS_CPP_ATTRIBUTE(attribute))
+-
+-#define FMT_HAS_CPP17_ATTRIBUTE(attribute) \
+-  (FMT_CPLUSPLUS >= 201703L && FMT_HAS_CPP_ATTRIBUTE(attribute))
+-
+-// Check if relaxed C++14 constexpr is supported.
+-// GCC doesn't allow throw in constexpr until version 6 (bug 67371).
+-#ifndef FMT_USE_CONSTEXPR
+-#  if (FMT_HAS_FEATURE(cxx_relaxed_constexpr) || FMT_MSC_VERSION >= 1912 || \
+-       (FMT_GCC_VERSION >= 600 && FMT_CPLUSPLUS >= 201402L)) &&             \
+-      !FMT_ICC_VERSION && !defined(__NVCC__)
+-#    define FMT_USE_CONSTEXPR 1
+-#  else
+-#    define FMT_USE_CONSTEXPR 0
+-#  endif
+-#endif
+-#if FMT_USE_CONSTEXPR
+-#  define FMT_CONSTEXPR constexpr
+-#else
+-#  define FMT_CONSTEXPR
+-#endif
+-
+-#if ((FMT_CPLUSPLUS >= 202002L) &&                            \
+-     (!defined(_GLIBCXX_RELEASE) || _GLIBCXX_RELEASE > 9)) || \
+-    (FMT_CPLUSPLUS >= 201709L && FMT_GCC_VERSION >= 1002)
+-#  define FMT_CONSTEXPR20 constexpr
+-#else
+-#  define FMT_CONSTEXPR20
+-#endif
+-
+-// Check if constexpr std::char_traits<>::{compare,length} are supported.
+-#if defined(__GLIBCXX__)
+-#  if FMT_CPLUSPLUS >= 201703L && defined(_GLIBCXX_RELEASE) && \
+-      _GLIBCXX_RELEASE >= 7  // GCC 7+ libstdc++ has _GLIBCXX_RELEASE.
+-#    define FMT_CONSTEXPR_CHAR_TRAITS constexpr
+-#  endif
+-#elif defined(_LIBCPP_VERSION) && FMT_CPLUSPLUS >= 201703L && \
+-    _LIBCPP_VERSION >= 4000
+-#  define FMT_CONSTEXPR_CHAR_TRAITS constexpr
+-#elif FMT_MSC_VERSION >= 1914 && FMT_CPLUSPLUS >= 201703L
+-#  define FMT_CONSTEXPR_CHAR_TRAITS constexpr
+-#endif
+-#ifndef FMT_CONSTEXPR_CHAR_TRAITS
+-#  define FMT_CONSTEXPR_CHAR_TRAITS
+-#endif
+-
+-// Check if exceptions are disabled.
+-#ifndef FMT_EXCEPTIONS
+-#  if (defined(__GNUC__) && !defined(__EXCEPTIONS)) || \
+-      (FMT_MSC_VERSION && !_HAS_EXCEPTIONS)
+-#    define FMT_EXCEPTIONS 0
+-#  else
+-#    define FMT_EXCEPTIONS 1
+-#  endif
+-#endif
+-
+-// Disable [[noreturn]] on MSVC/NVCC because of bogus unreachable code warnings.
+-#if FMT_EXCEPTIONS && FMT_HAS_CPP_ATTRIBUTE(noreturn) && !FMT_MSC_VERSION && \
+-    !defined(__NVCC__)
+-#  define FMT_NORETURN [[noreturn]]
+-#else
+-#  define FMT_NORETURN
+-#endif
+-
+-#ifndef FMT_NODISCARD
+-#  if FMT_HAS_CPP17_ATTRIBUTE(nodiscard)
+-#    define FMT_NODISCARD [[nodiscard]]
+-#  else
+-#    define FMT_NODISCARD
+-#  endif
+-#endif
+-
+-#ifndef FMT_INLINE
+-#  if FMT_GCC_VERSION || FMT_CLANG_VERSION
+-#    define FMT_INLINE inline __attribute__((always_inline))
+-#  else
+-#    define FMT_INLINE inline
+-#  endif
+-#endif
+-
+-#ifdef _MSC_VER
+-#  define FMT_UNCHECKED_ITERATOR(It) \
+-    using _Unchecked_type = It  // Mark iterator as checked.
+-#else
+-#  define FMT_UNCHECKED_ITERATOR(It) using unchecked_type = It
+-#endif
+-
+-#ifndef FMT_BEGIN_NAMESPACE
+-#  define FMT_BEGIN_NAMESPACE \
+-    namespace fmt {           \
+-    inline namespace v10 {
+-#  define FMT_END_NAMESPACE \
+-    }                       \
+-    }
+-#endif
+-
+-#ifndef FMT_EXPORT
+-#  define FMT_EXPORT
+-#  define FMT_BEGIN_EXPORT
+-#  define FMT_END_EXPORT
+-#endif
+-
+-#if !defined(FMT_HEADER_ONLY) && defined(_WIN32)
+-#  ifdef FMT_LIB_EXPORT
+-#    define FMT_API __declspec(dllexport)
+-#  elif defined(FMT_SHARED)
+-#    define FMT_API __declspec(dllimport)
+-#  endif
+-#else
+-#  if defined(FMT_LIB_EXPORT) || defined(FMT_SHARED)
+-#    if defined(__GNUC__) || defined(__clang__)
+-#      define FMT_API __attribute__((visibility("default")))
+-#    endif
+-#  endif
+-#endif
+-#ifndef FMT_API
+-#  define FMT_API
+-#endif
+-
+-// libc++ supports string_view in pre-c++17.
+-#if FMT_HAS_INCLUDE(<string_view>) && \
+-    (FMT_CPLUSPLUS >= 201703L || defined(_LIBCPP_VERSION))
+-#  include <string_view>
+-#  define FMT_USE_STRING_VIEW
+-#elif FMT_HAS_INCLUDE("experimental/string_view") && FMT_CPLUSPLUS >= 201402L
+-#  include <experimental/string_view>
+-#  define FMT_USE_EXPERIMENTAL_STRING_VIEW
+-#endif
+-
+-#ifndef FMT_UNICODE
+-#  define FMT_UNICODE !FMT_MSC_VERSION
+-#endif
+-
+-#ifndef FMT_CONSTEVAL
+-#  if ((FMT_GCC_VERSION >= 1000 || FMT_CLANG_VERSION >= 1101) && \
+-       (!defined(__apple_build_version__) ||                     \
+-        __apple_build_version__ >= 14000029L) &&                 \
+-       FMT_CPLUSPLUS >= 202002L) ||                              \
+-      (defined(__cpp_consteval) &&                               \
+-       (!FMT_MSC_VERSION || _MSC_FULL_VER >= 193030704))
+-// consteval is broken in MSVC before VS2022 and Apple clang before 14.
+-#    define FMT_CONSTEVAL consteval
+-#    define FMT_HAS_CONSTEVAL
+-#  else
+-#    define FMT_CONSTEVAL
+-#  endif
+-#endif
+-
+-#ifndef FMT_USE_NONTYPE_TEMPLATE_ARGS
+-#  if defined(__cpp_nontype_template_args) &&                  \
+-      ((FMT_GCC_VERSION >= 903 && FMT_CPLUSPLUS >= 201709L) || \
+-       __cpp_nontype_template_args >= 201911L) &&              \
+-      !defined(__NVCOMPILER) && !defined(__LCC__)
+-#    define FMT_USE_NONTYPE_TEMPLATE_ARGS 1
+-#  else
+-#    define FMT_USE_NONTYPE_TEMPLATE_ARGS 0
+-#  endif
+-#endif
+-
+-// Enable minimal optimizations for more compact code in debug mode.
+-FMT_GCC_PRAGMA("GCC push_options")
+-#if !defined(__OPTIMIZE__) && !defined(__NVCOMPILER) && !defined(__LCC__) && \
+-    !defined(__CUDACC__)
+-FMT_GCC_PRAGMA("GCC optimize(\"Og\")")
+-#endif
+-
+-FMT_BEGIN_NAMESPACE
+-
+-// Implementations of enable_if_t and other metafunctions for older systems.
+-template <bool B, typename T = void>
+-using enable_if_t = typename std::enable_if<B, T>::type;
+-template <bool B, typename T, typename F>
+-using conditional_t = typename std::conditional<B, T, F>::type;
+-template <bool B> using bool_constant = std::integral_constant<bool, B>;
+-template <typename T>
+-using remove_reference_t = typename std::remove_reference<T>::type;
+-template <typename T>
+-using remove_const_t = typename std::remove_const<T>::type;
+-template <typename T>
+-using remove_cvref_t = typename std::remove_cv<remove_reference_t<T>>::type;
+-template <typename T> struct type_identity { using type = T; };
+-template <typename T> using type_identity_t = typename type_identity<T>::type;
+-template <typename T>
+-using underlying_t = typename std::underlying_type<T>::type;
+-
+-// Checks whether T is a container with contiguous storage.
+-template <typename T> struct is_contiguous : std::false_type {};
+-template <typename Char>
+-struct is_contiguous<std::basic_string<Char>> : std::true_type {};
+-
+-struct monostate {
+-  constexpr monostate() {}
+-};
+-
+-// An enable_if helper to be used in template parameters which results in much
+-// shorter symbols: https://godbolt.org/z/sWw4vP. Extra parentheses are needed
+-// to workaround a bug in MSVC 2019 (see #1140 and #1186).
+-#ifdef FMT_DOC
+-#  define FMT_ENABLE_IF(...)
+-#else
+-#  define FMT_ENABLE_IF(...) fmt::enable_if_t<(__VA_ARGS__), int> = 0
+-#endif
+-
+-// This is defined in core.h instead of format.h to avoid injecting in std.
+-#ifdef __cpp_lib_byte
+-inline auto format_as(std::byte b) -> unsigned char {
+-  return static_cast<unsigned char>(b);
+-}
+-#endif
+-
+-namespace detail {
+-// Suppresses "unused variable" warnings with the method described in
+-// https://herbsutter.com/2009/10/18/mailbag-shutting-up-compiler-warnings/.
+-// (void)var does not work on many Intel compilers.
+-template <typename... T> FMT_CONSTEXPR void ignore_unused(const T&...) {}
+-
+-constexpr FMT_INLINE auto is_constant_evaluated(
+-    bool default_value = false) noexcept -> bool {
+-// Workaround for incompatibility between libstdc++ consteval-based
+-// std::is_constant_evaluated() implementation and clang-14.
+-// https://github.com/fmtlib/fmt/issues/3247
+-#if FMT_CPLUSPLUS >= 202002L && defined(_GLIBCXX_RELEASE) && \
+-    _GLIBCXX_RELEASE >= 12 &&                                \
+-    (FMT_CLANG_VERSION >= 1400 && FMT_CLANG_VERSION < 1500)
+-  ignore_unused(default_value);
+-  return __builtin_is_constant_evaluated();
+-#elif defined(__cpp_lib_is_constant_evaluated)
+-  ignore_unused(default_value);
+-  return std::is_constant_evaluated();
+-#else
+-  return default_value;
+-#endif
+-}
+-
+-// Suppresses "conditional expression is constant" warnings.
+-template <typename T> constexpr FMT_INLINE auto const_check(T value) -> T {
+-  return value;
+-}
+-
+-FMT_NORETURN FMT_API void assert_fail(const char* file, int line,
+-                                      const char* message);
+-
+-#ifndef FMT_ASSERT
+-#  ifdef NDEBUG
+-// FMT_ASSERT is not empty to avoid -Wempty-body.
+-#    define FMT_ASSERT(condition, message) \
+-      fmt::detail::ignore_unused((condition), (message))
+-#  else
+-#    define FMT_ASSERT(condition, message)                                    \
+-      ((condition) /* void() fails with -Winvalid-constexpr on clang 4.0.1 */ \
+-           ? (void)0                                                          \
+-           : fmt::detail::assert_fail(__FILE__, __LINE__, (message)))
+-#  endif
+-#endif
+-
+-#if defined(FMT_USE_STRING_VIEW)
+-template <typename Char> using std_string_view = std::basic_string_view<Char>;
+-#elif defined(FMT_USE_EXPERIMENTAL_STRING_VIEW)
+-template <typename Char>
+-using std_string_view = std::experimental::basic_string_view<Char>;
+-#else
+-template <typename T> struct std_string_view {};
+-#endif
+-
+-#ifdef FMT_USE_INT128
+-// Do nothing.
+-#elif defined(__SIZEOF_INT128__) && !defined(__NVCC__) && \
+-    !(FMT_CLANG_VERSION && FMT_MSC_VERSION)
+-#  define FMT_USE_INT128 1
+-using int128_opt = __int128_t;  // An optional native 128-bit integer.
+-using uint128_opt = __uint128_t;
+-template <typename T> inline auto convert_for_visit(T value) -> T {
+-  return value;
+-}
+-#else
+-#  define FMT_USE_INT128 0
+-#endif
+-#if !FMT_USE_INT128
+-enum class int128_opt {};
+-enum class uint128_opt {};
+-// Reduce template instantiations.
+-template <typename T> auto convert_for_visit(T) -> monostate { return {}; }
+-#endif
+-
+-// Casts a nonnegative integer to unsigned.
+-template <typename Int>
+-FMT_CONSTEXPR auto to_unsigned(Int value) ->
+-    typename std::make_unsigned<Int>::type {
+-  FMT_ASSERT(std::is_unsigned<Int>::value || value >= 0, "negative value");
+-  return static_cast<typename std::make_unsigned<Int>::type>(value);
+-}
+-
+-FMT_CONSTEXPR inline auto is_utf8() -> bool {
+-  FMT_MSC_WARNING(suppress : 4566) constexpr unsigned char section[] = "\u00A7";
+-
+-  // Avoid buggy sign extensions in MSVC's constant evaluation mode (#2297).
+-  using uchar = unsigned char;
+-  return FMT_UNICODE || (sizeof(section) == 3 && uchar(section[0]) == 0xC2 &&
+-                         uchar(section[1]) == 0xA7);
+-}
+-}  // namespace detail
+-
+-/**
+-  An implementation of ``std::basic_string_view`` for pre-C++17. It provides a
+-  subset of the API. ``fmt::basic_string_view`` is used for format strings even
+-  if ``std::string_view`` is available to prevent issues when a library is
+-  compiled with a different ``-std`` option than the client code (which is not
+-  recommended).
+- */
+-FMT_EXPORT
+-template <typename Char> class basic_string_view {
+- private:
+-  const Char* data_;
+-  size_t size_;
+-
+- public:
+-  using value_type = Char;
+-  using iterator = const Char*;
+-
+-  constexpr basic_string_view() noexcept : data_(nullptr), size_(0) {}
+-
+-  /** Constructs a string reference object from a C string and a size. */
+-  constexpr basic_string_view(const Char* s, size_t count) noexcept
+-      : data_(s), size_(count) {}
+-
+-  /**
+-    \rst
+-    Constructs a string reference object from a C string computing
+-    the size with ``std::char_traits<Char>::length``.
+-    \endrst
+-   */
+-  FMT_CONSTEXPR_CHAR_TRAITS
+-  FMT_INLINE
+-  basic_string_view(const Char* s)
+-      : data_(s),
+-        size_(detail::const_check(std::is_same<Char, char>::value &&
+-                                  !detail::is_constant_evaluated(true))
+-                  ? std::strlen(reinterpret_cast<const char*>(s))
+-                  : std::char_traits<Char>::length(s)) {}
+-
+-  /** Constructs a string reference from a ``std::basic_string`` object. */
+-  template <typename Traits, typename Alloc>
+-  FMT_CONSTEXPR basic_string_view(
+-      const std::basic_string<Char, Traits, Alloc>& s) noexcept
+-      : data_(s.data()), size_(s.size()) {}
+-
+-  template <typename S, FMT_ENABLE_IF(std::is_same<
+-                                      S, detail::std_string_view<Char>>::value)>
+-  FMT_CONSTEXPR basic_string_view(S s) noexcept
+-      : data_(s.data()), size_(s.size()) {}
+-
+-  /** Returns a pointer to the string data. */
+-  constexpr auto data() const noexcept -> const Char* { return data_; }
+-
+-  /** Returns the string size. */
+-  constexpr auto size() const noexcept -> size_t { return size_; }
+-
+-  constexpr auto begin() const noexcept -> iterator { return data_; }
+-  constexpr auto end() const noexcept -> iterator { return data_ + size_; }
+-
+-  constexpr auto operator[](size_t pos) const noexcept -> const Char& {
+-    return data_[pos];
+-  }
+-
+-  FMT_CONSTEXPR void remove_prefix(size_t n) noexcept {
+-    data_ += n;
+-    size_ -= n;
+-  }
+-
+-  FMT_CONSTEXPR_CHAR_TRAITS bool starts_with(
+-      basic_string_view<Char> sv) const noexcept {
+-    return size_ >= sv.size_ &&
+-           std::char_traits<Char>::compare(data_, sv.data_, sv.size_) == 0;
+-  }
+-  FMT_CONSTEXPR_CHAR_TRAITS bool starts_with(Char c) const noexcept {
+-    return size_ >= 1 && std::char_traits<Char>::eq(*data_, c);
+-  }
+-  FMT_CONSTEXPR_CHAR_TRAITS bool starts_with(const Char* s) const {
+-    return starts_with(basic_string_view<Char>(s));
+-  }
+-
+-  // Lexicographically compare this string reference to other.
+-  FMT_CONSTEXPR_CHAR_TRAITS auto compare(basic_string_view other) const -> int {
+-    size_t str_size = size_ < other.size_ ? size_ : other.size_;
+-    int result = std::char_traits<Char>::compare(data_, other.data_, str_size);
+-    if (result == 0)
+-      result = size_ == other.size_ ? 0 : (size_ < other.size_ ? -1 : 1);
+-    return result;
+-  }
+-
+-  FMT_CONSTEXPR_CHAR_TRAITS friend auto operator==(basic_string_view lhs,
+-                                                   basic_string_view rhs)
+-      -> bool {
+-    return lhs.compare(rhs) == 0;
+-  }
+-  friend auto operator!=(basic_string_view lhs, basic_string_view rhs) -> bool {
+-    return lhs.compare(rhs) != 0;
+-  }
+-  friend auto operator<(basic_string_view lhs, basic_string_view rhs) -> bool {
+-    return lhs.compare(rhs) < 0;
+-  }
+-  friend auto operator<=(basic_string_view lhs, basic_string_view rhs) -> bool {
+-    return lhs.compare(rhs) <= 0;
+-  }
+-  friend auto operator>(basic_string_view lhs, basic_string_view rhs) -> bool {
+-    return lhs.compare(rhs) > 0;
+-  }
+-  friend auto operator>=(basic_string_view lhs, basic_string_view rhs) -> bool {
+-    return lhs.compare(rhs) >= 0;
+-  }
+-};
+-
+-FMT_EXPORT
+-using string_view = basic_string_view<char>;
+-
+-/** Specifies if ``T`` is a character type. Can be specialized by users. */
+-FMT_EXPORT
+-template <typename T> struct is_char : std::false_type {};
+-template <> struct is_char<char> : std::true_type {};
+-
+-namespace detail {
+-
+-// A base class for compile-time strings.
+-struct compile_string {};
+-
+-template <typename S>
+-struct is_compile_string : std::is_base_of<compile_string, S> {};
+-
+-template <typename Char, FMT_ENABLE_IF(is_char<Char>::value)>
+-FMT_INLINE auto to_string_view(const Char* s) -> basic_string_view<Char> {
+-  return s;
+-}
+-template <typename Char, typename Traits, typename Alloc>
+-inline auto to_string_view(const std::basic_string<Char, Traits, Alloc>& s)
+-    -> basic_string_view<Char> {
+-  return s;
+-}
+-template <typename Char>
+-constexpr auto to_string_view(basic_string_view<Char> s)
+-    -> basic_string_view<Char> {
+-  return s;
+-}
+-template <typename Char,
+-          FMT_ENABLE_IF(!std::is_empty<std_string_view<Char>>::value)>
+-inline auto to_string_view(std_string_view<Char> s) -> basic_string_view<Char> {
+-  return s;
+-}
+-template <typename S, FMT_ENABLE_IF(is_compile_string<S>::value)>
+-constexpr auto to_string_view(const S& s)
+-    -> basic_string_view<typename S::char_type> {
+-  return basic_string_view<typename S::char_type>(s);
+-}
+-void to_string_view(...);
+-
+-// Specifies whether S is a string type convertible to fmt::basic_string_view.
+-// It should be a constexpr function but MSVC 2017 fails to compile it in
+-// enable_if and MSVC 2015 fails to compile it as an alias template.
+-// ADL is intentionally disabled as to_string_view is not an extension point.
+-template <typename S>
+-struct is_string
+-    : std::is_class<decltype(detail::to_string_view(std::declval<S>()))> {};
+-
+-template <typename S, typename = void> struct char_t_impl {};
+-template <typename S> struct char_t_impl<S, enable_if_t<is_string<S>::value>> {
+-  using result = decltype(to_string_view(std::declval<S>()));
+-  using type = typename result::value_type;
+-};
+-
+-enum class type {
+-  none_type,
+-  // Integer types should go first,
+-  int_type,
+-  uint_type,
+-  long_long_type,
+-  ulong_long_type,
+-  int128_type,
+-  uint128_type,
+-  bool_type,
+-  char_type,
+-  last_integer_type = char_type,
+-  // followed by floating-point types.
+-  float_type,
+-  double_type,
+-  long_double_type,
+-  last_numeric_type = long_double_type,
+-  cstring_type,
+-  string_type,
+-  pointer_type,
+-  custom_type
+-};
+-
+-// Maps core type T to the corresponding type enum constant.
+-template <typename T, typename Char>
+-struct type_constant : std::integral_constant<type, type::custom_type> {};
+-
+-#define FMT_TYPE_CONSTANT(Type, constant) \
+-  template <typename Char>                \
+-  struct type_constant<Type, Char>        \
+-      : std::integral_constant<type, type::constant> {}
+-
+-FMT_TYPE_CONSTANT(int, int_type);
+-FMT_TYPE_CONSTANT(unsigned, uint_type);
+-FMT_TYPE_CONSTANT(long long, long_long_type);
+-FMT_TYPE_CONSTANT(unsigned long long, ulong_long_type);
+-FMT_TYPE_CONSTANT(int128_opt, int128_type);
+-FMT_TYPE_CONSTANT(uint128_opt, uint128_type);
+-FMT_TYPE_CONSTANT(bool, bool_type);
+-FMT_TYPE_CONSTANT(Char, char_type);
+-FMT_TYPE_CONSTANT(float, float_type);
+-FMT_TYPE_CONSTANT(double, double_type);
+-FMT_TYPE_CONSTANT(long double, long_double_type);
+-FMT_TYPE_CONSTANT(const Char*, cstring_type);
+-FMT_TYPE_CONSTANT(basic_string_view<Char>, string_type);
+-FMT_TYPE_CONSTANT(const void*, pointer_type);
+-
+-constexpr bool is_integral_type(type t) {
+-  return t > type::none_type && t <= type::last_integer_type;
+-}
+-constexpr bool is_arithmetic_type(type t) {
+-  return t > type::none_type && t <= type::last_numeric_type;
+-}
+-
+-constexpr auto set(type rhs) -> int { return 1 << static_cast<int>(rhs); }
+-constexpr auto in(type t, int set) -> bool {
+-  return ((set >> static_cast<int>(t)) & 1) != 0;
+-}
+-
+-// Bitsets of types.
+-enum {
+-  sint_set =
+-      set(type::int_type) | set(type::long_long_type) | set(type::int128_type),
+-  uint_set = set(type::uint_type) | set(type::ulong_long_type) |
+-             set(type::uint128_type),
+-  bool_set = set(type::bool_type),
+-  char_set = set(type::char_type),
+-  float_set = set(type::float_type) | set(type::double_type) |
+-              set(type::long_double_type),
+-  string_set = set(type::string_type),
+-  cstring_set = set(type::cstring_type),
+-  pointer_set = set(type::pointer_type)
+-};
+-
+-FMT_NORETURN FMT_API void throw_format_error(const char* message);
+-
+-struct error_handler {
+-  constexpr error_handler() = default;
+-
+-  // This function is intentionally not constexpr to give a compile-time error.
+-  FMT_NORETURN void on_error(const char* message) {
+-    throw_format_error(message);
+-  }
+-};
+-}  // namespace detail
+-
+-/** String's character type. */
+-template <typename S> using char_t = typename detail::char_t_impl<S>::type;
+-
+-/**
+-  \rst
+-  Parsing context consisting of a format string range being parsed and an
+-  argument counter for automatic indexing.
+-  You can use the ``format_parse_context`` type alias for ``char`` instead.
+-  \endrst
+- */
+-FMT_EXPORT
+-template <typename Char> class basic_format_parse_context {
+- private:
+-  basic_string_view<Char> format_str_;
+-  int next_arg_id_;
+-
+-  FMT_CONSTEXPR void do_check_arg_id(int id);
+-
+- public:
+-  using char_type = Char;
+-  using iterator = const Char*;
+-
+-  explicit constexpr basic_format_parse_context(
+-      basic_string_view<Char> format_str, int next_arg_id = 0)
+-      : format_str_(format_str), next_arg_id_(next_arg_id) {}
+-
+-  /**
+-    Returns an iterator to the beginning of the format string range being
+-    parsed.
+-   */
+-  constexpr auto begin() const noexcept -> iterator {
+-    return format_str_.begin();
+-  }
+-
+-  /**
+-    Returns an iterator past the end of the format string range being parsed.
+-   */
+-  constexpr auto end() const noexcept -> iterator { return format_str_.end(); }
+-
+-  /** Advances the begin iterator to ``it``. */
+-  FMT_CONSTEXPR void advance_to(iterator it) {
+-    format_str_.remove_prefix(detail::to_unsigned(it - begin()));
+-  }
+-
+-  /**
+-    Reports an error if using the manual argument indexing; otherwise returns
+-    the next argument index and switches to the automatic indexing.
+-   */
+-  FMT_CONSTEXPR auto next_arg_id() -> int {
+-    if (next_arg_id_ < 0) {
+-      detail::throw_format_error(
+-          "cannot switch from manual to automatic argument indexing");
+-      return 0;
+-    }
+-    int id = next_arg_id_++;
+-    do_check_arg_id(id);
+-    return id;
+-  }
+-
+-  /**
+-    Reports an error if using the automatic argument indexing; otherwise
+-    switches to the manual indexing.
+-   */
+-  FMT_CONSTEXPR void check_arg_id(int id) {
+-    if (next_arg_id_ > 0) {
+-      detail::throw_format_error(
+-          "cannot switch from automatic to manual argument indexing");
+-      return;
+-    }
+-    next_arg_id_ = -1;
+-    do_check_arg_id(id);
+-  }
+-  FMT_CONSTEXPR void check_arg_id(basic_string_view<Char>) {}
+-  FMT_CONSTEXPR void check_dynamic_spec(int arg_id);
+-};
+-
+-FMT_EXPORT
+-using format_parse_context = basic_format_parse_context<char>;
+-
+-namespace detail {
+-// A parse context with extra data used only in compile-time checks.
+-template <typename Char>
+-class compile_parse_context : public basic_format_parse_context<Char> {
+- private:
+-  int num_args_;
+-  const type* types_;
+-  using base = basic_format_parse_context<Char>;
+-
+- public:
+-  explicit FMT_CONSTEXPR compile_parse_context(
+-      basic_string_view<Char> format_str, int num_args, const type* types,
+-      int next_arg_id = 0)
+-      : base(format_str, next_arg_id), num_args_(num_args), types_(types) {}
+-
+-  constexpr auto num_args() const -> int { return num_args_; }
+-  constexpr auto arg_type(int id) const -> type { return types_[id]; }
+-
+-  FMT_CONSTEXPR auto next_arg_id() -> int {
+-    int id = base::next_arg_id();
+-    if (id >= num_args_) throw_format_error("argument not found");
+-    return id;
+-  }
+-
+-  FMT_CONSTEXPR void check_arg_id(int id) {
+-    base::check_arg_id(id);
+-    if (id >= num_args_) throw_format_error("argument not found");
+-  }
+-  using base::check_arg_id;
+-
+-  FMT_CONSTEXPR void check_dynamic_spec(int arg_id) {
+-    detail::ignore_unused(arg_id);
+-#if !defined(__LCC__)
+-    if (arg_id < num_args_ && types_ && !is_integral_type(types_[arg_id]))
+-      throw_format_error("width/precision is not integer");
+-#endif
+-  }
+-};
+-
+-// Extracts a reference to the container from back_insert_iterator.
+-template <typename Container>
+-inline auto get_container(std::back_insert_iterator<Container> it)
+-    -> Container& {
+-  using base = std::back_insert_iterator<Container>;
+-  struct accessor : base {
+-    accessor(base b) : base(b) {}
+-    using base::container;
+-  };
+-  return *accessor(it).container;
+-}
+-
+-template <typename Char, typename InputIt, typename OutputIt>
+-FMT_CONSTEXPR auto copy_str(InputIt begin, InputIt end, OutputIt out)
+-    -> OutputIt {
+-  while (begin != end) *out++ = static_cast<Char>(*begin++);
+-  return out;
+-}
+-
+-template <typename Char, typename T, typename U,
+-          FMT_ENABLE_IF(
+-              std::is_same<remove_const_t<T>, U>::value&& is_char<U>::value)>
+-FMT_CONSTEXPR auto copy_str(T* begin, T* end, U* out) -> U* {
+-  if (is_constant_evaluated()) return copy_str<Char, T*, U*>(begin, end, out);
+-  auto size = to_unsigned(end - begin);
+-  if (size > 0) memcpy(out, begin, size * sizeof(U));
+-  return out + size;
+-}
+-
+-/**
+-  \rst
+-  A contiguous memory buffer with an optional growing ability. It is an internal
+-  class and shouldn't be used directly, only via `~fmt::basic_memory_buffer`.
+-  \endrst
+- */
+-template <typename T> class buffer {
+- private:
+-  T* ptr_;
+-  size_t size_;
+-  size_t capacity_;
+-
+- protected:
+-  // Don't initialize ptr_ since it is not accessed to save a few cycles.
+-  FMT_MSC_WARNING(suppress : 26495)
+-  buffer(size_t sz) noexcept : size_(sz), capacity_(sz) {}
+-
+-  FMT_CONSTEXPR20 buffer(T* p = nullptr, size_t sz = 0, size_t cap = 0) noexcept
+-      : ptr_(p), size_(sz), capacity_(cap) {}
+-
+-  FMT_CONSTEXPR20 ~buffer() = default;
+-  buffer(buffer&&) = default;
+-
+-  /** Sets the buffer data and capacity. */
+-  FMT_CONSTEXPR void set(T* buf_data, size_t buf_capacity) noexcept {
+-    ptr_ = buf_data;
+-    capacity_ = buf_capacity;
+-  }
+-
+-  /** Increases the buffer capacity to hold at least *capacity* elements. */
+-  virtual FMT_CONSTEXPR20 void grow(size_t capacity) = 0;
+-
+- public:
+-  using value_type = T;
+-  using const_reference = const T&;
+-
+-  buffer(const buffer&) = delete;
+-  void operator=(const buffer&) = delete;
+-
+-  FMT_INLINE auto begin() noexcept -> T* { return ptr_; }
+-  FMT_INLINE auto end() noexcept -> T* { return ptr_ + size_; }
+-
+-  FMT_INLINE auto begin() const noexcept -> const T* { return ptr_; }
+-  FMT_INLINE auto end() const noexcept -> const T* { return ptr_ + size_; }
+-
+-  /** Returns the size of this buffer. */
+-  constexpr auto size() const noexcept -> size_t { return size_; }
+-
+-  /** Returns the capacity of this buffer. */
+-  constexpr auto capacity() const noexcept -> size_t { return capacity_; }
+-
+-  /** Returns a pointer to the buffer data. */
+-  FMT_CONSTEXPR auto data() noexcept -> T* { return ptr_; }
+-
+-  /** Returns a pointer to the buffer data. */
+-  FMT_CONSTEXPR auto data() const noexcept -> const T* { return ptr_; }
+-
+-  /** Clears this buffer. */
+-  void clear() { size_ = 0; }
+-
+-  // Tries resizing the buffer to contain *count* elements. If T is a POD type
+-  // the new elements may not be initialized.
+-  FMT_CONSTEXPR20 void try_resize(size_t count) {
+-    try_reserve(count);
+-    size_ = count <= capacity_ ? count : capacity_;
+-  }
+-
+-  // Tries increasing the buffer capacity to *new_capacity*. It can increase the
+-  // capacity by a smaller amount than requested but guarantees there is space
+-  // for at least one additional element either by increasing the capacity or by
+-  // flushing the buffer if it is full.
+-  FMT_CONSTEXPR20 void try_reserve(size_t new_capacity) {
+-    if (new_capacity > capacity_) grow(new_capacity);
+-  }
+-
+-  FMT_CONSTEXPR20 void push_back(const T& value) {
+-    try_reserve(size_ + 1);
+-    ptr_[size_++] = value;
+-  }
+-
+-  /** Appends data to the end of the buffer. */
+-  template <typename U> void append(const U* begin, const U* end);
+-
+-  template <typename Idx> FMT_CONSTEXPR auto operator[](Idx index) -> T& {
+-    return ptr_[index];
+-  }
+-  template <typename Idx>
+-  FMT_CONSTEXPR auto operator[](Idx index) const -> const T& {
+-    return ptr_[index];
+-  }
+-};
+-
+-struct buffer_traits {
+-  explicit buffer_traits(size_t) {}
+-  auto count() const -> size_t { return 0; }
+-  auto limit(size_t size) -> size_t { return size; }
+-};
+-
+-class fixed_buffer_traits {
+- private:
+-  size_t count_ = 0;
+-  size_t limit_;
+-
+- public:
+-  explicit fixed_buffer_traits(size_t limit) : limit_(limit) {}
+-  auto count() const -> size_t { return count_; }
+-  auto limit(size_t size) -> size_t {
+-    size_t n = limit_ > count_ ? limit_ - count_ : 0;
+-    count_ += size;
+-    return size < n ? size : n;
+-  }
+-};
+-
+-// A buffer that writes to an output iterator when flushed.
+-template <typename OutputIt, typename T, typename Traits = buffer_traits>
+-class iterator_buffer final : public Traits, public buffer<T> {
+- private:
+-  OutputIt out_;
+-  enum { buffer_size = 256 };
+-  T data_[buffer_size];
+-
+- protected:
+-  FMT_CONSTEXPR20 void grow(size_t) override {
+-    if (this->size() == buffer_size) flush();
+-  }
+-
+-  void flush() {
+-    auto size = this->size();
+-    this->clear();
+-    out_ = copy_str<T>(data_, data_ + this->limit(size), out_);
+-  }
+-
+- public:
+-  explicit iterator_buffer(OutputIt out, size_t n = buffer_size)
+-      : Traits(n), buffer<T>(data_, 0, buffer_size), out_(out) {}
+-  iterator_buffer(iterator_buffer&& other)
+-      : Traits(other), buffer<T>(data_, 0, buffer_size), out_(other.out_) {}
+-  ~iterator_buffer() { flush(); }
+-
+-  auto out() -> OutputIt {
+-    flush();
+-    return out_;
+-  }
+-  auto count() const -> size_t { return Traits::count() + this->size(); }
+-};
+-
+-template <typename T>
+-class iterator_buffer<T*, T, fixed_buffer_traits> final
+-    : public fixed_buffer_traits,
+-      public buffer<T> {
+- private:
+-  T* out_;
+-  enum { buffer_size = 256 };
+-  T data_[buffer_size];
+-
+- protected:
+-  FMT_CONSTEXPR20 void grow(size_t) override {
+-    if (this->size() == this->capacity()) flush();
+-  }
+-
+-  void flush() {
+-    size_t n = this->limit(this->size());
+-    if (this->data() == out_) {
+-      out_ += n;
+-      this->set(data_, buffer_size);
+-    }
+-    this->clear();
+-  }
+-
+- public:
+-  explicit iterator_buffer(T* out, size_t n = buffer_size)
+-      : fixed_buffer_traits(n), buffer<T>(out, 0, n), out_(out) {}
+-  iterator_buffer(iterator_buffer&& other)
+-      : fixed_buffer_traits(other),
+-        buffer<T>(std::move(other)),
+-        out_(other.out_) {
+-    if (this->data() != out_) {
+-      this->set(data_, buffer_size);
+-      this->clear();
+-    }
+-  }
+-  ~iterator_buffer() { flush(); }
+-
+-  auto out() -> T* {
+-    flush();
+-    return out_;
+-  }
+-  auto count() const -> size_t {
+-    return fixed_buffer_traits::count() + this->size();
+-  }
+-};
+-
+-template <typename T> class iterator_buffer<T*, T> final : public buffer<T> {
+- protected:
+-  FMT_CONSTEXPR20 void grow(size_t) override {}
+-
+- public:
+-  explicit iterator_buffer(T* out, size_t = 0) : buffer<T>(out, 0, ~size_t()) {}
+-
+-  auto out() -> T* { return &*this->end(); }
+-};
+-
+-// A buffer that writes to a container with the contiguous storage.
+-template <typename Container>
+-class iterator_buffer<std::back_insert_iterator<Container>,
+-                      enable_if_t<is_contiguous<Container>::value,
+-                                  typename Container::value_type>>
+-    final : public buffer<typename Container::value_type> {
+- private:
+-  Container& container_;
+-
+- protected:
+-  FMT_CONSTEXPR20 void grow(size_t capacity) override {
+-    container_.resize(capacity);
+-    this->set(&container_[0], capacity);
+-  }
+-
+- public:
+-  explicit iterator_buffer(Container& c)
+-      : buffer<typename Container::value_type>(c.size()), container_(c) {}
+-  explicit iterator_buffer(std::back_insert_iterator<Container> out, size_t = 0)
+-      : iterator_buffer(get_container(out)) {}
+-
+-  auto out() -> std::back_insert_iterator<Container> {
+-    return std::back_inserter(container_);
+-  }
+-};
+-
+-// A buffer that counts the number of code units written discarding the output.
+-template <typename T = char> class counting_buffer final : public buffer<T> {
+- private:
+-  enum { buffer_size = 256 };
+-  T data_[buffer_size];
+-  size_t count_ = 0;
+-
+- protected:
+-  FMT_CONSTEXPR20 void grow(size_t) override {
+-    if (this->size() != buffer_size) return;
+-    count_ += this->size();
+-    this->clear();
+-  }
+-
+- public:
+-  counting_buffer() : buffer<T>(data_, 0, buffer_size) {}
+-
+-  auto count() -> size_t { return count_ + this->size(); }
+-};
+-}  // namespace detail
+-
+-template <typename Char>
+-FMT_CONSTEXPR void basic_format_parse_context<Char>::do_check_arg_id(int id) {
+-  // Argument id is only checked at compile-time during parsing because
+-  // formatting has its own validation.
+-  if (detail::is_constant_evaluated() &&
+-      (!FMT_GCC_VERSION || FMT_GCC_VERSION >= 1200)) {
+-    using context = detail::compile_parse_context<Char>;
+-    if (id >= static_cast<context*>(this)->num_args())
+-      detail::throw_format_error("argument not found");
+-  }
+-}
+-
+-template <typename Char>
+-FMT_CONSTEXPR void basic_format_parse_context<Char>::check_dynamic_spec(
+-    int arg_id) {
+-  if (detail::is_constant_evaluated() &&
+-      (!FMT_GCC_VERSION || FMT_GCC_VERSION >= 1200)) {
+-    using context = detail::compile_parse_context<Char>;
+-    static_cast<context*>(this)->check_dynamic_spec(arg_id);
+-  }
+-}
+-
+-FMT_EXPORT template <typename Context> class basic_format_arg;
+-FMT_EXPORT template <typename Context> class basic_format_args;
+-FMT_EXPORT template <typename Context> class dynamic_format_arg_store;
+-
+-// A formatter for objects of type T.
+-FMT_EXPORT
+-template <typename T, typename Char = char, typename Enable = void>
+-struct formatter {
+-  // A deleted default constructor indicates a disabled formatter.
+-  formatter() = delete;
+-};
+-
+-// Specifies if T has an enabled formatter specialization. A type can be
+-// formattable even if it doesn't have a formatter e.g. via a conversion.
+-template <typename T, typename Context>
+-using has_formatter =
+-    std::is_constructible<typename Context::template formatter_type<T>>;
+-
+-// An output iterator that appends to a buffer.
+-// It is used to reduce symbol sizes for the common case.
+-class appender : public std::back_insert_iterator<detail::buffer<char>> {
+-  using base = std::back_insert_iterator<detail::buffer<char>>;
+-
+- public:
+-  using std::back_insert_iterator<detail::buffer<char>>::back_insert_iterator;
+-  appender(base it) noexcept : base(it) {}
+-  FMT_UNCHECKED_ITERATOR(appender);
+-
+-  auto operator++() noexcept -> appender& { return *this; }
+-  auto operator++(int) noexcept -> appender { return *this; }
+-};
+-
+-namespace detail {
+-
+-template <typename Context, typename T>
+-constexpr auto has_const_formatter_impl(T*)
+-    -> decltype(typename Context::template formatter_type<T>().format(
+-                    std::declval<const T&>(), std::declval<Context&>()),
+-                true) {
+-  return true;
+-}
+-template <typename Context>
+-constexpr auto has_const_formatter_impl(...) -> bool {
+-  return false;
+-}
+-template <typename T, typename Context>
+-constexpr auto has_const_formatter() -> bool {
+-  return has_const_formatter_impl<Context>(static_cast<T*>(nullptr));
+-}
+-
+-template <typename T>
+-using buffer_appender = conditional_t<std::is_same<T, char>::value, appender,
+-                                      std::back_insert_iterator<buffer<T>>>;
+-
+-// Maps an output iterator to a buffer.
+-template <typename T, typename OutputIt>
+-auto get_buffer(OutputIt out) -> iterator_buffer<OutputIt, T> {
+-  return iterator_buffer<OutputIt, T>(out);
+-}
+-template <typename T, typename Buf,
+-          FMT_ENABLE_IF(std::is_base_of<buffer<char>, Buf>::value)>
+-auto get_buffer(std::back_insert_iterator<Buf> out) -> buffer<char>& {
+-  return get_container(out);
+-}
+-
+-template <typename Buf, typename OutputIt>
+-FMT_INLINE auto get_iterator(Buf& buf, OutputIt) -> decltype(buf.out()) {
+-  return buf.out();
+-}
+-template <typename T, typename OutputIt>
+-auto get_iterator(buffer<T>&, OutputIt out) -> OutputIt {
+-  return out;
+-}
+-
+-struct view {};
+-
+-template <typename Char, typename T> struct named_arg : view {
+-  const Char* name;
+-  const T& value;
+-  named_arg(const Char* n, const T& v) : name(n), value(v) {}
+-};
+-
+-template <typename Char> struct named_arg_info {
+-  const Char* name;
+-  int id;
+-};
+-
+-template <typename T, typename Char, size_t NUM_ARGS, size_t NUM_NAMED_ARGS>
+-struct arg_data {
+-  // args_[0].named_args points to named_args_ to avoid bloating format_args.
+-  // +1 to workaround a bug in gcc 7.5 that causes duplicated-branches warning.
+-  T args_[1 + (NUM_ARGS != 0 ? NUM_ARGS : +1)];
+-  named_arg_info<Char> named_args_[NUM_NAMED_ARGS];
+-
+-  template <typename... U>
+-  arg_data(const U&... init) : args_{T(named_args_, NUM_NAMED_ARGS), init...} {}
+-  arg_data(const arg_data& other) = delete;
+-  auto args() const -> const T* { return args_ + 1; }
+-  auto named_args() -> named_arg_info<Char>* { return named_args_; }
+-};
+-
+-template <typename T, typename Char, size_t NUM_ARGS>
+-struct arg_data<T, Char, NUM_ARGS, 0> {
+-  // +1 to workaround a bug in gcc 7.5 that causes duplicated-branches warning.
+-  T args_[NUM_ARGS != 0 ? NUM_ARGS : +1];
+-
+-  template <typename... U>
+-  FMT_CONSTEXPR FMT_INLINE arg_data(const U&... init) : args_{init...} {}
+-  FMT_CONSTEXPR FMT_INLINE auto args() const -> const T* { return args_; }
+-  FMT_CONSTEXPR FMT_INLINE auto named_args() -> std::nullptr_t {
+-    return nullptr;
+-  }
+-};
+-
+-template <typename Char>
+-inline void init_named_args(named_arg_info<Char>*, int, int) {}
+-
+-template <typename T> struct is_named_arg : std::false_type {};
+-template <typename T> struct is_statically_named_arg : std::false_type {};
+-
+-template <typename T, typename Char>
+-struct is_named_arg<named_arg<Char, T>> : std::true_type {};
+-
+-template <typename Char, typename T, typename... Tail,
+-          FMT_ENABLE_IF(!is_named_arg<T>::value)>
+-void init_named_args(named_arg_info<Char>* named_args, int arg_count,
+-                     int named_arg_count, const T&, const Tail&... args) {
+-  init_named_args(named_args, arg_count + 1, named_arg_count, args...);
+-}
+-
+-template <typename Char, typename T, typename... Tail,
+-          FMT_ENABLE_IF(is_named_arg<T>::value)>
+-void init_named_args(named_arg_info<Char>* named_args, int arg_count,
+-                     int named_arg_count, const T& arg, const Tail&... args) {
+-  named_args[named_arg_count++] = {arg.name, arg_count};
+-  init_named_args(named_args, arg_count + 1, named_arg_count, args...);
+-}
+-
+-template <typename... Args>
+-FMT_CONSTEXPR FMT_INLINE void init_named_args(std::nullptr_t, int, int,
+-                                              const Args&...) {}
+-
+-template <bool B = false> constexpr auto count() -> size_t { return B ? 1 : 0; }
+-template <bool B1, bool B2, bool... Tail> constexpr auto count() -> size_t {
+-  return (B1 ? 1 : 0) + count<B2, Tail...>();
+-}
+-
+-template <typename... Args> constexpr auto count_named_args() -> size_t {
+-  return count<is_named_arg<Args>::value...>();
+-}
+-
+-template <typename... Args>
+-constexpr auto count_statically_named_args() -> size_t {
+-  return count<is_statically_named_arg<Args>::value...>();
+-}
+-
+-struct unformattable {};
+-struct unformattable_char : unformattable {};
+-struct unformattable_pointer : unformattable {};
+-
+-template <typename Char> struct string_value {
+-  const Char* data;
+-  size_t size;
+-};
+-
+-template <typename Char> struct named_arg_value {
+-  const named_arg_info<Char>* data;
+-  size_t size;
+-};
+-
+-template <typename Context> struct custom_value {
+-  using parse_context = typename Context::parse_context_type;
+-  void* value;
+-  void (*format)(void* arg, parse_context& parse_ctx, Context& ctx);
+-};
+-
+-// A formatting argument value.
+-template <typename Context> class value {
+- public:
+-  using char_type = typename Context::char_type;
+-
+-  union {
+-    monostate no_value;
+-    int int_value;
+-    unsigned uint_value;
+-    long long long_long_value;
+-    unsigned long long ulong_long_value;
+-    int128_opt int128_value;
+-    uint128_opt uint128_value;
+-    bool bool_value;
+-    char_type char_value;
+-    float float_value;
+-    double double_value;
+-    long double long_double_value;
+-    const void* pointer;
+-    string_value<char_type> string;
+-    custom_value<Context> custom;
+-    named_arg_value<char_type> named_args;
+-  };
+-
+-  constexpr FMT_INLINE value() : no_value() {}
+-  constexpr FMT_INLINE value(int val) : int_value(val) {}
+-  constexpr FMT_INLINE value(unsigned val) : uint_value(val) {}
+-  constexpr FMT_INLINE value(long long val) : long_long_value(val) {}
+-  constexpr FMT_INLINE value(unsigned long long val) : ulong_long_value(val) {}
+-  FMT_INLINE value(int128_opt val) : int128_value(val) {}
+-  FMT_INLINE value(uint128_opt val) : uint128_value(val) {}
+-  constexpr FMT_INLINE value(float val) : float_value(val) {}
+-  constexpr FMT_INLINE value(double val) : double_value(val) {}
+-  FMT_INLINE value(long double val) : long_double_value(val) {}
+-  constexpr FMT_INLINE value(bool val) : bool_value(val) {}
+-  constexpr FMT_INLINE value(char_type val) : char_value(val) {}
+-  FMT_CONSTEXPR FMT_INLINE value(const char_type* val) {
+-    string.data = val;
+-    if (is_constant_evaluated()) string.size = {};
+-  }
+-  FMT_CONSTEXPR FMT_INLINE value(basic_string_view<char_type> val) {
+-    string.data = val.data();
+-    string.size = val.size();
+-  }
+-  FMT_INLINE value(const void* val) : pointer(val) {}
+-  FMT_INLINE value(const named_arg_info<char_type>* args, size_t size)
+-      : named_args{args, size} {}
+-
+-  template <typename T> FMT_CONSTEXPR FMT_INLINE value(T& val) {
+-    using value_type = remove_const_t<T>;
+-    custom.value = const_cast<value_type*>(&val);
+-    // Get the formatter type through the context to allow different contexts
+-    // have different extension points, e.g. `formatter<T>` for `format` and
+-    // `printf_formatter<T>` for `printf`.
+-    custom.format = format_custom_arg<
+-        value_type, typename Context::template formatter_type<value_type>>;
+-  }
+-  value(unformattable);
+-  value(unformattable_char);
+-  value(unformattable_pointer);
+-
+- private:
+-  // Formats an argument of a custom type, such as a user-defined class.
+-  template <typename T, typename Formatter>
+-  static void format_custom_arg(void* arg,
+-                                typename Context::parse_context_type& parse_ctx,
+-                                Context& ctx) {
+-    auto f = Formatter();
+-    parse_ctx.advance_to(f.parse(parse_ctx));
+-    using qualified_type =
+-        conditional_t<has_const_formatter<T, Context>(), const T, T>;
+-    ctx.advance_to(f.format(*static_cast<qualified_type*>(arg), ctx));
+-  }
+-};
+-
+-// To minimize the number of types we need to deal with, long is translated
+-// either to int or to long long depending on its size.
+-enum { long_short = sizeof(long) == sizeof(int) };
+-using long_type = conditional_t<long_short, int, long long>;
+-using ulong_type = conditional_t<long_short, unsigned, unsigned long long>;
+-
+-template <typename T> struct format_as_result {
+-  template <typename U,
+-            FMT_ENABLE_IF(std::is_enum<U>::value || std::is_class<U>::value)>
+-  static auto map(U*) -> decltype(format_as(std::declval<U>()));
+-  static auto map(...) -> void;
+-
+-  using type = decltype(map(static_cast<T*>(nullptr)));
+-};
+-template <typename T> using format_as_t = typename format_as_result<T>::type;
+-
+-template <typename T>
+-struct has_format_as
+-    : bool_constant<!std::is_same<format_as_t<T>, void>::value> {};
+-
+-// Maps formatting arguments to core types.
+-// arg_mapper reports errors by returning unformattable instead of using
+-// static_assert because it's used in the is_formattable trait.
+-template <typename Context> struct arg_mapper {
+-  using char_type = typename Context::char_type;
+-
+-  FMT_CONSTEXPR FMT_INLINE auto map(signed char val) -> int { return val; }
+-  FMT_CONSTEXPR FMT_INLINE auto map(unsigned char val) -> unsigned {
+-    return val;
+-  }
+-  FMT_CONSTEXPR FMT_INLINE auto map(short val) -> int { return val; }
+-  FMT_CONSTEXPR FMT_INLINE auto map(unsigned short val) -> unsigned {
+-    return val;
+-  }
+-  FMT_CONSTEXPR FMT_INLINE auto map(int val) -> int { return val; }
+-  FMT_CONSTEXPR FMT_INLINE auto map(unsigned val) -> unsigned { return val; }
+-  FMT_CONSTEXPR FMT_INLINE auto map(long val) -> long_type { return val; }
+-  FMT_CONSTEXPR FMT_INLINE auto map(unsigned long val) -> ulong_type {
+-    return val;
+-  }
+-  FMT_CONSTEXPR FMT_INLINE auto map(long long val) -> long long { return val; }
+-  FMT_CONSTEXPR FMT_INLINE auto map(unsigned long long val)
+-      -> unsigned long long {
+-    return val;
+-  }
+-  FMT_CONSTEXPR FMT_INLINE auto map(int128_opt val) -> int128_opt {
+-    return val;
+-  }
+-  FMT_CONSTEXPR FMT_INLINE auto map(uint128_opt val) -> uint128_opt {
+-    return val;
+-  }
+-  FMT_CONSTEXPR FMT_INLINE auto map(bool val) -> bool { return val; }
+-
+-  template <typename T, FMT_ENABLE_IF(std::is_same<T, char>::value ||
+-                                      std::is_same<T, char_type>::value)>
+-  FMT_CONSTEXPR FMT_INLINE auto map(T val) -> char_type {
+-    return val;
+-  }
+-  template <typename T, enable_if_t<(std::is_same<T, wchar_t>::value ||
+-#ifdef __cpp_char8_t
+-                                     std::is_same<T, char8_t>::value ||
+-#endif
+-                                     std::is_same<T, char16_t>::value ||
+-                                     std::is_same<T, char32_t>::value) &&
+-                                        !std::is_same<T, char_type>::value,
+-                                    int> = 0>
+-  FMT_CONSTEXPR FMT_INLINE auto map(T) -> unformattable_char {
+-    return {};
+-  }
+-
+-  FMT_CONSTEXPR FMT_INLINE auto map(float val) -> float { return val; }
+-  FMT_CONSTEXPR FMT_INLINE auto map(double val) -> double { return val; }
+-  FMT_CONSTEXPR FMT_INLINE auto map(long double val) -> long double {
+-    return val;
+-  }
+-
+-  FMT_CONSTEXPR FMT_INLINE auto map(char_type* val) -> const char_type* {
+-    return val;
+-  }
+-  FMT_CONSTEXPR FMT_INLINE auto map(const char_type* val) -> const char_type* {
+-    return val;
+-  }
+-  template <typename T,
+-            FMT_ENABLE_IF(is_string<T>::value && !std::is_pointer<T>::value &&
+-                          std::is_same<char_type, char_t<T>>::value)>
+-  FMT_CONSTEXPR FMT_INLINE auto map(const T& val)
+-      -> basic_string_view<char_type> {
+-    return to_string_view(val);
+-  }
+-  template <typename T,
+-            FMT_ENABLE_IF(is_string<T>::value && !std::is_pointer<T>::value &&
+-                          !std::is_same<char_type, char_t<T>>::value)>
+-  FMT_CONSTEXPR FMT_INLINE auto map(const T&) -> unformattable_char {
+-    return {};
+-  }
+-
+-  FMT_CONSTEXPR FMT_INLINE auto map(void* val) -> const void* { return val; }
+-  FMT_CONSTEXPR FMT_INLINE auto map(const void* val) -> const void* {
+-    return val;
+-  }
+-  FMT_CONSTEXPR FMT_INLINE auto map(std::nullptr_t val) -> const void* {
+-    return val;
+-  }
+-
+-  // Use SFINAE instead of a const T* parameter to avoid a conflict with the
+-  // array overload.
+-  template <
+-      typename T,
+-      FMT_ENABLE_IF(
+-          std::is_pointer<T>::value || std::is_member_pointer<T>::value ||
+-          std::is_function<typename std::remove_pointer<T>::type>::value ||
+-          (std::is_convertible<const T&, const void*>::value &&
+-           !std::is_convertible<const T&, const char_type*>::value &&
+-           !has_formatter<T, Context>::value))>
+-  FMT_CONSTEXPR auto map(const T&) -> unformattable_pointer {
+-    return {};
+-  }
+-
+-  template <typename T, std::size_t N,
+-            FMT_ENABLE_IF(!std::is_same<T, wchar_t>::value)>
+-  FMT_CONSTEXPR FMT_INLINE auto map(const T (&values)[N]) -> const T (&)[N] {
+-    return values;
+-  }
+-
+-  // Only map owning types because mapping views can be unsafe.
+-  template <typename T, typename U = format_as_t<T>,
+-            FMT_ENABLE_IF(std::is_arithmetic<U>::value)>
+-  FMT_CONSTEXPR FMT_INLINE auto map(const T& val) -> decltype(this->map(U())) {
+-    return map(format_as(val));
+-  }
+-
+-  template <typename T, typename U = remove_const_t<T>>
+-  struct formattable : bool_constant<has_const_formatter<U, Context>() ||
+-                                     (has_formatter<U, Context>::value &&
+-                                      !std::is_const<T>::value)> {};
+-
+-  template <typename T, FMT_ENABLE_IF(formattable<T>::value)>
+-  FMT_CONSTEXPR FMT_INLINE auto do_map(T& val) -> T& {
+-    return val;
+-  }
+-  template <typename T, FMT_ENABLE_IF(!formattable<T>::value)>
+-  FMT_CONSTEXPR FMT_INLINE auto do_map(T&) -> unformattable {
+-    return {};
+-  }
+-
+-  template <typename T, typename U = remove_const_t<T>,
+-            FMT_ENABLE_IF((std::is_class<U>::value || std::is_enum<U>::value ||
+-                           std::is_union<U>::value) &&
+-                          !is_string<U>::value && !is_char<U>::value &&
+-                          !is_named_arg<U>::value &&
+-                          !std::is_arithmetic<format_as_t<U>>::value)>
+-  FMT_CONSTEXPR FMT_INLINE auto map(T& val) -> decltype(this->do_map(val)) {
+-    return do_map(val);
+-  }
+-
+-  template <typename T, FMT_ENABLE_IF(is_named_arg<T>::value)>
+-  FMT_CONSTEXPR FMT_INLINE auto map(const T& named_arg)
+-      -> decltype(this->map(named_arg.value)) {
+-    return map(named_arg.value);
+-  }
+-
+-  auto map(...) -> unformattable { return {}; }
+-};
+-
+-// A type constant after applying arg_mapper<Context>.
+-template <typename T, typename Context>
+-using mapped_type_constant =
+-    type_constant<decltype(arg_mapper<Context>().map(std::declval<const T&>())),
+-                  typename Context::char_type>;
+-
+-enum { packed_arg_bits = 4 };
+-// Maximum number of arguments with packed types.
+-enum { max_packed_args = 62 / packed_arg_bits };
+-enum : unsigned long long { is_unpacked_bit = 1ULL << 63 };
+-enum : unsigned long long { has_named_args_bit = 1ULL << 62 };
+-
+-template <typename Char, typename InputIt>
+-auto copy_str(InputIt begin, InputIt end, appender out) -> appender {
+-  get_container(out).append(begin, end);
+-  return out;
+-}
+-
+-template <typename Char, typename R, typename OutputIt>
+-FMT_CONSTEXPR auto copy_str(R&& rng, OutputIt out) -> OutputIt {
+-  return detail::copy_str<Char>(rng.begin(), rng.end(), out);
+-}
+-
+-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 500
+-// A workaround for gcc 4.8 to make void_t work in a SFINAE context.
+-template <typename...> struct void_t_impl { using type = void; };
+-template <typename... T> using void_t = typename void_t_impl<T...>::type;
+-#else
+-template <typename...> using void_t = void;
+-#endif
+-
+-template <typename It, typename T, typename Enable = void>
+-struct is_output_iterator : std::false_type {};
+-
+-template <typename It, typename T>
+-struct is_output_iterator<
+-    It, T,
+-    void_t<typename std::iterator_traits<It>::iterator_category,
+-           decltype(*std::declval<It>() = std::declval<T>())>>
+-    : std::true_type {};
+-
+-template <typename It> struct is_back_insert_iterator : std::false_type {};
+-template <typename Container>
+-struct is_back_insert_iterator<std::back_insert_iterator<Container>>
+-    : std::true_type {};
+-
+-// A type-erased reference to an std::locale to avoid a heavy <locale> include.
+-class locale_ref {
+- private:
+-  const void* locale_;  // A type-erased pointer to std::locale.
+-
+- public:
+-  constexpr FMT_INLINE locale_ref() : locale_(nullptr) {}
+-  template <typename Locale> explicit locale_ref(const Locale& loc);
+-
+-  explicit operator bool() const noexcept { return locale_ != nullptr; }
+-
+-  template <typename Locale> auto get() const -> Locale;
+-};
+-
+-template <typename> constexpr auto encode_types() -> unsigned long long {
+-  return 0;
+-}
+-
+-template <typename Context, typename Arg, typename... Args>
+-constexpr auto encode_types() -> unsigned long long {
+-  return static_cast<unsigned>(mapped_type_constant<Arg, Context>::value) |
+-         (encode_types<Context, Args...>() << packed_arg_bits);
+-}
+-
+-template <bool PACKED, typename Context, typename T, FMT_ENABLE_IF(PACKED)>
+-FMT_CONSTEXPR FMT_INLINE auto make_arg(T& val) -> value<Context> {
+-  using arg_type = remove_cvref_t<decltype(arg_mapper<Context>().map(val))>;
+-
+-  constexpr bool formattable_char =
+-      !std::is_same<arg_type, unformattable_char>::value;
+-  static_assert(formattable_char, "Mixing character types is disallowed.");
+-
+-  // Formatting of arbitrary pointers is disallowed. If you want to format a
+-  // pointer cast it to `void*` or `const void*`. In particular, this forbids
+-  // formatting of `[const] volatile char*` printed as bool by iostreams.
+-  constexpr bool formattable_pointer =
+-      !std::is_same<arg_type, unformattable_pointer>::value;
+-  static_assert(formattable_pointer,
+-                "Formatting of non-void pointers is disallowed.");
+-
+-  constexpr bool formattable = !std::is_same<arg_type, unformattable>::value;
+-  static_assert(
+-      formattable,
+-      "Cannot format an argument. To make type T formattable provide a "
+-      "formatter<T> specialization: https://fmt.dev/latest/api.html#udt");
+-  return {arg_mapper<Context>().map(val)};
+-}
+-
+-template <typename Context, typename T>
+-FMT_CONSTEXPR auto make_arg(T& val) -> basic_format_arg<Context> {
+-  auto arg = basic_format_arg<Context>();
+-  arg.type_ = mapped_type_constant<T, Context>::value;
+-  arg.value_ = make_arg<true, Context>(val);
+-  return arg;
+-}
+-
+-template <bool PACKED, typename Context, typename T, FMT_ENABLE_IF(!PACKED)>
+-FMT_CONSTEXPR inline auto make_arg(T& val) -> basic_format_arg<Context> {
+-  return make_arg<Context>(val);
+-}
+-}  // namespace detail
+-FMT_BEGIN_EXPORT
+-
+-// A formatting argument. It is a trivially copyable/constructible type to
+-// allow storage in basic_memory_buffer.
+-template <typename Context> class basic_format_arg {
+- private:
+-  detail::value<Context> value_;
+-  detail::type type_;
+-
+-  template <typename ContextType, typename T>
+-  friend FMT_CONSTEXPR auto detail::make_arg(T& value)
+-      -> basic_format_arg<ContextType>;
+-
+-  template <typename Visitor, typename Ctx>
+-  friend FMT_CONSTEXPR auto visit_format_arg(Visitor&& vis,
+-                                             const basic_format_arg<Ctx>& arg)
+-      -> decltype(vis(0));
+-
+-  friend class basic_format_args<Context>;
+-  friend class dynamic_format_arg_store<Context>;
+-
+-  using char_type = typename Context::char_type;
+-
+-  template <typename T, typename Char, size_t NUM_ARGS, size_t NUM_NAMED_ARGS>
+-  friend struct detail::arg_data;
+-
+-  basic_format_arg(const detail::named_arg_info<char_type>* args, size_t size)
+-      : value_(args, size) {}
+-
+- public:
+-  class handle {
+-   public:
+-    explicit handle(detail::custom_value<Context> custom) : custom_(custom) {}
+-
+-    void format(typename Context::parse_context_type& parse_ctx,
+-                Context& ctx) const {
+-      custom_.format(custom_.value, parse_ctx, ctx);
+-    }
+-
+-   private:
+-    detail::custom_value<Context> custom_;
+-  };
+-
+-  constexpr basic_format_arg() : type_(detail::type::none_type) {}
+-
+-  constexpr explicit operator bool() const noexcept {
+-    return type_ != detail::type::none_type;
+-  }
+-
+-  auto type() const -> detail::type { return type_; }
+-
+-  auto is_integral() const -> bool { return detail::is_integral_type(type_); }
+-  auto is_arithmetic() const -> bool {
+-    return detail::is_arithmetic_type(type_);
+-  }
+-};
+-
+-/**
+-  \rst
+-  Visits an argument dispatching to the appropriate visit method based on
+-  the argument type. For example, if the argument type is ``double`` then
+-  ``vis(value)`` will be called with the value of type ``double``.
+-  \endrst
+- */
+-FMT_EXPORT
+-template <typename Visitor, typename Context>
+-FMT_CONSTEXPR FMT_INLINE auto visit_format_arg(
+-    Visitor&& vis, const basic_format_arg<Context>& arg) -> decltype(vis(0)) {
+-  switch (arg.type_) {
+-  case detail::type::none_type:
+-    break;
+-  case detail::type::int_type:
+-    return vis(arg.value_.int_value);
+-  case detail::type::uint_type:
+-    return vis(arg.value_.uint_value);
+-  case detail::type::long_long_type:
+-    return vis(arg.value_.long_long_value);
+-  case detail::type::ulong_long_type:
+-    return vis(arg.value_.ulong_long_value);
+-  case detail::type::int128_type:
+-    return vis(detail::convert_for_visit(arg.value_.int128_value));
+-  case detail::type::uint128_type:
+-    return vis(detail::convert_for_visit(arg.value_.uint128_value));
+-  case detail::type::bool_type:
+-    return vis(arg.value_.bool_value);
+-  case detail::type::char_type:
+-    return vis(arg.value_.char_value);
+-  case detail::type::float_type:
+-    return vis(arg.value_.float_value);
+-  case detail::type::double_type:
+-    return vis(arg.value_.double_value);
+-  case detail::type::long_double_type:
+-    return vis(arg.value_.long_double_value);
+-  case detail::type::cstring_type:
+-    return vis(arg.value_.string.data);
+-  case detail::type::string_type:
+-    using sv = basic_string_view<typename Context::char_type>;
+-    return vis(sv(arg.value_.string.data, arg.value_.string.size));
+-  case detail::type::pointer_type:
+-    return vis(arg.value_.pointer);
+-  case detail::type::custom_type:
+-    return vis(typename basic_format_arg<Context>::handle(arg.value_.custom));
+-  }
+-  return vis(monostate());
+-}
+-
+-// Formatting context.
+-template <typename OutputIt, typename Char> class basic_format_context {
+- private:
+-  OutputIt out_;
+-  basic_format_args<basic_format_context> args_;
+-  detail::locale_ref loc_;
+-
+- public:
+-  using iterator = OutputIt;
+-  using format_arg = basic_format_arg<basic_format_context>;
+-  using format_args = basic_format_args<basic_format_context>;
+-  using parse_context_type = basic_format_parse_context<Char>;
+-  template <typename T> using formatter_type = formatter<T, Char>;
+-
+-  /** The character type for the output. */
+-  using char_type = Char;
+-
+-  basic_format_context(basic_format_context&&) = default;
+-  basic_format_context(const basic_format_context&) = delete;
+-  void operator=(const basic_format_context&) = delete;
+-  /**
+-    Constructs a ``basic_format_context`` object. References to the arguments
+-    are stored in the object so make sure they have appropriate lifetimes.
+-   */
+-  constexpr basic_format_context(OutputIt out, format_args ctx_args,
+-                                 detail::locale_ref loc = {})
+-      : out_(out), args_(ctx_args), loc_(loc) {}
+-
+-  constexpr auto arg(int id) const -> format_arg { return args_.get(id); }
+-  FMT_CONSTEXPR auto arg(basic_string_view<Char> name) -> format_arg {
+-    return args_.get(name);
+-  }
+-  FMT_CONSTEXPR auto arg_id(basic_string_view<Char> name) -> int {
+-    return args_.get_id(name);
+-  }
+-  auto args() const -> const format_args& { return args_; }
+-
+-  FMT_CONSTEXPR auto error_handler() -> detail::error_handler { return {}; }
+-  void on_error(const char* message) { error_handler().on_error(message); }
+-
+-  // Returns an iterator to the beginning of the output range.
+-  FMT_CONSTEXPR auto out() -> iterator { return out_; }
+-
+-  // Advances the begin iterator to ``it``.
+-  void advance_to(iterator it) {
+-    if (!detail::is_back_insert_iterator<iterator>()) out_ = it;
+-  }
+-
+-  FMT_CONSTEXPR auto locale() -> detail::locale_ref { return loc_; }
+-};
+-
+-template <typename Char>
+-using buffer_context =
+-    basic_format_context<detail::buffer_appender<Char>, Char>;
+-using format_context = buffer_context<char>;
+-
+-template <typename T, typename Char = char>
+-using is_formattable = bool_constant<!std::is_base_of<
+-    detail::unformattable, decltype(detail::arg_mapper<buffer_context<Char>>()
+-                                        .map(std::declval<T&>()))>::value>;
+-
+-/**
+-  \rst
+-  An array of references to arguments. It can be implicitly converted into
+-  `~fmt::basic_format_args` for passing into type-erased formatting functions
+-  such as `~fmt::vformat`.
+-  \endrst
+- */
+-template <typename Context, typename... Args>
+-class format_arg_store
+-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+-    // Workaround a GCC template argument substitution bug.
+-    : public basic_format_args<Context>
+-#endif
+-{
+- private:
+-  static const size_t num_args = sizeof...(Args);
+-  static constexpr size_t num_named_args = detail::count_named_args<Args...>();
+-  static const bool is_packed = num_args <= detail::max_packed_args;
+-
+-  using value_type = conditional_t<is_packed, detail::value<Context>,
+-                                   basic_format_arg<Context>>;
+-
+-  detail::arg_data<value_type, typename Context::char_type, num_args,
+-                   num_named_args>
+-      data_;
+-
+-  friend class basic_format_args<Context>;
+-
+-  static constexpr unsigned long long desc =
+-      (is_packed ? detail::encode_types<Context, Args...>()
+-                 : detail::is_unpacked_bit | num_args) |
+-      (num_named_args != 0
+-           ? static_cast<unsigned long long>(detail::has_named_args_bit)
+-           : 0);
+-
+- public:
+-  template <typename... T>
+-  FMT_CONSTEXPR FMT_INLINE format_arg_store(T&... args)
+-      :
+-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+-        basic_format_args<Context>(*this),
+-#endif
+-        data_{detail::make_arg<is_packed, Context>(args)...} {
+-    if (num_named_args != 0)
+-      detail::init_named_args(data_.named_args(), 0, 0, args...);
+-  }
+-};
+-
+-/**
+-  \rst
+-  Constructs a `~fmt::format_arg_store` object that contains references to
+-  arguments and can be implicitly converted to `~fmt::format_args`. `Context`
+-  can be omitted in which case it defaults to `~fmt::format_context`.
+-  See `~fmt::arg` for lifetime considerations.
+-  \endrst
+- */
+-// Arguments are taken by lvalue references to avoid some lifetime issues.
+-template <typename Context = format_context, typename... T>
+-constexpr auto make_format_args(T&... args)
+-    -> format_arg_store<Context, remove_cvref_t<T>...> {
+-  return {args...};
+-}
+-
+-/**
+-  \rst
+-  Returns a named argument to be used in a formatting function.
+-  It should only be used in a call to a formatting function or
+-  `dynamic_format_arg_store::push_back`.
+-
+-  **Example**::
+-
+-    fmt::print("Elapsed time: {s:.2f} seconds", fmt::arg("s", 1.23));
+-  \endrst
+- */
+-template <typename Char, typename T>
+-inline auto arg(const Char* name, const T& arg) -> detail::named_arg<Char, T> {
+-  static_assert(!detail::is_named_arg<T>(), "nested named arguments");
+-  return {name, arg};
+-}
+-FMT_END_EXPORT
+-
+-/**
+-  \rst
+-  A view of a collection of formatting arguments. To avoid lifetime issues it
+-  should only be used as a parameter type in type-erased functions such as
+-  ``vformat``::
+-
+-    void vlog(string_view format_str, format_args args);  // OK
+-    format_args args = make_format_args();  // Error: dangling reference
+-  \endrst
+- */
+-template <typename Context> class basic_format_args {
+- public:
+-  using size_type = int;
+-  using format_arg = basic_format_arg<Context>;
+-
+- private:
+-  // A descriptor that contains information about formatting arguments.
+-  // If the number of arguments is less or equal to max_packed_args then
+-  // argument types are passed in the descriptor. This reduces binary code size
+-  // per formatting function call.
+-  unsigned long long desc_;
+-  union {
+-    // If is_packed() returns true then argument values are stored in values_;
+-    // otherwise they are stored in args_. This is done to improve cache
+-    // locality and reduce compiled code size since storing larger objects
+-    // may require more code (at least on x86-64) even if the same amount of
+-    // data is actually copied to stack. It saves ~10% on the bloat test.
+-    const detail::value<Context>* values_;
+-    const format_arg* args_;
+-  };
+-
+-  constexpr auto is_packed() const -> bool {
+-    return (desc_ & detail::is_unpacked_bit) == 0;
+-  }
+-  auto has_named_args() const -> bool {
+-    return (desc_ & detail::has_named_args_bit) != 0;
+-  }
+-
+-  FMT_CONSTEXPR auto type(int index) const -> detail::type {
+-    int shift = index * detail::packed_arg_bits;
+-    unsigned int mask = (1 << detail::packed_arg_bits) - 1;
+-    return static_cast<detail::type>((desc_ >> shift) & mask);
+-  }
+-
+-  constexpr FMT_INLINE basic_format_args(unsigned long long desc,
+-                                         const detail::value<Context>* values)
+-      : desc_(desc), values_(values) {}
+-  constexpr basic_format_args(unsigned long long desc, const format_arg* args)
+-      : desc_(desc), args_(args) {}
+-
+- public:
+-  constexpr basic_format_args() : desc_(0), args_(nullptr) {}
+-
+-  /**
+-   \rst
+-   Constructs a `basic_format_args` object from `~fmt::format_arg_store`.
+-   \endrst
+-   */
+-  template <typename... Args>
+-  constexpr FMT_INLINE basic_format_args(
+-      const format_arg_store<Context, Args...>& store)
+-      : basic_format_args(format_arg_store<Context, Args...>::desc,
+-                          store.data_.args()) {}
+-
+-  /**
+-   \rst
+-   Constructs a `basic_format_args` object from
+-   `~fmt::dynamic_format_arg_store`.
+-   \endrst
+-   */
+-  constexpr FMT_INLINE basic_format_args(
+-      const dynamic_format_arg_store<Context>& store)
+-      : basic_format_args(store.get_types(), store.data()) {}
+-
+-  /**
+-   \rst
+-   Constructs a `basic_format_args` object from a dynamic set of arguments.
+-   \endrst
+-   */
+-  constexpr basic_format_args(const format_arg* args, int count)
+-      : basic_format_args(detail::is_unpacked_bit | detail::to_unsigned(count),
+-                          args) {}
+-
+-  /** Returns the argument with the specified id. */
+-  FMT_CONSTEXPR auto get(int id) const -> format_arg {
+-    format_arg arg;
+-    if (!is_packed()) {
+-      if (id < max_size()) arg = args_[id];
+-      return arg;
+-    }
+-    if (id >= detail::max_packed_args) return arg;
+-    arg.type_ = type(id);
+-    if (arg.type_ == detail::type::none_type) return arg;
+-    arg.value_ = values_[id];
+-    return arg;
+-  }
+-
+-  template <typename Char>
+-  auto get(basic_string_view<Char> name) const -> format_arg {
+-    int id = get_id(name);
+-    return id >= 0 ? get(id) : format_arg();
+-  }
+-
+-  template <typename Char>
+-  auto get_id(basic_string_view<Char> name) const -> int {
+-    if (!has_named_args()) return -1;
+-    const auto& named_args =
+-        (is_packed() ? values_[-1] : args_[-1].value_).named_args;
+-    for (size_t i = 0; i < named_args.size; ++i) {
+-      if (named_args.data[i].name == name) return named_args.data[i].id;
+-    }
+-    return -1;
+-  }
+-
+-  auto max_size() const -> int {
+-    unsigned long long max_packed = detail::max_packed_args;
+-    return static_cast<int>(is_packed() ? max_packed
+-                                        : desc_ & ~detail::is_unpacked_bit);
+-  }
+-};
+-
+-/** An alias to ``basic_format_args<format_context>``. */
+-// A separate type would result in shorter symbols but break ABI compatibility
+-// between clang and gcc on ARM (#1919).
+-FMT_EXPORT using format_args = basic_format_args<format_context>;
+-
+-// We cannot use enum classes as bit fields because of a gcc bug, so we put them
+-// in namespaces instead (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61414).
+-// Additionally, if an underlying type is specified, older gcc incorrectly warns
+-// that the type is too small. Both bugs are fixed in gcc 9.3.
+-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 903
+-#  define FMT_ENUM_UNDERLYING_TYPE(type)
+-#else
+-#  define FMT_ENUM_UNDERLYING_TYPE(type) : type
+-#endif
+-namespace align {
+-enum type FMT_ENUM_UNDERLYING_TYPE(unsigned char){none, left, right, center,
+-                                                  numeric};
+-}
+-using align_t = align::type;
+-namespace sign {
+-enum type FMT_ENUM_UNDERLYING_TYPE(unsigned char){none, minus, plus, space};
+-}
+-using sign_t = sign::type;
+-
+-namespace detail {
+-
+-// Workaround an array initialization issue in gcc 4.8.
+-template <typename Char> struct fill_t {
+- private:
+-  enum { max_size = 4 };
+-  Char data_[max_size] = {Char(' '), Char(0), Char(0), Char(0)};
+-  unsigned char size_ = 1;
+-
+- public:
+-  FMT_CONSTEXPR void operator=(basic_string_view<Char> s) {
+-    auto size = s.size();
+-    FMT_ASSERT(size <= max_size, "invalid fill");
+-    for (size_t i = 0; i < size; ++i) data_[i] = s[i];
+-    size_ = static_cast<unsigned char>(size);
+-  }
+-
+-  constexpr auto size() const -> size_t { return size_; }
+-  constexpr auto data() const -> const Char* { return data_; }
+-
+-  FMT_CONSTEXPR auto operator[](size_t index) -> Char& { return data_[index]; }
+-  FMT_CONSTEXPR auto operator[](size_t index) const -> const Char& {
+-    return data_[index];
+-  }
+-};
+-}  // namespace detail
+-
+-enum class presentation_type : unsigned char {
+-  none,
+-  dec,             // 'd'
+-  oct,             // 'o'
+-  hex_lower,       // 'x'
+-  hex_upper,       // 'X'
+-  bin_lower,       // 'b'
+-  bin_upper,       // 'B'
+-  hexfloat_lower,  // 'a'
+-  hexfloat_upper,  // 'A'
+-  exp_lower,       // 'e'
+-  exp_upper,       // 'E'
+-  fixed_lower,     // 'f'
+-  fixed_upper,     // 'F'
+-  general_lower,   // 'g'
+-  general_upper,   // 'G'
+-  chr,             // 'c'
+-  string,          // 's'
+-  pointer,         // 'p'
+-  debug            // '?'
+-};
+-
+-// Format specifiers for built-in and string types.
+-template <typename Char = char> struct format_specs {
+-  int width;
+-  int precision;
+-  presentation_type type;
+-  align_t align : 4;
+-  sign_t sign : 3;
+-  bool alt : 1;  // Alternate form ('#').
+-  bool localized : 1;
+-  detail::fill_t<Char> fill;
+-
+-  constexpr format_specs()
+-      : width(0),
+-        precision(-1),
+-        type(presentation_type::none),
+-        align(align::none),
+-        sign(sign::none),
+-        alt(false),
+-        localized(false) {}
+-};
+-
+-namespace detail {
+-
+-enum class arg_id_kind { none, index, name };
+-
+-// An argument reference.
+-template <typename Char> struct arg_ref {
+-  FMT_CONSTEXPR arg_ref() : kind(arg_id_kind::none), val() {}
+-
+-  FMT_CONSTEXPR explicit arg_ref(int index)
+-      : kind(arg_id_kind::index), val(index) {}
+-  FMT_CONSTEXPR explicit arg_ref(basic_string_view<Char> name)
+-      : kind(arg_id_kind::name), val(name) {}
+-
+-  FMT_CONSTEXPR auto operator=(int idx) -> arg_ref& {
+-    kind = arg_id_kind::index;
+-    val.index = idx;
+-    return *this;
+-  }
+-
+-  arg_id_kind kind;
+-  union value {
+-    FMT_CONSTEXPR value(int idx = 0) : index(idx) {}
+-    FMT_CONSTEXPR value(basic_string_view<Char> n) : name(n) {}
+-
+-    int index;
+-    basic_string_view<Char> name;
+-  } val;
+-};
+-
+-// Format specifiers with width and precision resolved at formatting rather
+-// than parsing time to allow reusing the same parsed specifiers with
+-// different sets of arguments (precompilation of format strings).
+-template <typename Char = char>
+-struct dynamic_format_specs : format_specs<Char> {
+-  arg_ref<Char> width_ref;
+-  arg_ref<Char> precision_ref;
+-};
+-
+-// Converts a character to ASCII. Returns '\0' on conversion failure.
+-template <typename Char, FMT_ENABLE_IF(std::is_integral<Char>::value)>
+-constexpr auto to_ascii(Char c) -> char {
+-  return c <= 0xff ? static_cast<char>(c) : '\0';
+-}
+-template <typename Char, FMT_ENABLE_IF(std::is_enum<Char>::value)>
+-constexpr auto to_ascii(Char c) -> char {
+-  return c <= 0xff ? static_cast<char>(c) : '\0';
+-}
+-
+-// Returns the number of code units in a code point or 1 on error.
+-template <typename Char>
+-FMT_CONSTEXPR auto code_point_length(const Char* begin) -> int {
+-  if (const_check(sizeof(Char) != 1)) return 1;
+-  auto c = static_cast<unsigned char>(*begin);
+-  return static_cast<int>((0x3a55000000000000ull >> (2 * (c >> 3))) & 0x3) + 1;
+-}
+-
+-// Return the result via the out param to workaround gcc bug 77539.
+-template <bool IS_CONSTEXPR, typename T, typename Ptr = const T*>
+-FMT_CONSTEXPR auto find(Ptr first, Ptr last, T value, Ptr& out) -> bool {
+-  for (out = first; out != last; ++out) {
+-    if (*out == value) return true;
+-  }
+-  return false;
+-}
+-
+-template <>
+-inline auto find<false, char>(const char* first, const char* last, char value,
+-                              const char*& out) -> bool {
+-  out = static_cast<const char*>(
+-      std::memchr(first, value, to_unsigned(last - first)));
+-  return out != nullptr;
+-}
+-
+-// Parses the range [begin, end) as an unsigned integer. This function assumes
+-// that the range is non-empty and the first character is a digit.
+-template <typename Char>
+-FMT_CONSTEXPR auto parse_nonnegative_int(const Char*& begin, const Char* end,
+-                                         int error_value) noexcept -> int {
+-  FMT_ASSERT(begin != end && '0' <= *begin && *begin <= '9', "");
+-  unsigned value = 0, prev = 0;
+-  auto p = begin;
+-  do {
+-    prev = value;
+-    value = value * 10 + unsigned(*p - '0');
+-    ++p;
+-  } while (p != end && '0' <= *p && *p <= '9');
+-  auto num_digits = p - begin;
+-  begin = p;
+-  if (num_digits <= std::numeric_limits<int>::digits10)
+-    return static_cast<int>(value);
+-  // Check for overflow.
+-  const unsigned max = to_unsigned((std::numeric_limits<int>::max)());
+-  return num_digits == std::numeric_limits<int>::digits10 + 1 &&
+-                 prev * 10ull + unsigned(p[-1] - '0') <= max
+-             ? static_cast<int>(value)
+-             : error_value;
+-}
+-
+-FMT_CONSTEXPR inline auto parse_align(char c) -> align_t {
+-  switch (c) {
+-  case '<':
+-    return align::left;
+-  case '>':
+-    return align::right;
+-  case '^':
+-    return align::center;
+-  }
+-  return align::none;
+-}
+-
+-template <typename Char> constexpr auto is_name_start(Char c) -> bool {
+-  return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || c == '_';
+-}
+-
+-template <typename Char, typename Handler>
+-FMT_CONSTEXPR auto do_parse_arg_id(const Char* begin, const Char* end,
+-                                   Handler&& handler) -> const Char* {
+-  Char c = *begin;
+-  if (c >= '0' && c <= '9') {
+-    int index = 0;
+-    constexpr int max = (std::numeric_limits<int>::max)();
+-    if (c != '0')
+-      index = parse_nonnegative_int(begin, end, max);
+-    else
+-      ++begin;
+-    if (begin == end || (*begin != '}' && *begin != ':'))
+-      throw_format_error("invalid format string");
+-    else
+-      handler.on_index(index);
+-    return begin;
+-  }
+-  if (!is_name_start(c)) {
+-    throw_format_error("invalid format string");
+-    return begin;
+-  }
+-  auto it = begin;
+-  do {
+-    ++it;
+-  } while (it != end && (is_name_start(*it) || ('0' <= *it && *it <= '9')));
+-  handler.on_name({begin, to_unsigned(it - begin)});
+-  return it;
+-}
+-
+-template <typename Char, typename Handler>
+-FMT_CONSTEXPR FMT_INLINE auto parse_arg_id(const Char* begin, const Char* end,
+-                                           Handler&& handler) -> const Char* {
+-  FMT_ASSERT(begin != end, "");
+-  Char c = *begin;
+-  if (c != '}' && c != ':') return do_parse_arg_id(begin, end, handler);
+-  handler.on_auto();
+-  return begin;
+-}
+-
+-template <typename Char> struct dynamic_spec_id_handler {
+-  basic_format_parse_context<Char>& ctx;
+-  arg_ref<Char>& ref;
+-
+-  FMT_CONSTEXPR void on_auto() {
+-    int id = ctx.next_arg_id();
+-    ref = arg_ref<Char>(id);
+-    ctx.check_dynamic_spec(id);
+-  }
+-  FMT_CONSTEXPR void on_index(int id) {
+-    ref = arg_ref<Char>(id);
+-    ctx.check_arg_id(id);
+-    ctx.check_dynamic_spec(id);
+-  }
+-  FMT_CONSTEXPR void on_name(basic_string_view<Char> id) {
+-    ref = arg_ref<Char>(id);
+-    ctx.check_arg_id(id);
+-  }
+-};
+-
+-// Parses [integer | "{" [arg_id] "}"].
+-template <typename Char>
+-FMT_CONSTEXPR auto parse_dynamic_spec(const Char* begin, const Char* end,
+-                                      int& value, arg_ref<Char>& ref,
+-                                      basic_format_parse_context<Char>& ctx)
+-    -> const Char* {
+-  FMT_ASSERT(begin != end, "");
+-  if ('0' <= *begin && *begin <= '9') {
+-    int val = parse_nonnegative_int(begin, end, -1);
+-    if (val != -1)
+-      value = val;
+-    else
+-      throw_format_error("number is too big");
+-  } else if (*begin == '{') {
+-    ++begin;
+-    auto handler = dynamic_spec_id_handler<Char>{ctx, ref};
+-    if (begin != end) begin = parse_arg_id(begin, end, handler);
+-    if (begin != end && *begin == '}') return ++begin;
+-    throw_format_error("invalid format string");
+-  }
+-  return begin;
+-}
+-
+-template <typename Char>
+-FMT_CONSTEXPR auto parse_precision(const Char* begin, const Char* end,
+-                                   int& value, arg_ref<Char>& ref,
+-                                   basic_format_parse_context<Char>& ctx)
+-    -> const Char* {
+-  ++begin;
+-  if (begin == end || *begin == '}') {
+-    throw_format_error("invalid precision");
+-    return begin;
+-  }
+-  return parse_dynamic_spec(begin, end, value, ref, ctx);
+-}
+-
+-enum class state { start, align, sign, hash, zero, width, precision, locale };
+-
+-// Parses standard format specifiers.
+-template <typename Char>
+-FMT_CONSTEXPR FMT_INLINE auto parse_format_specs(
+-    const Char* begin, const Char* end, dynamic_format_specs<Char>& specs,
+-    basic_format_parse_context<Char>& ctx, type arg_type) -> const Char* {
+-  auto c = '\0';
+-  if (end - begin > 1) {
+-    auto next = to_ascii(begin[1]);
+-    c = parse_align(next) == align::none ? to_ascii(*begin) : '\0';
+-  } else {
+-    if (begin == end) return begin;
+-    c = to_ascii(*begin);
+-  }
+-
+-  struct {
+-    state current_state = state::start;
+-    FMT_CONSTEXPR void operator()(state s, bool valid = true) {
+-      if (current_state >= s || !valid)
+-        throw_format_error("invalid format specifier");
+-      current_state = s;
+-    }
+-  } enter_state;
+-
+-  using pres = presentation_type;
+-  constexpr auto integral_set = sint_set | uint_set | bool_set | char_set;
+-  struct {
+-    const Char*& begin;
+-    dynamic_format_specs<Char>& specs;
+-    type arg_type;
+-
+-    FMT_CONSTEXPR auto operator()(pres type, int set) -> const Char* {
+-      if (!in(arg_type, set)) throw_format_error("invalid format specifier");
+-      specs.type = type;
+-      return begin + 1;
+-    }
+-  } parse_presentation_type{begin, specs, arg_type};
+-
+-  for (;;) {
+-    switch (c) {
+-    case '<':
+-    case '>':
+-    case '^':
+-      enter_state(state::align);
+-      specs.align = parse_align(c);
+-      ++begin;
+-      break;
+-    case '+':
+-    case '-':
+-    case ' ':
+-      enter_state(state::sign, in(arg_type, sint_set | float_set));
+-      switch (c) {
+-      case '+':
+-        specs.sign = sign::plus;
+-        break;
+-      case '-':
+-        specs.sign = sign::minus;
+-        break;
+-      case ' ':
+-        specs.sign = sign::space;
+-        break;
+-      }
+-      ++begin;
+-      break;
+-    case '#':
+-      enter_state(state::hash, is_arithmetic_type(arg_type));
+-      specs.alt = true;
+-      ++begin;
+-      break;
+-    case '0':
+-      enter_state(state::zero);
+-      if (!is_arithmetic_type(arg_type))
+-        throw_format_error("format specifier requires numeric argument");
+-      if (specs.align == align::none) {
+-        // Ignore 0 if align is specified for compatibility with std::format.
+-        specs.align = align::numeric;
+-        specs.fill[0] = Char('0');
+-      }
+-      ++begin;
+-      break;
+-    case '1':
+-    case '2':
+-    case '3':
+-    case '4':
+-    case '5':
+-    case '6':
+-    case '7':
+-    case '8':
+-    case '9':
+-    case '{':
+-      enter_state(state::width);
+-      begin = parse_dynamic_spec(begin, end, specs.width, specs.width_ref, ctx);
+-      break;
+-    case '.':
+-      enter_state(state::precision,
+-                  in(arg_type, float_set | string_set | cstring_set));
+-      begin = parse_precision(begin, end, specs.precision, specs.precision_ref,
+-                              ctx);
+-      break;
+-    case 'L':
+-      enter_state(state::locale, is_arithmetic_type(arg_type));
+-      specs.localized = true;
+-      ++begin;
+-      break;
+-    case 'd':
+-      return parse_presentation_type(pres::dec, integral_set);
+-    case 'o':
+-      return parse_presentation_type(pres::oct, integral_set);
+-    case 'x':
+-      return parse_presentation_type(pres::hex_lower, integral_set);
+-    case 'X':
+-      return parse_presentation_type(pres::hex_upper, integral_set);
+-    case 'b':
+-      return parse_presentation_type(pres::bin_lower, integral_set);
+-    case 'B':
+-      return parse_presentation_type(pres::bin_upper, integral_set);
+-    case 'a':
+-      return parse_presentation_type(pres::hexfloat_lower, float_set);
+-    case 'A':
+-      return parse_presentation_type(pres::hexfloat_upper, float_set);
+-    case 'e':
+-      return parse_presentation_type(pres::exp_lower, float_set);
+-    case 'E':
+-      return parse_presentation_type(pres::exp_upper, float_set);
+-    case 'f':
+-      return parse_presentation_type(pres::fixed_lower, float_set);
+-    case 'F':
+-      return parse_presentation_type(pres::fixed_upper, float_set);
+-    case 'g':
+-      return parse_presentation_type(pres::general_lower, float_set);
+-    case 'G':
+-      return parse_presentation_type(pres::general_upper, float_set);
+-    case 'c':
+-      return parse_presentation_type(pres::chr, integral_set);
+-    case 's':
+-      return parse_presentation_type(pres::string,
+-                                     bool_set | string_set | cstring_set);
+-    case 'p':
+-      return parse_presentation_type(pres::pointer, pointer_set | cstring_set);
+-    case '?':
+-      return parse_presentation_type(pres::debug,
+-                                     char_set | string_set | cstring_set);
+-    case '}':
+-      return begin;
+-    default: {
+-      if (*begin == '}') return begin;
+-      // Parse fill and alignment.
+-      auto fill_end = begin + code_point_length(begin);
+-      if (end - fill_end <= 0) {
+-        throw_format_error("invalid format specifier");
+-        return begin;
+-      }
+-      if (*begin == '{') {
+-        throw_format_error("invalid fill character '{'");
+-        return begin;
+-      }
+-      auto align = parse_align(to_ascii(*fill_end));
+-      enter_state(state::align, align != align::none);
+-      specs.fill = {begin, to_unsigned(fill_end - begin)};
+-      specs.align = align;
+-      begin = fill_end + 1;
+-    }
+-    }
+-    if (begin == end) return begin;
+-    c = to_ascii(*begin);
+-  }
+-}
+-
+-template <typename Char, typename Handler>
+-FMT_CONSTEXPR auto parse_replacement_field(const Char* begin, const Char* end,
+-                                           Handler&& handler) -> const Char* {
+-  struct id_adapter {
+-    Handler& handler;
+-    int arg_id;
+-
+-    FMT_CONSTEXPR void on_auto() { arg_id = handler.on_arg_id(); }
+-    FMT_CONSTEXPR void on_index(int id) { arg_id = handler.on_arg_id(id); }
+-    FMT_CONSTEXPR void on_name(basic_string_view<Char> id) {
+-      arg_id = handler.on_arg_id(id);
+-    }
+-  };
+-
+-  ++begin;
+-  if (begin == end) return handler.on_error("invalid format string"), end;
+-  if (*begin == '}') {
+-    handler.on_replacement_field(handler.on_arg_id(), begin);
+-  } else if (*begin == '{') {
+-    handler.on_text(begin, begin + 1);
+-  } else {
+-    auto adapter = id_adapter{handler, 0};
+-    begin = parse_arg_id(begin, end, adapter);
+-    Char c = begin != end ? *begin : Char();
+-    if (c == '}') {
+-      handler.on_replacement_field(adapter.arg_id, begin);
+-    } else if (c == ':') {
+-      begin = handler.on_format_specs(adapter.arg_id, begin + 1, end);
+-      if (begin == end || *begin != '}')
+-        return handler.on_error("unknown format specifier"), end;
+-    } else {
+-      return handler.on_error("missing '}' in format string"), end;
+-    }
+-  }
+-  return begin + 1;
+-}
+-
+-template <bool IS_CONSTEXPR, typename Char, typename Handler>
+-FMT_CONSTEXPR FMT_INLINE void parse_format_string(
+-    basic_string_view<Char> format_str, Handler&& handler) {
+-  auto begin = format_str.data();
+-  auto end = begin + format_str.size();
+-  if (end - begin < 32) {
+-    // Use a simple loop instead of memchr for small strings.
+-    const Char* p = begin;
+-    while (p != end) {
+-      auto c = *p++;
+-      if (c == '{') {
+-        handler.on_text(begin, p - 1);
+-        begin = p = parse_replacement_field(p - 1, end, handler);
+-      } else if (c == '}') {
+-        if (p == end || *p != '}')
+-          return handler.on_error("unmatched '}' in format string");
+-        handler.on_text(begin, p);
+-        begin = ++p;
+-      }
+-    }
+-    handler.on_text(begin, end);
+-    return;
+-  }
+-  struct writer {
+-    FMT_CONSTEXPR void operator()(const Char* from, const Char* to) {
+-      if (from == to) return;
+-      for (;;) {
+-        const Char* p = nullptr;
+-        if (!find<IS_CONSTEXPR>(from, to, Char('}'), p))
+-          return handler_.on_text(from, to);
+-        ++p;
+-        if (p == to || *p != '}')
+-          return handler_.on_error("unmatched '}' in format string");
+-        handler_.on_text(from, p);
+-        from = p + 1;
+-      }
+-    }
+-    Handler& handler_;
+-  } write = {handler};
+-  while (begin != end) {
+-    // Doing two passes with memchr (one for '{' and another for '}') is up to
+-    // 2.5x faster than the naive one-pass implementation on big format strings.
+-    const Char* p = begin;
+-    if (*begin != '{' && !find<IS_CONSTEXPR>(begin + 1, end, Char('{'), p))
+-      return write(begin, end);
+-    write(begin, p);
+-    begin = parse_replacement_field(p, end, handler);
+-  }
+-}
+-
+-template <typename T, bool = is_named_arg<T>::value> struct strip_named_arg {
+-  using type = T;
+-};
+-template <typename T> struct strip_named_arg<T, true> {
+-  using type = remove_cvref_t<decltype(T::value)>;
+-};
+-
+-template <typename T, typename ParseContext>
+-FMT_CONSTEXPR auto parse_format_specs(ParseContext& ctx)
+-    -> decltype(ctx.begin()) {
+-  using char_type = typename ParseContext::char_type;
+-  using context = buffer_context<char_type>;
+-  using mapped_type = conditional_t<
+-      mapped_type_constant<T, context>::value != type::custom_type,
+-      decltype(arg_mapper<context>().map(std::declval<const T&>())),
+-      typename strip_named_arg<T>::type>;
+-  return formatter<mapped_type, char_type>().parse(ctx);
+-}
+-
+-// Checks char specs and returns true iff the presentation type is char-like.
+-template <typename Char>
+-FMT_CONSTEXPR auto check_char_specs(const format_specs<Char>& specs) -> bool {
+-  if (specs.type != presentation_type::none &&
+-      specs.type != presentation_type::chr &&
+-      specs.type != presentation_type::debug) {
+-    return false;
+-  }
+-  if (specs.align == align::numeric || specs.sign != sign::none || specs.alt)
+-    throw_format_error("invalid format specifier for char");
+-  return true;
+-}
+-
+-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
+-template <int N, typename T, typename... Args, typename Char>
+-constexpr auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
+-  if constexpr (is_statically_named_arg<T>()) {
+-    if (name == T::name) return N;
+-  }
+-  if constexpr (sizeof...(Args) > 0)
+-    return get_arg_index_by_name<N + 1, Args...>(name);
+-  (void)name;  // Workaround an MSVC bug about "unused" parameter.
+-  return -1;
+-}
+-#endif
+-
+-template <typename... Args, typename Char>
+-FMT_CONSTEXPR auto get_arg_index_by_name(basic_string_view<Char> name) -> int {
+-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
+-  if constexpr (sizeof...(Args) > 0)
+-    return get_arg_index_by_name<0, Args...>(name);
+-#endif
+-  (void)name;
+-  return -1;
+-}
+-
+-template <typename Char, typename... Args> class format_string_checker {
+- private:
+-  using parse_context_type = compile_parse_context<Char>;
+-  static constexpr int num_args = sizeof...(Args);
+-
+-  // Format specifier parsing function.
+-  // In the future basic_format_parse_context will replace compile_parse_context
+-  // here and will use is_constant_evaluated and downcasting to access the data
+-  // needed for compile-time checks: https://godbolt.org/z/GvWzcTjh1.
+-  using parse_func = const Char* (*)(parse_context_type&);
+-
+-  parse_context_type context_;
+-  parse_func parse_funcs_[num_args > 0 ? static_cast<size_t>(num_args) : 1];
+-  type types_[num_args > 0 ? static_cast<size_t>(num_args) : 1];
+-
+- public:
+-  explicit FMT_CONSTEXPR format_string_checker(basic_string_view<Char> fmt)
+-      : context_(fmt, num_args, types_),
+-        parse_funcs_{&parse_format_specs<Args, parse_context_type>...},
+-        types_{mapped_type_constant<Args, buffer_context<Char>>::value...} {}
+-
+-  FMT_CONSTEXPR void on_text(const Char*, const Char*) {}
+-
+-  FMT_CONSTEXPR auto on_arg_id() -> int { return context_.next_arg_id(); }
+-  FMT_CONSTEXPR auto on_arg_id(int id) -> int {
+-    return context_.check_arg_id(id), id;
+-  }
+-  FMT_CONSTEXPR auto on_arg_id(basic_string_view<Char> id) -> int {
+-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
+-    auto index = get_arg_index_by_name<Args...>(id);
+-    if (index < 0) on_error("named argument is not found");
+-    return index;
+-#else
+-    (void)id;
+-    on_error("compile-time checks for named arguments require C++20 support");
+-    return 0;
+-#endif
+-  }
+-
+-  FMT_CONSTEXPR void on_replacement_field(int, const Char*) {}
+-
+-  FMT_CONSTEXPR auto on_format_specs(int id, const Char* begin, const Char*)
+-      -> const Char* {
+-    context_.advance_to(begin);
+-    // id >= 0 check is a workaround for gcc 10 bug (#2065).
+-    return id >= 0 && id < num_args ? parse_funcs_[id](context_) : begin;
+-  }
+-
+-  FMT_CONSTEXPR void on_error(const char* message) {
+-    throw_format_error(message);
+-  }
+-};
+-
+-// Reports a compile-time error if S is not a valid format string.
+-template <typename..., typename S, FMT_ENABLE_IF(!is_compile_string<S>::value)>
+-FMT_INLINE void check_format_string(const S&) {
+-#ifdef FMT_ENFORCE_COMPILE_STRING
+-  static_assert(is_compile_string<S>::value,
+-                "FMT_ENFORCE_COMPILE_STRING requires all format strings to use "
+-                "FMT_STRING.");
+-#endif
+-}
+-template <typename... Args, typename S,
+-          FMT_ENABLE_IF(is_compile_string<S>::value)>
+-void check_format_string(S format_str) {
+-  using char_t = typename S::char_type;
+-  FMT_CONSTEXPR auto s = basic_string_view<char_t>(format_str);
+-  using checker = format_string_checker<char_t, remove_cvref_t<Args>...>;
+-  FMT_CONSTEXPR bool error = (parse_format_string<true>(s, checker(s)), true);
+-  ignore_unused(error);
+-}
+-
+-template <typename Char = char> struct vformat_args {
+-  using type = basic_format_args<
+-      basic_format_context<std::back_insert_iterator<buffer<Char>>, Char>>;
+-};
+-template <> struct vformat_args<char> { using type = format_args; };
+-
+-// Use vformat_args and avoid type_identity to keep symbols short.
+-template <typename Char>
+-void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
+-                typename vformat_args<Char>::type args, locale_ref loc = {});
+-
+-FMT_API void vprint_mojibake(std::FILE*, string_view, format_args);
+-#ifndef _WIN32
+-inline void vprint_mojibake(std::FILE*, string_view, format_args) {}
+-#endif
+-}  // namespace detail
+-
+-FMT_BEGIN_EXPORT
+-
+-// A formatter specialization for natively supported types.
+-template <typename T, typename Char>
+-struct formatter<T, Char,
+-                 enable_if_t<detail::type_constant<T, Char>::value !=
+-                             detail::type::custom_type>> {
+- private:
+-  detail::dynamic_format_specs<Char> specs_;
+-
+- public:
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const Char* {
+-    auto type = detail::type_constant<T, Char>::value;
+-    auto end =
+-        detail::parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx, type);
+-    if (type == detail::type::char_type) detail::check_char_specs(specs_);
+-    return end;
+-  }
+-
+-  template <detail::type U = detail::type_constant<T, Char>::value,
+-            FMT_ENABLE_IF(U == detail::type::string_type ||
+-                          U == detail::type::cstring_type ||
+-                          U == detail::type::char_type)>
+-  FMT_CONSTEXPR void set_debug_format(bool set = true) {
+-    specs_.type = set ? presentation_type::debug : presentation_type::none;
+-  }
+-
+-  template <typename FormatContext>
+-  FMT_CONSTEXPR auto format(const T& val, FormatContext& ctx) const
+-      -> decltype(ctx.out());
+-};
+-
+-#define FMT_FORMAT_AS(Type, Base) \
+-  template <typename Char>        \
+-  struct formatter<Type, Char> : formatter<Base, Char> {}
+-
+-FMT_FORMAT_AS(signed char, int);
+-FMT_FORMAT_AS(unsigned char, unsigned);
+-FMT_FORMAT_AS(short, int);
+-FMT_FORMAT_AS(unsigned short, unsigned);
+-FMT_FORMAT_AS(long, detail::long_type);
+-FMT_FORMAT_AS(unsigned long, detail::ulong_type);
+-FMT_FORMAT_AS(Char*, const Char*);
+-FMT_FORMAT_AS(std::basic_string<Char>, basic_string_view<Char>);
+-FMT_FORMAT_AS(std::nullptr_t, const void*);
+-FMT_FORMAT_AS(detail::std_string_view<Char>, basic_string_view<Char>);
+-
+-template <typename Char = char> struct runtime_format_string {
+-  basic_string_view<Char> str;
+-};
+-
+-/** A compile-time format string. */
+-template <typename Char, typename... Args> class basic_format_string {
+- private:
+-  basic_string_view<Char> str_;
+-
+- public:
+-  template <typename S,
+-            FMT_ENABLE_IF(
+-                std::is_convertible<const S&, basic_string_view<Char>>::value)>
+-  FMT_CONSTEVAL FMT_INLINE basic_format_string(const S& s) : str_(s) {
+-    static_assert(
+-        detail::count<
+-            (std::is_base_of<detail::view, remove_reference_t<Args>>::value &&
+-             std::is_reference<Args>::value)...>() == 0,
+-        "passing views as lvalues is disallowed");
+-#ifdef FMT_HAS_CONSTEVAL
+-    if constexpr (detail::count_named_args<Args...>() ==
+-                  detail::count_statically_named_args<Args...>()) {
+-      using checker =
+-          detail::format_string_checker<Char, remove_cvref_t<Args>...>;
+-      detail::parse_format_string<true>(str_, checker(s));
+-    }
+-#else
+-    detail::check_format_string<Args...>(s);
+-#endif
+-  }
+-  basic_format_string(runtime_format_string<Char> fmt) : str_(fmt.str) {}
+-
+-  FMT_INLINE operator basic_string_view<Char>() const { return str_; }
+-  FMT_INLINE auto get() const -> basic_string_view<Char> { return str_; }
+-};
+-
+-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+-// Workaround broken conversion on older gcc.
+-template <typename...> using format_string = string_view;
+-inline auto runtime(string_view s) -> string_view { return s; }
+-#else
+-template <typename... Args>
+-using format_string = basic_format_string<char, type_identity_t<Args>...>;
+-/**
+-  \rst
+-  Creates a runtime format string.
+-
+-  **Example**::
+-
+-    // Check format string at runtime instead of compile-time.
+-    fmt::print(fmt::runtime("{:d}"), "I am not a number");
+-  \endrst
+- */
+-inline auto runtime(string_view s) -> runtime_format_string<> { return {{s}}; }
+-#endif
+-
+-FMT_API auto vformat(string_view fmt, format_args args) -> std::string;
+-
+-/**
+-  \rst
+-  Formats ``args`` according to specifications in ``fmt`` and returns the result
+-  as a string.
+-
+-  **Example**::
+-
+-    #include <fmt/core.h>
+-    std::string message = fmt::format("The answer is {}.", 42);
+-  \endrst
+-*/
+-template <typename... T>
+-FMT_NODISCARD FMT_INLINE auto format(format_string<T...> fmt, T&&... args)
+-    -> std::string {
+-  return vformat(fmt, fmt::make_format_args(args...));
+-}
+-
+-/** Formats a string and writes the output to ``out``. */
+-template <typename OutputIt,
+-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
+-auto vformat_to(OutputIt out, string_view fmt, format_args args) -> OutputIt {
+-  auto&& buf = detail::get_buffer<char>(out);
+-  detail::vformat_to(buf, fmt, args, {});
+-  return detail::get_iterator(buf, out);
+-}
+-
+-/**
+- \rst
+- Formats ``args`` according to specifications in ``fmt``, writes the result to
+- the output iterator ``out`` and returns the iterator past the end of the output
+- range. `format_to` does not append a terminating null character.
+-
+- **Example**::
+-
+-   auto out = std::vector<char>();
+-   fmt::format_to(std::back_inserter(out), "{}", 42);
+- \endrst
+- */
+-template <typename OutputIt, typename... T,
+-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
+-FMT_INLINE auto format_to(OutputIt out, format_string<T...> fmt, T&&... args)
+-    -> OutputIt {
+-  return vformat_to(out, fmt, fmt::make_format_args(args...));
+-}
+-
+-template <typename OutputIt> struct format_to_n_result {
+-  /** Iterator past the end of the output range. */
+-  OutputIt out;
+-  /** Total (not truncated) output size. */
+-  size_t size;
+-};
+-
+-template <typename OutputIt, typename... T,
+-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
+-auto vformat_to_n(OutputIt out, size_t n, string_view fmt, format_args args)
+-    -> format_to_n_result<OutputIt> {
+-  using traits = detail::fixed_buffer_traits;
+-  auto buf = detail::iterator_buffer<OutputIt, char, traits>(out, n);
+-  detail::vformat_to(buf, fmt, args, {});
+-  return {buf.out(), buf.count()};
+-}
+-
+-/**
+-  \rst
+-  Formats ``args`` according to specifications in ``fmt``, writes up to ``n``
+-  characters of the result to the output iterator ``out`` and returns the total
+-  (not truncated) output size and the iterator past the end of the output range.
+-  `format_to_n` does not append a terminating null character.
+-  \endrst
+- */
+-template <typename OutputIt, typename... T,
+-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
+-FMT_INLINE auto format_to_n(OutputIt out, size_t n, format_string<T...> fmt,
+-                            T&&... args) -> format_to_n_result<OutputIt> {
+-  return vformat_to_n(out, n, fmt, fmt::make_format_args(args...));
+-}
+-
+-/** Returns the number of chars in the output of ``format(fmt, args...)``. */
+-template <typename... T>
+-FMT_NODISCARD FMT_INLINE auto formatted_size(format_string<T...> fmt,
+-                                             T&&... args) -> size_t {
+-  auto buf = detail::counting_buffer<>();
+-  detail::vformat_to<char>(buf, fmt, fmt::make_format_args(args...), {});
+-  return buf.count();
+-}
+-
+-FMT_API void vprint(string_view fmt, format_args args);
+-FMT_API void vprint(std::FILE* f, string_view fmt, format_args args);
+-
+-/**
+-  \rst
+-  Formats ``args`` according to specifications in ``fmt`` and writes the output
+-  to ``stdout``.
+-
+-  **Example**::
+-
+-    fmt::print("Elapsed time: {0:.2f} seconds", 1.23);
+-  \endrst
+- */
+-template <typename... T>
+-FMT_INLINE void print(format_string<T...> fmt, T&&... args) {
+-  const auto& vargs = fmt::make_format_args(args...);
+-  return detail::is_utf8() ? vprint(fmt, vargs)
+-                           : detail::vprint_mojibake(stdout, fmt, vargs);
+-}
+-
+-/**
+-  \rst
+-  Formats ``args`` according to specifications in ``fmt`` and writes the
+-  output to the file ``f``.
+-
+-  **Example**::
+-
+-    fmt::print(stderr, "Don't {}!", "panic");
+-  \endrst
+- */
+-template <typename... T>
+-FMT_INLINE void print(std::FILE* f, format_string<T...> fmt, T&&... args) {
+-  const auto& vargs = fmt::make_format_args(args...);
+-  return detail::is_utf8() ? vprint(f, fmt, vargs)
+-                           : detail::vprint_mojibake(f, fmt, vargs);
+-}
+-
+-/**
+-  Formats ``args`` according to specifications in ``fmt`` and writes the
+-  output to the file ``f`` followed by a newline.
+- */
+-template <typename... T>
+-FMT_INLINE void println(std::FILE* f, format_string<T...> fmt, T&&... args) {
+-  return fmt::print(f, "{}\n", fmt::format(fmt, std::forward<T>(args)...));
+-}
+-
+-/**
+-  Formats ``args`` according to specifications in ``fmt`` and writes the output
+-  to ``stdout`` followed by a newline.
+- */
+-template <typename... T>
+-FMT_INLINE void println(format_string<T...> fmt, T&&... args) {
+-  return fmt::println(stdout, fmt, std::forward<T>(args)...);
+-}
+-
+-FMT_END_EXPORT
+-FMT_GCC_PRAGMA("GCC pop_options")
+-FMT_END_NAMESPACE
+-
+-#ifdef FMT_HEADER_ONLY
+-#  include "format.h"
+-#endif
+-#endif  // FMT_CORE_H_
++#include "format.h"
+diff --git a/include/fmt/format-inl.h b/include/fmt/format-inl.h
+index dac2d43..66ee747 100644
+--- a/include/fmt/format-inl.h
++++ b/include/fmt/format-inl.h
+@@ -8,36 +8,36 @@
+ #ifndef FMT_FORMAT_INL_H_
+ #define FMT_FORMAT_INL_H_
+ 
+-#include <algorithm>
+-#include <cerrno>  // errno
+-#include <climits>
+-#include <cmath>
+-#include <exception>
+-
+-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
+-#  include <locale>
++#ifndef FMT_MODULE
++#  include <algorithm>
++#  include <cerrno>  // errno
++#  include <climits>
++#  include <cmath>
++#  include <exception>
+ #endif
+ 
+-#ifdef _WIN32
++#if defined(_WIN32) && !defined(FMT_USE_WRITE_CONSOLE)
+ #  include <io.h>  // _isatty
+ #endif
+ 
+ #include "format.h"
+ 
++#if FMT_USE_LOCALE
++#  include <locale>
++#endif
++
++#ifndef FMT_FUNC
++#  define FMT_FUNC
++#endif
++
+ FMT_BEGIN_NAMESPACE
+ namespace detail {
+ 
+ FMT_FUNC void assert_fail(const char* file, int line, const char* message) {
+   // Use unchecked std::fprintf to avoid triggering another assertion when
+-  // writing to stderr fails
+-  std::fprintf(stderr, "%s:%d: assertion failed: %s", file, line, message);
+-  // Chosen instead of std::abort to satisfy Clang in CUDA mode during device
+-  // code pass.
+-  std::terminate();
+-}
+-
+-FMT_FUNC void throw_format_error(const char* message) {
+-  FMT_THROW(format_error(message));
++  // writing to stderr fails.
++  fprintf(stderr, "%s:%d: assertion failed: %s", file, line, message);
++  abort();
+ }
+ 
+ FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
+@@ -56,112 +56,129 @@ FMT_FUNC void format_error_code(detail::buffer<char>& out, int error_code,
+     ++error_code_size;
+   }
+   error_code_size += detail::to_unsigned(detail::count_digits(abs_value));
+-  auto it = buffer_appender<char>(out);
++  auto it = appender(out);
+   if (message.size() <= inline_buffer_size - error_code_size)
+-    format_to(it, FMT_STRING("{}{}"), message, SEP);
+-  format_to(it, FMT_STRING("{}{}"), ERROR_STR, error_code);
++    fmt::format_to(it, FMT_STRING("{}{}"), message, SEP);
++  fmt::format_to(it, FMT_STRING("{}{}"), ERROR_STR, error_code);
+   FMT_ASSERT(out.size() <= inline_buffer_size, "");
+ }
+ 
+-FMT_FUNC void report_error(format_func func, int error_code,
+-                           const char* message) noexcept {
++FMT_FUNC void do_report_error(format_func func, int error_code,
++                              const char* message) noexcept {
+   memory_buffer full_message;
+   func(full_message, error_code, message);
+-  // Don't use fwrite_fully because the latter may throw.
++  // Don't use fwrite_all because the latter may throw.
+   if (std::fwrite(full_message.data(), full_message.size(), 1, stderr) > 0)
+     std::fputc('\n', stderr);
+ }
+ 
+ // A wrapper around fwrite that throws on error.
+-inline void fwrite_fully(const void* ptr, size_t size, size_t count,
+-                         FILE* stream) {
+-  size_t written = std::fwrite(ptr, size, count, stream);
++inline void fwrite_all(const void* ptr, size_t count, FILE* stream) {
++  size_t written = std::fwrite(ptr, 1, count, stream);
+   if (written < count)
+     FMT_THROW(system_error(errno, FMT_STRING("cannot write to file")));
+ }
+ 
+-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
++#if FMT_USE_LOCALE
++using std::locale;
++using std::numpunct;
++using std::use_facet;
++
+ template <typename Locale>
+ locale_ref::locale_ref(const Locale& loc) : locale_(&loc) {
+-  static_assert(std::is_same<Locale, std::locale>::value, "");
++  static_assert(std::is_same<Locale, locale>::value, "");
+ }
++#else
++struct locale {};
++template <typename Char> struct numpunct {
++  auto grouping() const -> std::string { return "\03"; }
++  auto thousands_sep() const -> Char { return ','; }
++  auto decimal_point() const -> Char { return '.'; }
++};
++template <typename Facet> Facet use_facet(locale) { return {}; }
++#endif  // FMT_USE_LOCALE
+ 
+-template <typename Locale> Locale locale_ref::get() const {
+-  static_assert(std::is_same<Locale, std::locale>::value, "");
+-  return locale_ ? *static_cast<const std::locale*>(locale_) : std::locale();
++template <typename Locale> auto locale_ref::get() const -> Locale {
++  static_assert(std::is_same<Locale, locale>::value, "");
++#if FMT_USE_LOCALE
++  if (locale_) return *static_cast<const locale*>(locale_);
++#endif
++  return locale();
+ }
+ 
+ template <typename Char>
+ FMT_FUNC auto thousands_sep_impl(locale_ref loc) -> thousands_sep_result<Char> {
+-  auto& facet = std::use_facet<std::numpunct<Char>>(loc.get<std::locale>());
++  auto&& facet = use_facet<numpunct<Char>>(loc.get<locale>());
+   auto grouping = facet.grouping();
+   auto thousands_sep = grouping.empty() ? Char() : facet.thousands_sep();
+   return {std::move(grouping), thousands_sep};
+ }
+-template <typename Char> FMT_FUNC Char decimal_point_impl(locale_ref loc) {
+-  return std::use_facet<std::numpunct<Char>>(loc.get<std::locale>())
+-      .decimal_point();
+-}
+-#else
+ template <typename Char>
+-FMT_FUNC auto thousands_sep_impl(locale_ref) -> thousands_sep_result<Char> {
+-  return {"\03", FMT_STATIC_THOUSANDS_SEPARATOR};
++FMT_FUNC auto decimal_point_impl(locale_ref loc) -> Char {
++  return use_facet<numpunct<Char>>(loc.get<locale>()).decimal_point();
+ }
+-template <typename Char> FMT_FUNC Char decimal_point_impl(locale_ref) {
+-  return '.';
+-}
+-#endif
+ 
++#if FMT_USE_LOCALE
+ FMT_FUNC auto write_loc(appender out, loc_value value,
+-                        const format_specs<>& specs, locale_ref loc) -> bool {
+-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
++                        const format_specs& specs, locale_ref loc) -> bool {
+   auto locale = loc.get<std::locale>();
+   // We cannot use the num_put<char> facet because it may produce output in
+   // a wrong encoding.
+   using facet = format_facet<std::locale>;
+   if (std::has_facet<facet>(locale))
+-    return std::use_facet<facet>(locale).put(out, value, specs);
++    return use_facet<facet>(locale).put(out, value, specs);
+   return facet(locale).put(out, value, specs);
+-#endif
+-  return false;
+ }
++#endif
+ }  // namespace detail
+ 
++FMT_FUNC void report_error(const char* message) {
++#if FMT_USE_EXCEPTIONS
++  // Use FMT_THROW instead of throw to avoid bogus unreachable code warnings
++  // from MSVC.
++  FMT_THROW(format_error(message));
++#else
++  fputs(message, stderr);
++  abort();
++#endif
++}
++
+ template <typename Locale> typename Locale::id format_facet<Locale>::id;
+ 
+-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
+ template <typename Locale> format_facet<Locale>::format_facet(Locale& loc) {
+-  auto& numpunct = std::use_facet<std::numpunct<char>>(loc);
+-  grouping_ = numpunct.grouping();
+-  if (!grouping_.empty()) separator_ = std::string(1, numpunct.thousands_sep());
++  auto& np = detail::use_facet<detail::numpunct<char>>(loc);
++  grouping_ = np.grouping();
++  if (!grouping_.empty()) separator_ = std::string(1, np.thousands_sep());
+ }
+ 
++#if FMT_USE_LOCALE
+ template <>
+ FMT_API FMT_FUNC auto format_facet<std::locale>::do_put(
+-    appender out, loc_value val, const format_specs<>& specs) const -> bool {
++    appender out, loc_value val, const format_specs& specs) const -> bool {
+   return val.visit(
+       detail::loc_writer<>{out, specs, separator_, grouping_, decimal_point_});
+ }
+ #endif
+ 
+-FMT_FUNC std::system_error vsystem_error(int error_code, string_view fmt,
+-                                         format_args args) {
++FMT_FUNC auto vsystem_error(int error_code, string_view fmt, format_args args)
++    -> std::system_error {
+   auto ec = std::error_code(error_code, std::generic_category());
+   return std::system_error(ec, vformat(fmt, args));
+ }
+ 
+ namespace detail {
+ 
+-template <typename F> inline bool operator==(basic_fp<F> x, basic_fp<F> y) {
++template <typename F>
++inline auto operator==(basic_fp<F> x, basic_fp<F> y) -> bool {
+   return x.f == y.f && x.e == y.e;
+ }
+ 
+ // Compilers should be able to optimize this into the ror instruction.
+-FMT_CONSTEXPR inline uint32_t rotr(uint32_t n, uint32_t r) noexcept {
++FMT_CONSTEXPR inline auto rotr(uint32_t n, uint32_t r) noexcept -> uint32_t {
+   r &= 31;
+   return (n >> r) | (n << (32 - r));
+ }
+-FMT_CONSTEXPR inline uint64_t rotr(uint64_t n, uint32_t r) noexcept {
++FMT_CONSTEXPR inline auto rotr(uint64_t n, uint32_t r) noexcept -> uint64_t {
+   r &= 63;
+   return (n >> r) | (n << (64 - r));
+ }
+@@ -170,14 +187,14 @@ FMT_CONSTEXPR inline uint64_t rotr(uint64_t n, uint32_t r) noexcept {
+ namespace dragonbox {
+ // Computes upper 64 bits of multiplication of a 32-bit unsigned integer and a
+ // 64-bit unsigned integer.
+-inline uint64_t umul96_upper64(uint32_t x, uint64_t y) noexcept {
++inline auto umul96_upper64(uint32_t x, uint64_t y) noexcept -> uint64_t {
+   return umul128_upper64(static_cast<uint64_t>(x) << 32, y);
+ }
+ 
+ // Computes lower 128 bits of multiplication of a 64-bit unsigned integer and a
+ // 128-bit unsigned integer.
+-inline uint128_fallback umul192_lower128(uint64_t x,
+-                                         uint128_fallback y) noexcept {
++inline auto umul192_lower128(uint64_t x, uint128_fallback y) noexcept
++    -> uint128_fallback {
+   uint64_t high = x * y.high();
+   uint128_fallback high_low = umul128(x, y.low());
+   return {high + high_low.high(), high_low.low()};
+@@ -185,17 +202,17 @@ inline uint128_fallback umul192_lower128(uint64_t x,
+ 
+ // Computes lower 64 bits of multiplication of a 32-bit unsigned integer and a
+ // 64-bit unsigned integer.
+-inline uint64_t umul96_lower64(uint32_t x, uint64_t y) noexcept {
++inline auto umul96_lower64(uint32_t x, uint64_t y) noexcept -> uint64_t {
+   return x * y;
+ }
+ 
+ // Various fast log computations.
+-inline int floor_log10_pow2_minus_log10_4_over_3(int e) noexcept {
++inline auto floor_log10_pow2_minus_log10_4_over_3(int e) noexcept -> int {
+   FMT_ASSERT(e <= 2936 && e >= -2985, "too large exponent");
+   return (e * 631305 - 261663) >> 21;
+ }
+ 
+-FMT_INLINE_VARIABLE constexpr struct {
++FMT_INLINE_VARIABLE constexpr struct div_small_pow10_infos_struct {
+   uint32_t divisor;
+   int shift_amount;
+ } div_small_pow10_infos[] = {{10, 16}, {100, 16}};
+@@ -204,7 +221,7 @@ FMT_INLINE_VARIABLE constexpr struct {
+ // divisible by pow(10, N).
+ // Precondition: n <= pow(10, N + 1).
+ template <int N>
+-bool check_divisibility_and_divide_by_pow10(uint32_t& n) noexcept {
++auto check_divisibility_and_divide_by_pow10(uint32_t& n) noexcept -> bool {
+   // The numbers below are chosen such that:
+   //   1. floor(n/d) = floor(nm / 2^k) where d=10 or d=100,
+   //   2. nm mod 2^k < m if and only if n is divisible by d,
+@@ -229,7 +246,7 @@ bool check_divisibility_and_divide_by_pow10(uint32_t& n) noexcept {
+ 
+ // Computes floor(n / pow(10, N)) for small n and N.
+ // Precondition: n <= pow(10, N + 1).
+-template <int N> uint32_t small_division_by_pow10(uint32_t n) noexcept {
++template <int N> auto small_division_by_pow10(uint32_t n) noexcept -> uint32_t {
+   constexpr auto info = div_small_pow10_infos[N - 1];
+   FMT_ASSERT(n <= info.divisor * 10, "n is too large");
+   constexpr uint32_t magic_number =
+@@ -238,12 +255,12 @@ template <int N> uint32_t small_division_by_pow10(uint32_t n) noexcept {
+ }
+ 
+ // Computes floor(n / 10^(kappa + 1)) (float)
+-inline uint32_t divide_by_10_to_kappa_plus_1(uint32_t n) noexcept {
++inline auto divide_by_10_to_kappa_plus_1(uint32_t n) noexcept -> uint32_t {
+   // 1374389535 = ceil(2^37/100)
+   return static_cast<uint32_t>((static_cast<uint64_t>(n) * 1374389535) >> 37);
+ }
+ // Computes floor(n / 10^(kappa + 1)) (double)
+-inline uint64_t divide_by_10_to_kappa_plus_1(uint64_t n) noexcept {
++inline auto divide_by_10_to_kappa_plus_1(uint64_t n) noexcept -> uint64_t {
+   // 2361183241434822607 = ceil(2^(64+7)/1000)
+   return umul128_upper64(n, 2361183241434822607ull) >> 7;
+ }
+@@ -255,7 +272,7 @@ template <> struct cache_accessor<float> {
+   using carrier_uint = float_info<float>::carrier_uint;
+   using cache_entry_type = uint64_t;
+ 
+-  static uint64_t get_cached_power(int k) noexcept {
++  static auto get_cached_power(int k) noexcept -> uint64_t {
+     FMT_ASSERT(k >= float_info<float>::min_k && k <= float_info<float>::max_k,
+                "k is out of range");
+     static constexpr const uint64_t pow10_significands[] = {
+@@ -297,20 +314,23 @@ template <> struct cache_accessor<float> {
+     bool is_integer;
+   };
+ 
+-  static compute_mul_result compute_mul(
+-      carrier_uint u, const cache_entry_type& cache) noexcept {
++  static auto compute_mul(carrier_uint u,
++                          const cache_entry_type& cache) noexcept
++      -> compute_mul_result {
+     auto r = umul96_upper64(u, cache);
+     return {static_cast<carrier_uint>(r >> 32),
+             static_cast<carrier_uint>(r) == 0};
+   }
+ 
+-  static uint32_t compute_delta(const cache_entry_type& cache,
+-                                int beta) noexcept {
++  static auto compute_delta(const cache_entry_type& cache, int beta) noexcept
++      -> uint32_t {
+     return static_cast<uint32_t>(cache >> (64 - 1 - beta));
+   }
+ 
+-  static compute_mul_parity_result compute_mul_parity(
+-      carrier_uint two_f, const cache_entry_type& cache, int beta) noexcept {
++  static auto compute_mul_parity(carrier_uint two_f,
++                                 const cache_entry_type& cache,
++                                 int beta) noexcept
++      -> compute_mul_parity_result {
+     FMT_ASSERT(beta >= 1, "");
+     FMT_ASSERT(beta < 64, "");
+ 
+@@ -319,22 +339,22 @@ template <> struct cache_accessor<float> {
+             static_cast<uint32_t>(r >> (32 - beta)) == 0};
+   }
+ 
+-  static carrier_uint compute_left_endpoint_for_shorter_interval_case(
+-      const cache_entry_type& cache, int beta) noexcept {
++  static auto compute_left_endpoint_for_shorter_interval_case(
++      const cache_entry_type& cache, int beta) noexcept -> carrier_uint {
+     return static_cast<carrier_uint>(
+         (cache - (cache >> (num_significand_bits<float>() + 2))) >>
+         (64 - num_significand_bits<float>() - 1 - beta));
+   }
+ 
+-  static carrier_uint compute_right_endpoint_for_shorter_interval_case(
+-      const cache_entry_type& cache, int beta) noexcept {
++  static auto compute_right_endpoint_for_shorter_interval_case(
++      const cache_entry_type& cache, int beta) noexcept -> carrier_uint {
+     return static_cast<carrier_uint>(
+         (cache + (cache >> (num_significand_bits<float>() + 1))) >>
+         (64 - num_significand_bits<float>() - 1 - beta));
+   }
+ 
+-  static carrier_uint compute_round_up_for_shorter_interval_case(
+-      const cache_entry_type& cache, int beta) noexcept {
++  static auto compute_round_up_for_shorter_interval_case(
++      const cache_entry_type& cache, int beta) noexcept -> carrier_uint {
+     return (static_cast<carrier_uint>(
+                 cache >> (64 - num_significand_bits<float>() - 2 - beta)) +
+             1) /
+@@ -346,7 +366,7 @@ template <> struct cache_accessor<double> {
+   using carrier_uint = float_info<double>::carrier_uint;
+   using cache_entry_type = uint128_fallback;
+ 
+-  static uint128_fallback get_cached_power(int k) noexcept {
++  static auto get_cached_power(int k) noexcept -> uint128_fallback {
+     FMT_ASSERT(k >= float_info<double>::min_k && k <= float_info<double>::max_k,
+                "k is out of range");
+ 
+@@ -985,8 +1005,7 @@ template <> struct cache_accessor<double> {
+       {0xe0accfa875af45a7, 0x93eb1b80a33b8606},
+       {0x8c6c01c9498d8b88, 0xbc72f130660533c4},
+       {0xaf87023b9bf0ee6a, 0xeb8fad7c7f8680b5},
+-      { 0xdb68c2ca82ed2a05,
+-        0xa67398db9f6820e2 }
++      {0xdb68c2ca82ed2a05, 0xa67398db9f6820e2},
+ #else
+       {0xff77b1fcbebcdc4f, 0x25e8e89c13bb0f7b},
+       {0xce5d73ff402d98e3, 0xfb0a3d212dc81290},
+@@ -1071,19 +1090,22 @@ template <> struct cache_accessor<double> {
+     bool is_integer;
+   };
+ 
+-  static compute_mul_result compute_mul(
+-      carrier_uint u, const cache_entry_type& cache) noexcept {
++  static auto compute_mul(carrier_uint u,
++                          const cache_entry_type& cache) noexcept
++      -> compute_mul_result {
+     auto r = umul192_upper128(u, cache);
+     return {r.high(), r.low() == 0};
+   }
+ 
+-  static uint32_t compute_delta(cache_entry_type const& cache,
+-                                int beta) noexcept {
++  static auto compute_delta(cache_entry_type const& cache, int beta) noexcept
++      -> uint32_t {
+     return static_cast<uint32_t>(cache.high() >> (64 - 1 - beta));
+   }
+ 
+-  static compute_mul_parity_result compute_mul_parity(
+-      carrier_uint two_f, const cache_entry_type& cache, int beta) noexcept {
++  static auto compute_mul_parity(carrier_uint two_f,
++                                 const cache_entry_type& cache,
++                                 int beta) noexcept
++      -> compute_mul_parity_result {
+     FMT_ASSERT(beta >= 1, "");
+     FMT_ASSERT(beta < 64, "");
+ 
+@@ -1092,35 +1114,35 @@ template <> struct cache_accessor<double> {
+             ((r.high() << beta) | (r.low() >> (64 - beta))) == 0};
+   }
+ 
+-  static carrier_uint compute_left_endpoint_for_shorter_interval_case(
+-      const cache_entry_type& cache, int beta) noexcept {
++  static auto compute_left_endpoint_for_shorter_interval_case(
++      const cache_entry_type& cache, int beta) noexcept -> carrier_uint {
+     return (cache.high() -
+             (cache.high() >> (num_significand_bits<double>() + 2))) >>
+            (64 - num_significand_bits<double>() - 1 - beta);
+   }
+ 
+-  static carrier_uint compute_right_endpoint_for_shorter_interval_case(
+-      const cache_entry_type& cache, int beta) noexcept {
++  static auto compute_right_endpoint_for_shorter_interval_case(
++      const cache_entry_type& cache, int beta) noexcept -> carrier_uint {
+     return (cache.high() +
+             (cache.high() >> (num_significand_bits<double>() + 1))) >>
+            (64 - num_significand_bits<double>() - 1 - beta);
+   }
+ 
+-  static carrier_uint compute_round_up_for_shorter_interval_case(
+-      const cache_entry_type& cache, int beta) noexcept {
++  static auto compute_round_up_for_shorter_interval_case(
++      const cache_entry_type& cache, int beta) noexcept -> carrier_uint {
+     return ((cache.high() >> (64 - num_significand_bits<double>() - 2 - beta)) +
+             1) /
+            2;
+   }
+ };
+ 
+-FMT_FUNC uint128_fallback get_cached_power(int k) noexcept {
++FMT_FUNC auto get_cached_power(int k) noexcept -> uint128_fallback {
+   return cache_accessor<double>::get_cached_power(k);
+ }
+ 
+ // Various integer checks
+ template <typename T>
+-bool is_left_endpoint_integer_shorter_interval(int exponent) noexcept {
++auto is_left_endpoint_integer_shorter_interval(int exponent) noexcept -> bool {
+   const int case_shorter_interval_left_endpoint_lower_threshold = 2;
+   const int case_shorter_interval_left_endpoint_upper_threshold = 3;
+   return exponent >= case_shorter_interval_left_endpoint_lower_threshold &&
+@@ -1132,7 +1154,7 @@ FMT_INLINE int remove_trailing_zeros(uint32_t& n, int s = 0) noexcept {
+   FMT_ASSERT(n != 0, "");
+   // Modular inverse of 5 (mod 2^32): (mod_inv_5 * 5) mod 2^32 = 1.
+   constexpr uint32_t mod_inv_5 = 0xcccccccd;
+-  constexpr uint32_t mod_inv_25 = 0xc28f5c29; // = mod_inv_5 * mod_inv_5
++  constexpr uint32_t mod_inv_25 = 0xc28f5c29;  // = mod_inv_5 * mod_inv_5
+ 
+   while (true) {
+     auto q = rotr(n * mod_inv_25, 2);
+@@ -1168,7 +1190,7 @@ FMT_INLINE int remove_trailing_zeros(uint64_t& n) noexcept {
+ 
+   // If n is not divisible by 10^8, work with n itself.
+   constexpr uint64_t mod_inv_5 = 0xcccccccccccccccd;
+-  constexpr uint64_t mod_inv_25 = 0x8f5c28f5c28f5c29; // = mod_inv_5 * mod_inv_5
++  constexpr uint64_t mod_inv_25 = 0x8f5c28f5c28f5c29;  // mod_inv_5 * mod_inv_5
+ 
+   int s = 0;
+   while (true) {
+@@ -1234,7 +1256,7 @@ FMT_INLINE decimal_fp<T> shorter_interval_case(int exponent) noexcept {
+   return ret_value;
+ }
+ 
+-template <typename T> decimal_fp<T> to_decimal(T x) noexcept {
++template <typename T> auto to_decimal(T x) noexcept -> decimal_fp<T> {
+   // Step 1: integer promotion & Schubfach multiplier calculation.
+ 
+   using carrier_uint = typename float_info<T>::carrier_uint;
+@@ -1373,15 +1395,15 @@ template <> struct formatter<detail::bigint> {
+     for (auto i = n.bigits_.size(); i > 0; --i) {
+       auto value = n.bigits_[i - 1u];
+       if (first) {
+-        out = format_to(out, FMT_STRING("{:x}"), value);
++        out = fmt::format_to(out, FMT_STRING("{:x}"), value);
+         first = false;
+         continue;
+       }
+-      out = format_to(out, FMT_STRING("{:08x}"), value);
++      out = fmt::format_to(out, FMT_STRING("{:08x}"), value);
+     }
+     if (n.exp_ > 0)
+-      out = format_to(out, FMT_STRING("p{}"),
+-                      n.exp_ * detail::bigint::bigit_bits);
++      out = fmt::format_to(out, FMT_STRING("p{}"),
++                           n.exp_ * detail::bigint::bigit_bits);
+     return out;
+   }
+ };
+@@ -1405,7 +1427,7 @@ FMT_FUNC void format_system_error(detail::buffer<char>& out, int error_code,
+                                   const char* message) noexcept {
+   FMT_TRY {
+     auto ec = std::error_code(error_code, std::generic_category());
+-    write(std::back_inserter(out), std::system_error(ec, message).what());
++    detail::write(appender(out), std::system_error(ec, message).what());
+     return;
+   }
+   FMT_CATCH(...) {}
+@@ -1414,10 +1436,10 @@ FMT_FUNC void format_system_error(detail::buffer<char>& out, int error_code,
+ 
+ FMT_FUNC void report_system_error(int error_code,
+                                   const char* message) noexcept {
+-  report_error(format_system_error, error_code, message);
++  do_report_error(format_system_error, error_code, message);
+ }
+ 
+-FMT_FUNC std::string vformat(string_view fmt, format_args args) {
++FMT_FUNC auto vformat(string_view fmt, format_args args) -> std::string {
+   // Don't optimize the "{}" case to keep the binary size small and because it
+   // can be better optimized in fmt::format anyway.
+   auto buffer = memory_buffer();
+@@ -1426,39 +1448,304 @@ FMT_FUNC std::string vformat(string_view fmt, format_args args) {
+ }
+ 
+ namespace detail {
+-#ifndef _WIN32
+-FMT_FUNC bool write_console(std::FILE*, string_view) { return false; }
++
++FMT_FUNC void vformat_to(buffer<char>& buf, string_view fmt, format_args args,
++                         locale_ref loc) {
++  auto out = appender(buf);
++  if (fmt.size() == 2 && equal2(fmt.data(), "{}"))
++    return args.get(0).visit(default_arg_formatter<char>{out});
++  parse_format_string(
++      fmt, format_handler<char>{parse_context<char>(fmt), {out, args, loc}});
++}
++
++template <typename T> struct span {
++  T* data;
++  size_t size;
++};
++
++template <typename F> auto flockfile(F* f) -> decltype(_lock_file(f)) {
++  _lock_file(f);
++}
++template <typename F> auto funlockfile(F* f) -> decltype(_unlock_file(f)) {
++  _unlock_file(f);
++}
++
++#ifndef getc_unlocked
++template <typename F> auto getc_unlocked(F* f) -> decltype(_fgetc_nolock(f)) {
++  return _fgetc_nolock(f);
++}
++#endif
++
++template <typename F = FILE, typename Enable = void>
++struct has_flockfile : std::false_type {};
++
++template <typename F>
++struct has_flockfile<F, void_t<decltype(flockfile(&std::declval<F&>()))>>
++    : std::true_type {};
++
++// A FILE wrapper. F is FILE defined as a template parameter to make system API
++// detection work.
++template <typename F> class file_base {
++ public:
++  F* file_;
++
++ public:
++  file_base(F* file) : file_(file) {}
++  operator F*() const { return file_; }
++
++  // Reads a code unit from the stream.
++  auto get() -> int {
++    int result = getc_unlocked(file_);
++    if (result == EOF && ferror(file_) != 0)
++      FMT_THROW(system_error(errno, FMT_STRING("getc failed")));
++    return result;
++  }
++
++  // Puts the code unit back into the stream buffer.
++  void unget(char c) {
++    if (ungetc(c, file_) == EOF)
++      FMT_THROW(system_error(errno, FMT_STRING("ungetc failed")));
++  }
++
++  void flush() { fflush(this->file_); }
++};
++
++// A FILE wrapper for glibc.
++template <typename F> class glibc_file : public file_base<F> {
++ private:
++  enum {
++    line_buffered = 0x200,  // _IO_LINE_BUF
++    unbuffered = 2          // _IO_UNBUFFERED
++  };
++
++ public:
++  using file_base<F>::file_base;
++
++  auto is_buffered() const -> bool {
++    return (this->file_->_flags & unbuffered) == 0;
++  }
++
++  void init_buffer() {
++    if (this->file_->_IO_write_ptr) return;
++    // Force buffer initialization by placing and removing a char in a buffer.
++    assume(this->file_->_IO_write_ptr >= this->file_->_IO_write_end);
++    putc_unlocked(0, this->file_);
++    --this->file_->_IO_write_ptr;
++  }
++
++  // Returns the file's read buffer.
++  auto get_read_buffer() const -> span<const char> {
++    auto ptr = this->file_->_IO_read_ptr;
++    return {ptr, to_unsigned(this->file_->_IO_read_end - ptr)};
++  }
++
++  // Returns the file's write buffer.
++  auto get_write_buffer() const -> span<char> {
++    auto ptr = this->file_->_IO_write_ptr;
++    return {ptr, to_unsigned(this->file_->_IO_buf_end - ptr)};
++  }
++
++  void advance_write_buffer(size_t size) { this->file_->_IO_write_ptr += size; }
++
++  bool needs_flush() const {
++    if ((this->file_->_flags & line_buffered) == 0) return false;
++    char* end = this->file_->_IO_write_end;
++    return memchr(end, '\n', to_unsigned(this->file_->_IO_write_ptr - end));
++  }
++
++  void flush() { fflush_unlocked(this->file_); }
++};
++
++// A FILE wrapper for Apple's libc.
++template <typename F> class apple_file : public file_base<F> {
++ private:
++  enum {
++    line_buffered = 1,  // __SNBF
++    unbuffered = 2      // __SLBF
++  };
++
++ public:
++  using file_base<F>::file_base;
++
++  auto is_buffered() const -> bool {
++    return (this->file_->_flags & unbuffered) == 0;
++  }
++
++  void init_buffer() {
++    if (this->file_->_p) return;
++    // Force buffer initialization by placing and removing a char in a buffer.
++    putc_unlocked(0, this->file_);
++    --this->file_->_p;
++    ++this->file_->_w;
++  }
++
++  auto get_read_buffer() const -> span<const char> {
++    return {reinterpret_cast<char*>(this->file_->_p),
++            to_unsigned(this->file_->_r)};
++  }
++
++  auto get_write_buffer() const -> span<char> {
++    return {reinterpret_cast<char*>(this->file_->_p),
++            to_unsigned(this->file_->_bf._base + this->file_->_bf._size -
++                        this->file_->_p)};
++  }
++
++  void advance_write_buffer(size_t size) {
++    this->file_->_p += size;
++    this->file_->_w -= size;
++  }
++
++  bool needs_flush() const {
++    if ((this->file_->_flags & line_buffered) == 0) return false;
++    return memchr(this->file_->_p + this->file_->_w, '\n',
++                  to_unsigned(-this->file_->_w));
++  }
++};
++
++// A fallback FILE wrapper.
++template <typename F> class fallback_file : public file_base<F> {
++ private:
++  char next_;  // The next unconsumed character in the buffer.
++  bool has_next_ = false;
++
++ public:
++  using file_base<F>::file_base;
++
++  auto is_buffered() const -> bool { return false; }
++  auto needs_flush() const -> bool { return false; }
++  void init_buffer() {}
++
++  auto get_read_buffer() const -> span<const char> {
++    return {&next_, has_next_ ? 1u : 0u};
++  }
++
++  auto get_write_buffer() const -> span<char> { return {nullptr, 0}; }
++
++  void advance_write_buffer(size_t) {}
++
++  auto get() -> int {
++    has_next_ = false;
++    return file_base<F>::get();
++  }
++
++  void unget(char c) {
++    file_base<F>::unget(c);
++    next_ = c;
++    has_next_ = true;
++  }
++};
++
++#ifndef FMT_USE_FALLBACK_FILE
++#  define FMT_USE_FALLBACK_FILE 0
++#endif
++
++template <typename F,
++          FMT_ENABLE_IF(sizeof(F::_p) != 0 && !FMT_USE_FALLBACK_FILE)>
++auto get_file(F* f, int) -> apple_file<F> {
++  return f;
++}
++template <typename F,
++          FMT_ENABLE_IF(sizeof(F::_IO_read_ptr) != 0 && !FMT_USE_FALLBACK_FILE)>
++inline auto get_file(F* f, int) -> glibc_file<F> {
++  return f;
++}
++
++inline auto get_file(FILE* f, ...) -> fallback_file<FILE> { return f; }
++
++using file_ref = decltype(get_file(static_cast<FILE*>(nullptr), 0));
++
++template <typename F = FILE, typename Enable = void>
++class file_print_buffer : public buffer<char> {
++ public:
++  explicit file_print_buffer(F*) : buffer(nullptr, size_t()) {}
++};
++
++template <typename F>
++class file_print_buffer<F, enable_if_t<has_flockfile<F>::value>>
++    : public buffer<char> {
++ private:
++  file_ref file_;
++
++  static void grow(buffer<char>& base, size_t) {
++    auto& self = static_cast<file_print_buffer&>(base);
++    self.file_.advance_write_buffer(self.size());
++    if (self.file_.get_write_buffer().size == 0) self.file_.flush();
++    auto buf = self.file_.get_write_buffer();
++    FMT_ASSERT(buf.size > 0, "");
++    self.set(buf.data, buf.size);
++    self.clear();
++  }
++
++ public:
++  explicit file_print_buffer(F* f) : buffer(grow, size_t()), file_(f) {
++    flockfile(f);
++    file_.init_buffer();
++    auto buf = file_.get_write_buffer();
++    set(buf.data, buf.size);
++  }
++  ~file_print_buffer() {
++    file_.advance_write_buffer(size());
++    bool flush = file_.needs_flush();
++    F* f = file_;    // Make funlockfile depend on the template parameter F
++    funlockfile(f);  // for the system API detection to work.
++    if (flush) fflush(file_);
++  }
++};
++
++#if !defined(_WIN32) || defined(FMT_USE_WRITE_CONSOLE)
++FMT_FUNC auto write_console(int, string_view) -> bool { return false; }
+ #else
+ using dword = conditional_t<sizeof(long) == 4, unsigned long, unsigned>;
+ extern "C" __declspec(dllimport) int __stdcall WriteConsoleW(  //
+     void*, const void*, dword, dword*, void*);
+ 
+-FMT_FUNC bool write_console(std::FILE* f, string_view text) {
+-  auto fd = _fileno(f);
+-  if (!_isatty(fd)) return false;
++FMT_FUNC bool write_console(int fd, string_view text) {
+   auto u16 = utf8_to_utf16(text);
+-  auto written = dword();
+   return WriteConsoleW(reinterpret_cast<void*>(_get_osfhandle(fd)), u16.c_str(),
+-                       static_cast<uint32_t>(u16.size()), &written, nullptr) != 0;
++                       static_cast<dword>(u16.size()), nullptr, nullptr) != 0;
+ }
++#endif
+ 
++#ifdef _WIN32
+ // Print assuming legacy (non-Unicode) encoding.
+-FMT_FUNC void vprint_mojibake(std::FILE* f, string_view fmt, format_args args) {
++FMT_FUNC void vprint_mojibake(std::FILE* f, string_view fmt, format_args args,
++                              bool newline) {
+   auto buffer = memory_buffer();
+-  detail::vformat_to(buffer, fmt,
+-                     basic_format_args<buffer_context<char>>(args));
+-  fwrite_fully(buffer.data(), 1, buffer.size(), f);
++  detail::vformat_to(buffer, fmt, args);
++  if (newline) buffer.push_back('\n');
++  fwrite_all(buffer.data(), buffer.size(), f);
+ }
+ #endif
+ 
+ FMT_FUNC void print(std::FILE* f, string_view text) {
+-  if (!write_console(f, text)) fwrite_fully(text.data(), 1, text.size(), f);
++#if defined(_WIN32) && !defined(FMT_USE_WRITE_CONSOLE)
++  int fd = _fileno(f);
++  if (_isatty(fd)) {
++    std::fflush(f);
++    if (write_console(fd, text)) return;
++  }
++#endif
++  fwrite_all(text.data(), text.size(), f);
+ }
+ }  // namespace detail
+ 
++FMT_FUNC void vprint_buffered(std::FILE* f, string_view fmt, format_args args) {
++  auto buffer = memory_buffer();
++  detail::vformat_to(buffer, fmt, args);
++  detail::print(f, {buffer.data(), buffer.size()});
++}
++
+ FMT_FUNC void vprint(std::FILE* f, string_view fmt, format_args args) {
++  if (!detail::file_ref(f).is_buffered() || !detail::has_flockfile<>())
++    return vprint_buffered(f, fmt, args);
++  auto&& buffer = detail::file_print_buffer<>(f);
++  return detail::vformat_to(buffer, fmt, args);
++}
++
++FMT_FUNC void vprintln(std::FILE* f, string_view fmt, format_args args) {
+   auto buffer = memory_buffer();
+   detail::vformat_to(buffer, fmt, args);
++  buffer.push_back('\n');
+   detail::print(f, {buffer.data(), buffer.size()});
+ }
+ 
+diff --git a/include/fmt/format.h b/include/fmt/format.h
+index a65d376..287e716 100644
+--- a/include/fmt/format.h
++++ b/include/fmt/format.h
+@@ -33,24 +33,58 @@
+ #ifndef FMT_FORMAT_H_
+ #define FMT_FORMAT_H_
+ 
+-#include <cmath>             // std::signbit
+-#include <cstdint>           // uint32_t
+-#include <cstring>           // std::memcpy
+-#include <initializer_list>  // std::initializer_list
+-#include <limits>            // std::numeric_limits
+-#include <memory>            // std::uninitialized_copy
+-#include <stdexcept>         // std::runtime_error
+-#include <system_error>      // std::system_error
+-
+-#ifdef __cpp_lib_bit_cast
+-#  include <bit>  // std::bitcast
++#ifndef _LIBCPP_REMOVE_TRANSITIVE_INCLUDES
++#  define _LIBCPP_REMOVE_TRANSITIVE_INCLUDES
++#  define FMT_REMOVE_TRANSITIVE_INCLUDES
+ #endif
+ 
+-#include "core.h"
++#include "base.h"
++
++#ifndef FMT_MODULE
++#  include <cmath>    // std::signbit
++#  include <cstddef>  // std::byte
++#  include <cstdint>  // uint32_t
++#  include <cstring>  // std::memcpy
++#  include <limits>   // std::numeric_limits
++#  include <new>      // std::bad_alloc
++#  if defined(__GLIBCXX__) && !defined(_GLIBCXX_USE_DUAL_ABI)
++// Workaround for pre gcc 5 libstdc++.
++#    include <memory>  // std::allocator_traits
++#  endif
++#  include <stdexcept>     // std::runtime_error
++#  include <string>        // std::string
++#  include <system_error>  // std::system_error
++
++// Check FMT_CPLUSPLUS to avoid a warning in MSVC.
++#  if FMT_HAS_INCLUDE(<bit>) && FMT_CPLUSPLUS > 201703L
++#    include <bit>  // std::bit_cast
++#  endif
++
++// libc++ supports string_view in pre-c++17.
++#  if FMT_HAS_INCLUDE(<string_view>) && \
++      (FMT_CPLUSPLUS >= 201703L || defined(_LIBCPP_VERSION))
++#    include <string_view>
++#    define FMT_USE_STRING_VIEW
++#  endif
+ 
+-#ifndef FMT_BEGIN_DETAIL_NAMESPACE
+-#  define FMT_BEGIN_DETAIL_NAMESPACE namespace detail {
+-#  define FMT_END_DETAIL_NAMESPACE }
++#  if FMT_MSC_VERSION
++#    include <intrin.h>  // _BitScanReverse[64], _umul128
++#  endif
++#endif  // FMT_MODULE
++
++#if defined(FMT_USE_NONTYPE_TEMPLATE_ARGS)
++// Use the provided definition.
++#elif defined(__NVCOMPILER)
++#  define FMT_USE_NONTYPE_TEMPLATE_ARGS 0
++#elif FMT_GCC_VERSION >= 903 && FMT_CPLUSPLUS >= 201709L
++#  define FMT_USE_NONTYPE_TEMPLATE_ARGS 1
++#elif defined(__cpp_nontype_template_args) && \
++    __cpp_nontype_template_args >= 201911L
++#  define FMT_USE_NONTYPE_TEMPLATE_ARGS 1
++#elif FMT_CLANG_VERSION >= 1200 && FMT_CPLUSPLUS >= 202002L
++#  define FMT_USE_NONTYPE_TEMPLATE_ARGS 1
++#else
++#  define FMT_USE_NONTYPE_TEMPLATE_ARGS 0
+ #endif
+ 
+ #if defined __cpp_inline_variables && __cpp_inline_variables >= 201606L
+@@ -59,41 +93,22 @@
+ #  define FMT_INLINE_VARIABLE
+ #endif
+ 
+-#if FMT_HAS_CPP17_ATTRIBUTE(fallthrough)
+-#  define FMT_FALLTHROUGH [[fallthrough]]
+-#elif defined(__clang__)
+-#  define FMT_FALLTHROUGH [[clang::fallthrough]]
+-#elif FMT_GCC_VERSION >= 700 && \
+-    (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= 520)
+-#  define FMT_FALLTHROUGH [[gnu::fallthrough]]
+-#else
+-#  define FMT_FALLTHROUGH
+-#endif
+-
+-#ifndef FMT_DEPRECATED
+-#  if FMT_HAS_CPP14_ATTRIBUTE(deprecated) || FMT_MSC_VERSION >= 1900
+-#    define FMT_DEPRECATED [[deprecated]]
+-#  else
+-#    if (defined(__GNUC__) && !defined(__LCC__)) || defined(__clang__)
+-#      define FMT_DEPRECATED __attribute__((deprecated))
+-#    elif FMT_MSC_VERSION
+-#      define FMT_DEPRECATED __declspec(deprecated)
+-#    else
+-#      define FMT_DEPRECATED /* deprecated */
+-#    endif
+-#  endif
+-#endif
+-
+-#if FMT_GCC_VERSION || defined(__clang__)
+-#  define FMT_VISIBILITY(value) __attribute__((visibility(value)))
++// Check if RTTI is disabled.
++#ifdef FMT_USE_RTTI
++// Use the provided definition.
++#elif defined(__GXX_RTTI) || FMT_HAS_FEATURE(cxx_rtti) || defined(_CPPRTTI) || \
++    defined(__INTEL_RTTI__) || defined(__RTTI)
++// __RTTI is for EDG compilers. _CPPRTTI is for MSVC.
++#  define FMT_USE_RTTI 1
+ #else
+-#  define FMT_VISIBILITY(value)
++#  define FMT_USE_RTTI 0
+ #endif
+ 
+-#ifdef __has_builtin
+-#  define FMT_HAS_BUILTIN(x) __has_builtin(x)
++// Visibility when compiled as a shared library/object.
++#if defined(FMT_LIB_EXPORT) || defined(FMT_SHARED)
++#  define FMT_SO_VISIBILITY(value) FMT_VISIBILITY(value)
+ #else
+-#  define FMT_HAS_BUILTIN(x) 0
++#  define FMT_SO_VISIBILITY(value)
+ #endif
+ 
+ #if FMT_GCC_VERSION || FMT_CLANG_VERSION
+@@ -102,8 +117,19 @@
+ #  define FMT_NOINLINE
+ #endif
+ 
++namespace std {
++template <typename T> struct iterator_traits<fmt::basic_appender<T>> {
++  using iterator_category = output_iterator_tag;
++  using value_type = T;
++  using difference_type =
++      decltype(static_cast<int*>(nullptr) - static_cast<int*>(nullptr));
++  using pointer = void;
++  using reference = void;
++};
++}  // namespace std
++
+ #ifndef FMT_THROW
+-#  if FMT_EXCEPTIONS
++#  if FMT_USE_EXCEPTIONS
+ #    if FMT_MSC_VERSION || defined(__NVCC__)
+ FMT_BEGIN_NAMESPACE
+ namespace detail {
+@@ -122,35 +148,8 @@ FMT_END_NAMESPACE
+ #  else
+ #    define FMT_THROW(x) \
+       ::fmt::detail::assert_fail(__FILE__, __LINE__, (x).what())
+-#  endif
+-#endif
+-
+-#if FMT_EXCEPTIONS
+-#  define FMT_TRY try
+-#  define FMT_CATCH(x) catch (x)
+-#else
+-#  define FMT_TRY if (true)
+-#  define FMT_CATCH(x) if (false)
+-#endif
+-
+-#ifndef FMT_MAYBE_UNUSED
+-#  if FMT_HAS_CPP17_ATTRIBUTE(maybe_unused)
+-#    define FMT_MAYBE_UNUSED [[maybe_unused]]
+-#  else
+-#    define FMT_MAYBE_UNUSED
+-#  endif
+-#endif
+-
+-#ifndef FMT_USE_USER_DEFINED_LITERALS
+-// EDG based compilers (Intel, NVIDIA, Elbrus, etc), GCC and MSVC support UDLs.
+-#  if (FMT_HAS_FEATURE(cxx_user_literals) || FMT_GCC_VERSION >= 407 || \
+-       FMT_MSC_VERSION >= 1900) &&                                     \
+-      (!defined(__EDG_VERSION__) || __EDG_VERSION__ >= /* UDL feature */ 480)
+-#    define FMT_USE_USER_DEFINED_LITERALS 1
+-#  else
+-#    define FMT_USE_USER_DEFINED_LITERALS 0
+-#  endif
+-#endif
++#  endif  // FMT_USE_EXCEPTIONS
++#endif    // FMT_THROW
+ 
+ // Defining FMT_REDUCE_INT_INSTANTIATIONS to 1, will reduce the number of
+ // integer formatter template instantiations to just one by only using the
+@@ -160,7 +159,15 @@ FMT_END_NAMESPACE
+ #  define FMT_REDUCE_INT_INSTANTIATIONS 0
+ #endif
+ 
+-// __builtin_clz is broken in clang with Microsoft CodeGen:
++FMT_BEGIN_NAMESPACE
++
++template <typename Char, typename Traits, typename Allocator>
++struct is_contiguous<std::basic_string<Char, Traits, Allocator>>
++    : std::true_type {};
++
++namespace detail {
++
++// __builtin_clz is broken in clang with Microsoft codegen:
+ // https://github.com/fmtlib/fmt/issues/519.
+ #if !FMT_MSC_VERSION
+ #  if FMT_HAS_BUILTIN(__builtin_clz) || FMT_GCC_VERSION || FMT_ICC_VERSION
+@@ -171,53 +178,30 @@ FMT_END_NAMESPACE
+ #  endif
+ #endif
+ 
+-// __builtin_ctz is broken in Intel Compiler Classic on Windows:
+-// https://github.com/fmtlib/fmt/issues/2510.
+-#ifndef __ICL
+-#  if FMT_HAS_BUILTIN(__builtin_ctz) || FMT_GCC_VERSION || FMT_ICC_VERSION || \
+-      defined(__NVCOMPILER)
+-#    define FMT_BUILTIN_CTZ(n) __builtin_ctz(n)
+-#  endif
+-#  if FMT_HAS_BUILTIN(__builtin_ctzll) || FMT_GCC_VERSION || \
+-      FMT_ICC_VERSION || defined(__NVCOMPILER)
+-#    define FMT_BUILTIN_CTZLL(n) __builtin_ctzll(n)
+-#  endif
+-#endif
+-
+-#if FMT_MSC_VERSION
+-#  include <intrin.h>  // _BitScanReverse[64], _BitScanForward[64], _umul128
+-#endif
+-
+-// Some compilers masquerade as both MSVC and GCC-likes or otherwise support
++// Some compilers masquerade as both MSVC and GCC but otherwise support
+ // __builtin_clz and __builtin_clzll, so only define FMT_BUILTIN_CLZ using the
+ // MSVC intrinsics if the clz and clzll builtins are not available.
+-#if FMT_MSC_VERSION && !defined(FMT_BUILTIN_CLZLL) && \
+-    !defined(FMT_BUILTIN_CTZLL)
+-FMT_BEGIN_NAMESPACE
+-namespace detail {
++#if FMT_MSC_VERSION && !defined(FMT_BUILTIN_CLZLL)
+ // Avoid Clang with Microsoft CodeGen's -Wunknown-pragmas warning.
+-#  if !defined(__clang__)
+-#    pragma intrinsic(_BitScanForward)
++#  ifndef __clang__
+ #    pragma intrinsic(_BitScanReverse)
+-#    if defined(_WIN64)
+-#      pragma intrinsic(_BitScanForward64)
++#    ifdef _WIN64
+ #      pragma intrinsic(_BitScanReverse64)
+ #    endif
+ #  endif
+ 
+ inline auto clz(uint32_t x) -> int {
++  FMT_ASSERT(x != 0, "");
++  FMT_MSC_WARNING(suppress : 6102)  // Suppress a bogus static analysis warning.
+   unsigned long r = 0;
+   _BitScanReverse(&r, x);
+-  FMT_ASSERT(x != 0, "");
+-  // Static analysis complains about using uninitialized data
+-  // "r", but the only way that can happen is if "x" is 0,
+-  // which the callers guarantee to not happen.
+-  FMT_MSC_WARNING(suppress : 6102)
+   return 31 ^ static_cast<int>(r);
+ }
+ #  define FMT_BUILTIN_CLZ(n) detail::clz(n)
+ 
+ inline auto clzll(uint64_t x) -> int {
++  FMT_ASSERT(x != 0, "");
++  FMT_MSC_WARNING(suppress : 6102)  // Suppress a bogus static analysis warning.
+   unsigned long r = 0;
+ #  ifdef _WIN64
+   _BitScanReverse64(&r, x);
+@@ -228,56 +212,10 @@ inline auto clzll(uint64_t x) -> int {
+   // Scan the low 32 bits.
+   _BitScanReverse(&r, static_cast<uint32_t>(x));
+ #  endif
+-  FMT_ASSERT(x != 0, "");
+-  FMT_MSC_WARNING(suppress : 6102)  // Suppress a bogus static analysis warning.
+   return 63 ^ static_cast<int>(r);
+ }
+ #  define FMT_BUILTIN_CLZLL(n) detail::clzll(n)
+-
+-inline auto ctz(uint32_t x) -> int {
+-  unsigned long r = 0;
+-  _BitScanForward(&r, x);
+-  FMT_ASSERT(x != 0, "");
+-  FMT_MSC_WARNING(suppress : 6102)  // Suppress a bogus static analysis warning.
+-  return static_cast<int>(r);
+-}
+-#  define FMT_BUILTIN_CTZ(n) detail::ctz(n)
+-
+-inline auto ctzll(uint64_t x) -> int {
+-  unsigned long r = 0;
+-  FMT_ASSERT(x != 0, "");
+-  FMT_MSC_WARNING(suppress : 6102)  // Suppress a bogus static analysis warning.
+-#  ifdef _WIN64
+-  _BitScanForward64(&r, x);
+-#  else
+-  // Scan the low 32 bits.
+-  if (_BitScanForward(&r, static_cast<uint32_t>(x))) return static_cast<int>(r);
+-  // Scan the high 32 bits.
+-  _BitScanForward(&r, static_cast<uint32_t>(x >> 32));
+-  r += 32;
+-#  endif
+-  return static_cast<int>(r);
+-}
+-#  define FMT_BUILTIN_CTZLL(n) detail::ctzll(n)
+-}  // namespace detail
+-FMT_END_NAMESPACE
+-#endif
+-
+-FMT_BEGIN_NAMESPACE
+-
+-template <typename...> struct disjunction : std::false_type {};
+-template <typename P> struct disjunction<P> : P {};
+-template <typename P1, typename... Pn>
+-struct disjunction<P1, Pn...>
+-    : conditional_t<bool(P1::value), P1, disjunction<Pn...>> {};
+-
+-template <typename...> struct conjunction : std::true_type {};
+-template <typename P> struct conjunction<P> : P {};
+-template <typename P1, typename... Pn>
+-struct conjunction<P1, Pn...>
+-    : conditional_t<bool(P1::value), conjunction<Pn...>, P1> {};
+-
+-namespace detail {
++#endif  // FMT_MSC_VERSION && !defined(FMT_BUILTIN_CLZLL)
+ 
+ FMT_CONSTEXPR inline void abort_fuzzing_if(bool condition) {
+   ignore_unused(condition);
+@@ -286,48 +224,24 @@ FMT_CONSTEXPR inline void abort_fuzzing_if(bool condition) {
+ #endif
+ }
+ 
+-template <typename CharT, CharT... C> struct string_literal {
+-  static constexpr CharT value[sizeof...(C)] = {C...};
+-  constexpr operator basic_string_view<CharT>() const {
+-    return {value, sizeof...(C)};
+-  }
++#if defined(FMT_USE_STRING_VIEW)
++template <typename Char> using std_string_view = std::basic_string_view<Char>;
++#else
++template <typename Char> struct std_string_view {
++  operator basic_string_view<Char>() const;
+ };
+-
+-#if FMT_CPLUSPLUS < 201703L
+-template <typename CharT, CharT... C>
+-constexpr CharT string_literal<CharT, C...>::value[sizeof...(C)];
+ #endif
+ 
+-template <typename Streambuf> class formatbuf : public Streambuf {
+- private:
+-  using char_type = typename Streambuf::char_type;
+-  using streamsize = decltype(std::declval<Streambuf>().sputn(nullptr, 0));
+-  using int_type = typename Streambuf::int_type;
+-  using traits_type = typename Streambuf::traits_type;
+-
+-  buffer<char_type>& buffer_;
+-
+- public:
+-  explicit formatbuf(buffer<char_type>& buf) : buffer_(buf) {}
+-
+- protected:
+-  // The put area is always empty. This makes the implementation simpler and has
+-  // the advantage that the streambuf and the buffer are always in sync and
+-  // sputc never writes into uninitialized memory. A disadvantage is that each
+-  // call to sputc always results in a (virtual) call to overflow. There is no
+-  // disadvantage here for sputn since this always results in a call to xsputn.
+-
+-  auto overflow(int_type ch) -> int_type override {
+-    if (!traits_type::eq_int_type(ch, traits_type::eof()))
+-      buffer_.push_back(static_cast<char_type>(ch));
+-    return ch;
+-  }
+-
+-  auto xsputn(const char_type* s, streamsize count) -> streamsize override {
+-    buffer_.append(s, s + count);
+-    return count;
++template <typename Char, Char... C> struct string_literal {
++  static constexpr Char value[sizeof...(C)] = {C...};
++  constexpr operator basic_string_view<Char>() const {
++    return {value, sizeof...(C)};
+   }
+ };
++#if FMT_CPLUSPLUS < 201703L
++template <typename Char, Char... C>
++constexpr Char string_literal<Char, C...>::value[sizeof...(C)];
++#endif
+ 
+ // Implementation of std::bit_cast for pre-C++20.
+ template <typename To, typename From, FMT_ENABLE_IF(sizeof(To) == sizeof(From))>
+@@ -360,14 +274,12 @@ class uint128_fallback {
+  private:
+   uint64_t lo_, hi_;
+ 
+-  friend uint128_fallback umul128(uint64_t x, uint64_t y) noexcept;
+-
+  public:
+   constexpr uint128_fallback(uint64_t hi, uint64_t lo) : lo_(lo), hi_(hi) {}
+   constexpr uint128_fallback(uint64_t value = 0) : lo_(value), hi_(0) {}
+ 
+-  constexpr uint64_t high() const noexcept { return hi_; }
+-  constexpr uint64_t low() const noexcept { return lo_; }
++  constexpr auto high() const noexcept -> uint64_t { return hi_; }
++  constexpr auto low() const noexcept -> uint64_t { return lo_; }
+ 
+   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
+   constexpr explicit operator T() const {
+@@ -400,13 +312,14 @@ class uint128_fallback {
+       -> uint128_fallback {
+     return {~n.hi_, ~n.lo_};
+   }
+-  friend auto operator+(const uint128_fallback& lhs,
+-                        const uint128_fallback& rhs) -> uint128_fallback {
++  friend FMT_CONSTEXPR auto operator+(const uint128_fallback& lhs,
++                                      const uint128_fallback& rhs)
++      -> uint128_fallback {
+     auto result = uint128_fallback(lhs);
+     result += rhs;
+     return result;
+   }
+-  friend auto operator*(const uint128_fallback& lhs, uint32_t rhs)
++  friend FMT_CONSTEXPR auto operator*(const uint128_fallback& lhs, uint32_t rhs)
+       -> uint128_fallback {
+     FMT_ASSERT(lhs.hi_ == 0, "");
+     uint64_t hi = (lhs.lo_ >> 32) * rhs;
+@@ -414,7 +327,7 @@ class uint128_fallback {
+     uint64_t new_lo = (hi << 32) + lo;
+     return {(hi >> 32) + (new_lo < lo ? 1 : 0), new_lo};
+   }
+-  friend auto operator-(const uint128_fallback& lhs, uint64_t rhs)
++  friend constexpr auto operator-(const uint128_fallback& lhs, uint64_t rhs)
+       -> uint128_fallback {
+     return {lhs.hi_ - (lhs.lo_ < rhs ? 1 : 0), lhs.lo_ - rhs};
+   }
+@@ -443,7 +356,7 @@ class uint128_fallback {
+     hi_ &= n.hi_;
+   }
+ 
+-  FMT_CONSTEXPR20 uint128_fallback& operator+=(uint64_t n) noexcept {
++  FMT_CONSTEXPR20 auto operator+=(uint64_t n) noexcept -> uint128_fallback& {
+     if (is_constant_evaluated()) {
+       lo_ += n;
+       hi_ += (lo_ < n ? 1 : 0);
+@@ -487,23 +400,24 @@ template <typename T> constexpr auto num_bits() -> int {
+ }
+ // std::numeric_limits<T>::digits may return 0 for 128-bit ints.
+ template <> constexpr auto num_bits<int128_opt>() -> int { return 128; }
+-template <> constexpr auto num_bits<uint128_t>() -> int { return 128; }
++template <> constexpr auto num_bits<uint128_opt>() -> int { return 128; }
++template <> constexpr auto num_bits<uint128_fallback>() -> int { return 128; }
+ 
+ // A heterogeneous bit_cast used for converting 96-bit long double to uint128_t
+ // and 128-bit pointers to uint128_fallback.
+ template <typename To, typename From, FMT_ENABLE_IF(sizeof(To) > sizeof(From))>
+ inline auto bit_cast(const From& from) -> To {
+-  constexpr auto size = static_cast<int>(sizeof(From) / sizeof(unsigned));
++  constexpr auto size = static_cast<int>(sizeof(From) / sizeof(unsigned short));
+   struct data_t {
+-    unsigned value[static_cast<unsigned>(size)];
++    unsigned short value[static_cast<unsigned>(size)];
+   } data = bit_cast<data_t>(from);
+   auto result = To();
+   if (const_check(is_big_endian())) {
+     for (int i = 0; i < size; ++i)
+-      result = (result << num_bits<unsigned>()) | data.value[i];
++      result = (result << num_bits<unsigned short>()) | data.value[i];
+   } else {
+     for (int i = size - 1; i >= 0; --i)
+-      result = (result << num_bits<unsigned>()) | data.value[i];
++      result = (result << num_bits<unsigned short>()) | data.value[i];
+   }
+   return result;
+ }
+@@ -534,55 +448,30 @@ FMT_INLINE void assume(bool condition) {
+   (void)condition;
+ #if FMT_HAS_BUILTIN(__builtin_assume) && !FMT_ICC_VERSION
+   __builtin_assume(condition);
++#elif FMT_GCC_VERSION
++  if (!condition) __builtin_unreachable();
+ #endif
+ }
+ 
+-// An approximation of iterator_t for pre-C++20 systems.
+-template <typename T>
+-using iterator_t = decltype(std::begin(std::declval<T&>()));
+-template <typename T> using sentinel_t = decltype(std::end(std::declval<T&>()));
+-
+-// A workaround for std::string not having mutable data() until C++17.
+-template <typename Char>
+-inline auto get_data(std::basic_string<Char>& s) -> Char* {
+-  return &s[0];
+-}
+-template <typename Container>
+-inline auto get_data(Container& c) -> typename Container::value_type* {
+-  return c.data();
+-}
+-
+-#if defined(_SECURE_SCL) && _SECURE_SCL
+-// Make a checked iterator to avoid MSVC warnings.
+-template <typename T> using checked_ptr = stdext::checked_array_iterator<T*>;
+-template <typename T>
+-constexpr auto make_checked(T* p, size_t size) -> checked_ptr<T> {
+-  return {p, size};
+-}
+-#else
+-template <typename T> using checked_ptr = T*;
+-template <typename T> constexpr auto make_checked(T* p, size_t) -> T* {
+-  return p;
+-}
+-#endif
+-
+ // Attempts to reserve space for n extra characters in the output range.
+ // Returns a pointer to the reserved range or a reference to it.
+-template <typename Container, FMT_ENABLE_IF(is_contiguous<Container>::value)>
++template <typename OutputIt,
++          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value&&
++                            is_contiguous<typename OutputIt::container>::value)>
+ #if FMT_CLANG_VERSION >= 307 && !FMT_ICC_VERSION
+ __attribute__((no_sanitize("undefined")))
+ #endif
+-inline auto
+-reserve(std::back_insert_iterator<Container> it, size_t n)
+-    -> checked_ptr<typename Container::value_type> {
+-  Container& c = get_container(it);
++FMT_CONSTEXPR20 inline auto
++reserve(OutputIt it, size_t n) -> typename OutputIt::value_type* {
++  auto& c = get_container(it);
+   size_t size = c.size();
+   c.resize(size + n);
+-  return make_checked(get_data(c) + size, n);
++  return &c[size];
+ }
+ 
+ template <typename T>
+-inline auto reserve(buffer_appender<T> it, size_t n) -> buffer_appender<T> {
++FMT_CONSTEXPR20 inline auto reserve(basic_appender<T> it, size_t n)
++    -> basic_appender<T> {
+   buffer<T>& buf = get_container(it);
+   buf.try_reserve(buf.size() + n);
+   return it;
+@@ -601,18 +490,22 @@ template <typename T, typename OutputIt>
+ constexpr auto to_pointer(OutputIt, size_t) -> T* {
+   return nullptr;
+ }
+-template <typename T> auto to_pointer(buffer_appender<T> it, size_t n) -> T* {
++template <typename T>
++FMT_CONSTEXPR20 auto to_pointer(basic_appender<T> it, size_t n) -> T* {
+   buffer<T>& buf = get_container(it);
++  buf.try_reserve(buf.size() + n);
+   auto size = buf.size();
+   if (buf.capacity() < size + n) return nullptr;
+   buf.try_resize(size + n);
+   return buf.data() + size;
+ }
+ 
+-template <typename Container, FMT_ENABLE_IF(is_contiguous<Container>::value)>
+-inline auto base_iterator(std::back_insert_iterator<Container>& it,
+-                          checked_ptr<typename Container::value_type>)
+-    -> std::back_insert_iterator<Container> {
++template <typename OutputIt,
++          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value&&
++                            is_contiguous<typename OutputIt::container>::value)>
++inline auto base_iterator(OutputIt it,
++                          typename OutputIt::container_type::value_type*)
++    -> OutputIt {
+   return it;
+ }
+ 
+@@ -631,23 +524,15 @@ FMT_CONSTEXPR auto fill_n(OutputIt out, Size count, const T& value)
+ }
+ template <typename T, typename Size>
+ FMT_CONSTEXPR20 auto fill_n(T* out, Size count, char value) -> T* {
+-  if (is_constant_evaluated()) {
+-    return fill_n<T*, Size, T>(out, count, value);
+-  }
++  if (is_constant_evaluated()) return fill_n<T*, Size, T>(out, count, value);
+   std::memset(out, value, to_unsigned(count));
+   return out + count;
+ }
+ 
+-#ifdef __cpp_char8_t
+-using char8_type = char8_t;
+-#else
+-enum char8_type : unsigned char {};
+-#endif
+-
+ template <typename OutChar, typename InputIt, typename OutputIt>
+-FMT_CONSTEXPR FMT_NOINLINE auto copy_str_noinline(InputIt begin, InputIt end,
+-                                                  OutputIt out) -> OutputIt {
+-  return copy_str<OutChar>(begin, end, out);
++FMT_CONSTEXPR FMT_NOINLINE auto copy_noinline(InputIt begin, InputIt end,
++                                              OutputIt out) -> OutputIt {
++  return copy<OutChar>(begin, end, out);
+ }
+ 
+ // A public domain branchless UTF-8 decoder by Christopher Wellons:
+@@ -718,6 +603,7 @@ FMT_CONSTEXPR void for_each_codepoint(string_view s, F f) {
+                     string_view(ptr, error ? 1 : to_unsigned(end - buf_ptr)));
+     return result ? (error ? buf_ptr + 1 : end) : nullptr;
+   };
++
+   auto p = s.data();
+   const size_t block_size = 4;  // utf8_decode always reads blocks of 4 chars.
+   if (s.size() >= block_size) {
+@@ -726,17 +612,20 @@ FMT_CONSTEXPR void for_each_codepoint(string_view s, F f) {
+       if (!p) return;
+     }
+   }
+-  if (auto num_chars_left = s.data() + s.size() - p) {
+-    char buf[2 * block_size - 1] = {};
+-    copy_str<char>(p, p + num_chars_left, buf);
+-    const char* buf_ptr = buf;
+-    do {
+-      auto end = decode(buf_ptr, p);
+-      if (!end) return;
+-      p += end - buf_ptr;
+-      buf_ptr = end;
+-    } while (buf_ptr - buf < num_chars_left);
+-  }
++  auto num_chars_left = to_unsigned(s.data() + s.size() - p);
++  if (num_chars_left == 0) return;
++
++  // Suppress bogus -Wstringop-overflow.
++  if (FMT_GCC_VERSION) num_chars_left &= 3;
++  char buf[2 * block_size - 1] = {};
++  copy<char>(p, p + num_chars_left, buf);
++  const char* buf_ptr = buf;
++  do {
++    auto end = decode(buf_ptr, p);
++    if (!end) return;
++    p += end - buf_ptr;
++    buf_ptr = end;
++  } while (buf_ptr < buf + num_chars_left);
+ }
+ 
+ template <typename Char>
+@@ -745,13 +634,13 @@ inline auto compute_width(basic_string_view<Char> s) -> size_t {
+ }
+ 
+ // Computes approximate display width of a UTF-8 string.
+-FMT_CONSTEXPR inline size_t compute_width(string_view s) {
++FMT_CONSTEXPR inline auto compute_width(string_view s) -> size_t {
+   size_t num_code_points = 0;
+   // It is not a lambda for compatibility with C++14.
+   struct count_code_points {
+     size_t* count;
+     FMT_CONSTEXPR auto operator()(uint32_t cp, string_view) const -> bool {
+-      *count += detail::to_unsigned(
++      *count += to_unsigned(
+           1 +
+           (cp >= 0x1100 &&
+            (cp <= 0x115f ||  // Hangul Jamo init. consonants
+@@ -779,31 +668,24 @@ FMT_CONSTEXPR inline size_t compute_width(string_view s) {
+   return num_code_points;
+ }
+ 
+-inline auto compute_width(basic_string_view<char8_type> s) -> size_t {
+-  return compute_width(
+-      string_view(reinterpret_cast<const char*>(s.data()), s.size()));
+-}
+-
+ template <typename Char>
+ inline auto code_point_index(basic_string_view<Char> s, size_t n) -> size_t {
+-  size_t size = s.size();
+-  return n < size ? n : size;
++  return min_of(n, s.size());
+ }
+ 
+ // Calculates the index of the nth code point in a UTF-8 string.
+ inline auto code_point_index(string_view s, size_t n) -> size_t {
+-  const char* data = s.data();
+-  size_t num_code_points = 0;
+-  for (size_t i = 0, size = s.size(); i != size; ++i) {
+-    if ((data[i] & 0xc0) != 0x80 && ++num_code_points > n) return i;
+-  }
+-  return s.size();
+-}
+-
+-inline auto code_point_index(basic_string_view<char8_type> s, size_t n)
+-    -> size_t {
+-  return code_point_index(
+-      string_view(reinterpret_cast<const char*>(s.data()), s.size()), n);
++  size_t result = s.size();
++  const char* begin = s.begin();
++  for_each_codepoint(s, [begin, &n, &result](uint32_t, string_view sv) {
++    if (n != 0) {
++      --n;
++      return true;
++    }
++    result = to_unsigned(sv.begin() - begin);
++    return false;
++  });
++  return result;
+ }
+ 
+ template <typename T> struct is_integral : std::is_integral<T> {};
+@@ -821,38 +703,22 @@ using is_integer =
+                   !std::is_same<T, char>::value &&
+                   !std::is_same<T, wchar_t>::value>;
+ 
+-#ifndef FMT_USE_FLOAT
+-#  define FMT_USE_FLOAT 1
+-#endif
+-#ifndef FMT_USE_DOUBLE
+-#  define FMT_USE_DOUBLE 1
+-#endif
+-#ifndef FMT_USE_LONG_DOUBLE
+-#  define FMT_USE_LONG_DOUBLE 1
+-#endif
+-
+-#ifndef FMT_USE_FLOAT128
+-#  ifdef __clang__
+-// Clang emulates GCC, so it has to appear early.
+-#    if FMT_HAS_INCLUDE(<quadmath.h>)
+-#      define FMT_USE_FLOAT128 1
+-#    endif
+-#  elif defined(__GNUC__)
+-// GNU C++:
+-#    if defined(_GLIBCXX_USE_FLOAT128) && !defined(__STRICT_ANSI__)
+-#      define FMT_USE_FLOAT128 1
+-#    endif
+-#  endif
+-#  ifndef FMT_USE_FLOAT128
+-#    define FMT_USE_FLOAT128 0
+-#  endif
++#if defined(FMT_USE_FLOAT128)
++// Use the provided definition.
++#elif FMT_CLANG_VERSION && FMT_HAS_INCLUDE(<quadmath.h>)
++#  define FMT_USE_FLOAT128 1
++#elif FMT_GCC_VERSION && defined(_GLIBCXX_USE_FLOAT128) && \
++    !defined(__STRICT_ANSI__)
++#  define FMT_USE_FLOAT128 1
++#else
++#  define FMT_USE_FLOAT128 0
+ #endif
+-
+ #if FMT_USE_FLOAT128
+ using float128 = __float128;
+ #else
+-using float128 = void;
++struct float128 {};
+ #endif
++
+ template <typename T> using is_float128 = std::is_same<T, float128>;
+ 
+ template <typename T>
+@@ -871,24 +737,21 @@ using is_double_double = bool_constant<std::numeric_limits<T>::digits == 106>;
+ #  define FMT_USE_FULL_CACHE_DRAGONBOX 0
+ #endif
+ 
+-template <typename T>
+-template <typename U>
+-void buffer<T>::append(const U* begin, const U* end) {
+-  while (begin != end) {
+-    auto count = to_unsigned(end - begin);
+-    try_reserve(size_ + count);
+-    auto free_cap = capacity_ - size_;
+-    if (free_cap < count) count = free_cap;
+-    std::uninitialized_copy_n(begin, count, make_checked(ptr_ + size_, count));
+-    size_ += count;
+-    begin += count;
++// An allocator that uses malloc/free to allow removing dependency on the C++
++// standard libary runtime.
++template <typename T> struct allocator {
++  using value_type = T;
++
++  T* allocate(size_t n) {
++    FMT_ASSERT(n <= max_value<size_t>() / sizeof(T), "");
++    T* p = static_cast<T*>(malloc(n * sizeof(T)));
++    if (!p) FMT_THROW(std::bad_alloc());
++    return p;
+   }
+-}
+ 
+-template <typename T, typename Enable = void>
+-struct is_locale : std::false_type {};
+-template <typename T>
+-struct is_locale<T, void_t<decltype(T::classic())>> : std::true_type {};
++  void deallocate(T* p, size_t) { free(p); }
++};
++
+ }  // namespace detail
+ 
+ FMT_BEGIN_EXPORT
+@@ -898,34 +761,26 @@ FMT_BEGIN_EXPORT
+ enum { inline_buffer_size = 500 };
+ 
+ /**
+-  \rst
+-  A dynamically growing memory buffer for trivially copyable/constructible types
+-  with the first ``SIZE`` elements stored in the object itself.
+-
+-  You can use the ``memory_buffer`` type alias for ``char`` instead.
+-
+-  **Example**::
+-
+-     auto out = fmt::memory_buffer();
+-     format_to(std::back_inserter(out), "The answer is {}.", 42);
+-
+-  This will append the following output to the ``out`` object:
+-
+-  .. code-block:: none
+-
+-     The answer is 42.
+-
+-  The output can be converted to an ``std::string`` with ``to_string(out)``.
+-  \endrst
++ * A dynamically growing memory buffer for trivially copyable/constructible
++ * types with the first `SIZE` elements stored in the object itself. Most
++ * commonly used via the `memory_buffer` alias for `char`.
++ *
++ * **Example**:
++ *
++ *     auto out = fmt::memory_buffer();
++ *     fmt::format_to(std::back_inserter(out), "The answer is {}.", 42);
++ *
++ * This will append "The answer is 42." to `out`. The buffer content can be
++ * converted to `std::string` with `to_string(out)`.
+  */
+ template <typename T, size_t SIZE = inline_buffer_size,
+-          typename Allocator = std::allocator<T>>
+-class basic_memory_buffer final : public detail::buffer<T> {
++          typename Allocator = detail::allocator<T>>
++class basic_memory_buffer : public detail::buffer<T> {
+  private:
+   T store_[SIZE];
+ 
+-  // Don't inherit from Allocator avoid generating type_info for it.
+-  Allocator alloc_;
++  // Don't inherit from Allocator to avoid generating type_info for it.
++  FMT_NO_UNIQUE_ADDRESS Allocator alloc_;
+ 
+   // Deallocate memory allocated by the buffer.
+   FMT_CONSTEXPR20 void deallocate() {
+@@ -933,36 +788,37 @@ class basic_memory_buffer final : public detail::buffer<T> {
+     if (data != store_) alloc_.deallocate(data, this->capacity());
+   }
+ 
+- protected:
+-  FMT_CONSTEXPR20 void grow(size_t size) override {
++  static FMT_CONSTEXPR20 void grow(detail::buffer<T>& buf, size_t size) {
+     detail::abort_fuzzing_if(size > 5000);
+-    const size_t max_size = std::allocator_traits<Allocator>::max_size(alloc_);
+-    size_t old_capacity = this->capacity();
++    auto& self = static_cast<basic_memory_buffer&>(buf);
++    const size_t max_size =
++        std::allocator_traits<Allocator>::max_size(self.alloc_);
++    size_t old_capacity = buf.capacity();
+     size_t new_capacity = old_capacity + old_capacity / 2;
+     if (size > new_capacity)
+       new_capacity = size;
+     else if (new_capacity > max_size)
+-      new_capacity = size > max_size ? size : max_size;
+-    T* old_data = this->data();
+-    T* new_data =
+-        std::allocator_traits<Allocator>::allocate(alloc_, new_capacity);
++      new_capacity = max_of(size, max_size);
++    T* old_data = buf.data();
++    T* new_data = self.alloc_.allocate(new_capacity);
++    // Suppress a bogus -Wstringop-overflow in gcc 13.1 (#3481).
++    detail::assume(buf.size() <= new_capacity);
+     // The following code doesn't throw, so the raw pointer above doesn't leak.
+-    std::uninitialized_copy(old_data, old_data + this->size(),
+-                            detail::make_checked(new_data, new_capacity));
+-    this->set(new_data, new_capacity);
++    memcpy(new_data, old_data, buf.size() * sizeof(T));
++    self.set(new_data, new_capacity);
+     // deallocate must not throw according to the standard, but even if it does,
+     // the buffer already uses the new storage and will deallocate it in
+     // destructor.
+-    if (old_data != store_) alloc_.deallocate(old_data, old_capacity);
++    if (old_data != self.store_) self.alloc_.deallocate(old_data, old_capacity);
+   }
+ 
+  public:
+   using value_type = T;
+   using const_reference = const T&;
+ 
+-  FMT_CONSTEXPR20 explicit basic_memory_buffer(
++  FMT_CONSTEXPR explicit basic_memory_buffer(
+       const Allocator& alloc = Allocator())
+-      : alloc_(alloc) {
++      : detail::buffer<T>(grow), alloc_(alloc) {
+     this->set(store_, SIZE);
+     if (detail::is_constant_evaluated()) detail::fill_n(store_, SIZE, T());
+   }
+@@ -976,8 +832,7 @@ class basic_memory_buffer final : public detail::buffer<T> {
+     size_t size = other.size(), capacity = other.capacity();
+     if (data == other.store_) {
+       this->set(store_, capacity);
+-      detail::copy_str<T>(other.store_, other.store_ + size,
+-                          detail::make_checked(store_, capacity));
++      detail::copy<T>(other.store_, other.store_ + size, store_);
+     } else {
+       this->set(data, capacity);
+       // Set pointer to the inline array so that delete is not called
+@@ -989,21 +844,14 @@ class basic_memory_buffer final : public detail::buffer<T> {
+   }
+ 
+  public:
+-  /**
+-    \rst
+-    Constructs a :class:`fmt::basic_memory_buffer` object moving the content
+-    of the other object to it.
+-    \endrst
+-   */
+-  FMT_CONSTEXPR20 basic_memory_buffer(basic_memory_buffer&& other) noexcept {
++  /// Constructs a `basic_memory_buffer` object moving the content of the other
++  /// object to it.
++  FMT_CONSTEXPR20 basic_memory_buffer(basic_memory_buffer&& other) noexcept
++      : detail::buffer<T>(grow) {
+     move(other);
+   }
+ 
+-  /**
+-    \rst
+-    Moves the content of the other ``basic_memory_buffer`` object to this one.
+-    \endrst
+-   */
++  /// Moves the content of the other `basic_memory_buffer` object to this one.
+   auto operator=(basic_memory_buffer&& other) noexcept -> basic_memory_buffer& {
+     FMT_ASSERT(this != &other, "");
+     deallocate();
+@@ -1014,119 +862,108 @@ class basic_memory_buffer final : public detail::buffer<T> {
+   // Returns a copy of the allocator associated with this buffer.
+   auto get_allocator() const -> Allocator { return alloc_; }
+ 
+-  /**
+-    Resizes the buffer to contain *count* elements. If T is a POD type new
+-    elements may not be initialized.
+-   */
+-  FMT_CONSTEXPR20 void resize(size_t count) { this->try_resize(count); }
++  /// Resizes the buffer to contain `count` elements. If T is a POD type new
++  /// elements may not be initialized.
++  FMT_CONSTEXPR void resize(size_t count) { this->try_resize(count); }
+ 
+-  /** Increases the buffer capacity to *new_capacity*. */
++  /// Increases the buffer capacity to `new_capacity`.
+   void reserve(size_t new_capacity) { this->try_reserve(new_capacity); }
+ 
+-  // Directly append data into the buffer
+   using detail::buffer<T>::append;
+   template <typename ContiguousRange>
+-  void append(const ContiguousRange& range) {
++  FMT_CONSTEXPR20 void append(const ContiguousRange& range) {
+     append(range.data(), range.data() + range.size());
+   }
+ };
+ 
+ using memory_buffer = basic_memory_buffer<char>;
+ 
++template <size_t SIZE>
++FMT_NODISCARD auto to_string(const basic_memory_buffer<char, SIZE>& buf)
++    -> std::string {
++  auto size = buf.size();
++  detail::assume(size < std::string().max_size());
++  return {buf.data(), size};
++}
++
++// A writer to a buffered stream. It doesn't own the underlying stream.
++class writer {
++ private:
++  detail::buffer<char>* buf_;
++
++  // We cannot create a file buffer in advance because any write to a FILE may
++  // invalidate it.
++  FILE* file_;
++
++ public:
++  inline writer(FILE* f) : buf_(nullptr), file_(f) {}
++  inline writer(detail::buffer<char>& buf) : buf_(&buf) {}
++
++  /// Formats `args` according to specifications in `fmt` and writes the
++  /// output to the file.
++  template <typename... T> void print(format_string<T...> fmt, T&&... args) {
++    if (buf_)
++      fmt::format_to(appender(*buf_), fmt, std::forward<T>(args)...);
++    else
++      fmt::print(file_, fmt, std::forward<T>(args)...);
++  }
++};
++
++class string_buffer {
++ private:
++  std::string str_;
++  detail::container_buffer<std::string> buf_;
++
++ public:
++  inline string_buffer() : buf_(str_) {}
++
++  inline operator writer() { return buf_; }
++  inline std::string& str() { return str_; }
++};
++
+ template <typename T, size_t SIZE, typename Allocator>
+ struct is_contiguous<basic_memory_buffer<T, SIZE, Allocator>> : std::true_type {
+ };
+ 
+-FMT_END_EXPORT
+-namespace detail {
+-FMT_API bool write_console(std::FILE* f, string_view text);
+-FMT_API void print(std::FILE*, string_view);
+-}  // namespace detail
+-FMT_BEGIN_EXPORT
+-
+ // Suppress a misleading warning in older versions of clang.
+-#if FMT_CLANG_VERSION
+-#  pragma clang diagnostic ignored "-Wweak-vtables"
+-#endif
++FMT_PRAGMA_CLANG(diagnostic ignored "-Wweak-vtables")
+ 
+-/** An error reported from a formatting function. */
+-class FMT_VISIBILITY("default") format_error : public std::runtime_error {
++/// An error reported from a formatting function.
++class FMT_SO_VISIBILITY("default") format_error : public std::runtime_error {
+  public:
+   using std::runtime_error::runtime_error;
+ };
+ 
+-namespace detail_exported {
+-#if FMT_USE_NONTYPE_TEMPLATE_ARGS
++class loc_value;
++
++FMT_END_EXPORT
++namespace detail {
++FMT_API auto write_console(int fd, string_view text) -> bool;
++FMT_API void print(FILE*, string_view);
++}  // namespace detail
++
++namespace detail {
+ template <typename Char, size_t N> struct fixed_string {
+-  constexpr fixed_string(const Char (&str)[N]) {
+-    detail::copy_str<Char, const Char*, Char*>(static_cast<const Char*>(str),
+-                                               str + N, data);
++  FMT_CONSTEXPR20 fixed_string(const Char (&s)[N]) {
++    detail::copy<Char, const Char*, Char*>(static_cast<const Char*>(s), s + N,
++                                           data);
+   }
+   Char data[N] = {};
+ };
+-#endif
+ 
+ // Converts a compile-time string to basic_string_view.
+-template <typename Char, size_t N>
++FMT_EXPORT template <typename Char, size_t N>
+ constexpr auto compile_string_to_view(const Char (&s)[N])
+     -> basic_string_view<Char> {
+   // Remove trailing NUL character if needed. Won't be present if this is used
+   // with a raw character array (i.e. not defined as a string).
+   return {s, N - (std::char_traits<Char>::to_int_type(s[N - 1]) == 0 ? 1 : 0)};
+ }
+-template <typename Char>
+-constexpr auto compile_string_to_view(detail::std_string_view<Char> s)
++FMT_EXPORT template <typename Char>
++constexpr auto compile_string_to_view(basic_string_view<Char> s)
+     -> basic_string_view<Char> {
+-  return {s.data(), s.size()};
++  return s;
+ }
+-}  // namespace detail_exported
+-
+-class loc_value {
+- private:
+-  basic_format_arg<format_context> value_;
+-
+- public:
+-  template <typename T, FMT_ENABLE_IF(!detail::is_float128<T>::value)>
+-  loc_value(T value) : value_(detail::make_arg<format_context>(value)) {}
+-
+-  template <typename T, FMT_ENABLE_IF(detail::is_float128<T>::value)>
+-  loc_value(T) {}
+-
+-  template <typename Visitor> auto visit(Visitor&& vis) -> decltype(vis(0)) {
+-    return visit_format_arg(vis, value_);
+-  }
+-};
+-
+-// A locale facet that formats values in UTF-8.
+-// It is parameterized on the locale to avoid the heavy <locale> include.
+-template <typename Locale> class format_facet : public Locale::facet {
+- private:
+-  std::string separator_;
+-  std::string grouping_;
+-  std::string decimal_point_;
+-
+- protected:
+-  virtual auto do_put(appender out, loc_value val,
+-                      const format_specs<>& specs) const -> bool;
+-
+- public:
+-  static FMT_API typename Locale::id id;
+-
+-  explicit format_facet(Locale& loc);
+-  explicit format_facet(string_view sep = "",
+-                        std::initializer_list<unsigned char> g = {3},
+-                        std::string decimal_point = ".")
+-      : separator_(sep.data(), sep.size()),
+-        grouping_(g.begin(), g.end()),
+-        decimal_point_(decimal_point) {}
+-
+-  auto put(appender out, loc_value val, const format_specs<>& specs) const
+-      -> bool {
+-    return do_put(out, val, specs);
+-  }
+-};
+-
+-FMT_BEGIN_DETAIL_NAMESPACE
+ 
+ // Returns true if value is negative, false otherwise.
+ // Same as `value < 0` but doesn't produce warnings if T is an unsigned type.
+@@ -1139,14 +976,6 @@ constexpr auto is_negative(T) -> bool {
+   return false;
+ }
+ 
+-template <typename T>
+-FMT_CONSTEXPR auto is_supported_floating_point(T) -> bool {
+-  if (std::is_same<T, float>()) return FMT_USE_FLOAT;
+-  if (std::is_same<T, double>()) return FMT_USE_DOUBLE;
+-  if (std::is_same<T, long double>()) return FMT_USE_LONG_DOUBLE;
+-  return true;
+-}
+-
+ // Smallest of uint32_t, uint64_t, uint128_t that is large enough to
+ // represent all values of an integral type T.
+ template <typename T>
+@@ -1157,27 +986,28 @@ using uint32_or_64_or_128_t =
+ template <typename T>
+ using uint64_or_128_t = conditional_t<num_bits<T>() <= 64, uint64_t, uint128_t>;
+ 
+-#define FMT_POWERS_OF_10(factor)                                             \
+-  factor * 10, (factor)*100, (factor)*1000, (factor)*10000, (factor)*100000, \
+-      (factor)*1000000, (factor)*10000000, (factor)*100000000,               \
+-      (factor)*1000000000
++#define FMT_POWERS_OF_10(factor)                                  \
++  factor * 10, (factor) * 100, (factor) * 1000, (factor) * 10000, \
++      (factor) * 100000, (factor) * 1000000, (factor) * 10000000, \
++      (factor) * 100000000, (factor) * 1000000000
+ 
+ // Converts value in the range [0, 100) to a string.
+-constexpr const char* digits2(size_t value) {
+-  // GCC generates slightly better code when value is pointer-size.
+-  return &"0001020304050607080910111213141516171819"
+-         "2021222324252627282930313233343536373839"
+-         "4041424344454647484950515253545556575859"
+-         "6061626364656667686970717273747576777879"
+-         "8081828384858687888990919293949596979899"[value * 2];
+-}
+-
+-// Sign is a template parameter to workaround a bug in gcc 4.8.
+-template <typename Char, typename Sign> constexpr Char sign(Sign s) {
+-#if !FMT_GCC_VERSION || FMT_GCC_VERSION >= 604
+-  static_assert(std::is_same<Sign, sign_t>::value, "");
+-#endif
+-  return static_cast<Char>("\0-+ "[s]);
++// GCC generates slightly better code when value is pointer-size.
++inline auto digits2(size_t value) -> const char* {
++  // Align data since unaligned access may be slower when crossing a
++  // hardware-specific boundary.
++  alignas(2) static const char data[] =
++      "0001020304050607080910111213141516171819"
++      "2021222324252627282930313233343536373839"
++      "4041424344454647484950515253545556575859"
++      "6061626364656667686970717273747576777879"
++      "8081828384858687888990919293949596979899";
++  return &data[value * 2];
++}
++
++template <typename Char> constexpr auto getsign(sign s) -> Char {
++  return static_cast<char>(((' ' << 24) | ('+' << 16) | ('-' << 8)) >>
++                           (static_cast<int>(s) * 8));
+ }
+ 
+ template <typename T> FMT_CONSTEXPR auto count_digits_fallback(T n) -> int {
+@@ -1225,9 +1055,7 @@ inline auto do_count_digits(uint64_t n) -> int {
+ // except for n == 0 in which case count_digits returns 1.
+ FMT_CONSTEXPR20 inline auto count_digits(uint64_t n) -> int {
+ #ifdef FMT_BUILTIN_CLZLL
+-  if (!is_constant_evaluated()) {
+-    return do_count_digits(n);
+-  }
++  if (!is_constant_evaluated() && !FMT_OPTIMIZE_SIZE) return do_count_digits(n);
+ #endif
+   return count_digits_fallback(n);
+ }
+@@ -1255,7 +1083,7 @@ FMT_CONSTEXPR auto count_digits(UInt n) -> int {
+ FMT_INLINE auto do_count_digits(uint32_t n) -> int {
+ // An optimization by Kendall Willets from https://bit.ly/3uOIQrB.
+ // This increments the upper 32 bits (log10(T) - 1) when >= T is added.
+-#  define FMT_INC(T) (((sizeof(#  T) - 1ull) << 32) - T)
++#  define FMT_INC(T) (((sizeof(#T) - 1ull) << 32) - T)
+   static constexpr uint64_t table[] = {
+       FMT_INC(0),          FMT_INC(0),          FMT_INC(0),           // 8
+       FMT_INC(10),         FMT_INC(10),         FMT_INC(10),          // 64
+@@ -1277,9 +1105,7 @@ FMT_INLINE auto do_count_digits(uint32_t n) -> int {
+ // Optional version of count_digits for better performance on 32-bit platforms.
+ FMT_CONSTEXPR20 inline auto count_digits(uint32_t n) -> int {
+ #ifdef FMT_BUILTIN_CLZ
+-  if (!is_constant_evaluated()) {
+-    return do_count_digits(n);
+-  }
++  if (!is_constant_evaluated() && !FMT_OPTIMIZE_SIZE) return do_count_digits(n);
+ #endif
+   return count_digits_fallback(n);
+ }
+@@ -1316,91 +1142,118 @@ template <> inline auto decimal_point(locale_ref loc) -> wchar_t {
+   return decimal_point_impl<wchar_t>(loc);
+ }
+ 
+-// Compares two characters for equality.
+-template <typename Char> auto equal2(const Char* lhs, const char* rhs) -> bool {
+-  return lhs[0] == Char(rhs[0]) && lhs[1] == Char(rhs[1]);
+-}
+-inline auto equal2(const char* lhs, const char* rhs) -> bool {
++#ifndef FMT_HEADER_ONLY
++FMT_BEGIN_EXPORT
++extern template FMT_API auto thousands_sep_impl<char>(locale_ref)
++    -> thousands_sep_result<char>;
++extern template FMT_API auto thousands_sep_impl<wchar_t>(locale_ref)
++    -> thousands_sep_result<wchar_t>;
++extern template FMT_API auto decimal_point_impl(locale_ref) -> char;
++extern template FMT_API auto decimal_point_impl(locale_ref) -> wchar_t;
++FMT_END_EXPORT
++#endif  // FMT_HEADER_ONLY
++
++// Compares two characters for equality.
++template <typename Char> auto equal2(const Char* lhs, const char* rhs) -> bool {
++  return lhs[0] == Char(rhs[0]) && lhs[1] == Char(rhs[1]);
++}
++inline auto equal2(const char* lhs, const char* rhs) -> bool {
+   return memcmp(lhs, rhs, 2) == 0;
+ }
+ 
+-// Copies two characters from src to dst.
++// Writes a two-digit value to out.
+ template <typename Char>
+-FMT_CONSTEXPR20 FMT_INLINE void copy2(Char* dst, const char* src) {
+-  if (!is_constant_evaluated() && sizeof(Char) == sizeof(char)) {
+-    memcpy(dst, src, 2);
++FMT_CONSTEXPR20 FMT_INLINE void write2digits(Char* out, size_t value) {
++  if (!is_constant_evaluated() && std::is_same<Char, char>::value &&
++      !FMT_OPTIMIZE_SIZE) {
++    memcpy(out, digits2(value), 2);
+     return;
+   }
+-  *dst++ = static_cast<Char>(*src++);
+-  *dst = static_cast<Char>(*src);
++  *out++ = static_cast<Char>('0' + value / 10);
++  *out = static_cast<Char>('0' + value % 10);
+ }
+ 
+-template <typename Iterator> struct format_decimal_result {
+-  Iterator begin;
+-  Iterator end;
+-};
+-
+-// Formats a decimal unsigned integer value writing into out pointing to a
+-// buffer of specified size. The caller must ensure that the buffer is large
+-// enough.
++// Formats a decimal unsigned integer value writing to out pointing to a buffer
++// of specified size. The caller must ensure that the buffer is large enough.
+ template <typename Char, typename UInt>
+-FMT_CONSTEXPR20 auto format_decimal(Char* out, UInt value, int size)
+-    -> format_decimal_result<Char*> {
++FMT_CONSTEXPR20 auto do_format_decimal(Char* out, UInt value, int size)
++    -> Char* {
+   FMT_ASSERT(size >= count_digits(value), "invalid digit count");
+-  out += size;
+-  Char* end = out;
++  unsigned n = to_unsigned(size);
+   while (value >= 100) {
+     // Integer division is slow so do it for a group of two digits instead
+     // of for every digit. The idea comes from the talk by Alexandrescu
+     // "Three Optimization Tips for C++". See speed-test for a comparison.
+-    out -= 2;
+-    copy2(out, digits2(static_cast<size_t>(value % 100)));
++    n -= 2;
++    write2digits(out + n, static_cast<unsigned>(value % 100));
+     value /= 100;
+   }
+-  if (value < 10) {
+-    *--out = static_cast<Char>('0' + value);
+-    return {out, end};
++  if (value >= 10) {
++    n -= 2;
++    write2digits(out + n, static_cast<unsigned>(value));
++  } else {
++    out[--n] = static_cast<Char>('0' + value);
+   }
+-  out -= 2;
+-  copy2(out, digits2(static_cast<size_t>(value)));
+-  return {out, end};
++  return out + n;
++}
++
++template <typename Char, typename UInt>
++FMT_CONSTEXPR FMT_INLINE auto format_decimal(Char* out, UInt value,
++                                             int num_digits) -> Char* {
++  do_format_decimal(out, value, num_digits);
++  return out + num_digits;
+ }
+ 
+-template <typename Char, typename UInt, typename Iterator,
+-          FMT_ENABLE_IF(!std::is_pointer<remove_cvref_t<Iterator>>::value)>
+-FMT_CONSTEXPR inline auto format_decimal(Iterator out, UInt value, int size)
+-    -> format_decimal_result<Iterator> {
++template <typename Char, typename UInt, typename OutputIt,
++          FMT_ENABLE_IF(!std::is_pointer<remove_cvref_t<OutputIt>>::value)>
++FMT_CONSTEXPR auto format_decimal(OutputIt out, UInt value, int num_digits)
++    -> OutputIt {
++  if (auto ptr = to_pointer<Char>(out, to_unsigned(num_digits))) {
++    do_format_decimal(ptr, value, num_digits);
++    return out;
++  }
+   // Buffer is large enough to hold all digits (digits10 + 1).
+-  Char buffer[digits10<UInt>() + 1] = {};
+-  auto end = format_decimal(buffer, value, size).end;
+-  return {out, detail::copy_str_noinline<Char>(buffer, end, out)};
++  char buffer[digits10<UInt>() + 1];
++  if (is_constant_evaluated()) fill_n(buffer, sizeof(buffer), '\0');
++  do_format_decimal(buffer, value, num_digits);
++  return copy_noinline<Char>(buffer, buffer + num_digits, out);
+ }
+ 
+-template <unsigned BASE_BITS, typename Char, typename UInt>
+-FMT_CONSTEXPR auto format_uint(Char* buffer, UInt value, int num_digits,
+-                               bool upper = false) -> Char* {
+-  buffer += num_digits;
+-  Char* end = buffer;
++template <typename Char, typename UInt>
++FMT_CONSTEXPR auto do_format_base2e(int base_bits, Char* out, UInt value,
++                                    int size, bool upper = false) -> Char* {
++  out += size;
+   do {
+     const char* digits = upper ? "0123456789ABCDEF" : "0123456789abcdef";
+-    unsigned digit = static_cast<unsigned>(value & ((1 << BASE_BITS) - 1));
+-    *--buffer = static_cast<Char>(BASE_BITS < 4 ? static_cast<char>('0' + digit)
+-                                                : digits[digit]);
+-  } while ((value >>= BASE_BITS) != 0);
+-  return end;
++    unsigned digit = static_cast<unsigned>(value & ((1 << base_bits) - 1));
++    *--out = static_cast<Char>(base_bits < 4 ? static_cast<char>('0' + digit)
++                                             : digits[digit]);
++  } while ((value >>= base_bits) != 0);
++  return out;
++}
++
++// Formats an unsigned integer in the power of two base (binary, octal, hex).
++template <typename Char, typename UInt>
++FMT_CONSTEXPR auto format_base2e(int base_bits, Char* out, UInt value,
++                                 int num_digits, bool upper = false) -> Char* {
++  do_format_base2e(base_bits, out, value, num_digits, upper);
++  return out + num_digits;
+ }
+ 
+-template <unsigned BASE_BITS, typename Char, typename It, typename UInt>
+-inline auto format_uint(It out, UInt value, int num_digits, bool upper = false)
+-    -> It {
++template <typename Char, typename OutputIt, typename UInt,
++          FMT_ENABLE_IF(is_back_insert_iterator<OutputIt>::value)>
++FMT_CONSTEXPR inline auto format_base2e(int base_bits, OutputIt out, UInt value,
++                                        int num_digits, bool upper = false)
++    -> OutputIt {
+   if (auto ptr = to_pointer<Char>(out, to_unsigned(num_digits))) {
+-    format_uint<BASE_BITS>(ptr, value, num_digits, upper);
++    format_base2e(base_bits, ptr, value, num_digits, upper);
+     return out;
+   }
+-  // Buffer should be large enough to hold all digits (digits / BASE_BITS + 1).
+-  char buffer[num_bits<UInt>() / BASE_BITS + 1];
+-  format_uint<BASE_BITS>(buffer, value, num_digits, upper);
+-  return detail::copy_str_noinline<Char>(buffer, buffer + num_digits, out);
++  // Make buffer large enough for any base.
++  char buffer[num_bits<UInt>()];
++  if (is_constant_evaluated()) fill_n(buffer, sizeof(buffer), '\0');
++  format_base2e(base_bits, buffer, value, num_digits, upper);
++  return detail::copy_noinline<Char>(buffer, buffer + num_digits, out);
+ }
+ 
+ // A converter from UTF-8 to UTF-16.
+@@ -1410,12 +1263,16 @@ class utf8_to_utf16 {
+ 
+  public:
+   FMT_API explicit utf8_to_utf16(string_view s);
+-  operator basic_string_view<wchar_t>() const { return {&buffer_[0], size()}; }
+-  auto size() const -> size_t { return buffer_.size() - 1; }
+-  auto c_str() const -> const wchar_t* { return &buffer_[0]; }
+-  auto str() const -> std::wstring { return {&buffer_[0], size()}; }
++  inline operator basic_string_view<wchar_t>() const {
++    return {&buffer_[0], size()};
++  }
++  inline auto size() const -> size_t { return buffer_.size() - 1; }
++  inline auto c_str() const -> const wchar_t* { return &buffer_[0]; }
++  inline auto str() const -> std::wstring { return {&buffer_[0], size()}; }
+ };
+ 
++enum class to_utf8_error_policy { abort, replace };
++
+ // A converter from UTF-16/UTF-32 (host endian) to UTF-8.
+ template <typename WChar, typename Buffer = memory_buffer> class to_utf8 {
+  private:
+@@ -1423,37 +1280,45 @@ template <typename WChar, typename Buffer = memory_buffer> class to_utf8 {
+ 
+  public:
+   to_utf8() {}
+-  explicit to_utf8(basic_string_view<WChar> s) {
++  explicit to_utf8(basic_string_view<WChar> s,
++                   to_utf8_error_policy policy = to_utf8_error_policy::abort) {
+     static_assert(sizeof(WChar) == 2 || sizeof(WChar) == 4,
+                   "Expect utf16 or utf32");
+-
+-    if (!convert(s))
++    if (!convert(s, policy))
+       FMT_THROW(std::runtime_error(sizeof(WChar) == 2 ? "invalid utf16"
+                                                       : "invalid utf32"));
+   }
+   operator string_view() const { return string_view(&buffer_[0], size()); }
+-  size_t size() const { return buffer_.size() - 1; }
+-  const char* c_str() const { return &buffer_[0]; }
+-  std::string str() const { return std::string(&buffer_[0], size()); }
++  auto size() const -> size_t { return buffer_.size() - 1; }
++  auto c_str() const -> const char* { return &buffer_[0]; }
++  auto str() const -> std::string { return std::string(&buffer_[0], size()); }
+ 
+   // Performs conversion returning a bool instead of throwing exception on
+   // conversion error. This method may still throw in case of memory allocation
+   // error.
+-  bool convert(basic_string_view<WChar> s) {
+-    if (!convert(buffer_, s)) return false;
++  auto convert(basic_string_view<WChar> s,
++               to_utf8_error_policy policy = to_utf8_error_policy::abort)
++      -> bool {
++    if (!convert(buffer_, s, policy)) return false;
+     buffer_.push_back(0);
+     return true;
+   }
+-  static bool convert(Buffer& buf, basic_string_view<WChar> s) {
++  static auto convert(Buffer& buf, basic_string_view<WChar> s,
++                      to_utf8_error_policy policy = to_utf8_error_policy::abort)
++      -> bool {
+     for (auto p = s.begin(); p != s.end(); ++p) {
+       uint32_t c = static_cast<uint32_t>(*p);
+       if (sizeof(WChar) == 2 && c >= 0xd800 && c <= 0xdfff) {
+-        // surrogate pair
++        // Handle a surrogate pair.
+         ++p;
+         if (p == s.end() || (c & 0xfc00) != 0xd800 || (*p & 0xfc00) != 0xdc00) {
+-          return false;
++          if (policy == to_utf8_error_policy::abort) return false;
++          buf.append(string_view("\xEF\xBF\xBD"));
++          --p;
++          continue;
++        } else {
++          c = (c << 10) + static_cast<uint32_t>(*p) - 0x35fdc00;
+         }
+-        c = (c << 10) + static_cast<uint32_t>(*p) - 0x35fdc00;
+       }
+       if (c < 0x80) {
+         buf.push_back(static_cast<char>(c));
+@@ -1478,14 +1343,14 @@ template <typename WChar, typename Buffer = memory_buffer> class to_utf8 {
+ };
+ 
+ // Computes 128-bit result of multiplication of two 64-bit unsigned integers.
+-inline uint128_fallback umul128(uint64_t x, uint64_t y) noexcept {
++inline auto umul128(uint64_t x, uint64_t y) noexcept -> uint128_fallback {
+ #if FMT_USE_INT128
+   auto p = static_cast<uint128_opt>(x) * static_cast<uint128_opt>(y);
+   return {static_cast<uint64_t>(p >> 64), static_cast<uint64_t>(p)};
+ #elif defined(_MSC_VER) && defined(_M_X64)
+-  auto result = uint128_fallback();
+-  result.lo_ = _umul128(x, y, &result.hi_);
+-  return result;
++  auto hi = uint64_t();
++  auto lo = _umul128(x, y, &hi);
++  return {hi, lo};
+ #else
+   const uint64_t mask = static_cast<uint64_t>(max_value<uint32_t>());
+ 
+@@ -1509,19 +1374,19 @@ inline uint128_fallback umul128(uint64_t x, uint64_t y) noexcept {
+ namespace dragonbox {
+ // Computes floor(log10(pow(2, e))) for e in [-2620, 2620] using the method from
+ // https://fmt.dev/papers/Dragonbox.pdf#page=28, section 6.1.
+-inline int floor_log10_pow2(int e) noexcept {
++inline auto floor_log10_pow2(int e) noexcept -> int {
+   FMT_ASSERT(e <= 2620 && e >= -2620, "too large exponent");
+   static_assert((-1 >> 1) == -1, "right shift is not arithmetic");
+   return (e * 315653) >> 20;
+ }
+ 
+-inline int floor_log2_pow10(int e) noexcept {
++inline auto floor_log2_pow10(int e) noexcept -> int {
+   FMT_ASSERT(e <= 1233 && e >= -1233, "too large exponent");
+   return (e * 1741647) >> 19;
+ }
+ 
+ // Computes upper 64 bits of multiplication of two 64-bit unsigned integers.
+-inline uint64_t umul128_upper64(uint64_t x, uint64_t y) noexcept {
++inline auto umul128_upper64(uint64_t x, uint64_t y) noexcept -> uint64_t {
+ #if FMT_USE_INT128
+   auto p = static_cast<uint128_opt>(x) * static_cast<uint128_opt>(y);
+   return static_cast<uint64_t>(p >> 64);
+@@ -1534,14 +1399,14 @@ inline uint64_t umul128_upper64(uint64_t x, uint64_t y) noexcept {
+ 
+ // Computes upper 128 bits of multiplication of a 64-bit unsigned integer and a
+ // 128-bit unsigned integer.
+-inline uint128_fallback umul192_upper128(uint64_t x,
+-                                         uint128_fallback y) noexcept {
++inline auto umul192_upper128(uint64_t x, uint128_fallback y) noexcept
++    -> uint128_fallback {
+   uint128_fallback r = umul128(x, y.high());
+   r += umul128_upper64(x, y.low());
+   return r;
+ }
+ 
+-FMT_API uint128_fallback get_cached_power(int k) noexcept;
++FMT_API auto get_cached_power(int k) noexcept -> uint128_fallback;
+ 
+ // Type-specific information that Dragonbox uses.
+ template <typename T, typename Enable = void> struct float_info;
+@@ -1595,14 +1460,14 @@ template <typename T> FMT_API auto to_decimal(T x) noexcept -> decimal_fp<T>;
+ }  // namespace dragonbox
+ 
+ // Returns true iff Float has the implicit bit which is not stored.
+-template <typename Float> constexpr bool has_implicit_bit() {
++template <typename Float> constexpr auto has_implicit_bit() -> bool {
+   // An 80-bit FP number has a 64-bit significand an no implicit bit.
+   return std::numeric_limits<Float>::digits != 64;
+ }
+ 
+ // Returns the number of significand bits stored in Float. The implicit bit is
+ // not counted since it is not stored.
+-template <typename Float> constexpr int num_significand_bits() {
++template <typename Float> constexpr auto num_significand_bits() -> int {
+   // std::numeric_limits may not support __float128.
+   return is_float128<Float>() ? 112
+                               : (std::numeric_limits<Float>::digits -
+@@ -1623,25 +1488,30 @@ template <typename Float> constexpr auto exponent_bias() -> int {
+ }
+ 
+ // Writes the exponent exp in the form "[+-]d{2,3}" to buffer.
+-template <typename Char, typename It>
+-FMT_CONSTEXPR auto write_exponent(int exp, It it) -> It {
++template <typename Char, typename OutputIt>
++FMT_CONSTEXPR auto write_exponent(int exp, OutputIt out) -> OutputIt {
+   FMT_ASSERT(-10000 < exp && exp < 10000, "exponent out of range");
+   if (exp < 0) {
+-    *it++ = static_cast<Char>('-');
++    *out++ = static_cast<Char>('-');
+     exp = -exp;
+   } else {
+-    *it++ = static_cast<Char>('+');
++    *out++ = static_cast<Char>('+');
+   }
+-  if (exp >= 100) {
+-    const char* top = digits2(to_unsigned(exp / 100));
+-    if (exp >= 1000) *it++ = static_cast<Char>(top[0]);
+-    *it++ = static_cast<Char>(top[1]);
+-    exp %= 100;
+-  }
+-  const char* d = digits2(to_unsigned(exp));
+-  *it++ = static_cast<Char>(d[0]);
+-  *it++ = static_cast<Char>(d[1]);
+-  return it;
++  auto uexp = static_cast<uint32_t>(exp);
++  if (is_constant_evaluated()) {
++    if (uexp < 10) *out++ = '0';
++    return format_decimal<Char>(out, uexp, count_digits(uexp));
++  }
++  if (uexp >= 100u) {
++    const char* top = digits2(uexp / 100);
++    if (uexp >= 1000u) *out++ = static_cast<Char>(top[0]);
++    *out++ = static_cast<Char>(top[1]);
++    uexp %= 100;
++  }
++  const char* d = digits2(uexp);
++  *out++ = static_cast<Char>(d[0]);
++  *out++ = static_cast<Char>(d[1]);
++  return out;
+ }
+ 
+ // A floating-point number f * pow(2, e) where F is an unsigned type.
+@@ -1695,7 +1565,7 @@ using fp = basic_fp<unsigned long long>;
+ 
+ // Normalizes the value converted from double and multiplied by (1 << SHIFT).
+ template <int SHIFT = 0, typename F>
+-FMT_CONSTEXPR basic_fp<F> normalize(basic_fp<F> value) {
++FMT_CONSTEXPR auto normalize(basic_fp<F> value) -> basic_fp<F> {
+   // Handle subnormals.
+   const auto implicit_bit = F(1) << num_significand_bits<double>();
+   const auto shifted_implicit_bit = implicit_bit << SHIFT;
+@@ -1712,7 +1582,7 @@ FMT_CONSTEXPR basic_fp<F> normalize(basic_fp<F> value) {
+ }
+ 
+ // Computes lhs * rhs / pow(2, 64) rounded to nearest with half-up tie breaking.
+-FMT_CONSTEXPR inline uint64_t multiply(uint64_t lhs, uint64_t rhs) {
++FMT_CONSTEXPR inline auto multiply(uint64_t lhs, uint64_t rhs) -> uint64_t {
+ #if FMT_USE_INT128
+   auto product = static_cast<__uint128_t>(lhs) * rhs;
+   auto f = static_cast<uint64_t>(product >> 64);
+@@ -1729,191 +1599,82 @@ FMT_CONSTEXPR inline uint64_t multiply(uint64_t lhs, uint64_t rhs) {
+ #endif
+ }
+ 
+-FMT_CONSTEXPR inline fp operator*(fp x, fp y) {
++FMT_CONSTEXPR inline auto operator*(fp x, fp y) -> fp {
+   return {multiply(x.f, y.f), x.e + y.e + 64};
+ }
+ 
+-template <typename T = void> struct basic_data {
+-  // Normalized 64-bit significands of pow(10, k), for k = -348, -340, ..., 340.
+-  // These are generated by support/compute-powers.py.
+-  static constexpr uint64_t pow10_significands[87] = {
+-      0xfa8fd5a0081c0288, 0xbaaee17fa23ebf76, 0x8b16fb203055ac76,
+-      0xcf42894a5dce35ea, 0x9a6bb0aa55653b2d, 0xe61acf033d1a45df,
+-      0xab70fe17c79ac6ca, 0xff77b1fcbebcdc4f, 0xbe5691ef416bd60c,
+-      0x8dd01fad907ffc3c, 0xd3515c2831559a83, 0x9d71ac8fada6c9b5,
+-      0xea9c227723ee8bcb, 0xaecc49914078536d, 0x823c12795db6ce57,
+-      0xc21094364dfb5637, 0x9096ea6f3848984f, 0xd77485cb25823ac7,
+-      0xa086cfcd97bf97f4, 0xef340a98172aace5, 0xb23867fb2a35b28e,
+-      0x84c8d4dfd2c63f3b, 0xc5dd44271ad3cdba, 0x936b9fcebb25c996,
+-      0xdbac6c247d62a584, 0xa3ab66580d5fdaf6, 0xf3e2f893dec3f126,
+-      0xb5b5ada8aaff80b8, 0x87625f056c7c4a8b, 0xc9bcff6034c13053,
+-      0x964e858c91ba2655, 0xdff9772470297ebd, 0xa6dfbd9fb8e5b88f,
+-      0xf8a95fcf88747d94, 0xb94470938fa89bcf, 0x8a08f0f8bf0f156b,
+-      0xcdb02555653131b6, 0x993fe2c6d07b7fac, 0xe45c10c42a2b3b06,
+-      0xaa242499697392d3, 0xfd87b5f28300ca0e, 0xbce5086492111aeb,
+-      0x8cbccc096f5088cc, 0xd1b71758e219652c, 0x9c40000000000000,
+-      0xe8d4a51000000000, 0xad78ebc5ac620000, 0x813f3978f8940984,
+-      0xc097ce7bc90715b3, 0x8f7e32ce7bea5c70, 0xd5d238a4abe98068,
+-      0x9f4f2726179a2245, 0xed63a231d4c4fb27, 0xb0de65388cc8ada8,
+-      0x83c7088e1aab65db, 0xc45d1df942711d9a, 0x924d692ca61be758,
+-      0xda01ee641a708dea, 0xa26da3999aef774a, 0xf209787bb47d6b85,
+-      0xb454e4a179dd1877, 0x865b86925b9bc5c2, 0xc83553c5c8965d3d,
+-      0x952ab45cfa97a0b3, 0xde469fbd99a05fe3, 0xa59bc234db398c25,
+-      0xf6c69a72a3989f5c, 0xb7dcbf5354e9bece, 0x88fcf317f22241e2,
+-      0xcc20ce9bd35c78a5, 0x98165af37b2153df, 0xe2a0b5dc971f303a,
+-      0xa8d9d1535ce3b396, 0xfb9b7cd9a4a7443c, 0xbb764c4ca7a44410,
+-      0x8bab8eefb6409c1a, 0xd01fef10a657842c, 0x9b10a4e5e9913129,
+-      0xe7109bfba19c0c9d, 0xac2820d9623bf429, 0x80444b5e7aa7cf85,
+-      0xbf21e44003acdd2d, 0x8e679c2f5e44ff8f, 0xd433179d9c8cb841,
+-      0x9e19db92b4e31ba9, 0xeb96bf6ebadf77d9, 0xaf87023b9bf0ee6b,
+-  };
+-
+-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+-#  pragma GCC diagnostic push
+-#  pragma GCC diagnostic ignored "-Wnarrowing"
+-#endif
+-  // Binary exponents of pow(10, k), for k = -348, -340, ..., 340, corresponding
+-  // to significands above.
+-  static constexpr int16_t pow10_exponents[87] = {
+-      -1220, -1193, -1166, -1140, -1113, -1087, -1060, -1034, -1007, -980, -954,
+-      -927,  -901,  -874,  -847,  -821,  -794,  -768,  -741,  -715,  -688, -661,
+-      -635,  -608,  -582,  -555,  -529,  -502,  -475,  -449,  -422,  -396, -369,
+-      -343,  -316,  -289,  -263,  -236,  -210,  -183,  -157,  -130,  -103, -77,
+-      -50,   -24,   3,     30,    56,    83,    109,   136,   162,   189,  216,
+-      242,   269,   295,   322,   348,   375,   402,   428,   455,   481,  508,
+-      534,   561,   588,   614,   641,   667,   694,   720,   747,   774,  800,
+-      827,   853,   880,   907,   933,   960,   986,   1013,  1039,  1066};
+-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+-#  pragma GCC diagnostic pop
+-#endif
+-
+-  static constexpr uint64_t power_of_10_64[20] = {
+-      1, FMT_POWERS_OF_10(1ULL), FMT_POWERS_OF_10(1000000000ULL),
+-      10000000000000000000ULL};
+-
+-  // For checking rounding thresholds.
+-  // The kth entry is chosen to be the smallest integer such that the
+-  // upper 32-bits of 10^(k+1) times it is strictly bigger than 5 * 10^k.
+-  static constexpr uint32_t fractional_part_rounding_thresholds[8] = {
+-      2576980378,  // ceil(2^31 + 2^32/10^1)
+-      2190433321,  // ceil(2^31 + 2^32/10^2)
+-      2151778616,  // ceil(2^31 + 2^32/10^3)
+-      2147913145,  // ceil(2^31 + 2^32/10^4)
+-      2147526598,  // ceil(2^31 + 2^32/10^5)
+-      2147487943,  // ceil(2^31 + 2^32/10^6)
+-      2147484078,  // ceil(2^31 + 2^32/10^7)
+-      2147483691   // ceil(2^31 + 2^32/10^8)
+-  };
+-};
+-
+-#if FMT_CPLUSPLUS < 201703L
+-template <typename T> constexpr uint64_t basic_data<T>::pow10_significands[];
+-template <typename T> constexpr int16_t basic_data<T>::pow10_exponents[];
+-template <typename T> constexpr uint64_t basic_data<T>::power_of_10_64[];
+-template <typename T>
+-constexpr uint32_t basic_data<T>::fractional_part_rounding_thresholds[];
+-#endif
+-
+-// This is a struct rather than an alias to avoid shadowing warnings in gcc.
+-struct data : basic_data<> {};
+-
+-// Returns a cached power of 10 `c_k = c_k.f * pow(2, c_k.e)` such that its
+-// (binary) exponent satisfies `min_exponent <= c_k.e <= min_exponent + 28`.
+-FMT_CONSTEXPR inline fp get_cached_power(int min_exponent,
+-                                         int& pow10_exponent) {
+-  const int shift = 32;
+-  // log10(2) = 0x0.4d104d427de7fbcc...
+-  const int64_t significand = 0x4d104d427de7fbcc;
+-  int index = static_cast<int>(
+-      ((min_exponent + fp::num_significand_bits - 1) * (significand >> shift) +
+-       ((int64_t(1) << shift) - 1))  // ceil
+-      >> 32                          // arithmetic shift
+-  );
+-  // Decimal exponent of the first (smallest) cached power of 10.
+-  const int first_dec_exp = -348;
+-  // Difference between 2 consecutive decimal exponents in cached powers of 10.
+-  const int dec_exp_step = 8;
+-  index = (index - first_dec_exp - 1) / dec_exp_step + 1;
+-  pow10_exponent = first_dec_exp + index * dec_exp_step;
+-  // Using *(x + index) instead of x[index] avoids an issue with some compilers
+-  // using the EDG frontend (e.g. nvhpc/22.3 in C++17 mode).
+-  return {*(data::pow10_significands + index),
+-          *(data::pow10_exponents + index)};
+-}
+-
+-template <typename T>
++template <typename T, bool doublish = num_bits<T>() == num_bits<double>()>
+ using convert_float_result =
+-    conditional_t<std::is_same<T, float>::value ||
+-                      std::numeric_limits<T>::digits ==
+-                          std::numeric_limits<double>::digits,
+-                  double, T>;
++    conditional_t<std::is_same<T, float>::value || doublish, double, T>;
+ 
+ template <typename T>
+ constexpr auto convert_float(T value) -> convert_float_result<T> {
+   return static_cast<convert_float_result<T>>(value);
+ }
+ 
+-template <typename OutputIt, typename Char>
++template <typename Char, typename OutputIt>
+ FMT_NOINLINE FMT_CONSTEXPR auto fill(OutputIt it, size_t n,
+-                                     const fill_t<Char>& fill) -> OutputIt {
+-  auto fill_size = fill.size();
+-  if (fill_size == 1) return detail::fill_n(it, n, fill[0]);
+-  auto data = fill.data();
+-  for (size_t i = 0; i < n; ++i)
+-    it = copy_str<Char>(data, data + fill_size, it);
++                                     const basic_specs& specs) -> OutputIt {
++  auto fill_size = specs.fill_size();
++  if (fill_size == 1) return detail::fill_n(it, n, specs.fill_unit<Char>());
++  if (const Char* data = specs.fill<Char>()) {
++    for (size_t i = 0; i < n; ++i) it = copy<Char>(data, data + fill_size, it);
++  }
+   return it;
+ }
+ 
+ // Writes the output of f, padded according to format specifications in specs.
+ // size: output size in code units.
+ // width: output display width in (terminal) column positions.
+-template <align::type align = align::left, typename OutputIt, typename Char,
++template <typename Char, align default_align = align::left, typename OutputIt,
+           typename F>
+-FMT_CONSTEXPR auto write_padded(OutputIt out, const format_specs<Char>& specs,
++FMT_CONSTEXPR auto write_padded(OutputIt out, const format_specs& specs,
+                                 size_t size, size_t width, F&& f) -> OutputIt {
+-  static_assert(align == align::left || align == align::right, "");
++  static_assert(default_align == align::left || default_align == align::right,
++                "");
+   unsigned spec_width = to_unsigned(specs.width);
+   size_t padding = spec_width > width ? spec_width - width : 0;
+   // Shifts are encoded as string literals because static constexpr is not
+   // supported in constexpr functions.
+-  auto* shifts = align == align::left ? "\x1f\x1f\x00\x01" : "\x00\x1f\x00\x01";
+-  size_t left_padding = padding >> shifts[specs.align];
++  auto* shifts =
++      default_align == align::left ? "\x1f\x1f\x00\x01" : "\x00\x1f\x00\x01";
++  size_t left_padding = padding >> shifts[static_cast<int>(specs.align())];
+   size_t right_padding = padding - left_padding;
+-  auto it = reserve(out, size + padding * specs.fill.size());
+-  if (left_padding != 0) it = fill(it, left_padding, specs.fill);
++  auto it = reserve(out, size + padding * specs.fill_size());
++  if (left_padding != 0) it = fill<Char>(it, left_padding, specs);
+   it = f(it);
+-  if (right_padding != 0) it = fill(it, right_padding, specs.fill);
++  if (right_padding != 0) it = fill<Char>(it, right_padding, specs);
+   return base_iterator(out, it);
+ }
+ 
+-template <align::type align = align::left, typename OutputIt, typename Char,
++template <typename Char, align default_align = align::left, typename OutputIt,
+           typename F>
+-constexpr auto write_padded(OutputIt out, const format_specs<Char>& specs,
++constexpr auto write_padded(OutputIt out, const format_specs& specs,
+                             size_t size, F&& f) -> OutputIt {
+-  return write_padded<align>(out, specs, size, size, f);
++  return write_padded<Char, default_align>(out, specs, size, size, f);
+ }
+ 
+-template <align::type align = align::left, typename Char, typename OutputIt>
++template <typename Char, align default_align = align::left, typename OutputIt>
+ FMT_CONSTEXPR auto write_bytes(OutputIt out, string_view bytes,
+-                               const format_specs<Char>& specs) -> OutputIt {
+-  return write_padded<align>(
++                               const format_specs& specs = {}) -> OutputIt {
++  return write_padded<Char, default_align>(
+       out, specs, bytes.size(), [bytes](reserve_iterator<OutputIt> it) {
+         const char* data = bytes.data();
+-        return copy_str<Char>(data, data + bytes.size(), it);
++        return copy<Char>(data, data + bytes.size(), it);
+       });
+ }
+ 
+ template <typename Char, typename OutputIt, typename UIntPtr>
+-auto write_ptr(OutputIt out, UIntPtr value, const format_specs<Char>* specs)
++auto write_ptr(OutputIt out, UIntPtr value, const format_specs* specs)
+     -> OutputIt {
+   int num_digits = count_digits<4>(value);
+   auto size = to_unsigned(num_digits) + size_t(2);
+   auto write = [=](reserve_iterator<OutputIt> it) {
+     *it++ = static_cast<Char>('0');
+     *it++ = static_cast<Char>('x');
+-    return format_uint<4, Char>(it, value, num_digits);
++    return format_base2e<Char>(4, it, value, num_digits);
+   };
+-  return specs ? write_padded<align::right>(out, *specs, size, write)
++  return specs ? write_padded<Char, align::right>(out, *specs, size, write)
+                : base_iterator(out, write(reserve(out, size)));
+ }
+ 
+@@ -1921,8 +1682,9 @@ auto write_ptr(OutputIt out, UIntPtr value, const format_specs<Char>* specs)
+ FMT_API auto is_printable(uint32_t cp) -> bool;
+ 
+ inline auto needs_escape(uint32_t cp) -> bool {
+-  return cp < 0x20 || cp == 0x7f || cp == '"' || cp == '\\' ||
+-         !is_printable(cp);
++  if (cp < 0x20 || cp == 0x7f || cp == '"' || cp == '\\') return true;
++  if (const_check(FMT_OPTIMIZE_SIZE > 1)) return false;
++  return !is_printable(cp);
+ }
+ 
+ template <typename Char> struct find_escape_result {
+@@ -1931,17 +1693,11 @@ template <typename Char> struct find_escape_result {
+   uint32_t cp;
+ };
+ 
+-template <typename Char>
+-using make_unsigned_char =
+-    typename conditional_t<std::is_integral<Char>::value,
+-                           std::make_unsigned<Char>,
+-                           type_identity<uint32_t>>::type;
+-
+ template <typename Char>
+ auto find_escape(const Char* begin, const Char* end)
+     -> find_escape_result<Char> {
+   for (; begin != end; ++begin) {
+-    uint32_t cp = static_cast<make_unsigned_char<Char>>(*begin);
++    uint32_t cp = static_cast<unsigned_char<Char>>(*begin);
+     if (const_check(sizeof(Char) == 1) && cp >= 0x80) continue;
+     if (needs_escape(cp)) return {begin, begin + 1, cp};
+   }
+@@ -1950,7 +1706,7 @@ auto find_escape(const Char* begin, const Char* end)
+ 
+ inline auto find_escape(const char* begin, const char* end)
+     -> find_escape_result<char> {
+-  if (!is_utf8()) return find_escape<char>(begin, end);
++  if (const_check(!use_utf8)) return find_escape<char>(begin, end);
+   auto result = find_escape_result<char>{end, nullptr, 0};
+   for_each_codepoint(string_view(begin, to_unsigned(end - begin)),
+                      [&](uint32_t cp, string_view sv) {
+@@ -1963,40 +1719,14 @@ inline auto find_escape(const char* begin, const char* end)
+   return result;
+ }
+ 
+-#define FMT_STRING_IMPL(s, base, explicit)                                    \
+-  [] {                                                                        \
+-    /* Use the hidden visibility as a workaround for a GCC bug (#1973). */    \
+-    /* Use a macro-like name to avoid shadowing warnings. */                  \
+-    struct FMT_VISIBILITY("hidden") FMT_COMPILE_STRING : base {               \
+-      using char_type FMT_MAYBE_UNUSED = fmt::remove_cvref_t<decltype(s[0])>; \
+-      FMT_MAYBE_UNUSED FMT_CONSTEXPR explicit                                 \
+-      operator fmt::basic_string_view<char_type>() const {                    \
+-        return fmt::detail_exported::compile_string_to_view<char_type>(s);    \
+-      }                                                                       \
+-    };                                                                        \
+-    return FMT_COMPILE_STRING();                                              \
+-  }()
+-
+-/**
+-  \rst
+-  Constructs a compile-time format string from a string literal *s*.
+-
+-  **Example**::
+-
+-    // A compile-time error because 'd' is an invalid specifier for strings.
+-    std::string s = fmt::format(FMT_STRING("{:d}"), "foo");
+-  \endrst
+- */
+-#define FMT_STRING(s) FMT_STRING_IMPL(s, fmt::detail::compile_string, )
+-
+ template <size_t width, typename Char, typename OutputIt>
+ auto write_codepoint(OutputIt out, char prefix, uint32_t cp) -> OutputIt {
+   *out++ = static_cast<Char>('\\');
+   *out++ = static_cast<Char>(prefix);
+   Char buf[width];
+   fill_n(buf, width, static_cast<Char>('0'));
+-  format_uint<4>(buf, cp, width);
+-  return copy_str<Char>(buf, buf + width, out);
++  format_base2e(4, buf, cp, width);
++  return copy<Char>(buf, buf + width, out);
+ }
+ 
+ template <typename OutputIt, typename Char>
+@@ -2016,23 +1746,15 @@ auto write_escaped_cp(OutputIt out, const find_escape_result<Char>& escape)
+     *out++ = static_cast<Char>('\\');
+     c = static_cast<Char>('t');
+     break;
+-  case '"':
+-    FMT_FALLTHROUGH;
+-  case '\'':
+-    FMT_FALLTHROUGH;
+-  case '\\':
+-    *out++ = static_cast<Char>('\\');
+-    break;
++  case '"':  FMT_FALLTHROUGH;
++  case '\'': FMT_FALLTHROUGH;
++  case '\\': *out++ = static_cast<Char>('\\'); break;
+   default:
+-    if (escape.cp < 0x100) {
+-      return write_codepoint<2, Char>(out, 'x', escape.cp);
+-    }
+-    if (escape.cp < 0x10000) {
++    if (escape.cp < 0x100) return write_codepoint<2, Char>(out, 'x', escape.cp);
++    if (escape.cp < 0x10000)
+       return write_codepoint<4, Char>(out, 'u', escape.cp);
+-    }
+-    if (escape.cp < 0x110000) {
++    if (escape.cp < 0x110000)
+       return write_codepoint<8, Char>(out, 'U', escape.cp);
+-    }
+     for (Char escape_char : basic_string_view<Char>(
+              escape.begin, to_unsigned(escape.end - escape.begin))) {
+       out = write_codepoint<2, Char>(out, 'x',
+@@ -2051,7 +1773,7 @@ auto write_escaped_string(OutputIt out, basic_string_view<Char> str)
+   auto begin = str.begin(), end = str.end();
+   do {
+     auto escape = find_escape(begin, end);
+-    out = copy_str<Char>(begin, escape.begin, out);
++    out = copy<Char>(begin, escape.begin, out);
+     begin = escape.end;
+     if (!begin) break;
+     out = write_escaped_cp<OutputIt, Char>(out, escape);
+@@ -2062,11 +1784,13 @@ auto write_escaped_string(OutputIt out, basic_string_view<Char> str)
+ 
+ template <typename Char, typename OutputIt>
+ auto write_escaped_char(OutputIt out, Char v) -> OutputIt {
++  Char v_array[1] = {v};
+   *out++ = static_cast<Char>('\'');
+   if ((needs_escape(static_cast<uint32_t>(v)) && v != static_cast<Char>('"')) ||
+       v == static_cast<Char>('\'')) {
+-    out = write_escaped_cp(
+-        out, find_escape_result<Char>{&v, &v + 1, static_cast<uint32_t>(v)});
++    out = write_escaped_cp(out,
++                           find_escape_result<Char>{v_array, v_array + 1,
++                                                    static_cast<uint32_t>(v)});
+   } else {
+     *out++ = v;
+   }
+@@ -2076,74 +1800,23 @@ auto write_escaped_char(OutputIt out, Char v) -> OutputIt {
+ 
+ template <typename Char, typename OutputIt>
+ FMT_CONSTEXPR auto write_char(OutputIt out, Char value,
+-                              const format_specs<Char>& specs) -> OutputIt {
+-  bool is_debug = specs.type == presentation_type::debug;
+-  return write_padded(out, specs, 1, [=](reserve_iterator<OutputIt> it) {
++                              const format_specs& specs) -> OutputIt {
++  bool is_debug = specs.type() == presentation_type::debug;
++  return write_padded<Char>(out, specs, 1, [=](reserve_iterator<OutputIt> it) {
+     if (is_debug) return write_escaped_char(it, value);
+     *it++ = value;
+     return it;
+   });
+ }
+ template <typename Char, typename OutputIt>
+-FMT_CONSTEXPR auto write(OutputIt out, Char value,
+-                         const format_specs<Char>& specs, locale_ref loc = {})
+-    -> OutputIt {
++FMT_CONSTEXPR auto write(OutputIt out, Char value, const format_specs& specs,
++                         locale_ref loc = {}) -> OutputIt {
+   // char is formatted as unsigned char for consistency across platforms.
+   using unsigned_type =
+       conditional_t<std::is_same<Char, char>::value, unsigned char, unsigned>;
+   return check_char_specs(specs)
+-             ? write_char(out, value, specs)
+-             : write(out, static_cast<unsigned_type>(value), specs, loc);
+-}
+-
+-// Data for write_int that doesn't depend on output iterator type. It is used to
+-// avoid template code bloat.
+-template <typename Char> struct write_int_data {
+-  size_t size;
+-  size_t padding;
+-
+-  FMT_CONSTEXPR write_int_data(int num_digits, unsigned prefix,
+-                               const format_specs<Char>& specs)
+-      : size((prefix >> 24) + to_unsigned(num_digits)), padding(0) {
+-    if (specs.align == align::numeric) {
+-      auto width = to_unsigned(specs.width);
+-      if (width > size) {
+-        padding = width - size;
+-        size = width;
+-      }
+-    } else if (specs.precision > num_digits) {
+-      size = (prefix >> 24) + to_unsigned(specs.precision);
+-      padding = to_unsigned(specs.precision - num_digits);
+-    }
+-  }
+-};
+-
+-// Writes an integer in the format
+-//   <left-padding><prefix><numeric-padding><digits><right-padding>
+-// where <digits> are written by write_digits(it).
+-// prefix contains chars in three lower bytes and the size in the fourth byte.
+-template <typename OutputIt, typename Char, typename W>
+-FMT_CONSTEXPR FMT_INLINE auto write_int(OutputIt out, int num_digits,
+-                                        unsigned prefix,
+-                                        const format_specs<Char>& specs,
+-                                        W write_digits) -> OutputIt {
+-  // Slightly faster check for specs.width == 0 && specs.precision == -1.
+-  if ((specs.width | (specs.precision + 1)) == 0) {
+-    auto it = reserve(out, to_unsigned(num_digits) + (prefix >> 24));
+-    if (prefix != 0) {
+-      for (unsigned p = prefix & 0xffffff; p != 0; p >>= 8)
+-        *it++ = static_cast<Char>(p & 0xff);
+-    }
+-    return base_iterator(out, write_digits(it));
+-  }
+-  auto data = write_int_data<Char>(num_digits, prefix, specs);
+-  return write_padded<align::right>(
+-      out, specs, data.size, [=](reserve_iterator<OutputIt> it) {
+-        for (unsigned p = prefix & 0xffffff; p != 0; p >>= 8)
+-          *it++ = static_cast<Char>(p & 0xff);
+-        it = detail::fill_n(it, data.padding, static_cast<Char>('0'));
+-        return write_digits(it);
+-      });
++             ? write_char<Char>(out, value, specs)
++             : write<Char>(out, static_cast<unsigned_type>(value), specs, loc);
+ }
+ 
+ template <typename Char> class digit_grouping {
+@@ -2155,10 +1828,10 @@ template <typename Char> class digit_grouping {
+     std::string::const_iterator group;
+     int pos;
+   };
+-  next_state initial_state() const { return {grouping_.begin(), 0}; }
++  auto initial_state() const -> next_state { return {grouping_.begin(), 0}; }
+ 
+   // Returns the next digit group separator position.
+-  int next(next_state& state) const {
++  auto next(next_state& state) const -> int {
+     if (thousands_sep_.empty()) return max_value<int>();
+     if (state.group == grouping_.end()) return state.pos += grouping_.back();
+     if (*state.group <= 0 || *state.group == max_value<char>())
+@@ -2168,7 +1841,9 @@ template <typename Char> class digit_grouping {
+   }
+ 
+  public:
+-  explicit digit_grouping(locale_ref loc, bool localized = true) {
++  template <typename Locale,
++            FMT_ENABLE_IF(std::is_same<Locale, locale_ref>::value)>
++  explicit digit_grouping(Locale loc, bool localized = true) {
+     if (!localized) return;
+     auto sep = thousands_sep<Char>(loc);
+     grouping_ = sep.grouping;
+@@ -2177,9 +1852,9 @@ template <typename Char> class digit_grouping {
+   digit_grouping(std::string grouping, std::basic_string<Char> sep)
+       : grouping_(std::move(grouping)), thousands_sep_(std::move(sep)) {}
+ 
+-  bool has_separator() const { return !thousands_sep_.empty(); }
++  auto has_separator() const -> bool { return !thousands_sep_.empty(); }
+ 
+-  int count_separators(int num_digits) const {
++  auto count_separators(int num_digits) const -> int {
+     int count = 0;
+     auto state = initial_state();
+     while (num_digits > next(state)) ++count;
+@@ -2188,7 +1863,7 @@ template <typename Char> class digit_grouping {
+ 
+   // Applies grouping to digits and write the output to out.
+   template <typename Out, typename C>
+-  Out apply(Out out, basic_string_view<C> digits) const {
++  auto apply(Out out, basic_string_view<C> digits) const -> Out {
+     auto num_digits = static_cast<int>(digits.size());
+     auto separators = basic_memory_buffer<int>();
+     separators.push_back(0);
+@@ -2200,9 +1875,8 @@ template <typename Char> class digit_grouping {
+     for (int i = 0, sep_index = static_cast<int>(separators.size() - 1);
+          i < num_digits; ++i) {
+       if (num_digits - i == separators[sep_index]) {
+-        out =
+-            copy_str<Char>(thousands_sep_.data(),
+-                           thousands_sep_.data() + thousands_sep_.size(), out);
++        out = copy<Char>(thousands_sep_.data(),
++                         thousands_sep_.data() + thousands_sep_.size(), out);
+         --sep_index;
+       }
+       *out++ = static_cast<Char>(digits[to_unsigned(i)]);
+@@ -2211,48 +1885,78 @@ template <typename Char> class digit_grouping {
+   }
+ };
+ 
++FMT_CONSTEXPR inline void prefix_append(unsigned& prefix, unsigned value) {
++  prefix |= prefix != 0 ? value << 8 : value;
++  prefix += (1u + (value > 0xff ? 1 : 0)) << 24;
++}
++
+ // Writes a decimal integer with digit grouping.
+ template <typename OutputIt, typename UInt, typename Char>
+ auto write_int(OutputIt out, UInt value, unsigned prefix,
+-               const format_specs<Char>& specs,
+-               const digit_grouping<Char>& grouping) -> OutputIt {
++               const format_specs& specs, const digit_grouping<Char>& grouping)
++    -> OutputIt {
+   static_assert(std::is_same<uint64_or_128_t<UInt>, UInt>::value, "");
+-  int num_digits = count_digits(value);
+-  char digits[40];
+-  format_decimal(digits, value, num_digits);
+-  unsigned size = to_unsigned((prefix != 0 ? 1 : 0) + num_digits +
+-                              grouping.count_separators(num_digits));
+-  return write_padded<align::right>(
++  int num_digits = 0;
++  auto buffer = memory_buffer();
++  switch (specs.type()) {
++  default: FMT_ASSERT(false, ""); FMT_FALLTHROUGH;
++  case presentation_type::none:
++  case presentation_type::dec:
++    num_digits = count_digits(value);
++    format_decimal<char>(appender(buffer), value, num_digits);
++    break;
++  case presentation_type::hex:
++    if (specs.alt())
++      prefix_append(prefix, unsigned(specs.upper() ? 'X' : 'x') << 8 | '0');
++    num_digits = count_digits<4>(value);
++    format_base2e<char>(4, appender(buffer), value, num_digits, specs.upper());
++    break;
++  case presentation_type::oct:
++    num_digits = count_digits<3>(value);
++    // Octal prefix '0' is counted as a digit, so only add it if precision
++    // is not greater than the number of digits.
++    if (specs.alt() && specs.precision <= num_digits && value != 0)
++      prefix_append(prefix, '0');
++    format_base2e<char>(3, appender(buffer), value, num_digits);
++    break;
++  case presentation_type::bin:
++    if (specs.alt())
++      prefix_append(prefix, unsigned(specs.upper() ? 'B' : 'b') << 8 | '0');
++    num_digits = count_digits<1>(value);
++    format_base2e<char>(1, appender(buffer), value, num_digits);
++    break;
++  case presentation_type::chr:
++    return write_char<Char>(out, static_cast<Char>(value), specs);
++  }
++
++  unsigned size = (prefix != 0 ? prefix >> 24 : 0) + to_unsigned(num_digits) +
++                  to_unsigned(grouping.count_separators(num_digits));
++  return write_padded<Char, align::right>(
+       out, specs, size, size, [&](reserve_iterator<OutputIt> it) {
+-        if (prefix != 0) {
+-          char sign = static_cast<char>(prefix);
+-          *it++ = static_cast<Char>(sign);
+-        }
+-        return grouping.apply(it, string_view(digits, to_unsigned(num_digits)));
++        for (unsigned p = prefix & 0xffffff; p != 0; p >>= 8)
++          *it++ = static_cast<Char>(p & 0xff);
++        return grouping.apply(it, string_view(buffer.data(), buffer.size()));
+       });
+ }
+ 
++#if FMT_USE_LOCALE
+ // Writes a localized value.
+-FMT_API auto write_loc(appender out, loc_value value,
+-                       const format_specs<>& specs, locale_ref loc) -> bool;
+-template <typename OutputIt, typename Char>
+-inline auto write_loc(OutputIt, loc_value, const format_specs<Char>&,
++FMT_API auto write_loc(appender out, loc_value value, const format_specs& specs,
++                       locale_ref loc) -> bool;
++#endif
++template <typename OutputIt>
++inline auto write_loc(OutputIt, const loc_value&, const format_specs&,
+                       locale_ref) -> bool {
+   return false;
+ }
+ 
+-FMT_CONSTEXPR inline void prefix_append(unsigned& prefix, unsigned value) {
+-  prefix |= prefix != 0 ? value << 8 : value;
+-  prefix += (1u + (value > 0xff ? 1 : 0)) << 24;
+-}
+-
+ template <typename UInt> struct write_int_arg {
+   UInt abs_value;
+   unsigned prefix;
+ };
+ 
+ template <typename T>
+-FMT_CONSTEXPR auto make_write_int_arg(T value, sign_t sign)
++FMT_CONSTEXPR auto make_write_int_arg(T value, sign s)
+     -> write_int_arg<uint32_or_64_or_128_t<T>> {
+   auto prefix = 0u;
+   auto abs_value = static_cast<uint32_or_64_or_128_t<T>>(value);
+@@ -2262,21 +1966,21 @@ FMT_CONSTEXPR auto make_write_int_arg(T value, sign_t sign)
+   } else {
+     constexpr const unsigned prefixes[4] = {0, 0, 0x1000000u | '+',
+                                             0x1000000u | ' '};
+-    prefix = prefixes[sign];
++    prefix = prefixes[static_cast<int>(s)];
+   }
+   return {abs_value, prefix};
+ }
+ 
+ template <typename Char = char> struct loc_writer {
+-  buffer_appender<Char> out;
+-  const format_specs<Char>& specs;
++  basic_appender<Char> out;
++  const format_specs& specs;
+   std::basic_string<Char> sep;
+   std::string grouping;
+   std::basic_string<Char> decimal_point;
+ 
+   template <typename T, FMT_ENABLE_IF(is_integer<T>::value)>
+   auto operator()(T value) -> bool {
+-    auto arg = make_write_int_arg(value, specs.sign);
++    auto arg = make_write_int_arg(value, specs.sign());
+     write_int(out, static_cast<uint64_or_128_t<T>>(arg.abs_value), arg.prefix,
+               specs, digit_grouping<Char>(grouping, sep));
+     return true;
+@@ -2288,166 +1992,162 @@ template <typename Char = char> struct loc_writer {
+   }
+ };
+ 
++// Size and padding computation separate from write_int to avoid template bloat.
++struct size_padding {
++  unsigned size;
++  unsigned padding;
++
++  FMT_CONSTEXPR size_padding(int num_digits, unsigned prefix,
++                             const format_specs& specs)
++      : size((prefix >> 24) + to_unsigned(num_digits)), padding(0) {
++    if (specs.align() == align::numeric) {
++      auto width = to_unsigned(specs.width);
++      if (width > size) {
++        padding = width - size;
++        size = width;
++      }
++    } else if (specs.precision > num_digits) {
++      size = (prefix >> 24) + to_unsigned(specs.precision);
++      padding = to_unsigned(specs.precision - num_digits);
++    }
++  }
++};
++
+ template <typename Char, typename OutputIt, typename T>
+ FMT_CONSTEXPR FMT_INLINE auto write_int(OutputIt out, write_int_arg<T> arg,
+-                                        const format_specs<Char>& specs,
+-                                        locale_ref) -> OutputIt {
++                                        const format_specs& specs) -> OutputIt {
+   static_assert(std::is_same<T, uint32_or_64_or_128_t<T>>::value, "");
++
++  constexpr int buffer_size = num_bits<T>();
++  char buffer[buffer_size];
++  if (is_constant_evaluated()) fill_n(buffer, buffer_size, '\0');
++  const char* begin = nullptr;
++  const char* end = buffer + buffer_size;
++
+   auto abs_value = arg.abs_value;
+   auto prefix = arg.prefix;
+-  switch (specs.type) {
++  switch (specs.type()) {
++  default: FMT_ASSERT(false, ""); FMT_FALLTHROUGH;
+   case presentation_type::none:
+-  case presentation_type::dec: {
+-    auto num_digits = count_digits(abs_value);
+-    return write_int(
+-        out, num_digits, prefix, specs, [=](reserve_iterator<OutputIt> it) {
+-          return format_decimal<Char>(it, abs_value, num_digits).end;
+-        });
+-  }
+-  case presentation_type::hex_lower:
+-  case presentation_type::hex_upper: {
+-    bool upper = specs.type == presentation_type::hex_upper;
+-    if (specs.alt)
+-      prefix_append(prefix, unsigned(upper ? 'X' : 'x') << 8 | '0');
+-    int num_digits = count_digits<4>(abs_value);
+-    return write_int(
+-        out, num_digits, prefix, specs, [=](reserve_iterator<OutputIt> it) {
+-          return format_uint<4, Char>(it, abs_value, num_digits, upper);
+-        });
+-  }
+-  case presentation_type::bin_lower:
+-  case presentation_type::bin_upper: {
+-    bool upper = specs.type == presentation_type::bin_upper;
+-    if (specs.alt)
+-      prefix_append(prefix, unsigned(upper ? 'B' : 'b') << 8 | '0');
+-    int num_digits = count_digits<1>(abs_value);
+-    return write_int(out, num_digits, prefix, specs,
+-                     [=](reserve_iterator<OutputIt> it) {
+-                       return format_uint<1, Char>(it, abs_value, num_digits);
+-                     });
+-  }
++  case presentation_type::dec:
++    begin = do_format_decimal(buffer, abs_value, buffer_size);
++    break;
++  case presentation_type::hex:
++    begin = do_format_base2e(4, buffer, abs_value, buffer_size, specs.upper());
++    if (specs.alt())
++      prefix_append(prefix, unsigned(specs.upper() ? 'X' : 'x') << 8 | '0');
++    break;
+   case presentation_type::oct: {
+-    int num_digits = count_digits<3>(abs_value);
++    begin = do_format_base2e(3, buffer, abs_value, buffer_size);
+     // Octal prefix '0' is counted as a digit, so only add it if precision
+     // is not greater than the number of digits.
+-    if (specs.alt && specs.precision <= num_digits && abs_value != 0)
++    auto num_digits = end - begin;
++    if (specs.alt() && specs.precision <= num_digits && abs_value != 0)
+       prefix_append(prefix, '0');
+-    return write_int(out, num_digits, prefix, specs,
+-                     [=](reserve_iterator<OutputIt> it) {
+-                       return format_uint<3, Char>(it, abs_value, num_digits);
+-                     });
++    break;
+   }
++  case presentation_type::bin:
++    begin = do_format_base2e(1, buffer, abs_value, buffer_size);
++    if (specs.alt())
++      prefix_append(prefix, unsigned(specs.upper() ? 'B' : 'b') << 8 | '0');
++    break;
+   case presentation_type::chr:
+-    return write_char(out, static_cast<Char>(abs_value), specs);
+-  default:
+-    throw_format_error("invalid format specifier");
++    return write_char<Char>(out, static_cast<Char>(abs_value), specs);
+   }
+-  return out;
++
++  // Write an integer in the format
++  //   <left-padding><prefix><numeric-padding><digits><right-padding>
++  // prefix contains chars in three lower bytes and the size in the fourth byte.
++  int num_digits = static_cast<int>(end - begin);
++  // Slightly faster check for specs.width == 0 && specs.precision == -1.
++  if ((specs.width | (specs.precision + 1)) == 0) {
++    auto it = reserve(out, to_unsigned(num_digits) + (prefix >> 24));
++    for (unsigned p = prefix & 0xffffff; p != 0; p >>= 8)
++      *it++ = static_cast<Char>(p & 0xff);
++    return base_iterator(out, copy<Char>(begin, end, it));
++  }
++  auto sp = size_padding(num_digits, prefix, specs);
++  unsigned padding = sp.padding;
++  return write_padded<Char, align::right>(
++      out, specs, sp.size, [=](reserve_iterator<OutputIt> it) {
++        for (unsigned p = prefix & 0xffffff; p != 0; p >>= 8)
++          *it++ = static_cast<Char>(p & 0xff);
++        it = detail::fill_n(it, padding, static_cast<Char>('0'));
++        return copy<Char>(begin, end, it);
++      });
+ }
++
+ template <typename Char, typename OutputIt, typename T>
+-FMT_CONSTEXPR FMT_NOINLINE auto write_int_noinline(
+-    OutputIt out, write_int_arg<T> arg, const format_specs<Char>& specs,
+-    locale_ref loc) -> OutputIt {
+-  return write_int(out, arg, specs, loc);
++FMT_CONSTEXPR FMT_NOINLINE auto write_int_noinline(OutputIt out,
++                                                   write_int_arg<T> arg,
++                                                   const format_specs& specs)
++    -> OutputIt {
++  return write_int<Char>(out, arg, specs);
+ }
+-template <typename Char, typename OutputIt, typename T,
++
++template <typename Char, typename T,
+           FMT_ENABLE_IF(is_integral<T>::value &&
+                         !std::is_same<T, bool>::value &&
+-                        std::is_same<OutputIt, buffer_appender<Char>>::value)>
+-FMT_CONSTEXPR FMT_INLINE auto write(OutputIt out, T value,
+-                                    const format_specs<Char>& specs,
+-                                    locale_ref loc) -> OutputIt {
+-  if (specs.localized && write_loc(out, value, specs, loc)) return out;
+-  return write_int_noinline(out, make_write_int_arg(value, specs.sign), specs,
+-                            loc);
++                        !std::is_same<T, Char>::value)>
++FMT_CONSTEXPR FMT_INLINE auto write(basic_appender<Char> out, T value,
++                                    const format_specs& specs, locale_ref loc)
++    -> basic_appender<Char> {
++  if (specs.localized() && write_loc(out, value, specs, loc)) return out;
++  return write_int_noinline<Char>(out, make_write_int_arg(value, specs.sign()),
++                                  specs);
+ }
++
+ // An inlined version of write used in format string compilation.
+ template <typename Char, typename OutputIt, typename T,
+           FMT_ENABLE_IF(is_integral<T>::value &&
+                         !std::is_same<T, bool>::value &&
+-                        !std::is_same<OutputIt, buffer_appender<Char>>::value)>
++                        !std::is_same<T, Char>::value &&
++                        !std::is_same<OutputIt, basic_appender<Char>>::value)>
+ FMT_CONSTEXPR FMT_INLINE auto write(OutputIt out, T value,
+-                                    const format_specs<Char>& specs,
+-                                    locale_ref loc) -> OutputIt {
+-  if (specs.localized && write_loc(out, value, specs, loc)) return out;
+-  return write_int(out, make_write_int_arg(value, specs.sign), specs, loc);
++                                    const format_specs& specs, locale_ref loc)
++    -> OutputIt {
++  if (specs.localized() && write_loc(out, value, specs, loc)) return out;
++  return write_int<Char>(out, make_write_int_arg(value, specs.sign()), specs);
+ }
+ 
+-// An output iterator that counts the number of objects written to it and
+-// discards them.
+-class counting_iterator {
+- private:
+-  size_t count_;
+-
+- public:
+-  using iterator_category = std::output_iterator_tag;
+-  using difference_type = std::ptrdiff_t;
+-  using pointer = void;
+-  using reference = void;
+-  FMT_UNCHECKED_ITERATOR(counting_iterator);
+-
+-  struct value_type {
+-    template <typename T> FMT_CONSTEXPR void operator=(const T&) {}
+-  };
+-
+-  FMT_CONSTEXPR counting_iterator() : count_(0) {}
+-
+-  FMT_CONSTEXPR size_t count() const { return count_; }
+-
+-  FMT_CONSTEXPR counting_iterator& operator++() {
+-    ++count_;
+-    return *this;
+-  }
+-  FMT_CONSTEXPR counting_iterator operator++(int) {
+-    auto it = *this;
+-    ++*this;
+-    return it;
+-  }
+-
+-  FMT_CONSTEXPR friend counting_iterator operator+(counting_iterator it,
+-                                                   difference_type n) {
+-    it.count_ += static_cast<size_t>(n);
+-    return it;
+-  }
+-
+-  FMT_CONSTEXPR value_type operator*() const { return {}; }
+-};
+-
+ template <typename Char, typename OutputIt>
+ FMT_CONSTEXPR auto write(OutputIt out, basic_string_view<Char> s,
+-                         const format_specs<Char>& specs) -> OutputIt {
++                         const format_specs& specs) -> OutputIt {
+   auto data = s.data();
+   auto size = s.size();
+   if (specs.precision >= 0 && to_unsigned(specs.precision) < size)
+     size = code_point_index(s, to_unsigned(specs.precision));
+-  bool is_debug = specs.type == presentation_type::debug;
++
++  bool is_debug = specs.type() == presentation_type::debug;
++  if (is_debug) {
++    auto buf = counting_buffer<Char>();
++    write_escaped_string(basic_appender<Char>(buf), s);
++    size = buf.count();
++  }
++
+   size_t width = 0;
+   if (specs.width != 0) {
+-    if (is_debug)
+-      width = write_escaped_string(counting_iterator{}, s).count();
+-    else
+-      width = compute_width(basic_string_view<Char>(data, size));
++    width =
++        is_debug ? size : compute_width(basic_string_view<Char>(data, size));
+   }
+-  return write_padded(out, specs, size, width,
+-                      [=](reserve_iterator<OutputIt> it) {
+-                        if (is_debug) return write_escaped_string(it, s);
+-                        return copy_str<Char>(data, data + size, it);
+-                      });
++  return write_padded<Char>(
++      out, specs, size, width, [=](reserve_iterator<OutputIt> it) {
++        return is_debug ? write_escaped_string(it, s)
++                        : copy<Char>(data, data + size, it);
++      });
+ }
+ template <typename Char, typename OutputIt>
+-FMT_CONSTEXPR auto write(OutputIt out,
+-                         basic_string_view<type_identity_t<Char>> s,
+-                         const format_specs<Char>& specs, locale_ref)
+-    -> OutputIt {
+-  return write(out, s, specs);
++FMT_CONSTEXPR auto write(OutputIt out, basic_string_view<Char> s,
++                         const format_specs& specs, locale_ref) -> OutputIt {
++  return write<Char>(out, s, specs);
+ }
+ template <typename Char, typename OutputIt>
+-FMT_CONSTEXPR auto write(OutputIt out, const Char* s,
+-                         const format_specs<Char>& specs, locale_ref)
+-    -> OutputIt {
+-  return specs.type != presentation_type::pointer
+-             ? write(out, basic_string_view<Char>(s), specs, {})
+-             : write_ptr<Char>(out, bit_cast<uintptr_t>(s), &specs);
++FMT_CONSTEXPR auto write(OutputIt out, const Char* s, const format_specs& specs,
++                         locale_ref) -> OutputIt {
++  if (specs.type() == presentation_type::pointer)
++    return write_ptr<Char>(out, bit_cast<uintptr_t>(s), &specs);
++  if (!s) report_error("string pointer is null");
++  return write<Char>(out, basic_string_view<Char>(s), specs, {});
+ }
+ 
+ template <typename Char, typename OutputIt, typename T,
+@@ -2461,96 +2161,68 @@ FMT_CONSTEXPR auto write(OutputIt out, T value) -> OutputIt {
+   if (negative) abs_value = ~abs_value + 1;
+   int num_digits = count_digits(abs_value);
+   auto size = (negative ? 1 : 0) + static_cast<size_t>(num_digits);
+-  auto it = reserve(out, size);
+-  if (auto ptr = to_pointer<Char>(it, size)) {
++  if (auto ptr = to_pointer<Char>(out, size)) {
+     if (negative) *ptr++ = static_cast<Char>('-');
+     format_decimal<Char>(ptr, abs_value, num_digits);
+     return out;
+   }
+-  if (negative) *it++ = static_cast<Char>('-');
+-  it = format_decimal<Char>(it, abs_value, num_digits).end;
+-  return base_iterator(out, it);
++  if (negative) *out++ = static_cast<Char>('-');
++  return format_decimal<Char>(out, abs_value, num_digits);
+ }
+ 
+-// A floating-point presentation format.
+-enum class float_format : unsigned char {
+-  general,  // General: exponent notation or fixed point based on magnitude.
+-  exp,      // Exponent notation with the default precision of 6, e.g. 1.2e-3.
+-  fixed,    // Fixed point with the default precision of 6, e.g. 0.0012.
+-  hex
+-};
+-
+-struct float_specs {
+-  int precision;
+-  float_format format : 8;
+-  sign_t sign : 8;
+-  bool upper : 1;
+-  bool locale : 1;
+-  bool binary32 : 1;
+-  bool showpoint : 1;
+-};
+-
+-template <typename ErrorHandler = error_handler, typename Char>
+-FMT_CONSTEXPR auto parse_float_type_spec(const format_specs<Char>& specs,
+-                                         ErrorHandler&& eh = {})
+-    -> float_specs {
+-  auto result = float_specs();
+-  result.showpoint = specs.alt;
+-  result.locale = specs.localized;
+-  switch (specs.type) {
+-  case presentation_type::none:
+-    result.format = float_format::general;
+-    break;
+-  case presentation_type::general_upper:
+-    result.upper = true;
+-    FMT_FALLTHROUGH;
+-  case presentation_type::general_lower:
+-    result.format = float_format::general;
+-    break;
+-  case presentation_type::exp_upper:
+-    result.upper = true;
+-    FMT_FALLTHROUGH;
+-  case presentation_type::exp_lower:
+-    result.format = float_format::exp;
+-    result.showpoint |= specs.precision != 0;
+-    break;
+-  case presentation_type::fixed_upper:
+-    result.upper = true;
+-    FMT_FALLTHROUGH;
+-  case presentation_type::fixed_lower:
+-    result.format = float_format::fixed;
+-    result.showpoint |= specs.precision != 0;
+-    break;
+-  case presentation_type::hexfloat_upper:
+-    result.upper = true;
+-    FMT_FALLTHROUGH;
+-  case presentation_type::hexfloat_lower:
+-    result.format = float_format::hex;
+-    break;
+-  default:
+-    eh.on_error("invalid format specifier");
+-    break;
++template <typename Char>
++FMT_CONSTEXPR auto parse_align(const Char* begin, const Char* end,
++                               format_specs& specs) -> const Char* {
++  FMT_ASSERT(begin != end, "");
++  auto alignment = align::none;
++  auto p = begin + code_point_length(begin);
++  if (end - p <= 0) p = begin;
++  for (;;) {
++    switch (to_ascii(*p)) {
++    case '<': alignment = align::left; break;
++    case '>': alignment = align::right; break;
++    case '^': alignment = align::center; break;
++    }
++    if (alignment != align::none) {
++      if (p != begin) {
++        auto c = *begin;
++        if (c == '}') return begin;
++        if (c == '{') {
++          report_error("invalid fill character '{'");
++          return begin;
++        }
++        specs.set_fill(basic_string_view<Char>(begin, to_unsigned(p - begin)));
++        begin = p + 1;
++      } else {
++        ++begin;
++      }
++      break;
++    } else if (p == begin) {
++      break;
++    }
++    p = begin;
+   }
+-  return result;
++  specs.set_align(alignment);
++  return begin;
+ }
+ 
+ template <typename Char, typename OutputIt>
+ FMT_CONSTEXPR20 auto write_nonfinite(OutputIt out, bool isnan,
+-                                     format_specs<Char> specs,
+-                                     const float_specs& fspecs) -> OutputIt {
++                                     format_specs specs, sign s) -> OutputIt {
+   auto str =
+-      isnan ? (fspecs.upper ? "NAN" : "nan") : (fspecs.upper ? "INF" : "inf");
++      isnan ? (specs.upper() ? "NAN" : "nan") : (specs.upper() ? "INF" : "inf");
+   constexpr size_t str_size = 3;
+-  auto sign = fspecs.sign;
+-  auto size = str_size + (sign ? 1 : 0);
++  auto size = str_size + (s != sign::none ? 1 : 0);
+   // Replace '0'-padding with space for non-finite values.
+   const bool is_zero_fill =
+-      specs.fill.size() == 1 && *specs.fill.data() == static_cast<Char>('0');
+-  if (is_zero_fill) specs.fill[0] = static_cast<Char>(' ');
+-  return write_padded(out, specs, size, [=](reserve_iterator<OutputIt> it) {
+-    if (sign) *it++ = detail::sign<Char>(sign);
+-    return copy_str<Char>(str, str + str_size, it);
+-  });
++      specs.fill_size() == 1 && specs.fill_unit<Char>() == '0';
++  if (is_zero_fill) specs.set_fill(' ');
++  return write_padded<Char>(out, specs, size,
++                            [=](reserve_iterator<OutputIt> it) {
++                              if (s != sign::none)
++                                *it++ = detail::getsign<Char>(s);
++                              return copy<Char>(str, str + str_size, it);
++                            });
+ }
+ 
+ // A decimal floating-point number significand * pow(10, exp).
+@@ -2571,12 +2243,12 @@ inline auto get_significand_size(const dragonbox::decimal_fp<T>& f) -> int {
+ template <typename Char, typename OutputIt>
+ constexpr auto write_significand(OutputIt out, const char* significand,
+                                  int significand_size) -> OutputIt {
+-  return copy_str<Char>(significand, significand + significand_size, out);
++  return copy<Char>(significand, significand + significand_size, out);
+ }
+ template <typename Char, typename OutputIt, typename UInt>
+ inline auto write_significand(OutputIt out, UInt significand,
+                               int significand_size) -> OutputIt {
+-  return format_decimal<Char>(out, significand, significand_size).end;
++  return format_decimal<Char>(out, significand, significand_size);
+ }
+ template <typename Char, typename OutputIt, typename T, typename Grouping>
+ FMT_CONSTEXPR20 auto write_significand(OutputIt out, T significand,
+@@ -2596,14 +2268,13 @@ template <typename Char, typename UInt,
+           FMT_ENABLE_IF(std::is_integral<UInt>::value)>
+ inline auto write_significand(Char* out, UInt significand, int significand_size,
+                               int integral_size, Char decimal_point) -> Char* {
+-  if (!decimal_point)
+-    return format_decimal(out, significand, significand_size).end;
++  if (!decimal_point) return format_decimal(out, significand, significand_size);
+   out += significand_size + 1;
+   Char* end = out;
+   int floating_size = significand_size - integral_size;
+   for (int i = floating_size / 2; i > 0; --i) {
+     out -= 2;
+-    copy2(out, digits2(static_cast<std::size_t>(significand % 100)));
++    write2digits(out, static_cast<std::size_t>(significand % 100));
+     significand /= 100;
+   }
+   if (floating_size % 2 != 0) {
+@@ -2624,19 +2295,19 @@ inline auto write_significand(OutputIt out, UInt significand,
+   Char buffer[digits10<UInt>() + 2];
+   auto end = write_significand(buffer, significand, significand_size,
+                                integral_size, decimal_point);
+-  return detail::copy_str_noinline<Char>(buffer, end, out);
++  return detail::copy_noinline<Char>(buffer, end, out);
+ }
+ 
+ template <typename OutputIt, typename Char>
+ FMT_CONSTEXPR auto write_significand(OutputIt out, const char* significand,
+                                      int significand_size, int integral_size,
+                                      Char decimal_point) -> OutputIt {
+-  out = detail::copy_str_noinline<Char>(significand,
+-                                        significand + integral_size, out);
++  out = detail::copy_noinline<Char>(significand, significand + integral_size,
++                                    out);
+   if (!decimal_point) return out;
+   *out++ = decimal_point;
+-  return detail::copy_str_noinline<Char>(significand + integral_size,
+-                                         significand + significand_size, out);
++  return detail::copy_noinline<Char>(significand + integral_size,
++                                     significand + significand_size, out);
+ }
+ 
+ template <typename OutputIt, typename Char, typename T, typename Grouping>
+@@ -2649,44 +2320,42 @@ FMT_CONSTEXPR20 auto write_significand(OutputIt out, T significand,
+                              decimal_point);
+   }
+   auto buffer = basic_memory_buffer<Char>();
+-  write_significand(buffer_appender<Char>(buffer), significand,
+-                    significand_size, integral_size, decimal_point);
++  write_significand(basic_appender<Char>(buffer), significand, significand_size,
++                    integral_size, decimal_point);
+   grouping.apply(
+       out, basic_string_view<Char>(buffer.data(), to_unsigned(integral_size)));
+-  return detail::copy_str_noinline<Char>(buffer.data() + integral_size,
+-                                         buffer.end(), out);
++  return detail::copy_noinline<Char>(buffer.data() + integral_size,
++                                     buffer.end(), out);
+ }
+ 
+-template <typename OutputIt, typename DecimalFP, typename Char,
++template <typename Char, typename OutputIt, typename DecimalFP,
+           typename Grouping = digit_grouping<Char>>
+ FMT_CONSTEXPR20 auto do_write_float(OutputIt out, const DecimalFP& f,
+-                                    const format_specs<Char>& specs,
+-                                    float_specs fspecs, locale_ref loc)
+-    -> OutputIt {
++                                    const format_specs& specs, sign s,
++                                    int exp_upper, locale_ref loc) -> OutputIt {
+   auto significand = f.significand;
+   int significand_size = get_significand_size(f);
+   const Char zero = static_cast<Char>('0');
+-  auto sign = fspecs.sign;
+-  size_t size = to_unsigned(significand_size) + (sign ? 1 : 0);
++  size_t size = to_unsigned(significand_size) + (s != sign::none ? 1 : 0);
+   using iterator = reserve_iterator<OutputIt>;
+ 
+-  Char decimal_point =
+-      fspecs.locale ? detail::decimal_point<Char>(loc) : static_cast<Char>('.');
++  Char decimal_point = specs.localized() ? detail::decimal_point<Char>(loc)
++                                         : static_cast<Char>('.');
+ 
+   int output_exp = f.exponent + significand_size - 1;
+   auto use_exp_format = [=]() {
+-    if (fspecs.format == float_format::exp) return true;
+-    if (fspecs.format != float_format::general) return false;
++    if (specs.type() == presentation_type::exp) return true;
++    if (specs.type() == presentation_type::fixed) return false;
+     // Use the fixed notation if the exponent is in [exp_lower, exp_upper),
+     // e.g. 0.0001 instead of 1e-04. Otherwise use the exponent notation.
+-    const int exp_lower = -4, exp_upper = 16;
++    const int exp_lower = -4;
+     return output_exp < exp_lower ||
+-           output_exp >= (fspecs.precision > 0 ? fspecs.precision : exp_upper);
++           output_exp >= (specs.precision > 0 ? specs.precision : exp_upper);
+   };
+   if (use_exp_format()) {
+     int num_zeros = 0;
+-    if (fspecs.showpoint) {
+-      num_zeros = fspecs.precision - significand_size;
++    if (specs.alt()) {
++      num_zeros = specs.precision - significand_size;
+       if (num_zeros < 0) num_zeros = 0;
+       size += to_unsigned(num_zeros);
+     } else if (significand_size == 1) {
+@@ -2697,9 +2366,9 @@ FMT_CONSTEXPR20 auto do_write_float(OutputIt out, const DecimalFP& f,
+     if (abs_output_exp >= 100) exp_digits = abs_output_exp >= 1000 ? 4 : 3;
+ 
+     size += to_unsigned((decimal_point ? 1 : 0) + 2 + exp_digits);
+-    char exp_char = fspecs.upper ? 'E' : 'e';
++    char exp_char = specs.upper() ? 'E' : 'e';
+     auto write = [=](iterator it) {
+-      if (sign) *it++ = detail::sign<Char>(sign);
++      if (s != sign::none) *it++ = detail::getsign<Char>(s);
+       // Insert a decimal point after the first digit and add an exponent.
+       it = write_significand(it, significand, significand_size, 1,
+                              decimal_point);
+@@ -2707,39 +2376,41 @@ FMT_CONSTEXPR20 auto do_write_float(OutputIt out, const DecimalFP& f,
+       *it++ = static_cast<Char>(exp_char);
+       return write_exponent<Char>(output_exp, it);
+     };
+-    return specs.width > 0 ? write_padded<align::right>(out, specs, size, write)
+-                           : base_iterator(out, write(reserve(out, size)));
++    return specs.width > 0
++               ? write_padded<Char, align::right>(out, specs, size, write)
++               : base_iterator(out, write(reserve(out, size)));
+   }
+ 
+   int exp = f.exponent + significand_size;
+   if (f.exponent >= 0) {
+     // 1234e5 -> 123400000[.0+]
+     size += to_unsigned(f.exponent);
+-    int num_zeros = fspecs.precision - exp;
++    int num_zeros = specs.precision - exp;
+     abort_fuzzing_if(num_zeros > 5000);
+-    if (fspecs.showpoint) {
++    if (specs.alt()) {
+       ++size;
+-      if (num_zeros <= 0 && fspecs.format != float_format::fixed) num_zeros = 0;
++      if (num_zeros <= 0 && specs.type() != presentation_type::fixed)
++        num_zeros = 0;
+       if (num_zeros > 0) size += to_unsigned(num_zeros);
+     }
+-    auto grouping = Grouping(loc, fspecs.locale);
++    auto grouping = Grouping(loc, specs.localized());
+     size += to_unsigned(grouping.count_separators(exp));
+-    return write_padded<align::right>(out, specs, size, [&](iterator it) {
+-      if (sign) *it++ = detail::sign<Char>(sign);
++    return write_padded<Char, align::right>(out, specs, size, [&](iterator it) {
++      if (s != sign::none) *it++ = detail::getsign<Char>(s);
+       it = write_significand<Char>(it, significand, significand_size,
+                                    f.exponent, grouping);
+-      if (!fspecs.showpoint) return it;
++      if (!specs.alt()) return it;
+       *it++ = decimal_point;
+       return num_zeros > 0 ? detail::fill_n(it, num_zeros, zero) : it;
+     });
+   } else if (exp > 0) {
+     // 1234e-2 -> 12.34[0+]
+-    int num_zeros = fspecs.showpoint ? fspecs.precision - significand_size : 0;
+-    size += 1 + to_unsigned(num_zeros > 0 ? num_zeros : 0);
+-    auto grouping = Grouping(loc, fspecs.locale);
++    int num_zeros = specs.alt() ? specs.precision - significand_size : 0;
++    size += 1 + static_cast<unsigned>(max_of(num_zeros, 0));
++    auto grouping = Grouping(loc, specs.localized());
+     size += to_unsigned(grouping.count_separators(exp));
+-    return write_padded<align::right>(out, specs, size, [&](iterator it) {
+-      if (sign) *it++ = detail::sign<Char>(sign);
++    return write_padded<Char, align::right>(out, specs, size, [&](iterator it) {
++      if (s != sign::none) *it++ = detail::getsign<Char>(s);
+       it = write_significand(it, significand, significand_size, exp,
+                              decimal_point, grouping);
+       return num_zeros > 0 ? detail::fill_n(it, num_zeros, zero) : it;
+@@ -2747,14 +2418,14 @@ FMT_CONSTEXPR20 auto do_write_float(OutputIt out, const DecimalFP& f,
+   }
+   // 1234e-6 -> 0.001234
+   int num_zeros = -exp;
+-  if (significand_size == 0 && fspecs.precision >= 0 &&
+-      fspecs.precision < num_zeros) {
+-    num_zeros = fspecs.precision;
++  if (significand_size == 0 && specs.precision >= 0 &&
++      specs.precision < num_zeros) {
++    num_zeros = specs.precision;
+   }
+-  bool pointy = num_zeros != 0 || significand_size != 0 || fspecs.showpoint;
++  bool pointy = num_zeros != 0 || significand_size != 0 || specs.alt();
+   size += 1 + (pointy ? 1 : 0) + to_unsigned(num_zeros);
+-  return write_padded<align::right>(out, specs, size, [&](iterator it) {
+-    if (sign) *it++ = detail::sign<Char>(sign);
++  return write_padded<Char, align::right>(out, specs, size, [&](iterator it) {
++    if (s != sign::none) *it++ = detail::getsign<Char>(s);
+     *it++ = zero;
+     if (!pointy) return it;
+     *it++ = decimal_point;
+@@ -2767,32 +2438,31 @@ template <typename Char> class fallback_digit_grouping {
+  public:
+   constexpr fallback_digit_grouping(locale_ref, bool) {}
+ 
+-  constexpr bool has_separator() const { return false; }
++  constexpr auto has_separator() const -> bool { return false; }
+ 
+-  constexpr int count_separators(int) const { return 0; }
++  constexpr auto count_separators(int) const -> int { return 0; }
+ 
+   template <typename Out, typename C>
+-  constexpr Out apply(Out out, basic_string_view<C>) const {
++  constexpr auto apply(Out out, basic_string_view<C>) const -> Out {
+     return out;
+   }
+ };
+ 
+-template <typename OutputIt, typename DecimalFP, typename Char>
++template <typename Char, typename OutputIt, typename DecimalFP>
+ FMT_CONSTEXPR20 auto write_float(OutputIt out, const DecimalFP& f,
+-                                 const format_specs<Char>& specs,
+-                                 float_specs fspecs, locale_ref loc)
+-    -> OutputIt {
++                                 const format_specs& specs, sign s,
++                                 int exp_upper, locale_ref loc) -> OutputIt {
+   if (is_constant_evaluated()) {
+-    return do_write_float<OutputIt, DecimalFP, Char,
+-                          fallback_digit_grouping<Char>>(out, f, specs, fspecs,
+-                                                         loc);
++    return do_write_float<Char, OutputIt, DecimalFP,
++                          fallback_digit_grouping<Char>>(out, f, specs, s,
++                                                         exp_upper, loc);
+   } else {
+-    return do_write_float(out, f, specs, fspecs, loc);
++    return do_write_float<Char>(out, f, specs, s, exp_upper, loc);
+   }
+ }
+ 
+-template <typename T> constexpr bool isnan(T value) {
+-  return !(value >= value);  // std::isnan doesn't support __float128.
++template <typename T> constexpr auto isnan(T value) -> bool {
++  return value != value;  // std::isnan doesn't support __float128.
+ }
+ 
+ template <typename T, typename Enable = void>
+@@ -2804,14 +2474,14 @@ struct has_isfinite<T, enable_if_t<sizeof(std::isfinite(T())) != 0>>
+ 
+ template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value&&
+                                         has_isfinite<T>::value)>
+-FMT_CONSTEXPR20 bool isfinite(T value) {
++FMT_CONSTEXPR20 auto isfinite(T value) -> bool {
+   constexpr T inf = T(std::numeric_limits<double>::infinity());
+   if (is_constant_evaluated())
+     return !detail::isnan(value) && value < inf && value > -inf;
+   return std::isfinite(value);
+ }
+ template <typename T, FMT_ENABLE_IF(!has_isfinite<T>::value)>
+-FMT_CONSTEXPR bool isfinite(T value) {
++FMT_CONSTEXPR auto isfinite(T value) -> bool {
+   T inf = T(std::numeric_limits<double>::infinity());
+   // std::isfinite doesn't support __float128.
+   return !detail::isnan(value) && value < inf && value > -inf;
+@@ -2830,78 +2500,6 @@ FMT_INLINE FMT_CONSTEXPR bool signbit(T value) {
+   return std::signbit(static_cast<double>(value));
+ }
+ 
+-enum class round_direction { unknown, up, down };
+-
+-// Given the divisor (normally a power of 10), the remainder = v % divisor for
+-// some number v and the error, returns whether v should be rounded up, down, or
+-// whether the rounding direction can't be determined due to error.
+-// error should be less than divisor / 2.
+-FMT_CONSTEXPR inline round_direction get_round_direction(uint64_t divisor,
+-                                                         uint64_t remainder,
+-                                                         uint64_t error) {
+-  FMT_ASSERT(remainder < divisor, "");  // divisor - remainder won't overflow.
+-  FMT_ASSERT(error < divisor, "");      // divisor - error won't overflow.
+-  FMT_ASSERT(error < divisor - error, "");  // error * 2 won't overflow.
+-  // Round down if (remainder + error) * 2 <= divisor.
+-  if (remainder <= divisor - remainder && error * 2 <= divisor - remainder * 2)
+-    return round_direction::down;
+-  // Round up if (remainder - error) * 2 >= divisor.
+-  if (remainder >= error &&
+-      remainder - error >= divisor - (remainder - error)) {
+-    return round_direction::up;
+-  }
+-  return round_direction::unknown;
+-}
+-
+-namespace digits {
+-enum result {
+-  more,  // Generate more digits.
+-  done,  // Done generating digits.
+-  error  // Digit generation cancelled due to an error.
+-};
+-}
+-
+-struct gen_digits_handler {
+-  char* buf;
+-  int size;
+-  int precision;
+-  int exp10;
+-  bool fixed;
+-
+-  FMT_CONSTEXPR digits::result on_digit(char digit, uint64_t divisor,
+-                                        uint64_t remainder, uint64_t error,
+-                                        bool integral) {
+-    FMT_ASSERT(remainder < divisor, "");
+-    buf[size++] = digit;
+-    if (!integral && error >= remainder) return digits::error;
+-    if (size < precision) return digits::more;
+-    if (!integral) {
+-      // Check if error * 2 < divisor with overflow prevention.
+-      // The check is not needed for the integral part because error = 1
+-      // and divisor > (1 << 32) there.
+-      if (error >= divisor || error >= divisor - error) return digits::error;
+-    } else {
+-      FMT_ASSERT(error == 1 && divisor > 2, "");
+-    }
+-    auto dir = get_round_direction(divisor, remainder, error);
+-    if (dir != round_direction::up)
+-      return dir == round_direction::down ? digits::done : digits::error;
+-    ++buf[size - 1];
+-    for (int i = size - 1; i > 0 && buf[i] > '9'; --i) {
+-      buf[i] = '0';
+-      ++buf[i - 1];
+-    }
+-    if (buf[0] > '9') {
+-      buf[0] = '1';
+-      if (fixed)
+-        buf[size++] = '0';
+-      else
+-        ++exp10;
+-    }
+-    return digits::done;
+-  }
+-};
+-
+ inline FMT_CONSTEXPR20 void adjust_precision(int& precision, int exp10) {
+   // Adjust fixed precision by exponent because it is relative to decimal
+   // point.
+@@ -2910,149 +2508,50 @@ inline FMT_CONSTEXPR20 void adjust_precision(int& precision, int exp10) {
+   precision += exp10;
+ }
+ 
+-// Generates output using the Grisu digit-gen algorithm.
+-// error: the size of the region (lower, upper) outside of which numbers
+-// definitely do not round to value (Delta in Grisu3).
+-FMT_INLINE FMT_CONSTEXPR20 auto grisu_gen_digits(fp value, uint64_t error,
+-                                                 int& exp,
+-                                                 gen_digits_handler& handler)
+-    -> digits::result {
+-  const fp one(1ULL << -value.e, value.e);
+-  // The integral part of scaled value (p1 in Grisu) = value / one. It cannot be
+-  // zero because it contains a product of two 64-bit numbers with MSB set (due
+-  // to normalization) - 1, shifted right by at most 60 bits.
+-  auto integral = static_cast<uint32_t>(value.f >> -one.e);
+-  FMT_ASSERT(integral != 0, "");
+-  FMT_ASSERT(integral == value.f >> -one.e, "");
+-  // The fractional part of scaled value (p2 in Grisu) c = value % one.
+-  uint64_t fractional = value.f & (one.f - 1);
+-  exp = count_digits(integral);  // kappa in Grisu.
+-  // Non-fixed formats require at least one digit and no precision adjustment.
+-  if (handler.fixed) {
+-    adjust_precision(handler.precision, exp + handler.exp10);
+-    // Check if precision is satisfied just by leading zeros, e.g.
+-    // format("{:.2f}", 0.001) gives "0.00" without generating any digits.
+-    if (handler.precision <= 0) {
+-      if (handler.precision < 0) return digits::done;
+-      // Divide by 10 to prevent overflow.
+-      uint64_t divisor = data::power_of_10_64[exp - 1] << -one.e;
+-      auto dir = get_round_direction(divisor, value.f / 10, error * 10);
+-      if (dir == round_direction::unknown) return digits::error;
+-      handler.buf[handler.size++] = dir == round_direction::up ? '1' : '0';
+-      return digits::done;
+-    }
+-  }
+-  // Generate digits for the integral part. This can produce up to 10 digits.
+-  do {
+-    uint32_t digit = 0;
+-    auto divmod_integral = [&](uint32_t divisor) {
+-      digit = integral / divisor;
+-      integral %= divisor;
+-    };
+-    // This optimization by Milo Yip reduces the number of integer divisions by
+-    // one per iteration.
+-    switch (exp) {
+-    case 10:
+-      divmod_integral(1000000000);
+-      break;
+-    case 9:
+-      divmod_integral(100000000);
+-      break;
+-    case 8:
+-      divmod_integral(10000000);
+-      break;
+-    case 7:
+-      divmod_integral(1000000);
+-      break;
+-    case 6:
+-      divmod_integral(100000);
+-      break;
+-    case 5:
+-      divmod_integral(10000);
+-      break;
+-    case 4:
+-      divmod_integral(1000);
+-      break;
+-    case 3:
+-      divmod_integral(100);
+-      break;
+-    case 2:
+-      divmod_integral(10);
+-      break;
+-    case 1:
+-      digit = integral;
+-      integral = 0;
+-      break;
+-    default:
+-      FMT_ASSERT(false, "invalid number of digits");
+-    }
+-    --exp;
+-    auto remainder = (static_cast<uint64_t>(integral) << -one.e) + fractional;
+-    auto result = handler.on_digit(static_cast<char>('0' + digit),
+-                                   data::power_of_10_64[exp] << -one.e,
+-                                   remainder, error, true);
+-    if (result != digits::more) return result;
+-  } while (exp > 0);
+-  // Generate digits for the fractional part.
+-  for (;;) {
+-    fractional *= 10;
+-    error *= 10;
+-    char digit = static_cast<char>('0' + (fractional >> -one.e));
+-    fractional &= one.f - 1;
+-    --exp;
+-    auto result = handler.on_digit(digit, one.f, fractional, error, false);
+-    if (result != digits::more) return result;
+-  }
+-}
+-
+ class bigint {
+  private:
+-  // A bigint is stored as an array of bigits (big digits), with bigit at index
+-  // 0 being the least significant one.
+-  using bigit = uint32_t;
++  // A bigint is a number in the form bigit_[N - 1] ... bigit_[0] * 32^exp_.
++  using bigit = uint32_t;  // A big digit.
+   using double_bigit = uint64_t;
++  enum { bigit_bits = num_bits<bigit>() };
+   enum { bigits_capacity = 32 };
+   basic_memory_buffer<bigit, bigits_capacity> bigits_;
+   int exp_;
+ 
+-  FMT_CONSTEXPR20 bigit operator[](int index) const {
+-    return bigits_[to_unsigned(index)];
+-  }
+-  FMT_CONSTEXPR20 bigit& operator[](int index) {
+-    return bigits_[to_unsigned(index)];
+-  }
+-
+-  static constexpr const int bigit_bits = num_bits<bigit>();
+-
+   friend struct formatter<bigint>;
+ 
+-  FMT_CONSTEXPR20 void subtract_bigits(int index, bigit other, bigit& borrow) {
+-    auto result = static_cast<double_bigit>((*this)[index]) - other - borrow;
+-    (*this)[index] = static_cast<bigit>(result);
++  FMT_CONSTEXPR auto get_bigit(int i) const -> bigit {
++    return i >= exp_ && i < num_bigits() ? bigits_[i - exp_] : 0;
++  }
++
++  FMT_CONSTEXPR void subtract_bigits(int index, bigit other, bigit& borrow) {
++    auto result = double_bigit(bigits_[index]) - other - borrow;
++    bigits_[index] = static_cast<bigit>(result);
+     borrow = static_cast<bigit>(result >> (bigit_bits * 2 - 1));
+   }
+ 
+-  FMT_CONSTEXPR20 void remove_leading_zeros() {
++  FMT_CONSTEXPR void remove_leading_zeros() {
+     int num_bigits = static_cast<int>(bigits_.size()) - 1;
+-    while (num_bigits > 0 && (*this)[num_bigits] == 0) --num_bigits;
++    while (num_bigits > 0 && bigits_[num_bigits] == 0) --num_bigits;
+     bigits_.resize(to_unsigned(num_bigits + 1));
+   }
+ 
+   // Computes *this -= other assuming aligned bigints and *this >= other.
+-  FMT_CONSTEXPR20 void subtract_aligned(const bigint& other) {
++  FMT_CONSTEXPR void subtract_aligned(const bigint& other) {
+     FMT_ASSERT(other.exp_ >= exp_, "unaligned bigints");
+     FMT_ASSERT(compare(*this, other) >= 0, "");
+     bigit borrow = 0;
+     int i = other.exp_ - exp_;
+     for (size_t j = 0, n = other.bigits_.size(); j != n; ++i, ++j)
+       subtract_bigits(i, other.bigits_[j], borrow);
+-    while (borrow > 0) subtract_bigits(i, 0, borrow);
++    if (borrow != 0) subtract_bigits(i, 0, borrow);
++    FMT_ASSERT(borrow == 0, "");
+     remove_leading_zeros();
+   }
+ 
+-  FMT_CONSTEXPR20 void multiply(uint32_t value) {
+-    const double_bigit wide_value = value;
++  FMT_CONSTEXPR void multiply(uint32_t value) {
+     bigit carry = 0;
++    const double_bigit wide_value = value;
+     for (size_t i = 0, n = bigits_.size(); i < n; ++i) {
+       double_bigit result = bigits_[i] * wide_value + carry;
+       bigits_[i] = static_cast<bigit>(result);
+@@ -3063,7 +2562,7 @@ class bigint {
+ 
+   template <typename UInt, FMT_ENABLE_IF(std::is_same<UInt, uint64_t>::value ||
+                                          std::is_same<UInt, uint128_t>::value)>
+-  FMT_CONSTEXPR20 void multiply(UInt value) {
++  FMT_CONSTEXPR void multiply(UInt value) {
+     using half_uint =
+         conditional_t<std::is_same<UInt, uint128_t>::value, uint64_t, uint32_t>;
+     const int shift = num_bits<half_uint>() - bigit_bits;
+@@ -3084,7 +2583,7 @@ class bigint {
+ 
+   template <typename UInt, FMT_ENABLE_IF(std::is_same<UInt, uint64_t>::value ||
+                                          std::is_same<UInt, uint128_t>::value)>
+-  FMT_CONSTEXPR20 void assign(UInt n) {
++  FMT_CONSTEXPR void assign(UInt n) {
+     size_t num_bigits = 0;
+     do {
+       bigits_[num_bigits++] = static_cast<bigit>(n);
+@@ -3095,30 +2594,30 @@ class bigint {
+   }
+ 
+  public:
+-  FMT_CONSTEXPR20 bigint() : exp_(0) {}
++  FMT_CONSTEXPR bigint() : exp_(0) {}
+   explicit bigint(uint64_t n) { assign(n); }
+ 
+   bigint(const bigint&) = delete;
+   void operator=(const bigint&) = delete;
+ 
+-  FMT_CONSTEXPR20 void assign(const bigint& other) {
++  FMT_CONSTEXPR void assign(const bigint& other) {
+     auto size = other.bigits_.size();
+     bigits_.resize(size);
+     auto data = other.bigits_.data();
+-    std::copy(data, data + size, make_checked(bigits_.data(), size));
++    copy<bigit>(data, data + size, bigits_.data());
+     exp_ = other.exp_;
+   }
+ 
+-  template <typename Int> FMT_CONSTEXPR20 void operator=(Int n) {
++  template <typename Int> FMT_CONSTEXPR void operator=(Int n) {
+     FMT_ASSERT(n > 0, "");
+     assign(uint64_or_128_t<Int>(n));
+   }
+ 
+-  FMT_CONSTEXPR20 int num_bigits() const {
++  FMT_CONSTEXPR auto num_bigits() const -> int {
+     return static_cast<int>(bigits_.size()) + exp_;
+   }
+ 
+-  FMT_NOINLINE FMT_CONSTEXPR20 bigint& operator<<=(int shift) {
++  FMT_CONSTEXPR auto operator<<=(int shift) -> bigint& {
+     FMT_ASSERT(shift >= 0, "");
+     exp_ += shift / bigit_bits;
+     shift %= bigit_bits;
+@@ -3133,46 +2632,39 @@ class bigint {
+     return *this;
+   }
+ 
+-  template <typename Int> FMT_CONSTEXPR20 bigint& operator*=(Int value) {
++  template <typename Int> FMT_CONSTEXPR auto operator*=(Int value) -> bigint& {
+     FMT_ASSERT(value > 0, "");
+     multiply(uint32_or_64_or_128_t<Int>(value));
+     return *this;
+   }
+ 
+-  friend FMT_CONSTEXPR20 int compare(const bigint& lhs, const bigint& rhs) {
+-    int num_lhs_bigits = lhs.num_bigits(), num_rhs_bigits = rhs.num_bigits();
+-    if (num_lhs_bigits != num_rhs_bigits)
+-      return num_lhs_bigits > num_rhs_bigits ? 1 : -1;
+-    int i = static_cast<int>(lhs.bigits_.size()) - 1;
+-    int j = static_cast<int>(rhs.bigits_.size()) - 1;
++  friend FMT_CONSTEXPR auto compare(const bigint& b1, const bigint& b2) -> int {
++    int num_bigits1 = b1.num_bigits(), num_bigits2 = b2.num_bigits();
++    if (num_bigits1 != num_bigits2) return num_bigits1 > num_bigits2 ? 1 : -1;
++    int i = static_cast<int>(b1.bigits_.size()) - 1;
++    int j = static_cast<int>(b2.bigits_.size()) - 1;
+     int end = i - j;
+     if (end < 0) end = 0;
+     for (; i >= end; --i, --j) {
+-      bigit lhs_bigit = lhs[i], rhs_bigit = rhs[j];
+-      if (lhs_bigit != rhs_bigit) return lhs_bigit > rhs_bigit ? 1 : -1;
++      bigit b1_bigit = b1.bigits_[i], b2_bigit = b2.bigits_[j];
++      if (b1_bigit != b2_bigit) return b1_bigit > b2_bigit ? 1 : -1;
+     }
+     if (i != j) return i > j ? 1 : -1;
+     return 0;
+   }
+ 
+   // Returns compare(lhs1 + lhs2, rhs).
+-  friend FMT_CONSTEXPR20 int add_compare(const bigint& lhs1, const bigint& lhs2,
+-                                         const bigint& rhs) {
+-    auto minimum = [](int a, int b) { return a < b ? a : b; };
+-    auto maximum = [](int a, int b) { return a > b ? a : b; };
+-    int max_lhs_bigits = maximum(lhs1.num_bigits(), lhs2.num_bigits());
++  friend FMT_CONSTEXPR auto add_compare(const bigint& lhs1, const bigint& lhs2,
++                                        const bigint& rhs) -> int {
++    int max_lhs_bigits = max_of(lhs1.num_bigits(), lhs2.num_bigits());
+     int num_rhs_bigits = rhs.num_bigits();
+     if (max_lhs_bigits + 1 < num_rhs_bigits) return -1;
+     if (max_lhs_bigits > num_rhs_bigits) return 1;
+-    auto get_bigit = [](const bigint& n, int i) -> bigit {
+-      return i >= n.exp_ && i < n.num_bigits() ? n[i - n.exp_] : 0;
+-    };
+     double_bigit borrow = 0;
+-    int min_exp = minimum(minimum(lhs1.exp_, lhs2.exp_), rhs.exp_);
++    int min_exp = min_of(min_of(lhs1.exp_, lhs2.exp_), rhs.exp_);
+     for (int i = num_rhs_bigits - 1; i >= min_exp; --i) {
+-      double_bigit sum =
+-          static_cast<double_bigit>(get_bigit(lhs1, i)) + get_bigit(lhs2, i);
+-      bigit rhs_bigit = get_bigit(rhs, i);
++      double_bigit sum = double_bigit(lhs1.get_bigit(i)) + lhs2.get_bigit(i);
++      bigit rhs_bigit = rhs.get_bigit(i);
+       if (sum > rhs_bigit + borrow) return 1;
+       borrow = rhs_bigit + borrow - sum;
+       if (borrow > 1) return -1;
+@@ -3185,10 +2677,8 @@ class bigint {
+   FMT_CONSTEXPR20 void assign_pow10(int exp) {
+     FMT_ASSERT(exp >= 0, "");
+     if (exp == 0) return *this = 1;
+-    // Find the top bit.
+-    int bitmask = 1;
+-    while (exp >= bitmask) bitmask <<= 1;
+-    bitmask >>= 1;
++    int bitmask = 1 << (num_bits<unsigned>() -
++                        countl_zero(static_cast<uint32_t>(exp)) - 1);
+     // pow(10, exp) = pow(5, exp) * pow(2, exp). First compute pow(5, exp) by
+     // repeated squaring and multiplication.
+     *this = 5;
+@@ -3212,17 +2702,17 @@ class bigint {
+       // cross-product terms n[i] * n[j] such that i + j == bigit_index.
+       for (int i = 0, j = bigit_index; j >= 0; ++i, --j) {
+         // Most terms are multiplied twice which can be optimized in the future.
+-        sum += static_cast<double_bigit>(n[i]) * n[j];
++        sum += double_bigit(n[i]) * n[j];
+       }
+-      (*this)[bigit_index] = static_cast<bigit>(sum);
++      bigits_[bigit_index] = static_cast<bigit>(sum);
+       sum >>= num_bits<bigit>();  // Compute the carry.
+     }
+     // Do the same for the top half.
+     for (int bigit_index = num_bigits; bigit_index < num_result_bigits;
+          ++bigit_index) {
+       for (int j = num_bigits - 1, i = bigit_index - j; i < num_bigits;)
+-        sum += static_cast<double_bigit>(n[i++]) * n[j--];
+-      (*this)[bigit_index] = static_cast<bigit>(sum);
++        sum += double_bigit(n[i++]) * n[j--];
++      bigits_[bigit_index] = static_cast<bigit>(sum);
+       sum >>= num_bits<bigit>();
+     }
+     remove_leading_zeros();
+@@ -3231,20 +2721,20 @@ class bigint {
+ 
+   // If this bigint has a bigger exponent than other, adds trailing zero to make
+   // exponents equal. This simplifies some operations such as subtraction.
+-  FMT_CONSTEXPR20 void align(const bigint& other) {
++  FMT_CONSTEXPR void align(const bigint& other) {
+     int exp_difference = exp_ - other.exp_;
+     if (exp_difference <= 0) return;
+     int num_bigits = static_cast<int>(bigits_.size());
+     bigits_.resize(to_unsigned(num_bigits + exp_difference));
+     for (int i = num_bigits - 1, j = i + exp_difference; i >= 0; --i, --j)
+       bigits_[j] = bigits_[i];
+-    std::uninitialized_fill_n(bigits_.data(), exp_difference, 0);
++    memset(bigits_.data(), 0, to_unsigned(exp_difference) * sizeof(bigit));
+     exp_ -= exp_difference;
+   }
+ 
+   // Divides this bignum by divisor, assigning the remainder to this and
+   // returning the quotient.
+-  FMT_CONSTEXPR20 int divmod_assign(const bigint& divisor) {
++  FMT_CONSTEXPR auto divmod_assign(const bigint& divisor) -> int {
+     FMT_ASSERT(this != &divisor, "");
+     if (compare(*this, divisor) < 0) return 0;
+     FMT_ASSERT(divisor.bigits_[divisor.bigits_.size() - 1u] != 0, "");
+@@ -3319,6 +2809,7 @@ FMT_CONSTEXPR20 inline void format_dragon(basic_fp<uint128_t> value,
+   }
+   int even = static_cast<int>((value.f & 1) == 0);
+   if (!upper) upper = &lower;
++  bool shortest = num_digits < 0;
+   if ((flags & dragon::fixup) != 0) {
+     if (add_compare(numerator, *upper, denominator) + even <= 0) {
+       --exp10;
+@@ -3331,7 +2822,7 @@ FMT_CONSTEXPR20 inline void format_dragon(basic_fp<uint128_t> value,
+     if ((flags & dragon::fixed) != 0) adjust_precision(num_digits, exp10 + 1);
+   }
+   // Invariant: value == (numerator / denominator) * pow(10, exp10).
+-  if (num_digits < 0) {
++  if (shortest) {
+     // Generate the shortest representation.
+     num_digits = 0;
+     char* data = buf.data();
+@@ -3361,9 +2852,12 @@ FMT_CONSTEXPR20 inline void format_dragon(basic_fp<uint128_t> value,
+   }
+   // Generate the given number of digits.
+   exp10 -= num_digits - 1;
+-  if (num_digits == 0) {
+-    denominator *= 10;
+-    auto digit = add_compare(numerator, numerator, denominator) > 0 ? '1' : '0';
++  if (num_digits <= 0) {
++    auto digit = '0';
++    if (num_digits == 0) {
++      denominator *= 10;
++      digit = add_compare(numerator, numerator, denominator) > 0 ? '1' : '0';
++    }
+     buf.push_back(digit);
+     return;
+   }
+@@ -3386,7 +2880,10 @@ FMT_CONSTEXPR20 inline void format_dragon(basic_fp<uint128_t> value,
+       }
+       if (buf[0] == overflow) {
+         buf[0] = '1';
+-        ++exp10;
++        if ((flags & dragon::fixed) != 0)
++          buf.push_back('0');
++        else
++          ++exp10;
+       }
+       return;
+     }
+@@ -3397,8 +2894,8 @@ FMT_CONSTEXPR20 inline void format_dragon(basic_fp<uint128_t> value,
+ 
+ // Formats a floating-point number using the hexfloat format.
+ template <typename Float, FMT_ENABLE_IF(!is_double_double<Float>::value)>
+-FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
+-                                     float_specs specs, buffer<char>& buf) {
++FMT_CONSTEXPR20 void format_hexfloat(Float value, format_specs specs,
++                                     buffer<char>& buf) {
+   // float is passed as double to reduce the number of instantiations and to
+   // simplify implementation.
+   static_assert(!std::is_same<Float, float>::value, "");
+@@ -3408,26 +2905,25 @@ FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
+   // Assume Float is in the format [sign][exponent][significand].
+   using carrier_uint = typename info::carrier_uint;
+ 
+-  constexpr auto num_float_significand_bits =
+-      detail::num_significand_bits<Float>();
++  const auto num_float_significand_bits = detail::num_significand_bits<Float>();
+ 
+   basic_fp<carrier_uint> f(value);
+   f.e += num_float_significand_bits;
+   if (!has_implicit_bit<Float>()) --f.e;
+ 
+-  constexpr auto num_fraction_bits =
++  const auto num_fraction_bits =
+       num_float_significand_bits + (has_implicit_bit<Float>() ? 1 : 0);
+-  constexpr auto num_xdigits = (num_fraction_bits + 3) / 4;
++  const auto num_xdigits = (num_fraction_bits + 3) / 4;
+ 
+-  constexpr auto leading_shift = ((num_xdigits - 1) * 4);
++  const auto leading_shift = ((num_xdigits - 1) * 4);
+   const auto leading_mask = carrier_uint(0xF) << leading_shift;
+   const auto leading_xdigit =
+       static_cast<uint32_t>((f.f & leading_mask) >> leading_shift);
+   if (leading_xdigit > 1) f.e -= (32 - countl_zero(leading_xdigit) - 1);
+ 
+   int print_xdigits = num_xdigits - 1;
+-  if (precision >= 0 && print_xdigits > precision) {
+-    const int shift = ((print_xdigits - precision - 1) * 4);
++  if (specs.precision >= 0 && print_xdigits > specs.precision) {
++    const int shift = ((print_xdigits - specs.precision - 1) * 4);
+     const auto mask = carrier_uint(0xF) << shift;
+     const auto v = static_cast<uint32_t>((f.f & mask) >> shift);
+ 
+@@ -3446,25 +2942,25 @@ FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
+       }
+     }
+ 
+-    print_xdigits = precision;
++    print_xdigits = specs.precision;
+   }
+ 
+   char xdigits[num_bits<carrier_uint>() / 4];
+   detail::fill_n(xdigits, sizeof(xdigits), '0');
+-  format_uint<4>(xdigits, f.f, num_xdigits, specs.upper);
++  format_base2e(4, xdigits, f.f, num_xdigits, specs.upper());
+ 
+   // Remove zero tail
+   while (print_xdigits > 0 && xdigits[print_xdigits] == '0') --print_xdigits;
+ 
+   buf.push_back('0');
+-  buf.push_back(specs.upper ? 'X' : 'x');
++  buf.push_back(specs.upper() ? 'X' : 'x');
+   buf.push_back(xdigits[0]);
+-  if (specs.showpoint || print_xdigits > 0 || print_xdigits < precision)
++  if (specs.alt() || print_xdigits > 0 || print_xdigits < specs.precision)
+     buf.push_back('.');
+   buf.append(xdigits + 1, xdigits + 1 + print_xdigits);
+-  for (; print_xdigits < precision; ++print_xdigits) buf.push_back('0');
++  for (; print_xdigits < specs.precision; ++print_xdigits) buf.push_back('0');
+ 
+-  buf.push_back(specs.upper ? 'P' : 'p');
++  buf.push_back(specs.upper() ? 'P' : 'p');
+ 
+   uint32_t abs_e;
+   if (f.e < 0) {
+@@ -3478,21 +2974,32 @@ FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
+ }
+ 
+ template <typename Float, FMT_ENABLE_IF(is_double_double<Float>::value)>
+-FMT_CONSTEXPR20 void format_hexfloat(Float value, int precision,
+-                                     float_specs specs, buffer<char>& buf) {
+-  format_hexfloat(static_cast<double>(value), precision, specs, buf);
++FMT_CONSTEXPR20 void format_hexfloat(Float value, format_specs specs,
++                                     buffer<char>& buf) {
++  format_hexfloat(static_cast<double>(value), specs, buf);
++}
++
++constexpr auto fractional_part_rounding_thresholds(int index) -> uint32_t {
++  // For checking rounding thresholds.
++  // The kth entry is chosen to be the smallest integer such that the
++  // upper 32-bits of 10^(k+1) times it is strictly bigger than 5 * 10^k.
++  // It is equal to ceil(2^31 + 2^32/10^(k + 1)).
++  // These are stored in a string literal because we cannot have static arrays
++  // in constexpr functions and non-static ones are poorly optimized.
++  return U"\x9999999a\x828f5c29\x80418938\x80068db9\x8000a7c6\x800010c7"
++         U"\x800001ae\x8000002b"[index];
+ }
+ 
+ template <typename Float>
+-FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
++FMT_CONSTEXPR20 auto format_float(Float value, int precision,
++                                  const format_specs& specs, bool binary32,
+                                   buffer<char>& buf) -> int {
+   // float is passed as double to reduce the number of instantiations.
+   static_assert(!std::is_same<Float, float>::value, "");
+-  FMT_ASSERT(value >= 0, "value is negative");
+   auto converted_value = convert_float(value);
+ 
+-  const bool fixed = specs.format == float_format::fixed;
+-  if (value <= 0) {  // <= instead of == to silence a warning.
++  const bool fixed = specs.type() == presentation_type::fixed;
++  if (value == 0) {
+     if (precision <= 0 || !fixed) {
+       buf.push_back('0');
+       return 0;
+@@ -3505,7 +3012,7 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+   int exp = 0;
+   bool use_dragon = true;
+   unsigned dragon_flags = 0;
+-  if (!is_fast_float<Float>()) {
++  if (!is_fast_float<Float>() || is_constant_evaluated()) {
+     const auto inv_log2_10 = 0.3010299956639812;  // 1 / log2(10)
+     using info = dragonbox::float_info<decltype(converted_value)>;
+     const auto f = basic_fp<typename info::carrier_uint>(converted_value);
+@@ -3513,38 +3020,10 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+     //   10^(exp - 1) <= value < 10^exp or 10^exp <= value < 10^(exp + 1).
+     // This is based on log10(value) == log2(value) / log2(10) and approximation
+     // of log2(value) by e + num_fraction_bits idea from double-conversion.
+-    exp = static_cast<int>(
+-        std::ceil((f.e + count_digits<1>(f.f) - 1) * inv_log2_10 - 1e-10));
++    auto e = (f.e + count_digits<1>(f.f) - 1) * inv_log2_10 - 1e-10;
++    exp = static_cast<int>(e);
++    if (e > exp) ++exp;  // Compute ceil.
+     dragon_flags = dragon::fixup;
+-  } else if (!is_constant_evaluated() && precision < 0) {
+-    // Use Dragonbox for the shortest format.
+-    if (specs.binary32) {
+-      auto dec = dragonbox::to_decimal(static_cast<float>(value));
+-      write<char>(buffer_appender<char>(buf), dec.significand);
+-      return dec.exponent;
+-    }
+-    auto dec = dragonbox::to_decimal(static_cast<double>(value));
+-    write<char>(buffer_appender<char>(buf), dec.significand);
+-    return dec.exponent;
+-  } else if (is_constant_evaluated()) {
+-    // Use Grisu + Dragon4 for the given precision:
+-    // https://www.cs.tufts.edu/~nr/cs257/archive/florian-loitsch/printf.pdf.
+-    const int min_exp = -60;  // alpha in Grisu.
+-    int cached_exp10 = 0;     // K in Grisu.
+-    fp normalized = normalize(fp(converted_value));
+-    const auto cached_pow = get_cached_power(
+-        min_exp - (normalized.e + fp::num_significand_bits), cached_exp10);
+-    normalized = normalized * cached_pow;
+-    gen_digits_handler handler{buf.data(), 0, precision, -cached_exp10, fixed};
+-    if (grisu_gen_digits(normalized, 1, exp, handler) != digits::error &&
+-        !is_constant_evaluated()) {
+-      exp += handler.exp10;
+-      buf.try_resize(to_unsigned(handler.size));
+-      use_dragon = false;
+-    } else {
+-      exp += handler.size - cached_exp10 - 1;
+-      precision = handler.precision;
+-    }
+   } else {
+     // Extract significand bits and exponent bits.
+     using info = dragonbox::float_info<double>;
+@@ -3563,7 +3042,7 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+       significand <<= 1;
+     } else {
+       // Normalize subnormal inputs.
+-      FMT_ASSERT(significand != 0, "zeros should not appear hear");
++      FMT_ASSERT(significand != 0, "zeros should not appear here");
+       int shift = countl_zero(significand);
+       FMT_ASSERT(shift >= num_bits<uint64_t>() - num_significand_bits<double>(),
+                  "");
+@@ -3600,9 +3079,7 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+     }
+ 
+     // Compute the actual number of decimal digits to print.
+-    if (fixed) {
+-      adjust_precision(precision, exp + digits_in_the_first_segment);
+-    }
++    if (fixed) adjust_precision(precision, exp + digits_in_the_first_segment);
+ 
+     // Use Dragon4 only when there might be not enough digits in the first
+     // segment.
+@@ -3645,7 +3122,7 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+         uint64_t prod;
+         uint32_t digits;
+         bool should_round_up;
+-        int number_of_digits_to_print = precision > 9 ? 9 : precision;
++        int number_of_digits_to_print = min_of(precision, 9);
+ 
+         // Print a 9-digits subsegment, either the first or the second.
+         auto print_subsegment = [&](uint32_t subsegment, char* buffer) {
+@@ -3673,7 +3150,7 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+             // for details.
+             prod = ((subsegment * static_cast<uint64_t>(450359963)) >> 20) + 1;
+             digits = static_cast<uint32_t>(prod >> 32);
+-            copy2(buffer, digits2(digits));
++            write2digits(buffer, digits);
+             number_of_digits_printed += 2;
+           }
+ 
+@@ -3681,7 +3158,7 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+           while (number_of_digits_printed < number_of_digits_to_print) {
+             prod = static_cast<uint32_t>(prod) * static_cast<uint64_t>(100);
+             digits = static_cast<uint32_t>(prod >> 32);
+-            copy2(buffer + number_of_digits_printed, digits2(digits));
++            write2digits(buffer + number_of_digits_printed, digits);
+             number_of_digits_printed += 2;
+           }
+         };
+@@ -3707,12 +3184,12 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+           //    fractional part is strictly larger than 1/2.
+           if (precision < 9) {
+             uint32_t fractional_part = static_cast<uint32_t>(prod);
+-            should_round_up = fractional_part >=
+-                                  data::fractional_part_rounding_thresholds
+-                                      [8 - number_of_digits_to_print] ||
+-                              ((fractional_part >> 31) &
+-                               ((digits & 1) | (second_third_subsegments != 0) |
+-                                has_more_segments)) != 0;
++            should_round_up =
++                fractional_part >= fractional_part_rounding_thresholds(
++                                       8 - number_of_digits_to_print) ||
++                ((fractional_part >> 31) &
++                 ((digits & 1) | (second_third_subsegments != 0) |
++                  has_more_segments)) != 0;
+           }
+           // Rounding at the subsegment boundary.
+           // In this case, the fractional part is at least 1/2 if and only if
+@@ -3747,12 +3224,12 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+             // of 19 digits, so in this case the third segment should be
+             // consisting of a genuine digit from the input.
+             uint32_t fractional_part = static_cast<uint32_t>(prod);
+-            should_round_up = fractional_part >=
+-                                  data::fractional_part_rounding_thresholds
+-                                      [8 - number_of_digits_to_print] ||
+-                              ((fractional_part >> 31) &
+-                               ((digits & 1) | (third_subsegment != 0) |
+-                                has_more_segments)) != 0;
++            should_round_up =
++                fractional_part >= fractional_part_rounding_thresholds(
++                                       8 - number_of_digits_to_print) ||
++                ((fractional_part >> 31) &
++                 ((digits & 1) | (third_subsegment != 0) |
++                  has_more_segments)) != 0;
+           }
+           // Rounding at the subsegment boundary.
+           else {
+@@ -3790,9 +3267,8 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+   }
+   if (use_dragon) {
+     auto f = basic_fp<uint128_t>();
+-    bool is_predecessor_closer = specs.binary32
+-                                     ? f.assign(static_cast<float>(value))
+-                                     : f.assign(converted_value);
++    bool is_predecessor_closer = binary32 ? f.assign(static_cast<float>(value))
++                                          : f.assign(converted_value);
+     if (is_predecessor_closer) dragon_flags |= dragon::predecessor_closer;
+     if (fixed) dragon_flags |= dragon::fixed;
+     // Limit precision to the maximum possible number of significant digits in
+@@ -3801,7 +3277,7 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+     if (precision > max_double_digits) precision = max_double_digits;
+     format_dragon(f, dragon_flags, precision, buf, exp);
+   }
+-  if (!fixed && !specs.showpoint) {
++  if (!fixed && !specs.alt()) {
+     // Remove trailing zeros.
+     auto num_digits = buf.size();
+     while (num_digits > 0 && buf[num_digits - 1] == '0') {
+@@ -3812,97 +3288,106 @@ FMT_CONSTEXPR20 auto format_float(Float value, int precision, float_specs specs,
+   }
+   return exp;
+ }
++
++// Numbers with exponents greater or equal to the returned value will use
++// the exponential notation.
++template <typename T> constexpr auto exp_upper() -> int {
++  return std::numeric_limits<T>::digits10 != 0
++             ? min_of(16, std::numeric_limits<T>::digits10 + 1)
++             : 16;
++}
++
+ template <typename Char, typename OutputIt, typename T>
+-FMT_CONSTEXPR20 auto write_float(OutputIt out, T value,
+-                                 format_specs<Char> specs, locale_ref loc)
+-    -> OutputIt {
+-  float_specs fspecs = parse_float_type_spec(specs);
+-  fspecs.sign = specs.sign;
+-  if (detail::signbit(value)) {  // value < 0 is false for NaN so use signbit.
+-    fspecs.sign = sign::minus;
+-    value = -value;
+-  } else if (fspecs.sign == sign::minus) {
+-    fspecs.sign = sign::none;
+-  }
++FMT_CONSTEXPR20 auto write_float(OutputIt out, T value, format_specs specs,
++                                 locale_ref loc) -> OutputIt {
++  // Use signbit because value < 0 is false for NaN.
++  sign s = detail::signbit(value) ? sign::minus : specs.sign();
+ 
+   if (!detail::isfinite(value))
+-    return write_nonfinite(out, detail::isnan(value), specs, fspecs);
++    return write_nonfinite<Char>(out, detail::isnan(value), specs, s);
+ 
+-  if (specs.align == align::numeric && fspecs.sign) {
+-    auto it = reserve(out, 1);
+-    *it++ = detail::sign<Char>(fspecs.sign);
+-    out = base_iterator(out, it);
+-    fspecs.sign = sign::none;
++  if (specs.align() == align::numeric && s != sign::none) {
++    *out++ = detail::getsign<Char>(s);
++    s = sign::none;
+     if (specs.width != 0) --specs.width;
+   }
+ 
++  constexpr int exp_upper = detail::exp_upper<T>();
++  int precision = specs.precision;
++  if (precision < 0) {
++    if (specs.type() != presentation_type::none) {
++      precision = 6;
++    } else if (is_fast_float<T>::value && !is_constant_evaluated()) {
++      // Use Dragonbox for the shortest format.
++      using floaty = conditional_t<sizeof(T) >= sizeof(double), double, float>;
++      auto dec = dragonbox::to_decimal(static_cast<floaty>(value));
++      return write_float<Char>(out, dec, specs, s, exp_upper, loc);
++    }
++  }
++
+   memory_buffer buffer;
+-  if (fspecs.format == float_format::hex) {
+-    if (fspecs.sign) buffer.push_back(detail::sign<char>(fspecs.sign));
+-    format_hexfloat(convert_float(value), specs.precision, fspecs, buffer);
+-    return write_bytes<align::right>(out, {buffer.data(), buffer.size()},
+-                                     specs);
+-  }
+-  int precision = specs.precision >= 0 || specs.type == presentation_type::none
+-                      ? specs.precision
+-                      : 6;
+-  if (fspecs.format == float_format::exp) {
++  if (specs.type() == presentation_type::hexfloat) {
++    if (s != sign::none) buffer.push_back(detail::getsign<char>(s));
++    format_hexfloat(convert_float(value), specs, buffer);
++    return write_bytes<Char, align::right>(out, {buffer.data(), buffer.size()},
++                                           specs);
++  }
++
++  if (specs.type() == presentation_type::exp) {
+     if (precision == max_value<int>())
+-      throw_format_error("number is too big");
++      report_error("number is too big");
+     else
+       ++precision;
+-  } else if (fspecs.format != float_format::fixed && precision == 0) {
++    if (specs.precision != 0) specs.set_alt();
++  } else if (specs.type() == presentation_type::fixed) {
++    if (specs.precision != 0) specs.set_alt();
++  } else if (precision == 0) {
+     precision = 1;
+   }
+-  if (const_check(std::is_same<T, float>())) fspecs.binary32 = true;
+-  int exp = format_float(convert_float(value), precision, fspecs, buffer);
+-  fspecs.precision = precision;
++  int exp = format_float(convert_float(value), precision, specs,
++                         std::is_same<T, float>(), buffer);
++
++  specs.precision = precision;
+   auto f = big_decimal_fp{buffer.data(), static_cast<int>(buffer.size()), exp};
+-  return write_float(out, f, specs, fspecs, loc);
++  return write_float<Char>(out, f, specs, s, exp_upper, loc);
+ }
+ 
+ template <typename Char, typename OutputIt, typename T,
+           FMT_ENABLE_IF(is_floating_point<T>::value)>
+-FMT_CONSTEXPR20 auto write(OutputIt out, T value, format_specs<Char> specs,
++FMT_CONSTEXPR20 auto write(OutputIt out, T value, format_specs specs,
+                            locale_ref loc = {}) -> OutputIt {
+-  if (const_check(!is_supported_floating_point(value))) return out;
+-  return specs.localized && write_loc(out, value, specs, loc)
++  return specs.localized() && write_loc(out, value, specs, loc)
+              ? out
+-             : write_float(out, value, specs, loc);
++             : write_float<Char>(out, value, specs, loc);
+ }
+ 
+ template <typename Char, typename OutputIt, typename T,
+           FMT_ENABLE_IF(is_fast_float<T>::value)>
+ FMT_CONSTEXPR20 auto write(OutputIt out, T value) -> OutputIt {
+-  if (is_constant_evaluated()) return write(out, value, format_specs<Char>());
+-  if (const_check(!is_supported_floating_point(value))) return out;
++  if (is_constant_evaluated()) return write<Char>(out, value, format_specs());
+ 
+-  auto fspecs = float_specs();
+-  if (detail::signbit(value)) {
+-    fspecs.sign = sign::minus;
+-    value = -value;
+-  }
++  auto s = detail::signbit(value) ? sign::minus : sign::none;
+ 
+-  constexpr auto specs = format_specs<Char>();
+-  using floaty = conditional_t<std::is_same<T, long double>::value, double, T>;
++  constexpr auto specs = format_specs();
++  using floaty = conditional_t<sizeof(T) >= sizeof(double), double, float>;
+   using floaty_uint = typename dragonbox::float_info<floaty>::carrier_uint;
+   floaty_uint mask = exponent_mask<floaty>();
+   if ((bit_cast<floaty_uint>(value) & mask) == mask)
+-    return write_nonfinite(out, std::isnan(value), specs, fspecs);
++    return write_nonfinite<Char>(out, std::isnan(value), specs, s);
+ 
+   auto dec = dragonbox::to_decimal(static_cast<floaty>(value));
+-  return write_float(out, dec, specs, fspecs, {});
++  return write_float<Char>(out, dec, specs, s, exp_upper<T>(), {});
+ }
+ 
+ template <typename Char, typename OutputIt, typename T,
+           FMT_ENABLE_IF(is_floating_point<T>::value &&
+                         !is_fast_float<T>::value)>
+ inline auto write(OutputIt out, T value) -> OutputIt {
+-  return write(out, value, format_specs<Char>());
++  return write<Char>(out, value, format_specs());
+ }
+ 
+ template <typename Char, typename OutputIt>
+-auto write(OutputIt out, monostate, format_specs<Char> = {}, locale_ref = {})
++auto write(OutputIt out, monostate, format_specs = {}, locale_ref = {})
+     -> OutputIt {
+   FMT_ASSERT(false, "");
+   return out;
+@@ -3911,13 +3396,11 @@ auto write(OutputIt out, monostate, format_specs<Char> = {}, locale_ref = {})
+ template <typename Char, typename OutputIt>
+ FMT_CONSTEXPR auto write(OutputIt out, basic_string_view<Char> value)
+     -> OutputIt {
+-  auto it = reserve(out, value.size());
+-  it = copy_str_noinline<Char>(value.begin(), value.end(), it);
+-  return base_iterator(out, it);
++  return copy_noinline<Char>(value.begin(), value.end(), out);
+ }
+ 
+ template <typename Char, typename OutputIt, typename T,
+-          FMT_ENABLE_IF(is_string<T>::value)>
++          FMT_ENABLE_IF(has_to_string_view<T>::value)>
+ constexpr auto write(OutputIt out, const T& value) -> OutputIt {
+   return write<Char>(out, to_string_view(value));
+ }
+@@ -3925,10 +3408,8 @@ constexpr auto write(OutputIt out, const T& value) -> OutputIt {
+ // FMT_ENABLE_IF() condition separated to workaround an MSVC bug.
+ template <
+     typename Char, typename OutputIt, typename T,
+-    bool check =
+-        std::is_enum<T>::value && !std::is_same<T, Char>::value &&
+-        mapped_type_constant<T, basic_format_context<OutputIt, Char>>::value !=
+-            type::custom_type,
++    bool check = std::is_enum<T>::value && !std::is_same<T, Char>::value &&
++                 mapped_type_constant<T, Char>::value != type::custom_type,
+     FMT_ENABLE_IF(check)>
+ FMT_CONSTEXPR auto write(OutputIt out, T value) -> OutputIt {
+   return write<Char>(out, static_cast<underlying_t<T>>(value));
+@@ -3936,13 +3417,12 @@ FMT_CONSTEXPR auto write(OutputIt out, T value) -> OutputIt {
+ 
+ template <typename Char, typename OutputIt, typename T,
+           FMT_ENABLE_IF(std::is_same<T, bool>::value)>
+-FMT_CONSTEXPR auto write(OutputIt out, T value,
+-                         const format_specs<Char>& specs = {}, locale_ref = {})
+-    -> OutputIt {
+-  return specs.type != presentation_type::none &&
+-                 specs.type != presentation_type::string
+-             ? write(out, value ? 1 : 0, specs, {})
+-             : write_bytes(out, value ? "true" : "false", specs);
++FMT_CONSTEXPR auto write(OutputIt out, T value, const format_specs& specs = {},
++                         locale_ref = {}) -> OutputIt {
++  return specs.type() != presentation_type::none &&
++                 specs.type() != presentation_type::string
++             ? write<Char>(out, value ? 1 : 0, specs, {})
++             : write_bytes<Char>(out, value ? "true" : "false", specs);
+ }
+ 
+ template <typename Char, typename OutputIt>
+@@ -3953,202 +3433,150 @@ FMT_CONSTEXPR auto write(OutputIt out, Char value) -> OutputIt {
+ }
+ 
+ template <typename Char, typename OutputIt>
+-FMT_CONSTEXPR_CHAR_TRAITS auto write(OutputIt out, const Char* value)
+-    -> OutputIt {
++FMT_CONSTEXPR20 auto write(OutputIt out, const Char* value) -> OutputIt {
+   if (value) return write(out, basic_string_view<Char>(value));
+-  throw_format_error("string pointer is null");
++  report_error("string pointer is null");
+   return out;
+ }
+ 
+ template <typename Char, typename OutputIt, typename T,
+           FMT_ENABLE_IF(std::is_same<T, void>::value)>
+-auto write(OutputIt out, const T* value, const format_specs<Char>& specs = {},
++auto write(OutputIt out, const T* value, const format_specs& specs = {},
+            locale_ref = {}) -> OutputIt {
+   return write_ptr<Char>(out, bit_cast<uintptr_t>(value), &specs);
+ }
+ 
+-// A write overload that handles implicit conversions.
+ template <typename Char, typename OutputIt, typename T,
+-          typename Context = basic_format_context<OutputIt, Char>>
+-FMT_CONSTEXPR auto write(OutputIt out, const T& value) -> enable_if_t<
+-    std::is_class<T>::value && !is_string<T>::value &&
+-        !is_floating_point<T>::value && !std::is_same<T, Char>::value &&
+-        !std::is_same<T, remove_cvref_t<decltype(arg_mapper<Context>().map(
+-                             value))>>::value,
+-    OutputIt> {
+-  return write<Char>(out, arg_mapper<Context>().map(value));
++          FMT_ENABLE_IF(mapped_type_constant<T, Char>::value ==
++                            type::custom_type &&
++                        !std::is_fundamental<T>::value)>
++FMT_CONSTEXPR auto write(OutputIt out, const T& value) -> OutputIt {
++  auto f = formatter<T, Char>();
++  auto parse_ctx = parse_context<Char>({});
++  f.parse(parse_ctx);
++  auto ctx = basic_format_context<OutputIt, Char>(out, {}, {});
++  return f.format(value, ctx);
+ }
+ 
+-template <typename Char, typename OutputIt, typename T,
+-          typename Context = basic_format_context<OutputIt, Char>>
+-FMT_CONSTEXPR auto write(OutputIt out, const T& value)
+-    -> enable_if_t<mapped_type_constant<T, Context>::value == type::custom_type,
+-                   OutputIt> {
+-  auto ctx = Context(out, {}, {});
+-  return typename Context::template formatter_type<T>().format(value, ctx);
+-}
++template <typename T>
++using is_builtin =
++    bool_constant<std::is_same<T, int>::value || FMT_BUILTIN_TYPES>;
+ 
+ // An argument visitor that formats the argument and writes it via the output
+ // iterator. It's a class and not a generic lambda for compatibility with C++11.
+ template <typename Char> struct default_arg_formatter {
+-  using iterator = buffer_appender<Char>;
+-  using context = buffer_context<Char>;
++  using context = buffered_context<Char>;
+ 
+-  iterator out;
+-  basic_format_args<context> args;
+-  locale_ref loc;
++  basic_appender<Char> out;
+ 
+-  template <typename T> auto operator()(T value) -> iterator {
+-    return write<Char>(out, value);
+-  }
+-  auto operator()(typename basic_format_arg<context>::handle h) -> iterator {
+-    basic_format_parse_context<Char> parse_ctx({});
+-    context format_ctx(out, args, loc);
+-    h.format(parse_ctx, format_ctx);
+-    return format_ctx.out();
+-  }
+-};
+-
+-template <typename Char> struct arg_formatter {
+-  using iterator = buffer_appender<Char>;
+-  using context = buffer_context<Char>;
++  void operator()(monostate) { report_error("argument not found"); }
+ 
+-  iterator out;
+-  const format_specs<Char>& specs;
+-  locale_ref locale;
+-
+-  template <typename T>
+-  FMT_CONSTEXPR FMT_INLINE auto operator()(T value) -> iterator {
+-    return detail::write(out, value, specs, locale);
+-  }
+-  auto operator()(typename basic_format_arg<context>::handle) -> iterator {
+-    // User-defined types are handled separately because they require access
+-    // to the parse context.
+-    return out;
++  template <typename T, FMT_ENABLE_IF(is_builtin<T>::value)>
++  void operator()(T value) {
++    write<Char>(out, value);
+   }
+-};
+ 
+-template <typename Char> struct custom_formatter {
+-  basic_format_parse_context<Char>& parse_ctx;
+-  buffer_context<Char>& ctx;
++  template <typename T, FMT_ENABLE_IF(!is_builtin<T>::value)>
++  void operator()(T) {
++    FMT_ASSERT(false, "");
++  }
+ 
+-  void operator()(
+-      typename basic_format_arg<buffer_context<Char>>::handle h) const {
+-    h.format(parse_ctx, ctx);
++  void operator()(typename basic_format_arg<context>::handle h) {
++    // Use a null locale since the default format must be unlocalized.
++    auto parse_ctx = parse_context<Char>({});
++    auto format_ctx = context(out, {}, {});
++    h.format(parse_ctx, format_ctx);
+   }
+-  template <typename T> void operator()(T) const {}
+ };
+ 
+-template <typename ErrorHandler> class width_checker {
+- public:
+-  explicit FMT_CONSTEXPR width_checker(ErrorHandler& eh) : handler_(eh) {}
++template <typename Char> struct arg_formatter {
++  basic_appender<Char> out;
++  const format_specs& specs;
++  FMT_NO_UNIQUE_ADDRESS locale_ref locale;
+ 
+-  template <typename T, FMT_ENABLE_IF(is_integer<T>::value)>
+-  FMT_CONSTEXPR auto operator()(T value) -> unsigned long long {
+-    if (is_negative(value)) handler_.on_error("negative width");
+-    return static_cast<unsigned long long>(value);
++  template <typename T, FMT_ENABLE_IF(is_builtin<T>::value)>
++  FMT_CONSTEXPR FMT_INLINE void operator()(T value) {
++    detail::write<Char>(out, value, specs, locale);
+   }
+ 
+-  template <typename T, FMT_ENABLE_IF(!is_integer<T>::value)>
+-  FMT_CONSTEXPR auto operator()(T) -> unsigned long long {
+-    handler_.on_error("width is not integer");
+-    return 0;
++  template <typename T, FMT_ENABLE_IF(!is_builtin<T>::value)>
++  void operator()(T) {
++    FMT_ASSERT(false, "");
+   }
+ 
+- private:
+-  ErrorHandler& handler_;
++  void operator()(typename basic_format_arg<buffered_context<Char>>::handle) {
++    // User-defined types are handled separately because they require access
++    // to the parse context.
++  }
+ };
+ 
+-template <typename ErrorHandler> class precision_checker {
+- public:
+-  explicit FMT_CONSTEXPR precision_checker(ErrorHandler& eh) : handler_(eh) {}
+-
++struct dynamic_spec_getter {
+   template <typename T, FMT_ENABLE_IF(is_integer<T>::value)>
+   FMT_CONSTEXPR auto operator()(T value) -> unsigned long long {
+-    if (is_negative(value)) handler_.on_error("negative precision");
+-    return static_cast<unsigned long long>(value);
++    return is_negative(value) ? ~0ull : static_cast<unsigned long long>(value);
+   }
+ 
+   template <typename T, FMT_ENABLE_IF(!is_integer<T>::value)>
+   FMT_CONSTEXPR auto operator()(T) -> unsigned long long {
+-    handler_.on_error("precision is not integer");
++    report_error("width/precision is not integer");
+     return 0;
+   }
+-
+- private:
+-  ErrorHandler& handler_;
+ };
+ 
+-template <template <typename> class Handler, typename FormatArg,
+-          typename ErrorHandler>
+-FMT_CONSTEXPR auto get_dynamic_spec(FormatArg arg, ErrorHandler eh) -> int {
+-  unsigned long long value = visit_format_arg(Handler<ErrorHandler>(eh), arg);
+-  if (value > to_unsigned(max_value<int>())) eh.on_error("number is too big");
+-  return static_cast<int>(value);
+-}
+-
+ template <typename Context, typename ID>
+-FMT_CONSTEXPR auto get_arg(Context& ctx, ID id) -> decltype(ctx.arg(id)) {
++FMT_CONSTEXPR auto get_arg(Context& ctx, ID id) -> basic_format_arg<Context> {
+   auto arg = ctx.arg(id);
+-  if (!arg) ctx.on_error("argument not found");
++  if (!arg) report_error("argument not found");
+   return arg;
+ }
+ 
+-template <template <typename> class Handler, typename Context>
+-FMT_CONSTEXPR void handle_dynamic_spec(int& value,
+-                                       arg_ref<typename Context::char_type> ref,
+-                                       Context& ctx) {
+-  switch (ref.kind) {
+-  case arg_id_kind::none:
+-    break;
+-  case arg_id_kind::index:
+-    value = detail::get_dynamic_spec<Handler>(get_arg(ctx, ref.val.index),
+-                                              ctx.error_handler());
+-    break;
+-  case arg_id_kind::name:
+-    value = detail::get_dynamic_spec<Handler>(get_arg(ctx, ref.val.name),
+-                                              ctx.error_handler());
+-    break;
+-  }
++template <typename Context>
++FMT_CONSTEXPR int get_dynamic_spec(
++    arg_id_kind kind, const arg_ref<typename Context::char_type>& ref,
++    Context& ctx) {
++  FMT_ASSERT(kind != arg_id_kind::none, "");
++  auto arg =
++      kind == arg_id_kind::index ? ctx.arg(ref.index) : ctx.arg(ref.name);
++  if (!arg) report_error("argument not found");
++  unsigned long long value = arg.visit(dynamic_spec_getter());
++  if (value > to_unsigned(max_value<int>()))
++    report_error("width/precision is out of range");
++  return static_cast<int>(value);
+ }
+ 
+-#if FMT_USE_USER_DEFINED_LITERALS
+-template <typename Char> struct udl_formatter {
+-  basic_string_view<Char> str;
+-
+-  template <typename... T>
+-  auto operator()(T&&... args) const -> std::basic_string<Char> {
+-    return vformat(str, fmt::make_format_args<buffer_context<Char>>(args...));
+-  }
+-};
++template <typename Context>
++FMT_CONSTEXPR void handle_dynamic_spec(
++    arg_id_kind kind, int& value,
++    const arg_ref<typename Context::char_type>& ref, Context& ctx) {
++  if (kind != arg_id_kind::none) value = get_dynamic_spec(kind, ref, ctx);
++}
+ 
+-#  if FMT_USE_NONTYPE_TEMPLATE_ARGS
++#if FMT_USE_NONTYPE_TEMPLATE_ARGS
+ template <typename T, typename Char, size_t N,
+-          fmt::detail_exported::fixed_string<Char, N> Str>
+-struct statically_named_arg : view {
++          fmt::detail::fixed_string<Char, N> Str>
++struct static_named_arg : view {
+   static constexpr auto name = Str.data;
+ 
+   const T& value;
+-  statically_named_arg(const T& v) : value(v) {}
++  static_named_arg(const T& v) : value(v) {}
+ };
+ 
+ template <typename T, typename Char, size_t N,
+-          fmt::detail_exported::fixed_string<Char, N> Str>
+-struct is_named_arg<statically_named_arg<T, Char, N, Str>> : std::true_type {};
++          fmt::detail::fixed_string<Char, N> Str>
++struct is_named_arg<static_named_arg<T, Char, N, Str>> : std::true_type {};
+ 
+ template <typename T, typename Char, size_t N,
+-          fmt::detail_exported::fixed_string<Char, N> Str>
+-struct is_statically_named_arg<statically_named_arg<T, Char, N, Str>>
+-    : std::true_type {};
++          fmt::detail::fixed_string<Char, N> Str>
++struct is_static_named_arg<static_named_arg<T, Char, N, Str>> : std::true_type {
++};
+ 
+-template <typename Char, size_t N,
+-          fmt::detail_exported::fixed_string<Char, N> Str>
++template <typename Char, size_t N, fmt::detail::fixed_string<Char, N> Str>
+ struct udl_arg {
+   template <typename T> auto operator=(T&& value) const {
+-    return statically_named_arg<T, Char, N, Str>(std::forward<T>(value));
++    return static_named_arg<T, Char, N, Str>(std::forward<T>(value));
+   }
+ };
+-#  else
++#else
+ template <typename Char> struct udl_arg {
+   const Char* str;
+ 
+@@ -4156,195 +3584,258 @@ template <typename Char> struct udl_arg {
+     return {str, std::forward<T>(value)};
+   }
+ };
+-#  endif
+-#endif  // FMT_USE_USER_DEFINED_LITERALS
++#endif  // FMT_USE_NONTYPE_TEMPLATE_ARGS
+ 
+-template <typename Locale, typename Char>
+-auto vformat(const Locale& loc, basic_string_view<Char> fmt,
+-             basic_format_args<buffer_context<type_identity_t<Char>>> args)
+-    -> std::basic_string<Char> {
+-  auto buf = basic_memory_buffer<Char>();
+-  detail::vformat_to(buf, fmt, args, detail::locale_ref(loc));
+-  return {buf.data(), buf.size()};
+-}
++template <typename Char> struct format_handler {
++  parse_context<Char> parse_ctx;
++  buffered_context<Char> ctx;
++
++  void on_text(const Char* begin, const Char* end) {
++    copy_noinline<Char>(begin, end, ctx.out());
++  }
++
++  FMT_CONSTEXPR auto on_arg_id() -> int { return parse_ctx.next_arg_id(); }
++  FMT_CONSTEXPR auto on_arg_id(int id) -> int {
++    parse_ctx.check_arg_id(id);
++    return id;
++  }
++  FMT_CONSTEXPR auto on_arg_id(basic_string_view<Char> id) -> int {
++    parse_ctx.check_arg_id(id);
++    int arg_id = ctx.arg_id(id);
++    if (arg_id < 0) report_error("argument not found");
++    return arg_id;
++  }
++
++  FMT_INLINE void on_replacement_field(int id, const Char*) {
++    ctx.arg(id).visit(default_arg_formatter<Char>{ctx.out()});
++  }
++
++  auto on_format_specs(int id, const Char* begin, const Char* end)
++      -> const Char* {
++    auto arg = get_arg(ctx, id);
++    // Not using a visitor for custom types gives better codegen.
++    if (arg.format_custom(begin, parse_ctx, ctx)) return parse_ctx.begin();
++
++    auto specs = dynamic_format_specs<Char>();
++    begin = parse_format_specs(begin, end, specs, parse_ctx, arg.type());
++    if (specs.dynamic()) {
++      handle_dynamic_spec(specs.dynamic_width(), specs.width, specs.width_ref,
++                          ctx);
++      handle_dynamic_spec(specs.dynamic_precision(), specs.precision,
++                          specs.precision_ref, ctx);
++    }
++
++    arg.visit(arg_formatter<Char>{ctx.out(), specs, ctx.locale()});
++    return begin;
++  }
++
++  FMT_NORETURN void on_error(const char* message) { report_error(message); }
++};
+ 
+ using format_func = void (*)(detail::buffer<char>&, int, const char*);
++FMT_API void do_report_error(format_func func, int error_code,
++                             const char* message) noexcept;
+ 
+ FMT_API void format_error_code(buffer<char>& out, int error_code,
+                                string_view message) noexcept;
+ 
+-FMT_API void report_error(format_func func, int error_code,
+-                          const char* message) noexcept;
+-FMT_END_DETAIL_NAMESPACE
++template <typename T, typename Char, type TYPE>
++template <typename FormatContext>
++FMT_CONSTEXPR auto native_formatter<T, Char, TYPE>::format(
++    const T& val, FormatContext& ctx) const -> decltype(ctx.out()) {
++  if (!specs_.dynamic())
++    return write<Char>(ctx.out(), val, specs_, ctx.locale());
++  auto specs = format_specs(specs_);
++  handle_dynamic_spec(specs.dynamic_width(), specs.width, specs_.width_ref,
++                      ctx);
++  handle_dynamic_spec(specs.dynamic_precision(), specs.precision,
++                      specs_.precision_ref, ctx);
++  return write<Char>(ctx.out(), val, specs, ctx.locale());
++}
++
++// DEPRECATED! https://github.com/fmtlib/fmt/issues/4292.
++template <typename T, typename Enable = void>
++struct is_locale : std::false_type {};
++template <typename T>
++struct is_locale<T, void_t<decltype(T::classic())>> : std::true_type {};
+ 
+-FMT_API auto vsystem_error(int error_code, string_view format_str,
+-                           format_args args) -> std::system_error;
++// DEPRECATED!
++template <typename Char = char> struct vformat_args {
++  using type = basic_format_args<buffered_context<Char>>;
++};
++template <> struct vformat_args<char> {
++  using type = format_args;
++};
+ 
+-/**
+-  \rst
+-  Constructs :class:`std::system_error` with a message formatted with
+-  ``fmt::format(fmt, args...)``.
+-  *error_code* is a system error code as given by ``errno``.
+-
+-  **Example**::
+-
+-    // This throws std::system_error with the description
+-    //   cannot open file 'madeup': No such file or directory
+-    // or similar (system message may vary).
+-    const char* filename = "madeup";
+-    std::FILE* file = std::fopen(filename, "r");
+-    if (!file)
+-      throw fmt::system_error(errno, "cannot open file '{}'", filename);
+-  \endrst
+- */
+-template <typename... T>
+-auto system_error(int error_code, format_string<T...> fmt, T&&... args)
+-    -> std::system_error {
+-  return vsystem_error(error_code, fmt, fmt::make_format_args(args...));
++template <typename Char>
++void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
++                typename vformat_args<Char>::type args, locale_ref loc = {}) {
++  auto out = basic_appender<Char>(buf);
++  parse_format_string(
++      fmt, format_handler<Char>{parse_context<Char>(fmt), {out, args, loc}});
+ }
++}  // namespace detail
+ 
+-/**
+-  \rst
+-  Formats an error message for an error returned by an operating system or a
+-  language runtime, for example a file opening error, and writes it to *out*.
+-  The format is the same as the one used by ``std::system_error(ec, message)``
+-  where ``ec`` is ``std::error_code(error_code, std::generic_category()})``.
+-  It is implementation-defined but normally looks like:
+-
+-  .. parsed-literal::
+-     *<message>*: *<system-message>*
+-
+-  where *<message>* is the passed message and *<system-message>* is the system
+-  message corresponding to the error code.
+-  *error_code* is a system error code as given by ``errno``.
+-  \endrst
+- */
+-FMT_API void format_system_error(detail::buffer<char>& out, int error_code,
+-                                 const char* message) noexcept;
+-
+-// Reports a system error without throwing an exception.
+-// Can be used to report errors from destructors.
+-FMT_API void report_system_error(int error_code, const char* message) noexcept;
++FMT_BEGIN_EXPORT
+ 
+-/** Fast integer formatter. */
+-class format_int {
++// A generic formatting context with custom output iterator and character
++// (code unit) support. Char is the format string code unit type which can be
++// different from OutputIt::value_type.
++template <typename OutputIt, typename Char> class generic_context {
+  private:
+-  // Buffer should be large enough to hold all digits (digits10 + 1),
+-  // a sign and a null character.
+-  enum { buffer_size = std::numeric_limits<unsigned long long>::digits10 + 3 };
+-  mutable char buffer_[buffer_size];
+-  char* str_;
+-
+-  template <typename UInt> auto format_unsigned(UInt value) -> char* {
+-    auto n = static_cast<detail::uint32_or_64_or_128_t<UInt>>(value);
+-    return detail::format_decimal(buffer_, n, buffer_size - 1).begin;
+-  }
+-
+-  template <typename Int> auto format_signed(Int value) -> char* {
+-    auto abs_value = static_cast<detail::uint32_or_64_or_128_t<Int>>(value);
+-    bool negative = value < 0;
+-    if (negative) abs_value = 0 - abs_value;
+-    auto begin = format_unsigned(abs_value);
+-    if (negative) *--begin = '-';
+-    return begin;
+-  }
++  OutputIt out_;
++  basic_format_args<generic_context> args_;
++  detail::locale_ref loc_;
+ 
+  public:
+-  explicit format_int(int value) : str_(format_signed(value)) {}
+-  explicit format_int(long value) : str_(format_signed(value)) {}
+-  explicit format_int(long long value) : str_(format_signed(value)) {}
+-  explicit format_int(unsigned value) : str_(format_unsigned(value)) {}
+-  explicit format_int(unsigned long value) : str_(format_unsigned(value)) {}
+-  explicit format_int(unsigned long long value)
+-      : str_(format_unsigned(value)) {}
++  using char_type = Char;
++  using iterator = OutputIt;
++  using parse_context_type FMT_DEPRECATED = parse_context<Char>;
++  template <typename T>
++  using formatter_type FMT_DEPRECATED = formatter<T, Char>;
++  enum { builtin_types = FMT_BUILTIN_TYPES };
+ 
+-  /** Returns the number of characters written to the output buffer. */
+-  auto size() const -> size_t {
+-    return detail::to_unsigned(buffer_ - str_ + buffer_size - 1);
++  constexpr generic_context(OutputIt out,
++                            basic_format_args<generic_context> args,
++                            detail::locale_ref loc = {})
++      : out_(out), args_(args), loc_(loc) {}
++  generic_context(generic_context&&) = default;
++  generic_context(const generic_context&) = delete;
++  void operator=(const generic_context&) = delete;
++
++  constexpr auto arg(int id) const -> basic_format_arg<generic_context> {
++    return args_.get(id);
++  }
++  auto arg(basic_string_view<Char> name) const
++      -> basic_format_arg<generic_context> {
++    return args_.get(name);
++  }
++  constexpr auto arg_id(basic_string_view<Char> name) const -> int {
++    return args_.get_id(name);
+   }
+ 
+-  /**
+-    Returns a pointer to the output buffer content. No terminating null
+-    character is appended.
+-   */
+-  auto data() const -> const char* { return str_; }
++  constexpr auto out() const -> iterator { return out_; }
+ 
+-  /**
+-    Returns a pointer to the output buffer content with terminating null
+-    character appended.
+-   */
+-  auto c_str() const -> const char* {
+-    buffer_[buffer_size - 1] = '\0';
+-    return str_;
++  void advance_to(iterator it) {
++    if (!detail::is_back_insert_iterator<iterator>()) out_ = it;
+   }
+ 
+-  /**
+-    \rst
+-    Returns the content of the output buffer as an ``std::string``.
+-    \endrst
+-   */
+-  auto str() const -> std::string { return std::string(str_, size()); }
++  constexpr auto locale() const -> detail::locale_ref { return loc_; }
+ };
+ 
+-template <typename T, typename Char>
+-struct formatter<T, Char, enable_if_t<detail::has_format_as<T>::value>>
+-    : private formatter<detail::format_as_t<T>> {
+-  using base = formatter<detail::format_as_t<T>>;
+-  using base::parse;
++class loc_value {
++ private:
++  basic_format_arg<context> value_;
+ 
+-  template <typename FormatContext>
+-  auto format(const T& value, FormatContext& ctx) const -> decltype(ctx.out()) {
+-    return base::format(format_as(value), ctx);
++ public:
++  template <typename T, FMT_ENABLE_IF(!detail::is_float128<T>::value)>
++  loc_value(T value) : value_(value) {}
++
++  template <typename T, FMT_ENABLE_IF(detail::is_float128<T>::value)>
++  loc_value(T) {}
++
++  template <typename Visitor> auto visit(Visitor&& vis) -> decltype(vis(0)) {
++    return value_.visit(vis);
+   }
+ };
+ 
+-template <typename Char>
+-struct formatter<void*, Char> : formatter<const void*, Char> {
+-  template <typename FormatContext>
+-  auto format(void* val, FormatContext& ctx) const -> decltype(ctx.out()) {
+-    return formatter<const void*, Char>::format(val, ctx);
++// A locale facet that formats values in UTF-8.
++// It is parameterized on the locale to avoid the heavy <locale> include.
++template <typename Locale> class format_facet : public Locale::facet {
++ private:
++  std::string separator_;
++  std::string grouping_;
++  std::string decimal_point_;
++
++ protected:
++  virtual auto do_put(appender out, loc_value val,
++                      const format_specs& specs) const -> bool;
++
++ public:
++  static FMT_API typename Locale::id id;
++
++  explicit format_facet(Locale& loc);
++  explicit format_facet(string_view sep = "", std::string grouping = "\3",
++                        std::string decimal_point = ".")
++      : separator_(sep.data(), sep.size()),
++        grouping_(grouping),
++        decimal_point_(decimal_point) {}
++
++  auto put(appender out, loc_value val, const format_specs& specs) const
++      -> bool {
++    return do_put(out, val, specs);
+   }
+ };
+ 
++#define FMT_FORMAT_AS(Type, Base)                                   \
++  template <typename Char>                                          \
++  struct formatter<Type, Char> : formatter<Base, Char> {            \
++    template <typename FormatContext>                               \
++    FMT_CONSTEXPR auto format(Type value, FormatContext& ctx) const \
++        -> decltype(ctx.out()) {                                    \
++      return formatter<Base, Char>::format(value, ctx);             \
++    }                                                               \
++  }
++
++FMT_FORMAT_AS(signed char, int);
++FMT_FORMAT_AS(unsigned char, unsigned);
++FMT_FORMAT_AS(short, int);
++FMT_FORMAT_AS(unsigned short, unsigned);
++FMT_FORMAT_AS(long, detail::long_type);
++FMT_FORMAT_AS(unsigned long, detail::ulong_type);
++FMT_FORMAT_AS(Char*, const Char*);
++FMT_FORMAT_AS(detail::std_string_view<Char>, basic_string_view<Char>);
++FMT_FORMAT_AS(std::nullptr_t, const void*);
++FMT_FORMAT_AS(void*, const void*);
++
+ template <typename Char, size_t N>
+-struct formatter<Char[N], Char> : formatter<basic_string_view<Char>, Char> {
++struct formatter<Char[N], Char> : formatter<basic_string_view<Char>, Char> {};
++
++template <typename Char, typename Traits, typename Allocator>
++class formatter<std::basic_string<Char, Traits, Allocator>, Char>
++    : public formatter<basic_string_view<Char>, Char> {};
++
++template <int N, typename Char>
++struct formatter<detail::bitint<N>, Char> : formatter<long long, Char> {};
++template <int N, typename Char>
++struct formatter<detail::ubitint<N>, Char>
++    : formatter<unsigned long long, Char> {};
++
++template <typename Char>
++struct formatter<detail::float128, Char>
++    : detail::native_formatter<detail::float128, Char,
++                               detail::type::float_type> {};
++
++template <typename T, typename Char>
++struct formatter<T, Char, void_t<detail::format_as_result<T>>>
++    : formatter<detail::format_as_result<T>, Char> {
+   template <typename FormatContext>
+-  FMT_CONSTEXPR auto format(const Char* val, FormatContext& ctx) const
++  FMT_CONSTEXPR auto format(const T& value, FormatContext& ctx) const
+       -> decltype(ctx.out()) {
+-    return formatter<basic_string_view<Char>, Char>::format(val, ctx);
++    auto&& val = format_as(value);  // Make an lvalue reference for format.
++    return formatter<detail::format_as_result<T>, Char>::format(val, ctx);
+   }
+ };
+ 
+ /**
+-  \rst
+-  Converts ``p`` to ``const void*`` for pointer formatting.
+-
+-  **Example**::
+-
+-    auto s = fmt::format("{}", fmt::ptr(p));
+-  \endrst
++ * Converts `p` to `const void*` for pointer formatting.
++ *
++ * **Example**:
++ *
++ *     auto s = fmt::format("{}", fmt::ptr(p));
+  */
+ template <typename T> auto ptr(T p) -> const void* {
+   static_assert(std::is_pointer<T>::value, "");
+   return detail::bit_cast<const void*>(p);
+ }
+-template <typename T, typename Deleter>
+-auto ptr(const std::unique_ptr<T, Deleter>& p) -> const void* {
+-  return p.get();
+-}
+-template <typename T> auto ptr(const std::shared_ptr<T>& p) -> const void* {
+-  return p.get();
+-}
+ 
+ /**
+-  \rst
+-  Converts ``e`` to the underlying type.
+-
+-  **Example**::
+-
+-    enum class color { red, green, blue };
+-    auto s = fmt::format("{}", fmt::underlying(color::red));
+-  \endrst
++ * Converts `e` to the underlying type.
++ *
++ * **Example**:
++ *
++ *     enum class color { red, green, blue };
++ *     auto s = fmt::format("{}", fmt::underlying(color::red));  // s == "0"
+  */
+ template <typename Enum>
+ constexpr auto underlying(Enum e) noexcept -> underlying_t<Enum> {
+@@ -4358,13 +3849,22 @@ constexpr auto format_as(Enum e) noexcept -> underlying_t<Enum> {
+ }
+ }  // namespace enums
+ 
+-class bytes {
+- private:
+-  string_view data_;
+-  friend struct formatter<bytes>;
++#ifdef __cpp_lib_byte
++template <> struct formatter<std::byte> : formatter<unsigned> {
++  static auto format_as(std::byte b) -> unsigned char {
++    return static_cast<unsigned char>(b);
++  }
++  template <typename Context>
++  auto format(std::byte b, Context& ctx) const -> decltype(ctx.out()) {
++    return formatter<unsigned>::format(format_as(b), ctx);
++  }
++};
++#endif
+ 
+- public:
+-  explicit bytes(string_view data) : data_(data) {}
++struct bytes {
++  string_view data;
++
++  inline explicit bytes(string_view s) : data(s) {}
+ };
+ 
+ template <> struct formatter<bytes> {
+@@ -4372,35 +3872,35 @@ template <> struct formatter<bytes> {
+   detail::dynamic_format_specs<> specs_;
+ 
+  public:
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const char* {
++  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
+     return parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx,
+                               detail::type::string_type);
+   }
+ 
+   template <typename FormatContext>
+-  auto format(bytes b, FormatContext& ctx) -> decltype(ctx.out()) {
+-    detail::handle_dynamic_spec<detail::width_checker>(specs_.width,
+-                                                       specs_.width_ref, ctx);
+-    detail::handle_dynamic_spec<detail::precision_checker>(
+-        specs_.precision, specs_.precision_ref, ctx);
+-    return detail::write_bytes(ctx.out(), b.data_, specs_);
++  auto format(bytes b, FormatContext& ctx) const -> decltype(ctx.out()) {
++    auto specs = specs_;
++    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width,
++                                specs.width_ref, ctx);
++    detail::handle_dynamic_spec(specs.dynamic_precision(), specs.precision,
++                                specs.precision_ref, ctx);
++    return detail::write_bytes<char>(ctx.out(), b.data, specs);
+   }
+ };
+ 
+ // group_digits_view is not derived from view because it copies the argument.
+-template <typename T> struct group_digits_view { T value; };
++template <typename T> struct group_digits_view {
++  T value;
++};
+ 
+ /**
+-  \rst
+-  Returns a view that formats an integer value using ',' as a locale-independent
+-  thousands separator.
+-
+-  **Example**::
+-
+-    fmt::print("{}", fmt::group_digits(12345));
+-    // Output: "12,345"
+-  \endrst
++ * Returns a view that formats an integer value using ',' as a
++ * locale-independent thousands separator.
++ *
++ * **Example**:
++ *
++ *     fmt::print("{}", fmt::group_digits(12345));
++ *     // Output: "12,345"
+  */
+ template <typename T> auto group_digits(T value) -> group_digits_view<T> {
+   return {value};
+@@ -4411,269 +3911,255 @@ template <typename T> struct formatter<group_digits_view<T>> : formatter<T> {
+   detail::dynamic_format_specs<> specs_;
+ 
+  public:
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const char* {
++  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
+     return parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx,
+                               detail::type::int_type);
+   }
+ 
+   template <typename FormatContext>
+-  auto format(group_digits_view<T> t, FormatContext& ctx)
++  auto format(group_digits_view<T> view, FormatContext& ctx) const
+       -> decltype(ctx.out()) {
+-    detail::handle_dynamic_spec<detail::width_checker>(specs_.width,
+-                                                       specs_.width_ref, ctx);
+-    detail::handle_dynamic_spec<detail::precision_checker>(
+-        specs_.precision, specs_.precision_ref, ctx);
++    auto specs = specs_;
++    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width,
++                                specs.width_ref, ctx);
++    detail::handle_dynamic_spec(specs.dynamic_precision(), specs.precision,
++                                specs.precision_ref, ctx);
++    auto arg = detail::make_write_int_arg(view.value, specs.sign());
+     return detail::write_int(
+-        ctx.out(), static_cast<detail::uint64_or_128_t<T>>(t.value), 0, specs_,
+-        detail::digit_grouping<char>("\3", ","));
++        ctx.out(), static_cast<detail::uint64_or_128_t<T>>(arg.abs_value),
++        arg.prefix, specs, detail::digit_grouping<char>("\3", ","));
+   }
+ };
+ 
+-// DEPRECATED! join_view will be moved to ranges.h.
+-template <typename It, typename Sentinel, typename Char = char>
+-struct join_view : detail::view {
+-  It begin;
+-  Sentinel end;
+-  basic_string_view<Char> sep;
++template <typename T, typename Char> struct nested_view {
++  const formatter<T, Char>* fmt;
++  const T* value;
++};
+ 
+-  join_view(It b, Sentinel e, basic_string_view<Char> s)
+-      : begin(b), end(e), sep(s) {}
++template <typename T, typename Char>
++struct formatter<nested_view<T, Char>, Char> {
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    return ctx.begin();
++  }
++  template <typename FormatContext>
++  auto format(nested_view<T, Char> view, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    return view.fmt->format(*view.value, ctx);
++  }
+ };
+ 
+-template <typename It, typename Sentinel, typename Char>
+-struct formatter<join_view<It, Sentinel, Char>, Char> {
++template <typename T, typename Char = char> struct nested_formatter {
+  private:
+-  using value_type =
+-#ifdef __cpp_lib_ranges
+-      std::iter_value_t<It>;
+-#else
+-      typename std::iterator_traits<It>::value_type;
+-#endif
+-  formatter<remove_cvref_t<value_type>, Char> value_formatter_;
++  basic_specs specs_;
++  int width_;
++  formatter<T, Char> formatter_;
+ 
+  public:
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> const Char* {
+-    return value_formatter_.parse(ctx);
++  constexpr nested_formatter() : width_(0) {}
++
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    auto it = ctx.begin(), end = ctx.end();
++    if (it == end) return it;
++    auto specs = format_specs();
++    it = detail::parse_align(it, end, specs);
++    specs_ = specs;
++    Char c = *it;
++    auto width_ref = detail::arg_ref<Char>();
++    if ((c >= '0' && c <= '9') || c == '{') {
++      it = detail::parse_width(it, end, specs, width_ref, ctx);
++      width_ = specs.width;
++    }
++    ctx.advance_to(it);
++    return formatter_.parse(ctx);
+   }
+ 
+-  template <typename FormatContext>
+-  auto format(const join_view<It, Sentinel, Char>& value,
+-              FormatContext& ctx) const -> decltype(ctx.out()) {
+-    auto it = value.begin;
+-    auto out = ctx.out();
+-    if (it != value.end) {
+-      out = value_formatter_.format(*it, ctx);
+-      ++it;
+-      while (it != value.end) {
+-        out = detail::copy_str<Char>(value.sep.begin(), value.sep.end(), out);
+-        ctx.advance_to(out);
+-        out = value_formatter_.format(*it, ctx);
+-        ++it;
+-      }
+-    }
+-    return out;
++  template <typename FormatContext, typename F>
++  auto write_padded(FormatContext& ctx, F write) const -> decltype(ctx.out()) {
++    if (width_ == 0) return write(ctx.out());
++    auto buf = basic_memory_buffer<Char>();
++    write(basic_appender<Char>(buf));
++    auto specs = format_specs();
++    specs.width = width_;
++    specs.copy_fill_from(specs_);
++    specs.set_align(specs_.align());
++    return detail::write<Char>(
++        ctx.out(), basic_string_view<Char>(buf.data(), buf.size()), specs);
++  }
++
++  auto nested(const T& value) const -> nested_view<T, Char> {
++    return nested_view<T, Char>{&formatter_, &value};
+   }
+ };
+ 
+-/**
+-  Returns a view that formats the iterator range `[begin, end)` with elements
+-  separated by `sep`.
+- */
+-template <typename It, typename Sentinel>
+-auto join(It begin, Sentinel end, string_view sep) -> join_view<It, Sentinel> {
+-  return {begin, end, sep};
++inline namespace literals {
++#if FMT_USE_NONTYPE_TEMPLATE_ARGS
++template <detail::fixed_string S> constexpr auto operator""_a() {
++  using char_t = remove_cvref_t<decltype(*S.data)>;
++  return detail::udl_arg<char_t, sizeof(S.data) / sizeof(char_t), S>();
+ }
+-
++#else
+ /**
+-  \rst
+-  Returns a view that formats `range` with elements separated by `sep`.
+-
+-  **Example**::
+-
+-    std::vector<int> v = {1, 2, 3};
+-    fmt::print("{}", fmt::join(v, ", "));
+-    // Output: "1, 2, 3"
+-
+-  ``fmt::join`` applies passed format specifiers to the range elements::
+-
+-    fmt::print("{:02}", fmt::join(v, ", "));
+-    // Output: "01, 02, 03"
+-  \endrst
++ * User-defined literal equivalent of `fmt::arg`.
++ *
++ * **Example**:
++ *
++ *     using namespace fmt::literals;
++ *     fmt::print("The answer is {answer}.", "answer"_a=42);
+  */
+-template <typename Range>
+-auto join(Range&& range, string_view sep)
+-    -> join_view<detail::iterator_t<Range>, detail::sentinel_t<Range>> {
+-  return join(std::begin(range), std::end(range), sep);
++constexpr auto operator""_a(const char* s, size_t) -> detail::udl_arg<char> {
++  return {s};
+ }
++#endif  // FMT_USE_NONTYPE_TEMPLATE_ARGS
++}  // namespace literals
+ 
+-/**
+-  \rst
+-  Converts *value* to ``std::string`` using the default format for type *T*.
+-
+-  **Example**::
++/// A fast integer formatter.
++class format_int {
++ private:
++  // Buffer should be large enough to hold all digits (digits10 + 1),
++  // a sign and a null character.
++  enum { buffer_size = std::numeric_limits<unsigned long long>::digits10 + 3 };
++  mutable char buffer_[buffer_size];
++  char* str_;
+ 
+-    #include <fmt/format.h>
++  template <typename UInt>
++  FMT_CONSTEXPR20 auto format_unsigned(UInt value) -> char* {
++    auto n = static_cast<detail::uint32_or_64_or_128_t<UInt>>(value);
++    return detail::do_format_decimal(buffer_, n, buffer_size - 1);
++  }
+ 
+-    std::string answer = fmt::to_string(42);
+-  \endrst
+- */
+-template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
+-inline auto to_string(const T& value) -> std::string {
+-  auto buffer = memory_buffer();
+-  detail::write<char>(appender(buffer), value);
+-  return {buffer.data(), buffer.size()};
+-}
++  template <typename Int>
++  FMT_CONSTEXPR20 auto format_signed(Int value) -> char* {
++    auto abs_value = static_cast<detail::uint32_or_64_or_128_t<Int>>(value);
++    bool negative = value < 0;
++    if (negative) abs_value = 0 - abs_value;
++    auto begin = format_unsigned(abs_value);
++    if (negative) *--begin = '-';
++    return begin;
++  }
+ 
+-template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
+-FMT_NODISCARD inline auto to_string(T value) -> std::string {
+-  // The buffer should be large enough to store the number including the sign
+-  // or "false" for bool.
+-  constexpr int max_size = detail::digits10<T>() + 2;
+-  char buffer[max_size > 5 ? static_cast<unsigned>(max_size) : 5];
+-  char* begin = buffer;
+-  return std::string(begin, detail::write<char>(begin, value));
+-}
++ public:
++  FMT_CONSTEXPR20 explicit format_int(int value) : str_(format_signed(value)) {}
++  FMT_CONSTEXPR20 explicit format_int(long value)
++      : str_(format_signed(value)) {}
++  FMT_CONSTEXPR20 explicit format_int(long long value)
++      : str_(format_signed(value)) {}
++  FMT_CONSTEXPR20 explicit format_int(unsigned value)
++      : str_(format_unsigned(value)) {}
++  FMT_CONSTEXPR20 explicit format_int(unsigned long value)
++      : str_(format_unsigned(value)) {}
++  FMT_CONSTEXPR20 explicit format_int(unsigned long long value)
++      : str_(format_unsigned(value)) {}
+ 
+-template <typename Char, size_t SIZE>
+-FMT_NODISCARD auto to_string(const basic_memory_buffer<Char, SIZE>& buf)
+-    -> std::basic_string<Char> {
+-  auto size = buf.size();
+-  detail::assume(size < std::basic_string<Char>().max_size());
+-  return std::basic_string<Char>(buf.data(), size);
+-}
++  /// Returns the number of characters written to the output buffer.
++  FMT_CONSTEXPR20 auto size() const -> size_t {
++    return detail::to_unsigned(buffer_ - str_ + buffer_size - 1);
++  }
+ 
+-FMT_BEGIN_DETAIL_NAMESPACE
++  /// Returns a pointer to the output buffer content. No terminating null
++  /// character is appended.
++  FMT_CONSTEXPR20 auto data() const -> const char* { return str_; }
+ 
+-template <typename Char>
+-void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
+-                typename vformat_args<Char>::type args, locale_ref loc) {
+-  auto out = buffer_appender<Char>(buf);
+-  if (fmt.size() == 2 && equal2(fmt.data(), "{}")) {
+-    auto arg = args.get(0);
+-    if (!arg) error_handler().on_error("argument not found");
+-    visit_format_arg(default_arg_formatter<Char>{out, args, loc}, arg);
+-    return;
++  /// Returns a pointer to the output buffer content with terminating null
++  /// character appended.
++  FMT_CONSTEXPR20 auto c_str() const -> const char* {
++    buffer_[buffer_size - 1] = '\0';
++    return str_;
+   }
+ 
+-  struct format_handler : error_handler {
+-    basic_format_parse_context<Char> parse_context;
+-    buffer_context<Char> context;
+-
+-    format_handler(buffer_appender<Char> p_out, basic_string_view<Char> str,
+-                   basic_format_args<buffer_context<Char>> p_args,
+-                   locale_ref p_loc)
+-        : parse_context(str), context(p_out, p_args, p_loc) {}
++  /// Returns the content of the output buffer as an `std::string`.
++  inline auto str() const -> std::string { return {str_, size()}; }
++};
+ 
+-    void on_text(const Char* begin, const Char* end) {
+-      auto text = basic_string_view<Char>(begin, to_unsigned(end - begin));
+-      context.advance_to(write<Char>(context.out(), text));
+-    }
++#define FMT_STRING_IMPL(s, base)                                              \
++  [] {                                                                        \
++    /* Use the hidden visibility as a workaround for a GCC bug (#1973). */    \
++    /* Use a macro-like name to avoid shadowing warnings. */                  \
++    struct FMT_VISIBILITY("hidden") FMT_COMPILE_STRING : base {               \
++      using char_type = fmt::remove_cvref_t<decltype(s[0])>;                  \
++      constexpr explicit operator fmt::basic_string_view<char_type>() const { \
++        return fmt::detail::compile_string_to_view<char_type>(s);             \
++      }                                                                       \
++    };                                                                        \
++    using FMT_STRING_VIEW =                                                   \
++        fmt::basic_string_view<typename FMT_COMPILE_STRING::char_type>;       \
++    fmt::detail::ignore_unused(FMT_STRING_VIEW(FMT_COMPILE_STRING()));        \
++    return FMT_COMPILE_STRING();                                              \
++  }()
+ 
+-    FMT_CONSTEXPR auto on_arg_id() -> int {
+-      return parse_context.next_arg_id();
+-    }
+-    FMT_CONSTEXPR auto on_arg_id(int id) -> int {
+-      return parse_context.check_arg_id(id), id;
+-    }
+-    FMT_CONSTEXPR auto on_arg_id(basic_string_view<Char> id) -> int {
+-      int arg_id = context.arg_id(id);
+-      if (arg_id < 0) on_error("argument not found");
+-      return arg_id;
+-    }
++/**
++ * Constructs a legacy compile-time format string from a string literal `s`.
++ *
++ * **Example**:
++ *
++ *     // A compile-time error because 'd' is an invalid specifier for strings.
++ *     std::string s = fmt::format(FMT_STRING("{:d}"), "foo");
++ */
++#define FMT_STRING(s) FMT_STRING_IMPL(s, fmt::detail::compile_string)
+ 
+-    FMT_INLINE void on_replacement_field(int id, const Char*) {
+-      auto arg = get_arg(context, id);
+-      context.advance_to(visit_format_arg(
+-          default_arg_formatter<Char>{context.out(), context.args(),
+-                                      context.locale()},
+-          arg));
+-    }
++FMT_API auto vsystem_error(int error_code, string_view fmt, format_args args)
++    -> std::system_error;
+ 
+-    auto on_format_specs(int id, const Char* begin, const Char* end)
+-        -> const Char* {
+-      auto arg = get_arg(context, id);
+-      if (arg.type() == type::custom_type) {
+-        parse_context.advance_to(begin);
+-        visit_format_arg(custom_formatter<Char>{parse_context, context}, arg);
+-        return parse_context.begin();
+-      }
+-      auto specs = detail::dynamic_format_specs<Char>();
+-      begin = parse_format_specs(begin, end, specs, parse_context, arg.type());
+-      detail::handle_dynamic_spec<detail::width_checker>(
+-          specs.width, specs.width_ref, context);
+-      detail::handle_dynamic_spec<detail::precision_checker>(
+-          specs.precision, specs.precision_ref, context);
+-      if (begin == end || *begin != '}')
+-        on_error("missing '}' in format string");
+-      auto f = arg_formatter<Char>{context.out(), specs, context.locale()};
+-      context.advance_to(visit_format_arg(f, arg));
+-      return begin;
+-    }
+-  };
+-  detail::parse_format_string<false>(fmt, format_handler(out, fmt, args, loc));
++/**
++ * Constructs `std::system_error` with a message formatted with
++ * `fmt::format(fmt, args...)`.
++ * `error_code` is a system error code as given by `errno`.
++ *
++ * **Example**:
++ *
++ *     // This throws std::system_error with the description
++ *     //   cannot open file 'madeup': No such file or directory
++ *     // or similar (system message may vary).
++ *     const char* filename = "madeup";
++ *     FILE* file = fopen(filename, "r");
++ *     if (!file)
++ *       throw fmt::system_error(errno, "cannot open file '{}'", filename);
++ */
++template <typename... T>
++auto system_error(int error_code, format_string<T...> fmt, T&&... args)
++    -> std::system_error {
++  return vsystem_error(error_code, fmt.str, vargs<T...>{{args...}});
+ }
+ 
+-#ifndef FMT_HEADER_ONLY
+-extern template FMT_API void vformat_to(buffer<char>&, string_view,
+-                                        typename vformat_args<>::type,
+-                                        locale_ref);
+-extern template FMT_API auto thousands_sep_impl<char>(locale_ref)
+-    -> thousands_sep_result<char>;
+-extern template FMT_API auto thousands_sep_impl<wchar_t>(locale_ref)
+-    -> thousands_sep_result<wchar_t>;
+-extern template FMT_API auto decimal_point_impl(locale_ref) -> char;
+-extern template FMT_API auto decimal_point_impl(locale_ref) -> wchar_t;
+-#endif  // FMT_HEADER_ONLY
+-
+-FMT_END_DETAIL_NAMESPACE
+-
+-#if FMT_USE_USER_DEFINED_LITERALS
+-inline namespace literals {
+ /**
+-  \rst
+-  User-defined literal equivalent of :func:`fmt::arg`.
+-
+-  **Example**::
+-
+-    using namespace fmt::literals;
+-    fmt::print("Elapsed time: {s:.2f} seconds", "s"_a=1.23);
+-  \endrst
++ * Formats an error message for an error returned by an operating system or a
++ * language runtime, for example a file opening error, and writes it to `out`.
++ * The format is the same as the one used by `std::system_error(ec, message)`
++ * where `ec` is `std::error_code(error_code, std::generic_category())`.
++ * It is implementation-defined but normally looks like:
++ *
++ *     <message>: <system-message>
++ *
++ * where `<message>` is the passed message and `<system-message>` is the system
++ * message corresponding to the error code.
++ * `error_code` is a system error code as given by `errno`.
+  */
+-#  if FMT_USE_NONTYPE_TEMPLATE_ARGS
+-template <detail_exported::fixed_string Str> constexpr auto operator""_a() {
+-  using char_t = remove_cvref_t<decltype(Str.data[0])>;
+-  return detail::udl_arg<char_t, sizeof(Str.data) / sizeof(char_t), Str>();
+-}
+-#  else
+-constexpr auto operator"" _a(const char* s, size_t) -> detail::udl_arg<char> {
+-  return {s};
+-}
+-#  endif
+-}  // namespace literals
+-#endif  // FMT_USE_USER_DEFINED_LITERALS
++FMT_API void format_system_error(detail::buffer<char>& out, int error_code,
++                                 const char* message) noexcept;
++
++// Reports a system error without throwing an exception.
++// Can be used to report errors from destructors.
++FMT_API void report_system_error(int error_code, const char* message) noexcept;
+ 
+ template <typename Locale, FMT_ENABLE_IF(detail::is_locale<Locale>::value)>
+ inline auto vformat(const Locale& loc, string_view fmt, format_args args)
+     -> std::string {
+-  return detail::vformat(loc, fmt, args);
++  auto buf = memory_buffer();
++  detail::vformat_to(buf, fmt, args, detail::locale_ref(loc));
++  return {buf.data(), buf.size()};
+ }
+ 
+ template <typename Locale, typename... T,
+           FMT_ENABLE_IF(detail::is_locale<Locale>::value)>
+-inline auto format(const Locale& loc, format_string<T...> fmt, T&&... args)
++FMT_INLINE auto format(const Locale& loc, format_string<T...> fmt, T&&... args)
+     -> std::string {
+-  return fmt::vformat(loc, string_view(fmt), fmt::make_format_args(args...));
++  return vformat(loc, fmt.str, vargs<T...>{{args...}});
+ }
+ 
+ template <typename OutputIt, typename Locale,
+-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value&&
+-                            detail::is_locale<Locale>::value)>
++          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, char>::value)>
+ auto vformat_to(OutputIt out, const Locale& loc, string_view fmt,
+                 format_args args) -> OutputIt {
+-  using detail::get_buffer;
+-  auto&& buf = get_buffer<char>(out);
++  auto&& buf = detail::get_buffer<char>(out);
+   detail::vformat_to(buf, fmt, args, detail::locale_ref(loc));
+   return detail::get_iterator(buf, out);
+ }
+@@ -4683,7 +4169,7 @@ template <typename OutputIt, typename Locale, typename... T,
+                             detail::is_locale<Locale>::value)>
+ FMT_INLINE auto format_to(OutputIt out, const Locale& loc,
+                           format_string<T...> fmt, T&&... args) -> OutputIt {
+-  return vformat_to(out, loc, fmt, fmt::make_format_args(args...));
++  return fmt::vformat_to(out, loc, fmt.str, vargs<T...>{{args...}});
+ }
+ 
+ template <typename Locale, typename... T,
+@@ -4692,40 +4178,67 @@ FMT_NODISCARD FMT_INLINE auto formatted_size(const Locale& loc,
+                                              format_string<T...> fmt,
+                                              T&&... args) -> size_t {
+   auto buf = detail::counting_buffer<>();
+-  detail::vformat_to<char>(buf, fmt, fmt::make_format_args(args...),
+-                           detail::locale_ref(loc));
++  detail::vformat_to(buf, fmt.str, vargs<T...>{{args...}},
++                     detail::locale_ref(loc));
+   return buf.count();
+ }
+ 
+-FMT_END_EXPORT
++FMT_API auto vformat(string_view fmt, format_args args) -> std::string;
+ 
+-template <typename T, typename Char>
+-template <typename FormatContext>
+-FMT_CONSTEXPR FMT_INLINE auto
+-formatter<T, Char,
+-          enable_if_t<detail::type_constant<T, Char>::value !=
+-                      detail::type::custom_type>>::format(const T& val,
+-                                                          FormatContext& ctx)
+-    const -> decltype(ctx.out()) {
+-  if (specs_.width_ref.kind != detail::arg_id_kind::none ||
+-      specs_.precision_ref.kind != detail::arg_id_kind::none) {
+-    auto specs = specs_;
+-    detail::handle_dynamic_spec<detail::width_checker>(specs.width,
+-                                                       specs.width_ref, ctx);
+-    detail::handle_dynamic_spec<detail::precision_checker>(
+-        specs.precision, specs.precision_ref, ctx);
+-    return detail::write<Char>(ctx.out(), val, specs, ctx.locale());
+-  }
+-  return detail::write<Char>(ctx.out(), val, specs_, ctx.locale());
++/**
++ * Formats `args` according to specifications in `fmt` and returns the result
++ * as a string.
++ *
++ * **Example**:
++ *
++ *     #include <fmt/format.h>
++ *     std::string message = fmt::format("The answer is {}.", 42);
++ */
++template <typename... T>
++FMT_NODISCARD FMT_INLINE auto format(format_string<T...> fmt, T&&... args)
++    -> std::string {
++  return vformat(fmt.str, vargs<T...>{{args...}});
++}
++
++/**
++ * Converts `value` to `std::string` using the default format for type `T`.
++ *
++ * **Example**:
++ *
++ *     std::string answer = fmt::to_string(42);
++ */
++template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
++FMT_NODISCARD auto to_string(T value) -> std::string {
++  // The buffer should be large enough to store the number including the sign
++  // or "false" for bool.
++  char buffer[max_of(detail::digits10<T>() + 2, 5)];
++  return {buffer, detail::write<char>(buffer, value)};
++}
++
++template <typename T, FMT_ENABLE_IF(detail::use_format_as<T>::value)>
++FMT_NODISCARD auto to_string(const T& value) -> std::string {
++  return to_string(format_as(value));
++}
++
++template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value &&
++                                    !detail::use_format_as<T>::value)>
++FMT_NODISCARD auto to_string(const T& value) -> std::string {
++  auto buffer = memory_buffer();
++  detail::write<char>(appender(buffer), value);
++  return {buffer.data(), buffer.size()};
+ }
+ 
++FMT_END_EXPORT
+ FMT_END_NAMESPACE
+ 
+ #ifdef FMT_HEADER_ONLY
+ #  define FMT_FUNC inline
+ #  include "format-inl.h"
+-#else
+-#  define FMT_FUNC
++#endif
++
++// Restore _LIBCPP_REMOVE_TRANSITIVE_INCLUDES.
++#ifdef FMT_REMOVE_TRANSITIVE_INCLUDES
++#  undef _LIBCPP_REMOVE_TRANSITIVE_INCLUDES
+ #endif
+ 
+ #endif  // FMT_FORMAT_H_
+diff --git a/include/fmt/os.h b/include/fmt/os.h
+index ec29040..b2cc5e4 100644
+--- a/include/fmt/os.h
++++ b/include/fmt/os.h
+@@ -8,16 +8,18 @@
+ #ifndef FMT_OS_H_
+ #define FMT_OS_H_
+ 
+-#include <cerrno>
+-#include <cstddef>
+-#include <cstdio>
+-#include <system_error>  // std::system_error
++#include "format.h"
+ 
+-#if defined __APPLE__ || defined(__FreeBSD__)
+-#  include <xlocale.h>  // for LC_NUMERIC_MASK on OS X
+-#endif
++#ifndef FMT_MODULE
++#  include <cerrno>
++#  include <cstddef>
++#  include <cstdio>
++#  include <system_error>  // std::system_error
+ 
+-#include "format.h"
++#  if FMT_HAS_INCLUDE(<xlocale.h>)
++#    include <xlocale.h>  // LC_NUMERIC_MASK on macOS
++#  endif
++#endif  // FMT_MODULE
+ 
+ #ifndef FMT_USE_FCNTL
+ // UWP doesn't provide _pipe.
+@@ -46,6 +48,7 @@
+ 
+ // Calls to system functions are wrapped in FMT_SYSTEM for testability.
+ #ifdef FMT_SYSTEM
++#  define FMT_HAS_SYSTEM
+ #  define FMT_POSIX_CALL(call) FMT_SYSTEM(call)
+ #else
+ #  define FMT_SYSTEM(call) ::call
+@@ -74,47 +77,34 @@ FMT_BEGIN_NAMESPACE
+ FMT_BEGIN_EXPORT
+ 
+ /**
+-  \rst
+-  A reference to a null-terminated string. It can be constructed from a C
+-  string or ``std::string``.
+-
+-  You can use one of the following type aliases for common character types:
+-
+-  +---------------+-----------------------------+
+-  | Type          | Definition                  |
+-  +===============+=============================+
+-  | cstring_view  | basic_cstring_view<char>    |
+-  +---------------+-----------------------------+
+-  | wcstring_view | basic_cstring_view<wchar_t> |
+-  +---------------+-----------------------------+
+-
+-  This class is most useful as a parameter type to allow passing
+-  different types of strings to a function, for example::
+-
+-    template <typename... Args>
+-    std::string format(cstring_view format_str, const Args & ... args);
+-
+-    format("{}", 42);
+-    format(std::string("{}"), 42);
+-  \endrst
++ * A reference to a null-terminated string. It can be constructed from a C
++ * string or `std::string`.
++ *
++ * You can use one of the following type aliases for common character types:
++ *
++ * +---------------+-----------------------------+
++ * | Type          | Definition                  |
++ * +===============+=============================+
++ * | cstring_view  | basic_cstring_view<char>    |
++ * +---------------+-----------------------------+
++ * | wcstring_view | basic_cstring_view<wchar_t> |
++ * +---------------+-----------------------------+
++ *
++ * This class is most useful as a parameter type for functions that wrap C APIs.
+  */
+ template <typename Char> class basic_cstring_view {
+  private:
+   const Char* data_;
+ 
+  public:
+-  /** Constructs a string reference object from a C string. */
++  /// Constructs a string reference object from a C string.
+   basic_cstring_view(const Char* s) : data_(s) {}
+ 
+-  /**
+-    \rst
+-    Constructs a string reference from an ``std::string`` object.
+-    \endrst
+-   */
++  /// Constructs a string reference from an `std::string` object.
+   basic_cstring_view(const std::basic_string<Char>& s) : data_(s.c_str()) {}
+ 
+-  /** Returns the pointer to a C string. */
+-  const Char* c_str() const { return data_; }
++  /// Returns the pointer to a C string.
++  auto c_str() const -> const Char* { return data_; }
+ };
+ 
+ using cstring_view = basic_cstring_view<char>;
+@@ -123,53 +113,50 @@ using wcstring_view = basic_cstring_view<wchar_t>;
+ #ifdef _WIN32
+ FMT_API const std::error_category& system_category() noexcept;
+ 
+-FMT_BEGIN_DETAIL_NAMESPACE
++namespace detail {
+ FMT_API void format_windows_error(buffer<char>& out, int error_code,
+                                   const char* message) noexcept;
+-FMT_END_DETAIL_NAMESPACE
++}
+ 
+-FMT_API std::system_error vwindows_error(int error_code, string_view format_str,
++FMT_API std::system_error vwindows_error(int error_code, string_view fmt,
+                                          format_args args);
+ 
+ /**
+- \rst
+- Constructs a :class:`std::system_error` object with the description
+- of the form
+-
+- .. parsed-literal::
+-   *<message>*: *<system-message>*
+-
+- where *<message>* is the formatted message and *<system-message>* is the
+- system message corresponding to the error code.
+- *error_code* is a Windows error code as given by ``GetLastError``.
+- If *error_code* is not a valid error code such as -1, the system message
+- will look like "error -1".
+-
+- **Example**::
+-
+-   // This throws a system_error with the description
+-   //   cannot open file 'madeup': The system cannot find the file specified.
+-   // or similar (system message may vary).
+-   const char *filename = "madeup";
+-   LPOFSTRUCT of = LPOFSTRUCT();
+-   HFILE file = OpenFile(filename, &of, OF_READ);
+-   if (file == HFILE_ERROR) {
+-     throw fmt::windows_error(GetLastError(),
+-                              "cannot open file '{}'", filename);
+-   }
+- \endrst
+-*/
+-template <typename... Args>
+-std::system_error windows_error(int error_code, string_view message,
+-                                const Args&... args) {
+-  return vwindows_error(error_code, message, fmt::make_format_args(args...));
++ * Constructs a `std::system_error` object with the description of the form
++ *
++ *     <message>: <system-message>
++ *
++ * where `<message>` is the formatted message and `<system-message>` is the
++ * system message corresponding to the error code.
++ * `error_code` is a Windows error code as given by `GetLastError`.
++ * If `error_code` is not a valid error code such as -1, the system message
++ * will look like "error -1".
++ *
++ * **Example**:
++ *
++ *     // This throws a system_error with the description
++ *     //   cannot open file 'madeup': The system cannot find the file
++ * specified.
++ *     // or similar (system message may vary).
++ *     const char *filename = "madeup";
++ *     LPOFSTRUCT of = LPOFSTRUCT();
++ *     HFILE file = OpenFile(filename, &of, OF_READ);
++ *     if (file == HFILE_ERROR) {
++ *       throw fmt::windows_error(GetLastError(),
++ *                                "cannot open file '{}'", filename);
++ *     }
++ */
++template <typename... T>
++auto windows_error(int error_code, string_view message, const T&... args)
++    -> std::system_error {
++  return vwindows_error(error_code, message, vargs<T...>{{args...}});
+ }
+ 
+ // Reports a Windows error without throwing an exception.
+ // Can be used to report errors from destructors.
+ FMT_API void report_windows_error(int error_code, const char* message) noexcept;
+ #else
+-inline const std::error_category& system_category() noexcept {
++inline auto system_category() noexcept -> const std::error_category& {
+   return std::system_category();
+ }
+ #endif  // _WIN32
+@@ -177,8 +164,8 @@ inline const std::error_category& system_category() noexcept {
+ // std::system is not available on some platforms such as iOS (#2248).
+ #ifdef __OSX__
+ template <typename S, typename... Args, typename Char = char_t<S>>
+-void say(const S& format_str, Args&&... args) {
+-  std::system(format("say \"{}\"", format(format_str, args...)).c_str());
++void say(const S& fmt, Args&&... args) {
++  std::system(format("say \"{}\"", format(fmt, args...)).c_str());
+ }
+ #endif
+ 
+@@ -189,24 +176,24 @@ class buffered_file {
+ 
+   friend class file;
+ 
+-  explicit buffered_file(FILE* f) : file_(f) {}
++  inline explicit buffered_file(FILE* f) : file_(f) {}
+ 
+  public:
+   buffered_file(const buffered_file&) = delete;
+   void operator=(const buffered_file&) = delete;
+ 
+   // Constructs a buffered_file object which doesn't represent any file.
+-  buffered_file() noexcept : file_(nullptr) {}
++  inline buffered_file() noexcept : file_(nullptr) {}
+ 
+   // Destroys the object closing the file it represents if any.
+   FMT_API ~buffered_file() noexcept;
+ 
+  public:
+-  buffered_file(buffered_file&& other) noexcept : file_(other.file_) {
++  inline buffered_file(buffered_file&& other) noexcept : file_(other.file_) {
+     other.file_ = nullptr;
+   }
+ 
+-  buffered_file& operator=(buffered_file&& other) {
++  inline auto operator=(buffered_file&& other) -> buffered_file& {
+     close();
+     file_ = other.file_;
+     other.file_ = nullptr;
+@@ -220,21 +207,20 @@ class buffered_file {
+   FMT_API void close();
+ 
+   // Returns the pointer to a FILE object representing this file.
+-  FILE* get() const noexcept { return file_; }
+-
+-  FMT_API int descriptor() const;
++  inline auto get() const noexcept -> FILE* { return file_; }
+ 
+-  void vprint(string_view format_str, format_args args) {
+-    fmt::vprint(file_, format_str, args);
+-  }
++  FMT_API auto descriptor() const -> int;
+ 
+-  template <typename... Args>
+-  inline void print(string_view format_str, const Args&... args) {
+-    vprint(format_str, fmt::make_format_args(args...));
++  template <typename... T>
++  inline void print(string_view fmt, const T&... args) {
++    fmt::vargs<T...> vargs = {{args...}};
++    detail::is_locking<T...>() ? fmt::vprint_buffered(file_, fmt, vargs)
++                               : fmt::vprint(file_, fmt, vargs);
+   }
+ };
+ 
+ #if FMT_USE_FCNTL
++
+ // A file. Closed file is represented by a file object with descriptor -1.
+ // Methods that are not declared with noexcept may throw
+ // fmt::system_error in case of failure. Note that some errors such as
+@@ -248,6 +234,8 @@ class FMT_API file {
+   // Constructs a file object with a given descriptor.
+   explicit file(int fd) : fd_(fd) {}
+ 
++  friend struct pipe;
++
+  public:
+   // Possible values for the oflag argument to the constructor.
+   enum {
+@@ -260,7 +248,7 @@ class FMT_API file {
+   };
+ 
+   // Constructs a file object which doesn't represent any file.
+-  file() noexcept : fd_(-1) {}
++  inline file() noexcept : fd_(-1) {}
+ 
+   // Opens a file and constructs a file object representing this file.
+   file(cstring_view path, int oflag);
+@@ -269,10 +257,10 @@ class FMT_API file {
+   file(const file&) = delete;
+   void operator=(const file&) = delete;
+ 
+-  file(file&& other) noexcept : fd_(other.fd_) { other.fd_ = -1; }
++  inline file(file&& other) noexcept : fd_(other.fd_) { other.fd_ = -1; }
+ 
+   // Move assignment is not noexcept because close may throw.
+-  file& operator=(file&& other) {
++  inline auto operator=(file&& other) -> file& {
+     close();
+     fd_ = other.fd_;
+     other.fd_ = -1;
+@@ -283,24 +271,24 @@ class FMT_API file {
+   ~file() noexcept;
+ 
+   // Returns the file descriptor.
+-  int descriptor() const noexcept { return fd_; }
++  inline auto descriptor() const noexcept -> int { return fd_; }
+ 
+   // Closes the file.
+   void close();
+ 
+   // Returns the file size. The size has signed type for consistency with
+   // stat::st_size.
+-  long long size() const;
++  auto size() const -> long long;
+ 
+   // Attempts to read count bytes from the file into the specified buffer.
+-  size_t read(void* buffer, size_t count);
++  auto read(void* buffer, size_t count) -> size_t;
+ 
+   // Attempts to write count bytes from the specified buffer to the file.
+-  size_t write(const void* buffer, size_t count);
++  auto write(const void* buffer, size_t count) -> size_t;
+ 
+   // Duplicates a file descriptor with the dup function and returns
+   // the duplicate as a file object.
+-  static file dup(int fd);
++  static auto dup(int fd) -> file;
+ 
+   // Makes fd be the copy of this file descriptor, closing fd first if
+   // necessary.
+@@ -310,13 +298,9 @@ class FMT_API file {
+   // necessary.
+   void dup2(int fd, std::error_code& ec) noexcept;
+ 
+-  // Creates a pipe setting up read_end and write_end file objects for reading
+-  // and writing respectively.
+-  static void pipe(file& read_end, file& write_end);
+-
+   // Creates a buffered_file object associated with this file and detaches
+   // this file object from the file.
+-  buffered_file fdopen(const char* mode);
++  auto fdopen(const char* mode) -> buffered_file;
+ 
+ #  if defined(_WIN32) && !defined(__MINGW32__)
+   // Opens a file and constructs a file object representing this file by
+@@ -325,15 +309,24 @@ class FMT_API file {
+ #  endif
+ };
+ 
++struct FMT_API pipe {
++  file read_end;
++  file write_end;
++
++  // Creates a pipe setting up read_end and write_end file objects for reading
++  // and writing respectively.
++  pipe();
++};
++
+ // Returns the memory page size.
+-long getpagesize();
++auto getpagesize() -> long;
+ 
+-FMT_BEGIN_DETAIL_NAMESPACE
++namespace detail {
+ 
+ struct buffer_size {
+-  buffer_size() = default;
++  constexpr buffer_size() = default;
+   size_t value = 0;
+-  buffer_size operator=(size_t val) const {
++  FMT_CONSTEXPR auto operator=(size_t val) const -> buffer_size {
+     auto bs = buffer_size();
+     bs.value = val;
+     return bs;
+@@ -344,7 +337,7 @@ struct ostream_params {
+   int oflag = file::WRONLY | file::CREATE | file::TRUNC;
+   size_t buffer_size = BUFSIZ > 32768 ? BUFSIZ : 32768;
+ 
+-  ostream_params() {}
++  constexpr ostream_params() {}
+ 
+   template <typename... T>
+   ostream_params(T... params, int new_oflag) : ostream_params(params...) {
+@@ -365,82 +358,65 @@ struct ostream_params {
+ #  endif
+ };
+ 
+-class file_buffer final : public buffer<char> {
++}  // namespace detail
++
++FMT_INLINE_VARIABLE constexpr auto buffer_size = detail::buffer_size();
++
++/// A fast buffered output stream for writing from a single thread. Writing from
++/// multiple threads without external synchronization may result in a data race.
++class FMT_API ostream : private detail::buffer<char> {
++ private:
+   file file_;
+ 
+-  FMT_API void grow(size_t) override;
++  ostream(cstring_view path, const detail::ostream_params& params);
++
++  static void grow(buffer<char>& buf, size_t);
+ 
+  public:
+-  FMT_API file_buffer(cstring_view path, const ostream_params& params);
+-  FMT_API file_buffer(file_buffer&& other);
+-  FMT_API ~file_buffer();
++  ostream(ostream&& other) noexcept;
++  ~ostream();
+ 
+-  void flush() {
++  operator writer() {
++    detail::buffer<char>& buf = *this;
++    return buf;
++  }
++
++  inline void flush() {
+     if (size() == 0) return;
+     file_.write(data(), size() * sizeof(data()[0]));
+     clear();
+   }
+ 
+-  void close() {
++  template <typename... T>
++  friend auto output_file(cstring_view path, T... params) -> ostream;
++
++  inline void close() {
+     flush();
+     file_.close();
+   }
+-};
+-
+-FMT_END_DETAIL_NAMESPACE
+-
+-// Added {} below to work around default constructor error known to
+-// occur in Xcode versions 7.2.1 and 8.2.1.
+-constexpr detail::buffer_size buffer_size{};
+-
+-/** A fast output stream which is not thread-safe. */
+-class FMT_API ostream {
+- private:
+-  FMT_MSC_WARNING(suppress : 4251)
+-  detail::file_buffer buffer_;
+ 
+-  ostream(cstring_view path, const detail::ostream_params& params)
+-      : buffer_(path, params) {}
+-
+- public:
+-  ostream(ostream&& other) : buffer_(std::move(other.buffer_)) {}
+-
+-  ~ostream();
+-
+-  void flush() { buffer_.flush(); }
+-
+-  template <typename... T>
+-  friend ostream output_file(cstring_view path, T... params);
+-
+-  void close() { buffer_.close(); }
+-
+-  /**
+-    Formats ``args`` according to specifications in ``fmt`` and writes the
+-    output to the file.
+-   */
++  /// Formats `args` according to specifications in `fmt` and writes the
++  /// output to the file.
+   template <typename... T> void print(format_string<T...> fmt, T&&... args) {
+-    vformat_to(detail::buffer_appender<char>(buffer_), fmt,
+-               fmt::make_format_args(args...));
++    vformat_to(appender(*this), fmt.str, vargs<T...>{{args...}});
+   }
+ };
+ 
+ /**
+-  \rst
+-  Opens a file for writing. Supported parameters passed in *params*:
+-
+-  * ``<integer>``: Flags passed to `open
+-    <https://pubs.opengroup.org/onlinepubs/007904875/functions/open.html>`_
+-    (``file::WRONLY | file::CREATE | file::TRUNC`` by default)
+-  * ``buffer_size=<integer>``: Output buffer size
+-
+-  **Example**::
+-
+-    auto out = fmt::output_file("guide.txt");
+-    out.print("Don't {}", "Panic");
+-  \endrst
++ * Opens a file for writing. Supported parameters passed in `params`:
++ *
++ * - `<integer>`: Flags passed to [open](
++ *   https://pubs.opengroup.org/onlinepubs/007904875/functions/open.html)
++ *   (`file::WRONLY | file::CREATE | file::TRUNC` by default)
++ * - `buffer_size=<integer>`: Output buffer size
++ *
++ * **Example**:
++ *
++ *     auto out = fmt::output_file("guide.txt");
++ *     out.print("Don't {}", "Panic");
+  */
+ template <typename... T>
+-inline ostream output_file(cstring_view path, T... params) {
++inline auto output_file(cstring_view path, T... params) -> ostream {
+   return {path, detail::ostream_params(params...)};
+ }
+ #endif  // FMT_USE_FCNTL
+diff --git a/include/fmt/ostream.h b/include/fmt/ostream.h
+index a112fe7..71fd6c8 100644
+--- a/include/fmt/ostream.h
++++ b/include/fmt/ostream.h
+@@ -8,19 +8,29 @@
+ #ifndef FMT_OSTREAM_H_
+ #define FMT_OSTREAM_H_
+ 
+-#include <fstream>  // std::filebuf
++#ifndef FMT_MODULE
++#  include <fstream>  // std::filebuf
++#endif
+ 
+-#if defined(_WIN32) && defined(__GLIBCXX__)
+-#  include <ext/stdio_filebuf.h>
+-#  include <ext/stdio_sync_filebuf.h>
+-#elif defined(_WIN32) && defined(_LIBCPP_VERSION)
+-#  include <__std_stream>
++#ifdef _WIN32
++#  ifdef __GLIBCXX__
++#    include <ext/stdio_filebuf.h>
++#    include <ext/stdio_sync_filebuf.h>
++#  endif
++#  include <io.h>
+ #endif
+ 
+-#include "format.h"
++#include "chrono.h"  // formatbuf
+ 
+-FMT_BEGIN_NAMESPACE
++#ifdef _MSVC_STL_UPDATE
++#  define FMT_MSVC_STL_UPDATE _MSVC_STL_UPDATE
++#elif defined(_MSC_VER) && _MSC_VER < 1912  // VS 15.5
++#  define FMT_MSVC_STL_UPDATE _MSVC_LANG
++#else
++#  define FMT_MSVC_STL_UPDATE 0
++#endif
+ 
++FMT_BEGIN_NAMESPACE
+ namespace detail {
+ 
+ // Generate a unique explicit instantion in every translation unit using a tag
+@@ -33,49 +43,18 @@ class file_access {
+   friend auto get_file(BufType& obj) -> FILE* { return obj.*FileMemberPtr; }
+ };
+ 
+-#if FMT_MSC_VERSION
++#if FMT_MSVC_STL_UPDATE
+ template class file_access<file_access_tag, std::filebuf,
+                            &std::filebuf::_Myfile>;
+ auto get_file(std::filebuf&) -> FILE*;
+-#elif defined(_WIN32) && defined(_LIBCPP_VERSION)
+-template class file_access<file_access_tag, std::__stdoutbuf<char>,
+-                           &std::__stdoutbuf<char>::__file_>;
+-auto get_file(std::__stdoutbuf<char>&) -> FILE*;
+-#endif
+-
+-inline bool write_ostream_unicode(std::ostream& os, fmt::string_view data) {
+-#if FMT_MSC_VERSION
+-  if (auto* buf = dynamic_cast<std::filebuf*>(os.rdbuf()))
+-    if (FILE* f = get_file(*buf)) return write_console(f, data);
+-#elif defined(_WIN32) && defined(__GLIBCXX__)
+-  auto* rdbuf = os.rdbuf();
+-  FILE* c_file;
+-  if (auto* sfbuf = dynamic_cast<__gnu_cxx::stdio_sync_filebuf<char>*>(rdbuf))
+-    c_file = sfbuf->file();
+-  else if (auto* fbuf = dynamic_cast<__gnu_cxx::stdio_filebuf<char>*>(rdbuf))
+-    c_file = fbuf->file();
+-  else
+-    return false;
+-  if (c_file) return write_console(c_file, data);
+-#elif defined(_WIN32) && defined(_LIBCPP_VERSION)
+-  if (auto* buf = dynamic_cast<std::__stdoutbuf<char>*>(os.rdbuf()))
+-    if (FILE* f = get_file(*buf)) return write_console(f, data);
+-#else
+-  ignore_unused(os, data);
+ #endif
+-  return false;
+-}
+-inline bool write_ostream_unicode(std::wostream&,
+-                                  fmt::basic_string_view<wchar_t>) {
+-  return false;
+-}
+ 
+ // Write the content of buf to os.
+ // It is a separate function rather than a part of vprint to simplify testing.
+ template <typename Char>
+ void write_buffer(std::basic_ostream<Char>& os, buffer<Char>& buf) {
+   const Char* buf_data = buf.data();
+-  using unsigned_streamsize = std::make_unsigned<std::streamsize>::type;
++  using unsigned_streamsize = make_unsigned_t<std::streamsize>;
+   unsigned_streamsize size = buf.size();
+   unsigned_streamsize max_size = to_unsigned(max_value<std::streamsize>());
+   do {
+@@ -86,20 +65,9 @@ void write_buffer(std::basic_ostream<Char>& os, buffer<Char>& buf) {
+   } while (size != 0);
+ }
+ 
+-template <typename Char, typename T>
+-void format_value(buffer<Char>& buf, const T& value,
+-                  locale_ref loc = locale_ref()) {
+-  auto&& format_buf = formatbuf<std::basic_streambuf<Char>>(buf);
+-  auto&& output = std::basic_ostream<Char>(&format_buf);
+-#if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
+-  if (loc) output.imbue(loc.get<std::locale>());
+-#endif
+-  output << value;
+-  output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
+-}
+-
+-template <typename T> struct streamed_view { const T& value; };
+-
++template <typename T> struct streamed_view {
++  const T& value;
++};
+ }  // namespace detail
+ 
+ // Formats an object of type T that has an overloaded ostream operator<<.
+@@ -107,11 +75,14 @@ template <typename Char>
+ struct basic_ostream_formatter : formatter<basic_string_view<Char>, Char> {
+   void set_debug_format() = delete;
+ 
+-  template <typename T, typename OutputIt>
+-  auto format(const T& value, basic_format_context<OutputIt, Char>& ctx) const
+-      -> OutputIt {
++  template <typename T, typename Context>
++  auto format(const T& value, Context& ctx) const -> decltype(ctx.out()) {
+     auto buffer = basic_memory_buffer<Char>();
+-    detail::format_value(buffer, value, ctx.locale());
++    auto&& formatbuf = detail::formatbuf<std::basic_streambuf<Char>>(buffer);
++    auto&& output = std::basic_ostream<Char>(&formatbuf);
++    output.imbue(std::locale::classic());  // The default is always unlocalized.
++    output << value;
++    output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
+     return formatter<basic_string_view<Char>, Char>::format(
+         {buffer.data(), buffer.size()}, ctx);
+   }
+@@ -122,73 +93,67 @@ using ostream_formatter = basic_ostream_formatter<char>;
+ template <typename T, typename Char>
+ struct formatter<detail::streamed_view<T>, Char>
+     : basic_ostream_formatter<Char> {
+-  template <typename OutputIt>
+-  auto format(detail::streamed_view<T> view,
+-              basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
++  template <typename Context>
++  auto format(detail::streamed_view<T> view, Context& ctx) const
++      -> decltype(ctx.out()) {
+     return basic_ostream_formatter<Char>::format(view.value, ctx);
+   }
+ };
+ 
+ /**
+-  \rst
+-  Returns a view that formats `value` via an ostream ``operator<<``.
+-
+-  **Example**::
+-
+-    fmt::print("Current thread id: {}\n",
+-               fmt::streamed(std::this_thread::get_id()));
+-  \endrst
++ * Returns a view that formats `value` via an ostream `operator<<`.
++ *
++ * **Example**:
++ *
++ *     fmt::print("Current thread id: {}\n",
++ *                fmt::streamed(std::this_thread::get_id()));
+  */
+ template <typename T>
+-auto streamed(const T& value) -> detail::streamed_view<T> {
++constexpr auto streamed(const T& value) -> detail::streamed_view<T> {
+   return {value};
+ }
+ 
+-namespace detail {
+-
+-inline void vprint_directly(std::ostream& os, string_view format_str,
+-                            format_args args) {
++inline void vprint(std::ostream& os, string_view fmt, format_args args) {
+   auto buffer = memory_buffer();
+-  detail::vformat_to(buffer, format_str, args);
+-  detail::write_buffer(os, buffer);
+-}
+-
+-}  // namespace detail
+-
+-FMT_EXPORT template <typename Char>
+-void vprint(std::basic_ostream<Char>& os,
+-            basic_string_view<type_identity_t<Char>> format_str,
+-            basic_format_args<buffer_context<type_identity_t<Char>>> args) {
+-  auto buffer = basic_memory_buffer<Char>();
+-  detail::vformat_to(buffer, format_str, args);
+-  if (detail::write_ostream_unicode(os, {buffer.data(), buffer.size()})) return;
++  detail::vformat_to(buffer, fmt, args);
++  FILE* f = nullptr;
++#if FMT_MSVC_STL_UPDATE && FMT_USE_RTTI
++  if (auto* buf = dynamic_cast<std::filebuf*>(os.rdbuf()))
++    f = detail::get_file(*buf);
++#elif defined(_WIN32) && defined(__GLIBCXX__) && FMT_USE_RTTI
++  auto* rdbuf = os.rdbuf();
++  if (auto* sfbuf = dynamic_cast<__gnu_cxx::stdio_sync_filebuf<char>*>(rdbuf))
++    f = sfbuf->file();
++  else if (auto* fbuf = dynamic_cast<__gnu_cxx::stdio_filebuf<char>*>(rdbuf))
++    f = fbuf->file();
++#endif
++#ifdef _WIN32
++  if (f) {
++    int fd = _fileno(f);
++    if (_isatty(fd)) {
++      os.flush();
++      if (detail::write_console(fd, {buffer.data(), buffer.size()})) return;
++    }
++  }
++#endif
++  detail::ignore_unused(f);
+   detail::write_buffer(os, buffer);
+ }
+ 
+ /**
+-  \rst
+-  Prints formatted data to the stream *os*.
+-
+-  **Example**::
+-
+-    fmt::print(cerr, "Don't {}!", "panic");
+-  \endrst
++ * Prints formatted data to the stream `os`.
++ *
++ * **Example**:
++ *
++ *     fmt::print(cerr, "Don't {}!", "panic");
+  */
+ FMT_EXPORT template <typename... T>
+ void print(std::ostream& os, format_string<T...> fmt, T&&... args) {
+-  const auto& vargs = fmt::make_format_args(args...);
+-  if (detail::is_utf8())
+-    vprint(os, fmt, vargs);
+-  else
+-    detail::vprint_directly(os, fmt, vargs);
+-}
+-
+-FMT_EXPORT
+-template <typename... Args>
+-void print(std::wostream& os,
+-           basic_format_string<wchar_t, type_identity_t<Args>...> fmt,
+-           Args&&... args) {
+-  vprint(os, fmt, fmt::make_format_args<buffer_context<wchar_t>>(args...));
++  fmt::vargs<T...> vargs = {{args...}};
++  if (detail::const_check(detail::use_utf8)) return vprint(os, fmt.str, vargs);
++  auto buffer = memory_buffer();
++  detail::vformat_to(buffer, fmt.str, vargs);
++  detail::write_buffer(os, buffer);
+ }
+ 
+ FMT_EXPORT template <typename... T>
+@@ -196,14 +161,6 @@ void println(std::ostream& os, format_string<T...> fmt, T&&... args) {
+   fmt::print(os, "{}\n", fmt::format(fmt, std::forward<T>(args)...));
+ }
+ 
+-FMT_EXPORT
+-template <typename... Args>
+-void println(std::wostream& os,
+-             basic_format_string<wchar_t, type_identity_t<Args>...> fmt,
+-             Args&&... args) {
+-  print(os, L"{}\n", fmt::format(fmt, std::forward<Args>(args)...));
+-}
+-
+ FMT_END_NAMESPACE
+ 
+ #endif  // FMT_OSTREAM_H_
+diff --git a/include/fmt/printf.h b/include/fmt/printf.h
+index 5d1aeb7..e726840 100644
+--- a/include/fmt/printf.h
++++ b/include/fmt/printf.h
+@@ -8,60 +8,78 @@
+ #ifndef FMT_PRINTF_H_
+ #define FMT_PRINTF_H_
+ 
+-#include <algorithm>  // std::max
+-#include <limits>     // std::numeric_limits
++#ifndef FMT_MODULE
++#  include <algorithm>  // std::max
++#  include <limits>     // std::numeric_limits
++#endif
+ 
+ #include "format.h"
+ 
+ FMT_BEGIN_NAMESPACE
+ FMT_BEGIN_EXPORT
+ 
+-template <typename T> struct printf_formatter { printf_formatter() = delete; };
++template <typename T> struct printf_formatter {
++  printf_formatter() = delete;
++};
+ 
+ template <typename Char> class basic_printf_context {
+  private:
+-  detail::buffer_appender<Char> out_;
++  basic_appender<Char> out_;
+   basic_format_args<basic_printf_context> args_;
+ 
++  static_assert(std::is_same<Char, char>::value ||
++                    std::is_same<Char, wchar_t>::value,
++                "Unsupported code unit type.");
++
+  public:
+   using char_type = Char;
+-  using parse_context_type = basic_format_parse_context<Char>;
++  using parse_context_type = parse_context<Char>;
+   template <typename T> using formatter_type = printf_formatter<T>;
++  enum { builtin_types = 1 };
+ 
+-  /**
+-    \rst
+-    Constructs a ``printf_context`` object. References to the arguments are
+-    stored in the context object so make sure they have appropriate lifetimes.
+-    \endrst
+-   */
+-  basic_printf_context(detail::buffer_appender<Char> out,
++  /// Constructs a `printf_context` object. References to the arguments are
++  /// stored in the context object so make sure they have appropriate lifetimes.
++  basic_printf_context(basic_appender<Char> out,
+                        basic_format_args<basic_printf_context> args)
+       : out_(out), args_(args) {}
+ 
+-  auto out() -> detail::buffer_appender<Char> { return out_; }
+-  void advance_to(detail::buffer_appender<Char>) {}
++  auto out() -> basic_appender<Char> { return out_; }
++  void advance_to(basic_appender<Char>) {}
+ 
+   auto locale() -> detail::locale_ref { return {}; }
+ 
+   auto arg(int id) const -> basic_format_arg<basic_printf_context> {
+     return args_.get(id);
+   }
++};
+ 
+-  FMT_CONSTEXPR void on_error(const char* message) {
+-    detail::error_handler().on_error(message);
++namespace detail {
++
++// Return the result via the out param to workaround gcc bug 77539.
++template <bool IS_CONSTEXPR, typename T, typename Ptr = const T*>
++FMT_CONSTEXPR auto find(Ptr first, Ptr last, T value, Ptr& out) -> bool {
++  for (out = first; out != last; ++out) {
++    if (*out == value) return true;
+   }
+-};
++  return false;
++}
+ 
+-FMT_BEGIN_DETAIL_NAMESPACE
++template <>
++inline auto find<false, char>(const char* first, const char* last, char value,
++                              const char*& out) -> bool {
++  out =
++      static_cast<const char*>(memchr(first, value, to_unsigned(last - first)));
++  return out != nullptr;
++}
+ 
+ // Checks if a value fits in int - used to avoid warnings about comparing
+ // signed and unsigned integers.
+ template <bool IsSigned> struct int_checker {
+   template <typename T> static auto fits_in_int(T value) -> bool {
+-    unsigned max = max_value<int>();
++    unsigned max = to_unsigned(max_value<int>());
+     return value <= max;
+   }
+-  static auto fits_in_int(bool) -> bool { return true; }
++  inline static auto fits_in_int(bool) -> bool { return true; }
+ };
+ 
+ template <> struct int_checker<true> {
+@@ -69,20 +87,20 @@ template <> struct int_checker<true> {
+     return value >= (std::numeric_limits<int>::min)() &&
+            value <= max_value<int>();
+   }
+-  static auto fits_in_int(int) -> bool { return true; }
++  inline static auto fits_in_int(int) -> bool { return true; }
+ };
+ 
+ struct printf_precision_handler {
+   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
+   auto operator()(T value) -> int {
+     if (!int_checker<std::numeric_limits<T>::is_signed>::fits_in_int(value))
+-      throw_format_error("number is too big");
++      report_error("number is too big");
+     return (std::max)(static_cast<int>(value), 0);
+   }
+ 
+   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
+   auto operator()(T) -> int {
+-    throw_format_error("precision is not integer");
++    report_error("precision is not integer");
+     return 0;
+   }
+ };
+@@ -102,7 +120,9 @@ struct is_zero_int {
+ 
+ template <typename T> struct make_unsigned_or_bool : std::make_unsigned<T> {};
+ 
+-template <> struct make_unsigned_or_bool<bool> { using type = bool; };
++template <> struct make_unsigned_or_bool<bool> {
++  using type = bool;
++};
+ 
+ template <typename T, typename Context> class arg_converter {
+  private:
+@@ -125,25 +145,19 @@ template <typename T, typename Context> class arg_converter {
+     using target_type = conditional_t<std::is_same<T, void>::value, U, T>;
+     if (const_check(sizeof(target_type) <= sizeof(int))) {
+       // Extra casts are used to silence warnings.
+-      if (is_signed) {
+-        auto n = static_cast<int>(static_cast<target_type>(value));
+-        arg_ = detail::make_arg<Context>(n);
+-      } else {
+-        using unsigned_type = typename make_unsigned_or_bool<target_type>::type;
+-        auto n = static_cast<unsigned>(static_cast<unsigned_type>(value));
+-        arg_ = detail::make_arg<Context>(n);
+-      }
++      using unsigned_type = typename make_unsigned_or_bool<target_type>::type;
++      if (is_signed)
++        arg_ = static_cast<int>(static_cast<target_type>(value));
++      else
++        arg_ = static_cast<unsigned>(static_cast<unsigned_type>(value));
+     } else {
+-      if (is_signed) {
+-        // glibc's printf doesn't sign extend arguments of smaller types:
+-        //   std::printf("%lld", -42);  // prints "4294967254"
+-        // but we don't have to do the same because it's a UB.
+-        auto n = static_cast<long long>(value);
+-        arg_ = detail::make_arg<Context>(n);
+-      } else {
+-        auto n = static_cast<typename make_unsigned_or_bool<U>::type>(value);
+-        arg_ = detail::make_arg<Context>(n);
+-      }
++      // glibc's printf doesn't sign extend arguments of smaller types:
++      //   std::printf("%lld", -42);  // prints "4294967254"
++      // but we don't have to do the same because it's a UB.
++      if (is_signed)
++        arg_ = static_cast<long long>(value);
++      else
++        arg_ = static_cast<typename make_unsigned_or_bool<U>::type>(value);
+     }
+   }
+ 
+@@ -157,7 +171,7 @@ template <typename T, typename Context> class arg_converter {
+ // unsigned).
+ template <typename T, typename Context, typename Char>
+ void convert_arg(basic_format_arg<Context>& arg, Char type) {
+-  visit_format_arg(arg_converter<T, Context>(arg, type), arg);
++  arg.visit(arg_converter<T, Context>(arg, type));
+ }
+ 
+ // Converts an integer argument to char for printf.
+@@ -170,8 +184,7 @@ template <typename Context> class char_converter {
+ 
+   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
+   void operator()(T value) {
+-    auto c = static_cast<typename Context::char_type>(value);
+-    arg_ = detail::make_arg<Context>(c);
++    arg_ = static_cast<typename Context::char_type>(value);
+   }
+ 
+   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
+@@ -187,28 +200,28 @@ template <typename Char> struct get_cstring {
+ 
+ // Checks if an argument is a valid printf width specifier and sets
+ // left alignment if it is negative.
+-template <typename Char> class printf_width_handler {
++class printf_width_handler {
+  private:
+-  format_specs<Char>& specs_;
++  format_specs& specs_;
+ 
+  public:
+-  explicit printf_width_handler(format_specs<Char>& specs) : specs_(specs) {}
++  inline explicit printf_width_handler(format_specs& specs) : specs_(specs) {}
+ 
+   template <typename T, FMT_ENABLE_IF(std::is_integral<T>::value)>
+   auto operator()(T value) -> unsigned {
+     auto width = static_cast<uint32_or_64_or_128_t<T>>(value);
+     if (detail::is_negative(value)) {
+-      specs_.align = align::left;
++      specs_.set_align(align::left);
+       width = 0 - width;
+     }
+-    unsigned int_max = max_value<int>();
+-    if (width > int_max) throw_format_error("number is too big");
++    unsigned int_max = to_unsigned(max_value<int>());
++    if (width > int_max) report_error("number is too big");
+     return static_cast<unsigned>(width);
+   }
+ 
+   template <typename T, FMT_ENABLE_IF(!std::is_integral<T>::value)>
+   auto operator()(T) -> unsigned {
+-    throw_format_error("width is not integer");
++    report_error("width is not integer");
+     return 0;
+   }
+ };
+@@ -216,12 +229,12 @@ template <typename Char> class printf_width_handler {
+ // Workaround for a bug with the XL compiler when initializing
+ // printf_arg_formatter's base class.
+ template <typename Char>
+-auto make_arg_formatter(buffer_appender<Char> iter, format_specs<Char>& s)
++auto make_arg_formatter(basic_appender<Char> iter, format_specs& s)
+     -> arg_formatter<Char> {
+   return {iter, s, locale_ref()};
+ }
+ 
+-// The ``printf`` argument formatter.
++// The `printf` argument formatter.
+ template <typename Char>
+ class printf_arg_formatter : public arg_formatter<Char> {
+  private:
+@@ -232,105 +245,96 @@ class printf_arg_formatter : public arg_formatter<Char> {
+ 
+   void write_null_pointer(bool is_string = false) {
+     auto s = this->specs;
+-    s.type = presentation_type::none;
+-    write_bytes(this->out, is_string ? "(null)" : "(nil)", s);
++    s.set_type(presentation_type::none);
++    write_bytes<Char>(this->out, is_string ? "(null)" : "(nil)", s);
++  }
++
++  template <typename T> void write(T value) {
++    detail::write<Char>(this->out, value, this->specs, this->locale);
+   }
+ 
+  public:
+-  printf_arg_formatter(buffer_appender<Char> iter, format_specs<Char>& s,
++  printf_arg_formatter(basic_appender<Char> iter, format_specs& s,
+                        context_type& ctx)
+       : base(make_arg_formatter(iter, s)), context_(ctx) {}
+ 
+-  void operator()(monostate value) { base::operator()(value); }
++  void operator()(monostate value) { write(value); }
+ 
+   template <typename T, FMT_ENABLE_IF(detail::is_integral<T>::value)>
+   void operator()(T value) {
+     // MSVC2013 fails to compile separate overloads for bool and Char so use
+     // std::is_same instead.
+     if (!std::is_same<T, Char>::value) {
+-      base::operator()(value);
++      write(value);
+       return;
+     }
+-    format_specs<Char> fmt_specs = this->specs;
+-    if (fmt_specs.type != presentation_type::none &&
+-        fmt_specs.type != presentation_type::chr) {
++    format_specs s = this->specs;
++    if (s.type() != presentation_type::none &&
++        s.type() != presentation_type::chr) {
+       return (*this)(static_cast<int>(value));
+     }
+-    fmt_specs.sign = sign::none;
+-    fmt_specs.alt = false;
+-    fmt_specs.fill[0] = ' ';  // Ignore '0' flag for char types.
++    s.set_sign(sign::none);
++    s.clear_alt();
++    s.set_fill(' ');  // Ignore '0' flag for char types.
+     // align::numeric needs to be overwritten here since the '0' flag is
+     // ignored for non-numeric types
+-    if (fmt_specs.align == align::none || fmt_specs.align == align::numeric)
+-      fmt_specs.align = align::right;
+-    write<Char>(this->out, static_cast<Char>(value), fmt_specs);
++    if (s.align() == align::none || s.align() == align::numeric)
++      s.set_align(align::right);
++    detail::write<Char>(this->out, static_cast<Char>(value), s);
+   }
+ 
+   template <typename T, FMT_ENABLE_IF(std::is_floating_point<T>::value)>
+   void operator()(T value) {
+-    base::operator()(value);
++    write(value);
+   }
+ 
+-  /** Formats a null-terminated C string. */
+   void operator()(const char* value) {
+     if (value)
+-      base::operator()(value);
++      write(value);
+     else
+-      write_null_pointer(this->specs.type != presentation_type::pointer);
++      write_null_pointer(this->specs.type() != presentation_type::pointer);
+   }
+ 
+-  /** Formats a null-terminated wide C string. */
+   void operator()(const wchar_t* value) {
+     if (value)
+-      base::operator()(value);
++      write(value);
+     else
+-      write_null_pointer(this->specs.type != presentation_type::pointer);
++      write_null_pointer(this->specs.type() != presentation_type::pointer);
+   }
+ 
+-  void operator()(basic_string_view<Char> value) { base::operator()(value); }
++  void operator()(basic_string_view<Char> value) { write(value); }
+ 
+-  /** Formats a pointer. */
+   void operator()(const void* value) {
+     if (value)
+-      base::operator()(value);
++      write(value);
+     else
+       write_null_pointer();
+   }
+ 
+-  /** Formats an argument of a custom (user-defined) type. */
+   void operator()(typename basic_format_arg<context_type>::handle handle) {
+-    auto parse_ctx = basic_format_parse_context<Char>({});
++    auto parse_ctx = parse_context<Char>({});
+     handle.format(parse_ctx, context_);
+   }
+ };
+ 
+ template <typename Char>
+-void parse_flags(format_specs<Char>& specs, const Char*& it, const Char* end) {
++void parse_flags(format_specs& specs, const Char*& it, const Char* end) {
+   for (; it != end; ++it) {
+     switch (*it) {
+-    case '-':
+-      specs.align = align::left;
+-      break;
+-    case '+':
+-      specs.sign = sign::plus;
+-      break;
+-    case '0':
+-      specs.fill[0] = '0';
+-      break;
++    case '-': specs.set_align(align::left); break;
++    case '+': specs.set_sign(sign::plus); break;
++    case '0': specs.set_fill('0'); break;
+     case ' ':
+-      if (specs.sign != sign::plus) specs.sign = sign::space;
+-      break;
+-    case '#':
+-      specs.alt = true;
++      if (specs.sign() != sign::plus) specs.set_sign(sign::space);
+       break;
+-    default:
+-      return;
++    case '#': specs.set_alt(); break;
++    default:  return;
+     }
+   }
+ }
+ 
+ template <typename Char, typename GetArg>
+-auto parse_header(const Char*& it, const Char* end, format_specs<Char>& specs,
++auto parse_header(const Char*& it, const Char* end, format_specs& specs,
+                   GetArg get_arg) -> int {
+   int arg_index = -1;
+   Char c = *it;
+@@ -342,11 +346,11 @@ auto parse_header(const Char*& it, const Char* end, format_specs<Char>& specs,
+       ++it;
+       arg_index = value != -1 ? value : max_value<int>();
+     } else {
+-      if (c == '0') specs.fill[0] = '0';
++      if (c == '0') specs.set_fill('0');
+       if (value != 0) {
+         // Nonzero value means that we parsed width and don't need to
+         // parse it or flags again, so return now.
+-        if (value == -1) throw_format_error("number is too big");
++        if (value == -1) report_error("number is too big");
+         specs.width = value;
+         return arg_index;
+       }
+@@ -357,63 +361,47 @@ auto parse_header(const Char*& it, const Char* end, format_specs<Char>& specs,
+   if (it != end) {
+     if (*it >= '0' && *it <= '9') {
+       specs.width = parse_nonnegative_int(it, end, -1);
+-      if (specs.width == -1) throw_format_error("number is too big");
++      if (specs.width == -1) report_error("number is too big");
+     } else if (*it == '*') {
+       ++it;
+-      specs.width = static_cast<int>(visit_format_arg(
+-          detail::printf_width_handler<Char>(specs), get_arg(-1)));
++      specs.width = static_cast<int>(
++          get_arg(-1).visit(detail::printf_width_handler(specs)));
+     }
+   }
+   return arg_index;
+ }
+ 
+-inline auto parse_printf_presentation_type(char c, type t)
++inline auto parse_printf_presentation_type(char c, type t, bool& upper)
+     -> presentation_type {
+   using pt = presentation_type;
+   constexpr auto integral_set = sint_set | uint_set | bool_set | char_set;
+   switch (c) {
+-  case 'd':
+-    return in(t, integral_set) ? pt::dec : pt::none;
+-  case 'o':
+-    return in(t, integral_set) ? pt::oct : pt::none;
+-  case 'x':
+-    return in(t, integral_set) ? pt::hex_lower : pt::none;
+-  case 'X':
+-    return in(t, integral_set) ? pt::hex_upper : pt::none;
+-  case 'a':
+-    return in(t, float_set) ? pt::hexfloat_lower : pt::none;
+-  case 'A':
+-    return in(t, float_set) ? pt::hexfloat_upper : pt::none;
+-  case 'e':
+-    return in(t, float_set) ? pt::exp_lower : pt::none;
+-  case 'E':
+-    return in(t, float_set) ? pt::exp_upper : pt::none;
+-  case 'f':
+-    return in(t, float_set) ? pt::fixed_lower : pt::none;
+-  case 'F':
+-    return in(t, float_set) ? pt::fixed_upper : pt::none;
+-  case 'g':
+-    return in(t, float_set) ? pt::general_lower : pt::none;
+-  case 'G':
+-    return in(t, float_set) ? pt::general_upper : pt::none;
+-  case 'c':
+-    return in(t, integral_set) ? pt::chr : pt::none;
+-  case 's':
+-    return in(t, string_set | cstring_set) ? pt::string : pt::none;
+-  case 'p':
+-    return in(t, pointer_set | cstring_set) ? pt::pointer : pt::none;
+-  default:
+-    return pt::none;
++  case 'd': return in(t, integral_set) ? pt::dec : pt::none;
++  case 'o': return in(t, integral_set) ? pt::oct : pt::none;
++  case 'X': upper = true; FMT_FALLTHROUGH;
++  case 'x': return in(t, integral_set) ? pt::hex : pt::none;
++  case 'E': upper = true; FMT_FALLTHROUGH;
++  case 'e': return in(t, float_set) ? pt::exp : pt::none;
++  case 'F': upper = true; FMT_FALLTHROUGH;
++  case 'f': return in(t, float_set) ? pt::fixed : pt::none;
++  case 'G': upper = true; FMT_FALLTHROUGH;
++  case 'g': return in(t, float_set) ? pt::general : pt::none;
++  case 'A': upper = true; FMT_FALLTHROUGH;
++  case 'a': return in(t, float_set) ? pt::hexfloat : pt::none;
++  case 'c': return in(t, integral_set) ? pt::chr : pt::none;
++  case 's': return in(t, string_set | cstring_set) ? pt::string : pt::none;
++  case 'p': return in(t, pointer_set | cstring_set) ? pt::pointer : pt::none;
++  default:  return pt::none;
+   }
+ }
+ 
+ template <typename Char, typename Context>
+ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
+              basic_format_args<Context> args) {
+-  using iterator = buffer_appender<Char>;
++  using iterator = basic_appender<Char>;
+   auto out = iterator(buf);
+   auto context = basic_printf_context<Char>(out, args);
+-  auto parse_ctx = basic_format_parse_context<Char>(format);
++  auto parse_ctx = parse_context<Char>(format);
+ 
+   // Returns the argument with specified index or, if arg_index is -1, the next
+   // argument.
+@@ -441,12 +429,12 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
+     }
+     write(out, basic_string_view<Char>(start, to_unsigned(it - 1 - start)));
+ 
+-    auto specs = format_specs<Char>();
+-    specs.align = align::right;
++    auto specs = format_specs();
++    specs.set_align(align::right);
+ 
+     // Parse argument index, flags and width.
+     int arg_index = parse_header(it, end, specs, get_arg);
+-    if (arg_index == 0) throw_format_error("argument not found");
++    if (arg_index == 0) report_error("argument not found");
+ 
+     // Parse precision.
+     if (it != end && *it == '.') {
+@@ -456,8 +444,8 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
+         specs.precision = parse_nonnegative_int(it, end, 0);
+       } else if (c == '*') {
+         ++it;
+-        specs.precision = static_cast<int>(
+-            visit_format_arg(printf_precision_handler(), get_arg(-1)));
++        specs.precision =
++            static_cast<int>(get_arg(-1).visit(printf_precision_handler()));
+       } else {
+         specs.precision = 0;
+       }
+@@ -466,25 +454,26 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
+     auto arg = get_arg(arg_index);
+     // For d, i, o, u, x, and X conversion specifiers, if a precision is
+     // specified, the '0' flag is ignored
+-    if (specs.precision >= 0 && arg.is_integral()) {
++    if (specs.precision >= 0 && is_integral_type(arg.type())) {
+       // Ignore '0' for non-numeric types or if '-' present.
+-      specs.fill[0] = ' ';
++      specs.set_fill(' ');
+     }
+     if (specs.precision >= 0 && arg.type() == type::cstring_type) {
+-      auto str = visit_format_arg(get_cstring<Char>(), arg);
++      auto str = arg.visit(get_cstring<Char>());
+       auto str_end = str + specs.precision;
+       auto nul = std::find(str, str_end, Char());
+       auto sv = basic_string_view<Char>(
+           str, to_unsigned(nul != str_end ? nul - str : specs.precision));
+-      arg = make_arg<basic_printf_context<Char>>(sv);
++      arg = sv;
+     }
+-    if (specs.alt && visit_format_arg(is_zero_int(), arg)) specs.alt = false;
+-    if (specs.fill[0] == '0') {
+-      if (arg.is_arithmetic() && specs.align != align::left)
+-        specs.align = align::numeric;
+-      else
+-        specs.fill[0] = ' ';  // Ignore '0' flag for non-numeric types or if '-'
+-                              // flag is also present.
++    if (specs.alt() && arg.visit(is_zero_int())) specs.clear_alt();
++    if (specs.fill_unit<Char>() == '0') {
++      if (is_arithmetic_type(arg.type()) && specs.align() != align::left) {
++        specs.set_align(align::numeric);
++      } else {
++        // Ignore '0' flag for non-numeric types or if '-' flag is also present.
++        specs.set_fill(' ');
++      }
+     }
+ 
+     // Parse length and convert the argument to the required type.
+@@ -509,51 +498,43 @@ void vprintf(buffer<Char>& buf, basic_string_view<Char> format,
+         convert_arg<long>(arg, t);
+       }
+       break;
+-    case 'j':
+-      convert_arg<intmax_t>(arg, t);
+-      break;
+-    case 'z':
+-      convert_arg<size_t>(arg, t);
+-      break;
+-    case 't':
+-      convert_arg<std::ptrdiff_t>(arg, t);
+-      break;
++    case 'j': convert_arg<intmax_t>(arg, t); break;
++    case 'z': convert_arg<size_t>(arg, t); break;
++    case 't': convert_arg<std::ptrdiff_t>(arg, t); break;
+     case 'L':
+       // printf produces garbage when 'L' is omitted for long double, no
+       // need to do the same.
+       break;
+-    default:
+-      --it;
+-      convert_arg<void>(arg, c);
++    default: --it; convert_arg<void>(arg, c);
+     }
+ 
+     // Parse type.
+-    if (it == end) throw_format_error("invalid format string");
++    if (it == end) report_error("invalid format string");
+     char type = static_cast<char>(*it++);
+-    if (arg.is_integral()) {
++    if (is_integral_type(arg.type())) {
+       // Normalize type.
+       switch (type) {
+       case 'i':
+-      case 'u':
+-        type = 'd';
+-        break;
++      case 'u': type = 'd'; break;
+       case 'c':
+-        visit_format_arg(char_converter<basic_printf_context<Char>>(arg), arg);
++        arg.visit(char_converter<basic_printf_context<Char>>(arg));
+         break;
+       }
+     }
+-    specs.type = parse_printf_presentation_type(type, arg.type());
+-    if (specs.type == presentation_type::none)
+-      throw_format_error("invalid format specifier");
++    bool upper = false;
++    specs.set_type(parse_printf_presentation_type(type, arg.type(), upper));
++    if (specs.type() == presentation_type::none)
++      report_error("invalid format specifier");
++    if (upper) specs.set_upper();
+ 
+     start = it;
+ 
+     // Format argument.
+-    visit_format_arg(printf_arg_formatter<Char>(out, specs, context), arg);
++    arg.visit(printf_arg_formatter<Char>(out, specs, context));
+   }
+   write(out, basic_string_view<Char>(start, to_unsigned(it - start)));
+ }
+-FMT_END_DETAIL_NAMESPACE
++}  // namespace detail
+ 
+ using printf_context = basic_printf_context<char>;
+ using wprintf_context = basic_printf_context<wchar_t>;
+@@ -561,56 +542,44 @@ using wprintf_context = basic_printf_context<wchar_t>;
+ using printf_args = basic_format_args<printf_context>;
+ using wprintf_args = basic_format_args<wprintf_context>;
+ 
+-/**
+-  \rst
+-  Constructs an `~fmt::format_arg_store` object that contains references to
+-  arguments and can be implicitly converted to `~fmt::printf_args`.
+-  \endrst
+- */
+-template <typename... T>
+-inline auto make_printf_args(const T&... args)
+-    -> format_arg_store<printf_context, T...> {
+-  return {args...};
++/// Constructs an `format_arg_store` object that contains references to
++/// arguments and can be implicitly converted to `printf_args`.
++template <typename Char = char, typename... T>
++inline auto make_printf_args(T&... args)
++    -> decltype(fmt::make_format_args<basic_printf_context<Char>>(args...)) {
++  return fmt::make_format_args<basic_printf_context<Char>>(args...);
+ }
+ 
+-// DEPRECATED!
+-template <typename... T>
+-inline auto make_wprintf_args(const T&... args)
+-    -> format_arg_store<wprintf_context, T...> {
+-  return {args...};
+-}
++template <typename Char> struct vprintf_args {
++  using type = basic_format_args<basic_printf_context<Char>>;
++};
+ 
+ template <typename Char>
+-inline auto vsprintf(
+-    basic_string_view<Char> fmt,
+-    basic_format_args<basic_printf_context<type_identity_t<Char>>> args)
++inline auto vsprintf(basic_string_view<Char> fmt,
++                     typename vprintf_args<Char>::type args)
+     -> std::basic_string<Char> {
+   auto buf = basic_memory_buffer<Char>();
+   detail::vprintf(buf, fmt, args);
+-  return to_string(buf);
++  return {buf.data(), buf.size()};
+ }
+ 
+ /**
+-  \rst
+-  Formats arguments and returns the result as a string.
+-
+-  **Example**::
+-
+-    std::string message = fmt::sprintf("The answer is %d", 42);
+-  \endrst
+-*/
+-template <typename S, typename... T,
+-          typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
++ * Formats `args` according to specifications in `fmt` and returns the result
++ * as as string.
++ *
++ * **Example**:
++ *
++ *     std::string message = fmt::sprintf("The answer is %d", 42);
++ */
++template <typename S, typename... T, typename Char = detail::char_t<S>>
+ inline auto sprintf(const S& fmt, const T&... args) -> std::basic_string<Char> {
+   return vsprintf(detail::to_string_view(fmt),
+                   fmt::make_format_args<basic_printf_context<Char>>(args...));
+ }
+ 
+ template <typename Char>
+-inline auto vfprintf(
+-    std::FILE* f, basic_string_view<Char> fmt,
+-    basic_format_args<basic_printf_context<type_identity_t<Char>>> args)
+-    -> int {
++inline auto vfprintf(std::FILE* f, basic_string_view<Char> fmt,
++                     typename vprintf_args<Char>::type args) -> int {
+   auto buf = basic_memory_buffer<Char>();
+   detail::vprintf(buf, fmt, args);
+   size_t size = buf.size();
+@@ -620,36 +589,33 @@ inline auto vfprintf(
+ }
+ 
+ /**
+-  \rst
+-  Prints formatted data to the file *f*.
+-
+-  **Example**::
+-
+-    fmt::fprintf(stderr, "Don't %s!", "panic");
+-  \endrst
++ * Formats `args` according to specifications in `fmt` and writes the output
++ * to `f`.
++ *
++ * **Example**:
++ *
++ *     fmt::fprintf(stderr, "Don't %s!", "panic");
+  */
+-template <typename S, typename... T, typename Char = char_t<S>>
++template <typename S, typename... T, typename Char = detail::char_t<S>>
+ inline auto fprintf(std::FILE* f, const S& fmt, const T&... args) -> int {
+   return vfprintf(f, detail::to_string_view(fmt),
+-                  fmt::make_format_args<basic_printf_context<Char>>(args...));
++                  make_printf_args<Char>(args...));
+ }
+ 
+ template <typename Char>
+-FMT_DEPRECATED inline auto vprintf(
+-    basic_string_view<Char> fmt,
+-    basic_format_args<basic_printf_context<type_identity_t<Char>>> args)
++FMT_DEPRECATED inline auto vprintf(basic_string_view<Char> fmt,
++                                   typename vprintf_args<Char>::type args)
+     -> int {
+   return vfprintf(stdout, fmt, args);
+ }
+ 
+ /**
+-  \rst
+-  Prints formatted data to ``stdout``.
+-
+-  **Example**::
+-
+-    fmt::printf("Elapsed time: %.2f seconds", 1.23);
+-  \endrst
++ * Formats `args` according to specifications in `fmt` and writes the output
++ * to `stdout`.
++ *
++ * **Example**:
++ *
++ *   fmt::printf("Elapsed time: %.2f seconds", 1.23);
+  */
+ template <typename... T>
+ inline auto printf(string_view fmt, const T&... args) -> int {
+@@ -658,7 +624,7 @@ inline auto printf(string_view fmt, const T&... args) -> int {
+ template <typename... T>
+ FMT_DEPRECATED inline auto printf(basic_string_view<wchar_t> fmt,
+                                   const T&... args) -> int {
+-  return vfprintf(stdout, fmt, make_wprintf_args(args...));
++  return vfprintf(stdout, fmt, make_printf_args<wchar_t>(args...));
+ }
+ 
+ FMT_END_EXPORT
+diff --git a/include/fmt/ranges.h b/include/fmt/ranges.h
+index 266b9e1..77d645f 100644
+--- a/include/fmt/ranges.h
++++ b/include/fmt/ranges.h
+@@ -1,78 +1,38 @@
+-// Formatting library for C++ - experimental range support
++// Formatting library for C++ - range and tuple support
+ //
+-// Copyright (c) 2012 - present, Victor Zverovich
++// Copyright (c) 2012 - present, Victor Zverovich and {fmt} contributors
+ // All rights reserved.
+ //
+ // For the license information refer to format.h.
+-//
+-// Copyright (c) 2018 - present, Remotion (Igor Schulz)
+-// All Rights Reserved
+-// {fmt} support for ranges, containers and types tuple interface.
+ 
+ #ifndef FMT_RANGES_H_
+ #define FMT_RANGES_H_
+ 
+-#include <initializer_list>
+-#include <tuple>
+-#include <type_traits>
++#ifndef FMT_MODULE
++#  include <initializer_list>
++#  include <iterator>
++#  include <string>
++#  include <tuple>
++#  include <type_traits>
++#  include <utility>
++#endif
+ 
+ #include "format.h"
+ 
+ FMT_BEGIN_NAMESPACE
+ 
+-namespace detail {
+-
+-template <typename Range, typename OutputIt>
+-auto copy(const Range& range, OutputIt out) -> OutputIt {
+-  for (auto it = range.begin(), end = range.end(); it != end; ++it)
+-    *out++ = *it;
+-  return out;
+-}
+-
+-template <typename OutputIt>
+-auto copy(const char* str, OutputIt out) -> OutputIt {
+-  while (*str) *out++ = *str++;
+-  return out;
+-}
+-
+-template <typename OutputIt> auto copy(char ch, OutputIt out) -> OutputIt {
+-  *out++ = ch;
+-  return out;
+-}
+-
+-template <typename OutputIt> auto copy(wchar_t ch, OutputIt out) -> OutputIt {
+-  *out++ = ch;
+-  return out;
+-}
+-
+-// Returns true if T has a std::string-like interface, like std::string_view.
+-template <typename T> class is_std_string_like {
+-  template <typename U>
+-  static auto check(U* p)
+-      -> decltype((void)p->find('a'), p->length(), (void)p->data(), int());
+-  template <typename> static void check(...);
+-
+- public:
+-  static constexpr const bool value =
+-      is_string<T>::value ||
+-      std::is_convertible<T, std_string_view<char>>::value ||
+-      !std::is_void<decltype(check<T>(nullptr))>::value;
+-};
++FMT_EXPORT
++enum class range_format { disabled, map, set, sequence, string, debug_string };
+ 
+-template <typename Char>
+-struct is_std_string_like<fmt::basic_string_view<Char>> : std::true_type {};
++namespace detail {
+ 
+ template <typename T> class is_map {
+   template <typename U> static auto check(U*) -> typename U::mapped_type;
+   template <typename> static void check(...);
+ 
+  public:
+-#ifdef FMT_FORMAT_MAP_AS_LIST  // DEPRECATED!
+-  static constexpr const bool value = false;
+-#else
+   static constexpr const bool value =
+       !std::is_void<decltype(check<T>(nullptr))>::value;
+-#endif
+ };
+ 
+ template <typename T> class is_set {
+@@ -80,26 +40,10 @@ template <typename T> class is_set {
+   template <typename> static void check(...);
+ 
+  public:
+-#ifdef FMT_FORMAT_SET_AS_LIST  // DEPRECATED!
+-  static constexpr const bool value = false;
+-#else
+   static constexpr const bool value =
+       !std::is_void<decltype(check<T>(nullptr))>::value && !is_map<T>::value;
+-#endif
+ };
+ 
+-template <typename... Ts> struct conditional_helper {};
+-
+-template <typename T, typename _ = void> struct is_range_ : std::false_type {};
+-
+-#if !FMT_MSC_VERSION || FMT_MSC_VERSION > 1800
+-
+-#  define FMT_DECLTYPE_RETURN(val)  \
+-    ->decltype(val) { return val; } \
+-    static_assert(                  \
+-        true, "")  // This makes it so that a semicolon is required after the
+-                   // macro, which helps clang-format handle the formatting.
+-
+ // C array overload
+ template <typename T, std::size_t N>
+ auto range_begin(const T (&arr)[N]) -> const T* {
+@@ -114,17 +58,21 @@ template <typename T, typename Enable = void>
+ struct has_member_fn_begin_end_t : std::false_type {};
+ 
+ template <typename T>
+-struct has_member_fn_begin_end_t<T, void_t<decltype(std::declval<T>().begin()),
++struct has_member_fn_begin_end_t<T, void_t<decltype(*std::declval<T>().begin()),
+                                            decltype(std::declval<T>().end())>>
+     : std::true_type {};
+ 
+-// Member function overload
++// Member function overloads.
+ template <typename T>
+-auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin());
++auto range_begin(T&& rng) -> decltype(static_cast<T&&>(rng).begin()) {
++  return static_cast<T&&>(rng).begin();
++}
+ template <typename T>
+-auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end());
++auto range_end(T&& rng) -> decltype(static_cast<T&&>(rng).end()) {
++  return static_cast<T&&>(rng).end();
++}
+ 
+-// ADL overload. Only participates in overload resolution if member functions
++// ADL overloads. Only participate in overload resolution if member functions
+ // are not found.
+ template <typename T>
+ auto range_begin(T&& rng)
+@@ -145,31 +93,30 @@ struct has_mutable_begin_end : std::false_type {};
+ 
+ template <typename T>
+ struct has_const_begin_end<
+-    T,
+-    void_t<
+-        decltype(detail::range_begin(std::declval<const remove_cvref_t<T>&>())),
+-        decltype(detail::range_end(std::declval<const remove_cvref_t<T>&>()))>>
++    T, void_t<decltype(*detail::range_begin(
++                  std::declval<const remove_cvref_t<T>&>())),
++              decltype(detail::range_end(
++                  std::declval<const remove_cvref_t<T>&>()))>>
+     : std::true_type {};
+ 
+ template <typename T>
+ struct has_mutable_begin_end<
+-    T, void_t<decltype(detail::range_begin(std::declval<T>())),
+-              decltype(detail::range_end(std::declval<T>())),
++    T, void_t<decltype(*detail::range_begin(std::declval<T&>())),
++              decltype(detail::range_end(std::declval<T&>())),
+               // the extra int here is because older versions of MSVC don't
+               // SFINAE properly unless there are distinct types
+               int>> : std::true_type {};
+ 
++template <typename T, typename _ = void> struct is_range_ : std::false_type {};
+ template <typename T>
+ struct is_range_<T, void>
+     : std::integral_constant<bool, (has_const_begin_end<T>::value ||
+                                     has_mutable_begin_end<T>::value)> {};
+-#  undef FMT_DECLTYPE_RETURN
+-#endif
+ 
+ // tuple_size and tuple_element check.
+ template <typename T> class is_tuple_like_ {
+-  template <typename U>
+-  static auto check(U* p) -> decltype(std::tuple_size<U>::value, int());
++  template <typename U, typename V = typename std::remove_cv<U>::type>
++  static auto check(U* p) -> decltype(std::tuple_size<V>::value, 0);
+   template <typename> static void check(...);
+ 
+  public:
+@@ -187,7 +134,7 @@ template <size_t N> using make_index_sequence = std::make_index_sequence<N>;
+ template <typename T, T... N> struct integer_sequence {
+   using value_type = T;
+ 
+-  static FMT_CONSTEXPR size_t size() { return sizeof...(N); }
++  static FMT_CONSTEXPR auto size() -> size_t { return sizeof...(N); }
+ };
+ 
+ template <size_t... N> using index_sequence = integer_sequence<size_t, N...>;
+@@ -210,16 +157,17 @@ class is_tuple_formattable_ {
+   static constexpr const bool value = false;
+ };
+ template <typename T, typename C> class is_tuple_formattable_<T, C, true> {
+-  template <std::size_t... Is>
+-  static std::true_type check2(index_sequence<Is...>,
+-                               integer_sequence<bool, (Is == Is)...>);
+-  static std::false_type check2(...);
+-  template <std::size_t... Is>
+-  static decltype(check2(
++  template <size_t... Is>
++  static auto all_true(index_sequence<Is...>,
++                       integer_sequence<bool, (Is >= 0)...>) -> std::true_type;
++  static auto all_true(...) -> std::false_type;
++
++  template <size_t... Is>
++  static auto check(index_sequence<Is...>) -> decltype(all_true(
+       index_sequence<Is...>{},
+-      integer_sequence<
+-          bool, (is_formattable<typename std::tuple_element<Is, T>::type,
+-                                C>::value)...>{})) check(index_sequence<Is...>);
++      integer_sequence<bool,
++                       (is_formattable<typename std::tuple_element<Is, T>::type,
++                                       C>::value)...>{}));
+ 
+  public:
+   static constexpr const bool value =
+@@ -296,21 +244,32 @@ FMT_CONSTEXPR auto maybe_set_debug_format(Formatter& f, bool set)
+ template <typename Formatter>
+ FMT_CONSTEXPR void maybe_set_debug_format(Formatter&, ...) {}
+ 
++template <typename T>
++struct range_format_kind_
++    : std::integral_constant<range_format,
++                             std::is_same<uncvref_type<T>, T>::value
++                                 ? range_format::disabled
++                             : is_map<T>::value ? range_format::map
++                             : is_set<T>::value ? range_format::set
++                                                : range_format::sequence> {};
++
++template <range_format K>
++using range_format_constant = std::integral_constant<range_format, K>;
++
+ // These are not generic lambdas for compatibility with C++11.
+-template <typename ParseContext> struct parse_empty_specs {
++template <typename Char> struct parse_empty_specs {
+   template <typename Formatter> FMT_CONSTEXPR void operator()(Formatter& f) {
+     f.parse(ctx);
+     detail::maybe_set_debug_format(f, true);
+   }
+-  ParseContext& ctx;
++  parse_context<Char>& ctx;
+ };
+ template <typename FormatContext> struct format_tuple_element {
+   using char_type = typename FormatContext::char_type;
+ 
+   template <typename T>
+   void operator()(const formatter<T, char_type>& f, const T& v) {
+-    if (i > 0)
+-      ctx.advance_to(detail::copy_str<char_type>(separator, ctx.out()));
++    if (i > 0) ctx.advance_to(detail::copy<char_type>(separator, ctx.out()));
+     ctx.advance_to(f.format(v, ctx));
+     ++i;
+   }
+@@ -359,68 +318,56 @@ struct formatter<Tuple, Char,
+     closing_bracket_ = close;
+   }
+ 
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+     auto it = ctx.begin();
+-    if (it != ctx.end() && *it != '}')
+-      FMT_THROW(format_error("invalid format specifier"));
+-    detail::for_each(formatters_, detail::parse_empty_specs<ParseContext>{ctx});
++    auto end = ctx.end();
++    if (it != end && detail::to_ascii(*it) == 'n') {
++      ++it;
++      set_brackets({}, {});
++      set_separator({});
++    }
++    if (it != end && *it != '}') report_error("invalid format specifier");
++    ctx.advance_to(it);
++    detail::for_each(formatters_, detail::parse_empty_specs<Char>{ctx});
+     return it;
+   }
+ 
+   template <typename FormatContext>
+   auto format(const Tuple& value, FormatContext& ctx) const
+       -> decltype(ctx.out()) {
+-    ctx.advance_to(detail::copy_str<Char>(opening_bracket_, ctx.out()));
++    ctx.advance_to(detail::copy<Char>(opening_bracket_, ctx.out()));
+     detail::for_each2(
+         formatters_, value,
+         detail::format_tuple_element<FormatContext>{0, ctx, separator_});
+-    return detail::copy_str<Char>(closing_bracket_, ctx.out());
++    return detail::copy<Char>(closing_bracket_, ctx.out());
+   }
+ };
+ 
+ template <typename T, typename Char> struct is_range {
+   static constexpr const bool value =
+-      detail::is_range_<T>::value && !detail::is_std_string_like<T>::value &&
+-      !std::is_convertible<T, std::basic_string<Char>>::value &&
+-      !std::is_convertible<T, detail::std_string_view<Char>>::value;
++      detail::is_range_<T>::value && !detail::has_to_string_view<T>::value;
+ };
+ 
+ namespace detail {
+-template <typename Context> struct range_mapper {
+-  using mapper = arg_mapper<Context>;
+-
+-  template <typename T,
+-            FMT_ENABLE_IF(has_formatter<remove_cvref_t<T>, Context>::value)>
+-  static auto map(T&& value) -> T&& {
+-    return static_cast<T&&>(value);
+-  }
+-  template <typename T,
+-            FMT_ENABLE_IF(!has_formatter<remove_cvref_t<T>, Context>::value)>
+-  static auto map(T&& value)
+-      -> decltype(mapper().map(static_cast<T&&>(value))) {
+-    return mapper().map(static_cast<T&&>(value));
+-  }
+-};
+ 
+ template <typename Char, typename Element>
+-using range_formatter_type =
+-    formatter<remove_cvref_t<decltype(range_mapper<buffer_context<Char>>{}.map(
+-                  std::declval<Element>()))>,
+-              Char>;
++using range_formatter_type = formatter<remove_cvref_t<Element>, Char>;
+ 
+ template <typename R>
+ using maybe_const_range =
+     conditional_t<has_const_begin_end<R>::value, const R, R>;
+ 
+-// Workaround a bug in MSVC 2015 and earlier.
+-#if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
+ template <typename R, typename Char>
+ struct is_formattable_delayed
+     : is_formattable<uncvref_type<maybe_const_range<R>>, Char> {};
+-#endif
+ }  // namespace detail
+ 
++template <typename...> struct conjunction : std::true_type {};
++template <typename P> struct conjunction<P> : P {};
++template <typename P1, typename... Pn>
++struct conjunction<P1, Pn...>
++    : conditional_t<bool(P1::value), conjunction<Pn...>, P1> {};
++
+ template <typename T, typename Char, typename Enable = void>
+ struct range_formatter;
+ 
+@@ -436,6 +383,24 @@ struct range_formatter<
+       detail::string_literal<Char, '['>{};
+   basic_string_view<Char> closing_bracket_ =
+       detail::string_literal<Char, ']'>{};
++  bool is_debug = false;
++
++  template <typename Output, typename It, typename Sentinel, typename U = T,
++            FMT_ENABLE_IF(std::is_same<U, Char>::value)>
++  auto write_debug_string(Output& out, It it, Sentinel end) const -> Output {
++    auto buf = basic_memory_buffer<Char>();
++    for (; it != end; ++it) buf.push_back(*it);
++    auto specs = format_specs();
++    specs.set_type(presentation_type::debug);
++    return detail::write<Char>(
++        out, basic_string_view<Char>(buf.data(), buf.size()), specs);
++  }
++
++  template <typename Output, typename It, typename Sentinel, typename U = T,
++            FMT_ENABLE_IF(!std::is_same<U, Char>::value)>
++  auto write_debug_string(Output& out, It, Sentinel) const -> Output {
++    return out;
++  }
+ 
+  public:
+   FMT_CONSTEXPR range_formatter() {}
+@@ -454,21 +419,40 @@ struct range_formatter<
+     closing_bracket_ = close;
+   }
+ 
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+     auto it = ctx.begin();
+     auto end = ctx.end();
++    detail::maybe_set_debug_format(underlying_, true);
++    if (it == end) return underlying_.parse(ctx);
+ 
+-    if (it != end && *it == 'n') {
++    switch (detail::to_ascii(*it)) {
++    case 'n':
++      set_brackets({}, {});
++      ++it;
++      break;
++    case '?':
++      is_debug = true;
+       set_brackets({}, {});
+       ++it;
++      if (it == end || *it != 's') report_error("invalid format specifier");
++      FMT_FALLTHROUGH;
++    case 's':
++      if (!std::is_same<T, Char>::value)
++        report_error("invalid format specifier");
++      if (!is_debug) {
++        set_brackets(detail::string_literal<Char, '"'>{},
++                     detail::string_literal<Char, '"'>{});
++        set_separator({});
++        detail::maybe_set_debug_format(underlying_, false);
++      }
++      ++it;
++      return it;
+     }
+ 
+     if (it != end && *it != '}') {
+-      if (*it != ':') FMT_THROW(format_error("invalid format specifier"));
++      if (*it != ':') report_error("invalid format specifier");
++      detail::maybe_set_debug_format(underlying_, false);
+       ++it;
+-    } else {
+-      detail::maybe_set_debug_format(underlying_, true);
+     }
+ 
+     ctx.advance_to(it);
+@@ -477,105 +461,220 @@ struct range_formatter<
+ 
+   template <typename R, typename FormatContext>
+   auto format(R&& range, FormatContext& ctx) const -> decltype(ctx.out()) {
+-    detail::range_mapper<buffer_context<Char>> mapper;
+     auto out = ctx.out();
+-    out = detail::copy_str<Char>(opening_bracket_, out);
+-    int i = 0;
+     auto it = detail::range_begin(range);
+     auto end = detail::range_end(range);
++    if (is_debug) return write_debug_string(out, std::move(it), end);
++
++    out = detail::copy<Char>(opening_bracket_, out);
++    int i = 0;
+     for (; it != end; ++it) {
+-      if (i > 0) out = detail::copy_str<Char>(separator_, out);
++      if (i > 0) out = detail::copy<Char>(separator_, out);
+       ctx.advance_to(out);
+-      out = underlying_.format(mapper.map(*it), ctx);
++      auto&& item = *it;  // Need an lvalue
++      out = underlying_.format(item, ctx);
+       ++i;
+     }
+-    out = detail::copy_str<Char>(closing_bracket_, out);
++    out = detail::copy<Char>(closing_bracket_, out);
+     return out;
+   }
+ };
+ 
+-enum class range_format { disabled, map, set, sequence, string, debug_string };
++FMT_EXPORT
++template <typename T, typename Char, typename Enable = void>
++struct range_format_kind
++    : conditional_t<
++          is_range<T, Char>::value, detail::range_format_kind_<T>,
++          std::integral_constant<range_format, range_format::disabled>> {};
+ 
+-namespace detail {
+-template <typename T>
+-struct range_format_kind_
+-    : std::integral_constant<range_format,
+-                             std::is_same<uncvref_type<T>, T>::value
+-                                 ? range_format::disabled
+-                             : is_map<T>::value ? range_format::map
+-                             : is_set<T>::value ? range_format::set
+-                                                : range_format::sequence> {};
++template <typename R, typename Char>
++struct formatter<
++    R, Char,
++    enable_if_t<conjunction<
++        bool_constant<
++            range_format_kind<R, Char>::value != range_format::disabled &&
++            range_format_kind<R, Char>::value != range_format::map &&
++            range_format_kind<R, Char>::value != range_format::string &&
++            range_format_kind<R, Char>::value != range_format::debug_string>,
++        detail::is_formattable_delayed<R, Char>>::value>> {
++ private:
++  using range_type = detail::maybe_const_range<R>;
++  range_formatter<detail::uncvref_type<range_type>, Char> range_formatter_;
+ 
+-template <range_format K, typename R, typename Char, typename Enable = void>
+-struct range_default_formatter;
++ public:
++  using nonlocking = void;
++
++  FMT_CONSTEXPR formatter() {
++    if (detail::const_check(range_format_kind<R, Char>::value !=
++                            range_format::set))
++      return;
++    range_formatter_.set_brackets(detail::string_literal<Char, '{'>{},
++                                  detail::string_literal<Char, '}'>{});
++  }
+ 
+-template <range_format K>
+-using range_format_constant = std::integral_constant<range_format, K>;
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    return range_formatter_.parse(ctx);
++  }
+ 
+-template <range_format K, typename R, typename Char>
+-struct range_default_formatter<
+-    K, R, Char,
+-    enable_if_t<(K == range_format::sequence || K == range_format::map ||
+-                 K == range_format::set)>> {
+-  using range_type = detail::maybe_const_range<R>;
+-  range_formatter<detail::uncvref_type<range_type>, Char> underlying_;
++  template <typename FormatContext>
++  auto format(range_type& range, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    return range_formatter_.format(range, ctx);
++  }
++};
++
++// A map formatter.
++template <typename R, typename Char>
++struct formatter<
++    R, Char,
++    enable_if_t<conjunction<
++        bool_constant<range_format_kind<R, Char>::value == range_format::map>,
++        detail::is_formattable_delayed<R, Char>>::value>> {
++ private:
++  using map_type = detail::maybe_const_range<R>;
++  using element_type = detail::uncvref_type<map_type>;
+ 
+-  FMT_CONSTEXPR range_default_formatter() { init(range_format_constant<K>()); }
++  decltype(detail::tuple::get_formatters<element_type, Char>(
++      detail::tuple_index_sequence<element_type>())) formatters_;
++  bool no_delimiters_ = false;
+ 
+-  FMT_CONSTEXPR void init(range_format_constant<range_format::set>) {
+-    underlying_.set_brackets(detail::string_literal<Char, '{'>{},
+-                             detail::string_literal<Char, '}'>{});
++ public:
++  FMT_CONSTEXPR formatter() {}
++
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    auto it = ctx.begin();
++    auto end = ctx.end();
++    if (it != end) {
++      if (detail::to_ascii(*it) == 'n') {
++        no_delimiters_ = true;
++        ++it;
++      }
++      if (it != end && *it != '}') {
++        if (*it != ':') report_error("invalid format specifier");
++        ++it;
++      }
++      ctx.advance_to(it);
++    }
++    detail::for_each(formatters_, detail::parse_empty_specs<Char>{ctx});
++    return it;
+   }
+ 
+-  FMT_CONSTEXPR void init(range_format_constant<range_format::map>) {
+-    underlying_.set_brackets(detail::string_literal<Char, '{'>{},
+-                             detail::string_literal<Char, '}'>{});
+-    underlying_.underlying().set_brackets({}, {});
+-    underlying_.underlying().set_separator(
+-        detail::string_literal<Char, ':', ' '>{});
++  template <typename FormatContext>
++  auto format(map_type& map, FormatContext& ctx) const -> decltype(ctx.out()) {
++    auto out = ctx.out();
++    basic_string_view<Char> open = detail::string_literal<Char, '{'>{};
++    if (!no_delimiters_) out = detail::copy<Char>(open, out);
++    int i = 0;
++    basic_string_view<Char> sep = detail::string_literal<Char, ',', ' '>{};
++    for (auto&& value : map) {
++      if (i > 0) out = detail::copy<Char>(sep, out);
++      ctx.advance_to(out);
++      detail::for_each2(formatters_, value,
++                        detail::format_tuple_element<FormatContext>{
++                            0, ctx, detail::string_literal<Char, ':', ' '>{}});
++      ++i;
++    }
++    basic_string_view<Char> close = detail::string_literal<Char, '}'>{};
++    if (!no_delimiters_) out = detail::copy<Char>(close, out);
++    return out;
+   }
++};
+ 
+-  FMT_CONSTEXPR void init(range_format_constant<range_format::sequence>) {}
++// A (debug_)string formatter.
++template <typename R, typename Char>
++struct formatter<
++    R, Char,
++    enable_if_t<range_format_kind<R, Char>::value == range_format::string ||
++                range_format_kind<R, Char>::value ==
++                    range_format::debug_string>> {
++ private:
++  using range_type = detail::maybe_const_range<R>;
++  using string_type =
++      conditional_t<std::is_constructible<
++                        detail::std_string_view<Char>,
++                        decltype(detail::range_begin(std::declval<R>())),
++                        decltype(detail::range_end(std::declval<R>()))>::value,
++                    detail::std_string_view<Char>, std::basic_string<Char>>;
+ 
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
++  formatter<string_type, Char> underlying_;
++
++ public:
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+     return underlying_.parse(ctx);
+   }
+ 
+   template <typename FormatContext>
+   auto format(range_type& range, FormatContext& ctx) const
+       -> decltype(ctx.out()) {
+-    return underlying_.format(range, ctx);
++    auto out = ctx.out();
++    if (detail::const_check(range_format_kind<R, Char>::value ==
++                            range_format::debug_string))
++      *out++ = '"';
++    out = underlying_.format(
++        string_type{detail::range_begin(range), detail::range_end(range)}, ctx);
++    if (detail::const_check(range_format_kind<R, Char>::value ==
++                            range_format::debug_string))
++      *out++ = '"';
++    return out;
+   }
+ };
+-}  // namespace detail
+ 
+-template <typename T, typename Char, typename Enable = void>
+-struct range_format_kind
+-    : conditional_t<
+-          is_range<T, Char>::value, detail::range_format_kind_<T>,
+-          std::integral_constant<range_format, range_format::disabled>> {};
++template <typename It, typename Sentinel, typename Char = char>
++struct join_view : detail::view {
++  It begin;
++  Sentinel end;
++  basic_string_view<Char> sep;
+ 
+-template <typename R, typename Char>
+-struct formatter<
+-    R, Char,
+-    enable_if_t<conjunction<bool_constant<range_format_kind<R, Char>::value !=
+-                                          range_format::disabled>
+-// Workaround a bug in MSVC 2015 and earlier.
+-#if !FMT_MSC_VERSION || FMT_MSC_VERSION >= 1910
+-                            ,
+-                            detail::is_formattable_delayed<R, Char>
++  join_view(It b, Sentinel e, basic_string_view<Char> s)
++      : begin(std::move(b)), end(e), sep(s) {}
++};
++
++template <typename It, typename Sentinel, typename Char>
++struct formatter<join_view<It, Sentinel, Char>, Char> {
++ private:
++  using value_type =
++#ifdef __cpp_lib_ranges
++      std::iter_value_t<It>;
++#else
++      typename std::iterator_traits<It>::value_type;
+ #endif
+-                            >::value>>
+-    : detail::range_default_formatter<range_format_kind<R, Char>::value, R,
+-                                      Char> {
++  formatter<remove_cvref_t<value_type>, Char> value_formatter_;
++
++  using view = conditional_t<std::is_copy_constructible<It>::value,
++                             const join_view<It, Sentinel, Char>,
++                             join_view<It, Sentinel, Char>>;
++
++ public:
++  using nonlocking = void;
++
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    return value_formatter_.parse(ctx);
++  }
++
++  template <typename FormatContext>
++  auto format(view& value, FormatContext& ctx) const -> decltype(ctx.out()) {
++    using iter =
++        conditional_t<std::is_copy_constructible<view>::value, It, It&>;
++    iter it = value.begin;
++    auto out = ctx.out();
++    if (it == value.end) return out;
++    out = value_formatter_.format(*it, ctx);
++    ++it;
++    while (it != value.end) {
++      out = detail::copy<Char>(value.sep.begin(), value.sep.end(), out);
++      ctx.advance_to(out);
++      out = value_formatter_.format(*it, ctx);
++      ++it;
++    }
++    return out;
++  }
+ };
+ 
+-template <typename Char, typename... T> struct tuple_join_view : detail::view {
+-  const std::tuple<T...>& tuple;
++template <typename Char, typename Tuple> struct tuple_join_view : detail::view {
++  const Tuple& tuple;
+   basic_string_view<Char> sep;
+ 
+-  tuple_join_view(const std::tuple<T...>& t, basic_string_view<Char> s)
++  tuple_join_view(const Tuple& t, basic_string_view<Char> s)
+       : tuple(t), sep{s} {}
+ };
+ 
+@@ -586,65 +685,64 @@ template <typename Char, typename... T> struct tuple_join_view : detail::view {
+ #  define FMT_TUPLE_JOIN_SPECIFIERS 0
+ #endif
+ 
+-template <typename Char, typename... T>
+-struct formatter<tuple_join_view<Char, T...>, Char> {
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+-    return do_parse(ctx, std::integral_constant<size_t, sizeof...(T)>());
++template <typename Char, typename Tuple>
++struct formatter<tuple_join_view<Char, Tuple>, Char,
++                 enable_if_t<is_tuple_like<Tuple>::value>> {
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    return do_parse(ctx, std::tuple_size<Tuple>());
+   }
+ 
+   template <typename FormatContext>
+-  auto format(const tuple_join_view<Char, T...>& value,
++  auto format(const tuple_join_view<Char, Tuple>& value,
+               FormatContext& ctx) const -> typename FormatContext::iterator {
+-    return do_format(value, ctx,
+-                     std::integral_constant<size_t, sizeof...(T)>());
++    return do_format(value, ctx, std::tuple_size<Tuple>());
+   }
+ 
+  private:
+-  std::tuple<formatter<typename std::decay<T>::type, Char>...> formatters_;
++  decltype(detail::tuple::get_formatters<Tuple, Char>(
++      detail::tuple_index_sequence<Tuple>())) formatters_;
+ 
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
++  FMT_CONSTEXPR auto do_parse(parse_context<Char>& ctx,
+                               std::integral_constant<size_t, 0>)
+-      -> decltype(ctx.begin()) {
++      -> const Char* {
+     return ctx.begin();
+   }
+ 
+-  template <typename ParseContext, size_t N>
+-  FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
++  template <size_t N>
++  FMT_CONSTEXPR auto do_parse(parse_context<Char>& ctx,
+                               std::integral_constant<size_t, N>)
+-      -> decltype(ctx.begin()) {
++      -> const Char* {
+     auto end = ctx.begin();
+ #if FMT_TUPLE_JOIN_SPECIFIERS
+-    end = std::get<sizeof...(T) - N>(formatters_).parse(ctx);
++    end = std::get<std::tuple_size<Tuple>::value - N>(formatters_).parse(ctx);
+     if (N > 1) {
+       auto end1 = do_parse(ctx, std::integral_constant<size_t, N - 1>());
+       if (end != end1)
+-        FMT_THROW(format_error("incompatible format specs for tuple elements"));
++        report_error("incompatible format specs for tuple elements");
+     }
+ #endif
+     return end;
+   }
+ 
+   template <typename FormatContext>
+-  auto do_format(const tuple_join_view<Char, T...>&, FormatContext& ctx,
++  auto do_format(const tuple_join_view<Char, Tuple>&, FormatContext& ctx,
+                  std::integral_constant<size_t, 0>) const ->
+       typename FormatContext::iterator {
+     return ctx.out();
+   }
+ 
+   template <typename FormatContext, size_t N>
+-  auto do_format(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
++  auto do_format(const tuple_join_view<Char, Tuple>& value, FormatContext& ctx,
+                  std::integral_constant<size_t, N>) const ->
+       typename FormatContext::iterator {
+-    auto out = std::get<sizeof...(T) - N>(formatters_)
+-                   .format(std::get<sizeof...(T) - N>(value.tuple), ctx);
+-    if (N > 1) {
+-      out = std::copy(value.sep.begin(), value.sep.end(), out);
+-      ctx.advance_to(out);
+-      return do_format(value, ctx, std::integral_constant<size_t, N - 1>());
+-    }
+-    return out;
++    using std::get;
++    auto out =
++        std::get<std::tuple_size<Tuple>::value - N>(formatters_)
++            .format(get<std::tuple_size<Tuple>::value - N>(value.tuple), ctx);
++    if (N <= 1) return out;
++    out = detail::copy<Char>(value.sep, out);
++    ctx.advance_to(out);
++    return do_format(value, ctx, std::integral_constant<size_t, N - 1>());
+   }
+ };
+ 
+@@ -668,8 +766,11 @@ template <typename Container> struct all {
+ }  // namespace detail
+ 
+ template <typename T, typename Char>
+-struct formatter<T, Char,
+-                 enable_if_t<detail::is_container_adaptor_like<T>::value>>
++struct formatter<
++    T, Char,
++    enable_if_t<conjunction<detail::is_container_adaptor_like<T>,
++                            bool_constant<range_format_kind<T, Char>::value ==
++                                          range_format::disabled>>::value>>
+     : formatter<detail::all<typename T::container_type>, Char> {
+   using all = detail::all<typename T::container_type>;
+   template <typename FormatContext>
+@@ -685,40 +786,57 @@ struct formatter<T, Char,
+ 
+ FMT_BEGIN_EXPORT
+ 
+-/**
+-  \rst
+-  Returns an object that formats `tuple` with elements separated by `sep`.
+-
+-  **Example**::
++/// Returns a view that formats the iterator range `[begin, end)` with elements
++/// separated by `sep`.
++template <typename It, typename Sentinel>
++auto join(It begin, Sentinel end, string_view sep) -> join_view<It, Sentinel> {
++  return {std::move(begin), end, sep};
++}
+ 
+-    std::tuple<int, char> t = {1, 'a'};
+-    fmt::print("{}", fmt::join(t, ", "));
+-    // Output: "1, a"
+-  \endrst
++/**
++ * Returns a view that formats `range` with elements separated by `sep`.
++ *
++ * **Example**:
++ *
++ *     auto v = std::vector<int>{1, 2, 3};
++ *     fmt::print("{}", fmt::join(v, ", "));
++ *     // Output: 1, 2, 3
++ *
++ * `fmt::join` applies passed format specifiers to the range elements:
++ *
++ *     fmt::print("{:02}", fmt::join(v, ", "));
++ *     // Output: 01, 02, 03
+  */
+-template <typename... T>
+-FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple, string_view sep)
+-    -> tuple_join_view<char, T...> {
+-  return {tuple, sep};
++template <typename Range, FMT_ENABLE_IF(!is_tuple_like<Range>::value)>
++auto join(Range&& r, string_view sep)
++    -> join_view<decltype(detail::range_begin(r)),
++                 decltype(detail::range_end(r))> {
++  return {detail::range_begin(r), detail::range_end(r), sep};
+ }
+ 
+-template <typename... T>
+-FMT_CONSTEXPR auto join(const std::tuple<T...>& tuple,
+-                        basic_string_view<wchar_t> sep)
+-    -> tuple_join_view<wchar_t, T...> {
++/**
++ * Returns an object that formats `std::tuple` with elements separated by `sep`.
++ *
++ * **Example**:
++ *
++ *     auto t = std::tuple<int, char>{1, 'a'};
++ *     fmt::print("{}", fmt::join(t, ", "));
++ *     // Output: 1, a
++ */
++template <typename Tuple, FMT_ENABLE_IF(is_tuple_like<Tuple>::value)>
++FMT_CONSTEXPR auto join(const Tuple& tuple, string_view sep)
++    -> tuple_join_view<char, Tuple> {
+   return {tuple, sep};
+ }
+ 
+ /**
+-  \rst
+-  Returns an object that formats `initializer_list` with elements separated by
+-  `sep`.
+-
+-  **Example**::
+-
+-    fmt::print("{}", fmt::join({1, 2, 3}, ", "));
+-    // Output: "1, 2, 3"
+-  \endrst
++ * Returns an object that formats `std::initializer_list` with elements
++ * separated by `sep`.
++ *
++ * **Example**:
++ *
++ *     fmt::print("{}", fmt::join({1, 2, 3}, ", "));
++ *     // Output: "1, 2, 3"
+  */
+ template <typename T>
+ auto join(std::initializer_list<T> list, string_view sep)
+diff --git a/include/fmt/std.h b/include/fmt/std.h
+index ac39565..1b0ea5a 100644
+--- a/include/fmt/std.h
++++ b/include/fmt/std.h
+@@ -8,30 +8,48 @@
+ #ifndef FMT_STD_H_
+ #define FMT_STD_H_
+ 
+-#include <cstdlib>
+-#include <exception>
+-#include <memory>
+-#include <thread>
+-#include <type_traits>
+-#include <typeinfo>
+-#include <utility>
+-
++#include "format.h"
+ #include "ostream.h"
+ 
+-#if FMT_HAS_INCLUDE(<version>)
+-#  include <version>
+-#endif
+-// Checking FMT_CPLUSPLUS for warning suppression in MSVC.
+-#if FMT_CPLUSPLUS >= 201703L
+-#  if FMT_HAS_INCLUDE(<filesystem>)
+-#    include <filesystem>
++#ifndef FMT_MODULE
++#  include <atomic>
++#  include <bitset>
++#  include <complex>
++#  include <cstdlib>
++#  include <exception>
++#  include <functional>
++#  include <memory>
++#  include <thread>
++#  include <type_traits>
++#  include <typeinfo>
++#  include <utility>
++#  include <vector>
++
++// Check FMT_CPLUSPLUS to suppress a bogus warning in MSVC.
++#  if FMT_CPLUSPLUS >= 201703L
++#    if FMT_HAS_INCLUDE(<filesystem>) && \
++        (!defined(FMT_CPP_LIB_FILESYSTEM) || FMT_CPP_LIB_FILESYSTEM != 0)
++#      include <filesystem>
++#    endif
++#    if FMT_HAS_INCLUDE(<variant>)
++#      include <variant>
++#    endif
++#    if FMT_HAS_INCLUDE(<optional>)
++#      include <optional>
++#    endif
+ #  endif
+-#  if FMT_HAS_INCLUDE(<variant>)
+-#    include <variant>
++// Use > instead of >= in the version check because <source_location> may be
++// available after C++17 but before C++20 is marked as implemented.
++#  if FMT_CPLUSPLUS > 201703L && FMT_HAS_INCLUDE(<source_location>)
++#    include <source_location>
+ #  endif
+-#  if FMT_HAS_INCLUDE(<optional>)
+-#    include <optional>
++#  if FMT_CPLUSPLUS > 202002L && FMT_HAS_INCLUDE(<expected>)
++#    include <expected>
+ #  endif
++#endif  // FMT_MODULE
++
++#if FMT_HAS_INCLUDE(<version>)
++#  include <version>
+ #endif
+ 
+ // GCC 4 does not support FMT_HAS_INCLUDE.
+@@ -44,67 +62,157 @@
+ #  endif
+ #endif
+ 
+-#ifdef __cpp_lib_filesystem
++// For older Xcode versions, __cpp_lib_xxx flags are inaccurately defined.
++#ifndef FMT_CPP_LIB_FILESYSTEM
++#  ifdef __cpp_lib_filesystem
++#    define FMT_CPP_LIB_FILESYSTEM __cpp_lib_filesystem
++#  else
++#    define FMT_CPP_LIB_FILESYSTEM 0
++#  endif
++#endif
++
++#ifndef FMT_CPP_LIB_VARIANT
++#  ifdef __cpp_lib_variant
++#    define FMT_CPP_LIB_VARIANT __cpp_lib_variant
++#  else
++#    define FMT_CPP_LIB_VARIANT 0
++#  endif
++#endif
++
++#if FMT_CPP_LIB_FILESYSTEM
+ FMT_BEGIN_NAMESPACE
+ 
+ namespace detail {
+ 
+-template <typename Char>
+-void write_escaped_path(basic_memory_buffer<Char>& quoted,
+-                        const std::filesystem::path& p) {
+-  write_escaped_string<Char>(std::back_inserter(quoted), p.string<Char>());
+-}
+-#  ifdef _WIN32
+-template <>
+-inline void write_escaped_path<char>(memory_buffer& quoted,
+-                                     const std::filesystem::path& p) {
+-  auto buf = basic_memory_buffer<wchar_t>();
+-  write_escaped_string<wchar_t>(std::back_inserter(buf), p.native());
+-  // Convert UTF-16 to UTF-8.
+-  if (!to_utf8<wchar_t>::convert(quoted, {buf.data(), buf.size()}))
+-    FMT_THROW(std::runtime_error("invalid utf16"));
++template <typename Char, typename PathChar>
++auto get_path_string(const std::filesystem::path& p,
++                     const std::basic_string<PathChar>& native) {
++  if constexpr (std::is_same_v<Char, char> && std::is_same_v<PathChar, wchar_t>)
++    return to_utf8<wchar_t>(native, to_utf8_error_policy::replace);
++  else
++    return p.string<Char>();
+ }
+-#  endif
+-template <>
+-inline void write_escaped_path<std::filesystem::path::value_type>(
+-    basic_memory_buffer<std::filesystem::path::value_type>& quoted,
+-    const std::filesystem::path& p) {
+-  write_escaped_string<std::filesystem::path::value_type>(
+-      std::back_inserter(quoted), p.native());
++
++template <typename Char, typename PathChar>
++void write_escaped_path(basic_memory_buffer<Char>& quoted,
++                        const std::filesystem::path& p,
++                        const std::basic_string<PathChar>& native) {
++  if constexpr (std::is_same_v<Char, char> &&
++                std::is_same_v<PathChar, wchar_t>) {
++    auto buf = basic_memory_buffer<wchar_t>();
++    write_escaped_string<wchar_t>(std::back_inserter(buf), native);
++    bool valid = to_utf8<wchar_t>::convert(quoted, {buf.data(), buf.size()});
++    FMT_ASSERT(valid, "invalid utf16");
++  } else if constexpr (std::is_same_v<Char, PathChar>) {
++    write_escaped_string<std::filesystem::path::value_type>(
++        std::back_inserter(quoted), native);
++  } else {
++    write_escaped_string<Char>(std::back_inserter(quoted), p.string<Char>());
++  }
+ }
+ 
+ }  // namespace detail
+ 
+-FMT_EXPORT
+-template <typename Char>
+-struct formatter<std::filesystem::path, Char>
+-    : formatter<basic_string_view<Char>> {
+-  template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
+-    auto out = formatter<basic_string_view<Char>>::parse(ctx);
+-    this->set_debug_format(false);
+-    return out;
++template <typename Char> struct formatter<std::filesystem::path, Char> {
++ private:
++  format_specs specs_;
++  detail::arg_ref<Char> width_ref_;
++  bool debug_ = false;
++  char path_type_ = 0;
++
++ public:
++  FMT_CONSTEXPR void set_debug_format(bool set = true) { debug_ = set; }
++
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) {
++    auto it = ctx.begin(), end = ctx.end();
++    if (it == end) return it;
++
++    it = detail::parse_align(it, end, specs_);
++    if (it == end) return it;
++
++    Char c = *it;
++    if ((c >= '0' && c <= '9') || c == '{')
++      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
++    if (it != end && *it == '?') {
++      debug_ = true;
++      ++it;
++    }
++    if (it != end && (*it == 'g')) path_type_ = detail::to_ascii(*it++);
++    return it;
+   }
++
+   template <typename FormatContext>
+-  auto format(const std::filesystem::path& p, FormatContext& ctx) const ->
+-      typename FormatContext::iterator {
++  auto format(const std::filesystem::path& p, FormatContext& ctx) const {
++    auto specs = specs_;
++    auto path_string =
++        !path_type_ ? p.native()
++                    : p.generic_string<std::filesystem::path::value_type>();
++
++    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
++                                ctx);
++    if (!debug_) {
++      auto s = detail::get_path_string<Char>(p, path_string);
++      return detail::write(ctx.out(), basic_string_view<Char>(s), specs);
++    }
+     auto quoted = basic_memory_buffer<Char>();
+-    detail::write_escaped_path(quoted, p);
+-    return formatter<basic_string_view<Char>>::format(
+-        basic_string_view<Char>(quoted.data(), quoted.size()), ctx);
++    detail::write_escaped_path(quoted, p, path_string);
++    return detail::write(ctx.out(),
++                         basic_string_view<Char>(quoted.data(), quoted.size()),
++                         specs);
+   }
+ };
++
++class path : public std::filesystem::path {
++ public:
++  auto display_string() const -> std::string {
++    const std::filesystem::path& base = *this;
++    return fmt::format(FMT_STRING("{}"), base);
++  }
++  auto system_string() const -> std::string { return string(); }
++
++  auto generic_display_string() const -> std::string {
++    const std::filesystem::path& base = *this;
++    return fmt::format(FMT_STRING("{:g}"), base);
++  }
++  auto generic_system_string() const -> std::string { return generic_string(); }
++};
++
+ FMT_END_NAMESPACE
+-#endif
++#endif  // FMT_CPP_LIB_FILESYSTEM
+ 
+ FMT_BEGIN_NAMESPACE
+-FMT_EXPORT
++template <std::size_t N, typename Char>
++struct formatter<std::bitset<N>, Char>
++    : nested_formatter<basic_string_view<Char>, Char> {
++ private:
++  // Functor because C++11 doesn't support generic lambdas.
++  struct writer {
++    const std::bitset<N>& bs;
++
++    template <typename OutputIt>
++    FMT_CONSTEXPR auto operator()(OutputIt out) -> OutputIt {
++      for (auto pos = N; pos > 0; --pos) {
++        out = detail::write<Char>(out, bs[pos - 1] ? Char('1') : Char('0'));
++      }
++
++      return out;
++    }
++  };
++
++ public:
++  template <typename FormatContext>
++  auto format(const std::bitset<N>& bs, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    return this->write_padded(ctx, writer{bs});
++  }
++};
++
+ template <typename Char>
+ struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
+ FMT_END_NAMESPACE
+ 
+ #ifdef __cpp_lib_optional
+ FMT_BEGIN_NAMESPACE
+-FMT_EXPORT
+ template <typename T, typename Char>
+ struct formatter<std::optional<T>, Char,
+                  std::enable_if_t<is_formattable<T, Char>::value>> {
+@@ -126,13 +234,13 @@ struct formatter<std::optional<T>, Char,
+   FMT_CONSTEXPR static void maybe_set_debug_format(U&, ...) {}
+ 
+  public:
+-  template <typename ParseContext> FMT_CONSTEXPR auto parse(ParseContext& ctx) {
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) {
+     maybe_set_debug_format(underlying_, true);
+     return underlying_.parse(ctx);
+   }
+ 
+   template <typename FormatContext>
+-  auto format(std::optional<T> const& opt, FormatContext& ctx) const
++  auto format(const std::optional<T>& opt, FormatContext& ctx) const
+       -> decltype(ctx.out()) {
+     if (!opt) return detail::write<Char>(ctx.out(), none);
+ 
+@@ -146,24 +254,80 @@ struct formatter<std::optional<T>, Char,
+ FMT_END_NAMESPACE
+ #endif  // __cpp_lib_optional
+ 
+-#ifdef __cpp_lib_variant
++#if defined(__cpp_lib_expected) || FMT_CPP_LIB_VARIANT
++
+ FMT_BEGIN_NAMESPACE
+-FMT_EXPORT
+-template <typename Char> struct formatter<std::monostate, Char> {
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
++namespace detail {
++
++template <typename Char, typename OutputIt, typename T>
++auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
++  if constexpr (has_to_string_view<T>::value)
++    return write_escaped_string<Char>(out, detail::to_string_view(v));
++  if constexpr (std::is_same_v<T, Char>) return write_escaped_char(out, v);
++  return write<Char>(out, v);
++}
++
++}  // namespace detail
++
++FMT_END_NAMESPACE
++#endif
++
++#ifdef __cpp_lib_expected
++FMT_BEGIN_NAMESPACE
++
++template <typename T, typename E, typename Char>
++struct formatter<std::expected<T, E>, Char,
++                 std::enable_if_t<(std::is_void<T>::value ||
++                                   is_formattable<T, Char>::value) &&
++                                  is_formattable<E, Char>::value>> {
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+     return ctx.begin();
+   }
+ 
+   template <typename FormatContext>
+-  auto format(const std::monostate&, FormatContext& ctx) const
++  auto format(const std::expected<T, E>& value, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    auto out = ctx.out();
++
++    if (value.has_value()) {
++      out = detail::write<Char>(out, "expected(");
++      if constexpr (!std::is_void<T>::value)
++        out = detail::write_escaped_alternative<Char>(out, *value);
++    } else {
++      out = detail::write<Char>(out, "unexpected(");
++      out = detail::write_escaped_alternative<Char>(out, value.error());
++    }
++    *out++ = ')';
++    return out;
++  }
++};
++FMT_END_NAMESPACE
++#endif  // __cpp_lib_expected
++
++#ifdef __cpp_lib_source_location
++FMT_BEGIN_NAMESPACE
++template <> struct formatter<std::source_location> {
++  FMT_CONSTEXPR auto parse(parse_context<>& ctx) { return ctx.begin(); }
++
++  template <typename FormatContext>
++  auto format(const std::source_location& loc, FormatContext& ctx) const
+       -> decltype(ctx.out()) {
+     auto out = ctx.out();
+-    out = detail::write<Char>(out, "monostate");
++    out = detail::write(out, loc.file_name());
++    out = detail::write(out, ':');
++    out = detail::write<char>(out, loc.line());
++    out = detail::write(out, ':');
++    out = detail::write<char>(out, loc.column());
++    out = detail::write(out, ": ");
++    out = detail::write(out, loc.function_name());
+     return out;
+   }
+ };
++FMT_END_NAMESPACE
++#endif
+ 
++#if FMT_CPP_LIB_VARIANT
++FMT_BEGIN_NAMESPACE
+ namespace detail {
+ 
+ template <typename T>
+@@ -186,17 +350,8 @@ template <typename T, typename C> class is_variant_formattable_ {
+       decltype(check(variant_index_sequence<T>{}))::value;
+ };
+ 
+-template <typename Char, typename OutputIt, typename T>
+-auto write_variant_alternative(OutputIt out, const T& v) -> OutputIt {
+-  if constexpr (is_string<T>::value)
+-    return write_escaped_string<Char>(out, detail::to_string_view(v));
+-  else if constexpr (std::is_same_v<T, Char>)
+-    return write_escaped_char(out, v);
+-  else
+-    return write<Char>(out, v);
+-}
+-
+ }  // namespace detail
++
+ template <typename T> struct is_variant_like {
+   static constexpr const bool value = detail::is_variant_like_<T>::value;
+ };
+@@ -206,14 +361,24 @@ template <typename T, typename C> struct is_variant_formattable {
+       detail::is_variant_formattable_<T, C>::value;
+ };
+ 
+-FMT_EXPORT
++template <typename Char> struct formatter<std::monostate, Char> {
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    return ctx.begin();
++  }
++
++  template <typename FormatContext>
++  auto format(const std::monostate&, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    return detail::write<Char>(ctx.out(), "monostate");
++  }
++};
++
+ template <typename Variant, typename Char>
+ struct formatter<
+     Variant, Char,
+     std::enable_if_t<std::conjunction_v<
+         is_variant_like<Variant>, is_variant_formattable<Variant, Char>>>> {
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+     return ctx.begin();
+   }
+ 
+@@ -223,13 +388,14 @@ struct formatter<
+     auto out = ctx.out();
+ 
+     out = detail::write<Char>(out, "variant(");
+-    try {
++    FMT_TRY {
+       std::visit(
+           [&](const auto& v) {
+-            out = detail::write_variant_alternative<Char>(out, v);
++            out = detail::write_escaped_alternative<Char>(out, v);
+           },
+           value);
+-    } catch (const std::bad_variant_access&) {
++    }
++    FMT_CATCH(const std::bad_variant_access&) {
+       detail::write<Char>(out, "valueless by exception");
+     }
+     *out++ = ')';
+@@ -237,113 +403,308 @@ struct formatter<
+   }
+ };
+ FMT_END_NAMESPACE
+-#endif  // __cpp_lib_variant
++#endif  // FMT_CPP_LIB_VARIANT
+ 
+ FMT_BEGIN_NAMESPACE
+-FMT_EXPORT
+-template <typename Char> struct formatter<std::error_code, Char> {
+-  template <typename ParseContext>
+-  FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
+-    return ctx.begin();
++template <> struct formatter<std::error_code> {
++ private:
++  format_specs specs_;
++  detail::arg_ref<char> width_ref_;
++
++ public:
++  FMT_CONSTEXPR auto parse(parse_context<>& ctx) -> const char* {
++    auto it = ctx.begin(), end = ctx.end();
++    if (it == end) return it;
++
++    it = detail::parse_align(it, end, specs_);
++    if (it == end) return it;
++
++    char c = *it;
++    if ((c >= '0' && c <= '9') || c == '{')
++      it = detail::parse_width(it, end, specs_, width_ref_, ctx);
++    return it;
+   }
+ 
+   template <typename FormatContext>
+-  FMT_CONSTEXPR auto format(const std::error_code& ec, FormatContext& ctx) const
++  FMT_CONSTEXPR20 auto format(const std::error_code& ec,
++                              FormatContext& ctx) const -> decltype(ctx.out()) {
++    auto specs = specs_;
++    detail::handle_dynamic_spec(specs.dynamic_width(), specs.width, width_ref_,
++                                ctx);
++    memory_buffer buf;
++    buf.append(string_view(ec.category().name()));
++    buf.push_back(':');
++    detail::write<char>(appender(buf), ec.value());
++    return detail::write<char>(ctx.out(), string_view(buf.data(), buf.size()),
++                               specs);
++  }
++};
++
++#if FMT_USE_RTTI
++namespace detail {
++
++template <typename Char, typename OutputIt>
++auto write_demangled_name(OutputIt out, const std::type_info& ti) -> OutputIt {
++#  ifdef FMT_HAS_ABI_CXA_DEMANGLE
++  int status = 0;
++  std::size_t size = 0;
++  std::unique_ptr<char, void (*)(void*)> demangled_name_ptr(
++      abi::__cxa_demangle(ti.name(), nullptr, &size, &status), &std::free);
++
++  string_view demangled_name_view;
++  if (demangled_name_ptr) {
++    demangled_name_view = demangled_name_ptr.get();
++
++    // Normalization of stdlib inline namespace names.
++    // libc++ inline namespaces.
++    //  std::__1::*       -> std::*
++    //  std::__1::__fs::* -> std::*
++    // libstdc++ inline namespaces.
++    //  std::__cxx11::*             -> std::*
++    //  std::filesystem::__cxx11::* -> std::filesystem::*
++    if (demangled_name_view.starts_with("std::")) {
++      char* begin = demangled_name_ptr.get();
++      char* to = begin + 5;  // std::
++      for (char *from = to, *end = begin + demangled_name_view.size();
++           from < end;) {
++        // This is safe, because demangled_name is NUL-terminated.
++        if (from[0] == '_' && from[1] == '_') {
++          char* next = from + 1;
++          while (next < end && *next != ':') next++;
++          if (next[0] == ':' && next[1] == ':') {
++            from = next + 2;
++            continue;
++          }
++        }
++        *to++ = *from++;
++      }
++      demangled_name_view = {begin, detail::to_unsigned(to - begin)};
++    }
++  } else {
++    demangled_name_view = string_view(ti.name());
++  }
++  return detail::write_bytes<Char>(out, demangled_name_view);
++#  elif FMT_MSC_VERSION
++  const string_view demangled_name(ti.name());
++  for (std::size_t i = 0; i < demangled_name.size(); ++i) {
++    auto sub = demangled_name;
++    sub.remove_prefix(i);
++    if (sub.starts_with("enum ")) {
++      i += 4;
++      continue;
++    }
++    if (sub.starts_with("class ") || sub.starts_with("union ")) {
++      i += 5;
++      continue;
++    }
++    if (sub.starts_with("struct ")) {
++      i += 6;
++      continue;
++    }
++    if (*sub.begin() != ' ') *out++ = *sub.begin();
++  }
++  return out;
++#  else
++  return detail::write_bytes<Char>(out, string_view(ti.name()));
++#  endif
++}
++
++}  // namespace detail
++
++template <typename Char>
++struct formatter<std::type_info, Char  // DEPRECATED! Mixing code unit types.
++                 > {
++ public:
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    return ctx.begin();
++  }
++
++  template <typename Context>
++  auto format(const std::type_info& ti, Context& ctx) const
+       -> decltype(ctx.out()) {
+-    auto out = ctx.out();
+-    out = detail::write_bytes(out, ec.category().name(), format_specs<Char>());
+-    out = detail::write<Char>(out, Char(':'));
+-    out = detail::write<Char>(out, ec.value());
+-    return out;
++    return detail::write_demangled_name<Char>(ctx.out(), ti);
+   }
+ };
++#endif
+ 
+-FMT_EXPORT
+ template <typename T, typename Char>
+ struct formatter<
+-    T, Char,
++    T, Char,  // DEPRECATED! Mixing code unit types.
+     typename std::enable_if<std::is_base_of<std::exception, T>::value>::type> {
+  private:
+   bool with_typename_ = false;
+ 
+  public:
+-  FMT_CONSTEXPR auto parse(basic_format_parse_context<Char>& ctx)
+-      -> decltype(ctx.begin()) {
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
+     auto it = ctx.begin();
+     auto end = ctx.end();
+     if (it == end || *it == '}') return it;
+     if (*it == 't') {
+       ++it;
+-      with_typename_ = true;
++      with_typename_ = FMT_USE_RTTI != 0;
+     }
+     return it;
+   }
+ 
+-  template <typename OutputIt>
+-  auto format(const std::exception& ex,
+-              basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
+-    format_specs<Char> spec;
++  template <typename Context>
++  auto format(const std::exception& ex, Context& ctx) const
++      -> decltype(ctx.out()) {
+     auto out = ctx.out();
+-    if (!with_typename_)
+-      return detail::write_bytes(out, string_view(ex.what()), spec);
+-
+-    const std::type_info& ti = typeid(ex);
+-#ifdef FMT_HAS_ABI_CXA_DEMANGLE
+-    int status = 0;
+-    std::size_t size = 0;
+-    std::unique_ptr<char, decltype(&std::free)> demangled_name_ptr(
+-        abi::__cxa_demangle(ti.name(), nullptr, &size, &status), &std::free);
+-
+-    string_view demangled_name_view;
+-    if (demangled_name_ptr) {
+-      demangled_name_view = demangled_name_ptr.get();
+-
+-      // Normalization of stdlib inline namespace names.
+-      // libc++ inline namespaces.
+-      //  std::__1::*       -> std::*
+-      //  std::__1::__fs::* -> std::*
+-      // libstdc++ inline namespaces.
+-      //  std::__cxx11::*             -> std::*
+-      //  std::filesystem::__cxx11::* -> std::filesystem::*
+-      if (demangled_name_view.starts_with("std::")) {
+-        char* begin = demangled_name_ptr.get();
+-        char* to = begin + 5;  // std::
+-        for (char *from = to, *end = begin + demangled_name_view.size();
+-             from < end;) {
+-          // This is safe, because demangled_name is NUL-terminated.
+-          if (from[0] == '_' && from[1] == '_') {
+-            char* next = from + 1;
+-            while (next < end && *next != ':') next++;
+-            if (next[0] == ':' && next[1] == ':') {
+-              from = next + 2;
+-              continue;
+-            }
+-          }
+-          *to++ = *from++;
+-        }
+-        demangled_name_view = {begin, detail::to_unsigned(to - begin)};
+-      }
+-    } else {
+-      demangled_name_view = string_view(ti.name());
++#if FMT_USE_RTTI
++    if (with_typename_) {
++      out = detail::write_demangled_name<Char>(out, typeid(ex));
++      *out++ = ':';
++      *out++ = ' ';
+     }
+-    out = detail::write_bytes(out, demangled_name_view, spec);
+-#elif FMT_MSC_VERSION
+-    string_view demangled_name_view(ti.name());
+-    if (demangled_name_view.starts_with("class "))
+-      demangled_name_view.remove_prefix(6);
+-    else if (demangled_name_view.starts_with("struct "))
+-      demangled_name_view.remove_prefix(7);
+-    out = detail::write_bytes(out, demangled_name_view, spec);
+-#else
+-    out = detail::write_bytes(out, string_view(ti.name()), spec);
+ #endif
+-    out = detail::write<Char>(out, Char(':'));
+-    out = detail::write<Char>(out, Char(' '));
+-    out = detail::write_bytes(out, string_view(ex.what()), spec);
++    return detail::write_bytes<Char>(out, string_view(ex.what()));
++  }
++};
++
++namespace detail {
++
++template <typename T, typename Enable = void>
++struct has_flip : std::false_type {};
++
++template <typename T>
++struct has_flip<T, void_t<decltype(std::declval<T>().flip())>>
++    : std::true_type {};
++
++template <typename T> struct is_bit_reference_like {
++  static constexpr const bool value =
++      std::is_convertible<T, bool>::value &&
++      std::is_nothrow_assignable<T, bool>::value && has_flip<T>::value;
++};
++
++#ifdef _LIBCPP_VERSION
++
++// Workaround for libc++ incompatibility with C++ standard.
++// According to the Standard, `bitset::operator[] const` returns bool.
++template <typename C>
++struct is_bit_reference_like<std::__bit_const_reference<C>> {
++  static constexpr const bool value = true;
++};
++
++#endif
++
++}  // namespace detail
++
++// We can't use std::vector<bool, Allocator>::reference and
++// std::bitset<N>::reference because the compiler can't deduce Allocator and N
++// in partial specialization.
++template <typename BitRef, typename Char>
++struct formatter<BitRef, Char,
++                 enable_if_t<detail::is_bit_reference_like<BitRef>::value>>
++    : formatter<bool, Char> {
++  template <typename FormatContext>
++  FMT_CONSTEXPR auto format(const BitRef& v, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    return formatter<bool, Char>::format(v, ctx);
++  }
++};
++
++template <typename T, typename Deleter>
++auto ptr(const std::unique_ptr<T, Deleter>& p) -> const void* {
++  return p.get();
++}
++template <typename T> auto ptr(const std::shared_ptr<T>& p) -> const void* {
++  return p.get();
++}
++
++template <typename T, typename Char>
++struct formatter<std::atomic<T>, Char,
++                 enable_if_t<is_formattable<T, Char>::value>>
++    : formatter<T, Char> {
++  template <typename FormatContext>
++  auto format(const std::atomic<T>& v, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    return formatter<T, Char>::format(v.load(), ctx);
++  }
++};
++
++#ifdef __cpp_lib_atomic_flag_test
++template <typename Char>
++struct formatter<std::atomic_flag, Char> : formatter<bool, Char> {
++  template <typename FormatContext>
++  auto format(const std::atomic_flag& v, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    return formatter<bool, Char>::format(v.test(), ctx);
++  }
++};
++#endif  // __cpp_lib_atomic_flag_test
+ 
++template <typename T, typename Char> struct formatter<std::complex<T>, Char> {
++ private:
++  detail::dynamic_format_specs<Char> specs_;
++
++  template <typename FormatContext, typename OutputIt>
++  FMT_CONSTEXPR auto do_format(const std::complex<T>& c,
++                               detail::dynamic_format_specs<Char>& specs,
++                               FormatContext& ctx, OutputIt out) const
++      -> OutputIt {
++    if (c.real() != 0) {
++      *out++ = Char('(');
++      out = detail::write<Char>(out, c.real(), specs, ctx.locale());
++      specs.set_sign(sign::plus);
++      out = detail::write<Char>(out, c.imag(), specs, ctx.locale());
++      if (!detail::isfinite(c.imag())) *out++ = Char(' ');
++      *out++ = Char('i');
++      *out++ = Char(')');
++      return out;
++    }
++    out = detail::write<Char>(out, c.imag(), specs, ctx.locale());
++    if (!detail::isfinite(c.imag())) *out++ = Char(' ');
++    *out++ = Char('i');
+     return out;
+   }
++
++ public:
++  FMT_CONSTEXPR auto parse(parse_context<Char>& ctx) -> const Char* {
++    if (ctx.begin() == ctx.end() || *ctx.begin() == '}') return ctx.begin();
++    return parse_format_specs(ctx.begin(), ctx.end(), specs_, ctx,
++                              detail::type_constant<T, Char>::value);
++  }
++
++  template <typename FormatContext>
++  auto format(const std::complex<T>& c, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    auto specs = specs_;
++    if (specs.dynamic()) {
++      detail::handle_dynamic_spec(specs.dynamic_width(), specs.width,
++                                  specs.width_ref, ctx);
++      detail::handle_dynamic_spec(specs.dynamic_precision(), specs.precision,
++                                  specs.precision_ref, ctx);
++    }
++
++    if (specs.width == 0) return do_format(c, specs, ctx, ctx.out());
++    auto buf = basic_memory_buffer<Char>();
++
++    auto outer_specs = format_specs();
++    outer_specs.width = specs.width;
++    outer_specs.copy_fill_from(specs);
++    outer_specs.set_align(specs.align());
++
++    specs.width = 0;
++    specs.set_fill({});
++    specs.set_align(align::none);
++
++    do_format(c, specs, ctx, basic_appender<Char>(buf));
++    return detail::write<Char>(ctx.out(),
++                               basic_string_view<Char>(buf.data(), buf.size()),
++                               outer_specs);
++  }
++};
++
++template <typename T, typename Char>
++struct formatter<std::reference_wrapper<T>, Char,
++                 enable_if_t<is_formattable<remove_cvref_t<T>, Char>::value>>
++    : formatter<remove_cvref_t<T>, Char> {
++  template <typename FormatContext>
++  auto format(std::reference_wrapper<T> ref, FormatContext& ctx) const
++      -> decltype(ctx.out()) {
++    return formatter<remove_cvref_t<T>, Char>::format(ref.get(), ctx);
++  }
+ };
+-FMT_END_NAMESPACE
+ 
++FMT_END_NAMESPACE
+ #endif  // FMT_STD_H_
+diff --git a/include/fmt/xchar.h b/include/fmt/xchar.h
+index 625ec36..d959010 100644
+--- a/include/fmt/xchar.h
++++ b/include/fmt/xchar.h
+@@ -8,12 +8,16 @@
+ #ifndef FMT_XCHAR_H_
+ #define FMT_XCHAR_H_
+ 
+-#include <cwchar>
+-
++#include "color.h"
+ #include "format.h"
+-
+-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
+-#  include <locale>
++#include "ostream.h"
++#include "ranges.h"
++
++#ifndef FMT_MODULE
++#  include <cwchar>
++#  if FMT_USE_LOCALE
++#    include <locale>
++#  endif
+ #endif
+ 
+ FMT_BEGIN_NAMESPACE
+@@ -22,10 +26,26 @@ namespace detail {
+ template <typename T>
+ using is_exotic_char = bool_constant<!std::is_same<T, char>::value>;
+ 
+-inline auto write_loc(std::back_insert_iterator<detail::buffer<wchar_t>> out,
+-                      loc_value value, const format_specs<wchar_t>& specs,
+-                      locale_ref loc) -> bool {
+-#ifndef FMT_STATIC_THOUSANDS_SEPARATOR
++template <typename S, typename = void> struct format_string_char {};
++
++template <typename S>
++struct format_string_char<
++    S, void_t<decltype(sizeof(detail::to_string_view(std::declval<S>())))>> {
++  using type = char_t<S>;
++};
++
++template <typename S>
++struct format_string_char<
++    S, enable_if_t<std::is_base_of<detail::compile_string, S>::value>> {
++  using type = typename S::char_type;
++};
++
++template <typename S>
++using format_string_char_t = typename format_string_char<S>::type;
++
++inline auto write_loc(basic_appender<wchar_t> out, loc_value value,
++                      const format_specs& specs, locale_ref loc) -> bool {
++#if FMT_USE_LOCALE
+   auto& numpunct =
+       std::use_facet<std::numpunct<wchar_t>>(loc.get<std::locale>());
+   auto separator = std::wstring();
+@@ -40,41 +60,79 @@ inline auto write_loc(std::back_insert_iterator<detail::buffer<wchar_t>> out,
+ FMT_BEGIN_EXPORT
+ 
+ using wstring_view = basic_string_view<wchar_t>;
+-using wformat_parse_context = basic_format_parse_context<wchar_t>;
+-using wformat_context = buffer_context<wchar_t>;
++using wformat_parse_context = parse_context<wchar_t>;
++using wformat_context = buffered_context<wchar_t>;
+ using wformat_args = basic_format_args<wformat_context>;
+ using wmemory_buffer = basic_memory_buffer<wchar_t>;
+ 
+-#if FMT_GCC_VERSION && FMT_GCC_VERSION < 409
+-// Workaround broken conversion on older gcc.
+-template <typename... Args> using wformat_string = wstring_view;
+-inline auto runtime(wstring_view s) -> wstring_view { return s; }
+-#else
+-template <typename... Args>
+-using wformat_string = basic_format_string<wchar_t, type_identity_t<Args>...>;
++template <typename Char, typename... T> struct basic_fstring {
++ private:
++  basic_string_view<Char> str_;
++
++  static constexpr int num_static_named_args =
++      detail::count_static_named_args<T...>();
++
++  using checker = detail::format_string_checker<
++      Char, static_cast<int>(sizeof...(T)), num_static_named_args,
++      num_static_named_args != detail::count_named_args<T...>()>;
++
++  using arg_pack = detail::arg_pack<T...>;
++
++ public:
++  using t = basic_fstring;
++
++  template <typename S,
++            FMT_ENABLE_IF(
++                std::is_convertible<const S&, basic_string_view<Char>>::value)>
++  FMT_CONSTEVAL FMT_ALWAYS_INLINE basic_fstring(const S& s) : str_(s) {
++    if (FMT_USE_CONSTEVAL)
++      detail::parse_format_string<Char>(s, checker(s, arg_pack()));
++  }
++  template <typename S,
++            FMT_ENABLE_IF(std::is_base_of<detail::compile_string, S>::value&&
++                              std::is_same<typename S::char_type, Char>::value)>
++  FMT_ALWAYS_INLINE basic_fstring(const S&) : str_(S()) {
++    FMT_CONSTEXPR auto sv = basic_string_view<Char>(S());
++    FMT_CONSTEXPR int ignore =
++        (parse_format_string(sv, checker(sv, arg_pack())), 0);
++    detail::ignore_unused(ignore);
++  }
++  basic_fstring(runtime_format_string<Char> fmt) : str_(fmt.str) {}
++
++  operator basic_string_view<Char>() const { return str_; }
++  auto get() const -> basic_string_view<Char> { return str_; }
++};
++
++template <typename Char, typename... T>
++using basic_format_string = basic_fstring<Char, T...>;
++
++template <typename... T>
++using wformat_string = typename basic_format_string<wchar_t, T...>::t;
+ inline auto runtime(wstring_view s) -> runtime_format_string<wchar_t> {
+   return {{s}};
+ }
+-#endif
+ 
+ template <> struct is_char<wchar_t> : std::true_type {};
+-template <> struct is_char<detail::char8_type> : std::true_type {};
+ template <> struct is_char<char16_t> : std::true_type {};
+ template <> struct is_char<char32_t> : std::true_type {};
+ 
++#ifdef __cpp_char8_t
++template <> struct is_char<char8_t> : bool_constant<detail::is_utf8_enabled> {};
++#endif
++
+ template <typename... T>
+-constexpr format_arg_store<wformat_context, T...> make_wformat_args(
+-    const T&... args) {
+-  return {args...};
++constexpr auto make_wformat_args(T&... args)
++    -> decltype(fmt::make_format_args<wformat_context>(args...)) {
++  return fmt::make_format_args<wformat_context>(args...);
+ }
+ 
++#if !FMT_USE_NONTYPE_TEMPLATE_ARGS
+ inline namespace literals {
+-#if FMT_USE_USER_DEFINED_LITERALS && !FMT_USE_NONTYPE_TEMPLATE_ARGS
+-constexpr detail::udl_arg<wchar_t> operator"" _a(const wchar_t* s, size_t) {
++inline auto operator""_a(const wchar_t* s, size_t) -> detail::udl_arg<wchar_t> {
+   return {s};
+ }
+-#endif
+ }  // namespace literals
++#endif
+ 
+ template <typename It, typename Sentinel>
+ auto join(It begin, Sentinel end, wstring_view sep)
+@@ -82,9 +140,9 @@ auto join(It begin, Sentinel end, wstring_view sep)
+   return {begin, end, sep};
+ }
+ 
+-template <typename Range>
++template <typename Range, FMT_ENABLE_IF(!is_tuple_like<Range>::value)>
+ auto join(Range&& range, wstring_view sep)
+-    -> join_view<detail::iterator_t<Range>, detail::sentinel_t<Range>,
++    -> join_view<decltype(std::begin(range)), decltype(std::end(range)),
+                  wchar_t> {
+   return join(std::begin(range), std::end(range), sep);
+ }
+@@ -95,13 +153,19 @@ auto join(std::initializer_list<T> list, wstring_view sep)
+   return join(std::begin(list), std::end(list), sep);
+ }
+ 
++template <typename Tuple, FMT_ENABLE_IF(is_tuple_like<Tuple>::value)>
++auto join(const Tuple& tuple, basic_string_view<wchar_t> sep)
++    -> tuple_join_view<wchar_t, Tuple> {
++  return {tuple, sep};
++}
++
+ template <typename Char, FMT_ENABLE_IF(!std::is_same<Char, char>::value)>
+-auto vformat(basic_string_view<Char> format_str,
+-             basic_format_args<buffer_context<type_identity_t<Char>>> args)
++auto vformat(basic_string_view<Char> fmt,
++             typename detail::vformat_args<Char>::type args)
+     -> std::basic_string<Char> {
+   auto buf = basic_memory_buffer<Char>();
+-  detail::vformat_to(buf, format_str, args);
+-  return to_string(buf);
++  detail::vformat_to(buf, fmt, args);
++  return {buf.data(), buf.size()};
+ }
+ 
+ template <typename... T>
+@@ -109,110 +173,122 @@ auto format(wformat_string<T...> fmt, T&&... args) -> std::wstring {
+   return vformat(fmt::wstring_view(fmt), fmt::make_wformat_args(args...));
+ }
+ 
++template <typename OutputIt, typename... T>
++auto format_to(OutputIt out, wformat_string<T...> fmt, T&&... args)
++    -> OutputIt {
++  return vformat_to(out, fmt::wstring_view(fmt),
++                    fmt::make_wformat_args(args...));
++}
++
+ // Pass char_t as a default template parameter instead of using
+ // std::basic_string<char_t<S>> to reduce the symbol size.
+-template <typename S, typename... T, typename Char = char_t<S>,
++template <typename S, typename... T,
++          typename Char = detail::format_string_char_t<S>,
+           FMT_ENABLE_IF(!std::is_same<Char, char>::value &&
+                         !std::is_same<Char, wchar_t>::value)>
+-auto format(const S& format_str, T&&... args) -> std::basic_string<Char> {
+-  return vformat(detail::to_string_view(format_str),
+-                 fmt::make_format_args<buffer_context<Char>>(args...));
++auto format(const S& fmt, T&&... args) -> std::basic_string<Char> {
++  return vformat(detail::to_string_view(fmt),
++                 fmt::make_format_args<buffered_context<Char>>(args...));
+ }
+ 
+-template <typename Locale, typename S, typename Char = char_t<S>,
++template <typename Locale, typename S,
++          typename Char = detail::format_string_char_t<S>,
+           FMT_ENABLE_IF(detail::is_locale<Locale>::value&&
+                             detail::is_exotic_char<Char>::value)>
+-inline auto vformat(
+-    const Locale& loc, const S& format_str,
+-    basic_format_args<buffer_context<type_identity_t<Char>>> args)
++inline auto vformat(const Locale& loc, const S& fmt,
++                    typename detail::vformat_args<Char>::type args)
+     -> std::basic_string<Char> {
+-  return detail::vformat(loc, detail::to_string_view(format_str), args);
++  auto buf = basic_memory_buffer<Char>();
++  detail::vformat_to(buf, detail::to_string_view(fmt), args,
++                     detail::locale_ref(loc));
++  return {buf.data(), buf.size()};
+ }
+ 
+-template <typename Locale, typename S, typename... T, typename Char = char_t<S>,
++template <typename Locale, typename S, typename... T,
++          typename Char = detail::format_string_char_t<S>,
+           FMT_ENABLE_IF(detail::is_locale<Locale>::value&&
+                             detail::is_exotic_char<Char>::value)>
+-inline auto format(const Locale& loc, const S& format_str, T&&... args)
++inline auto format(const Locale& loc, const S& fmt, T&&... args)
+     -> std::basic_string<Char> {
+-  return detail::vformat(loc, detail::to_string_view(format_str),
+-                         fmt::make_format_args<buffer_context<Char>>(args...));
++  return vformat(loc, detail::to_string_view(fmt),
++                 fmt::make_format_args<buffered_context<Char>>(args...));
+ }
+ 
+-template <typename OutputIt, typename S, typename Char = char_t<S>,
++template <typename OutputIt, typename S,
++          typename Char = detail::format_string_char_t<S>,
+           FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
+                             detail::is_exotic_char<Char>::value)>
+-auto vformat_to(OutputIt out, const S& format_str,
+-                basic_format_args<buffer_context<type_identity_t<Char>>> args)
+-    -> OutputIt {
++auto vformat_to(OutputIt out, const S& fmt,
++                typename detail::vformat_args<Char>::type args) -> OutputIt {
+   auto&& buf = detail::get_buffer<Char>(out);
+-  detail::vformat_to(buf, detail::to_string_view(format_str), args);
++  detail::vformat_to(buf, detail::to_string_view(fmt), args);
+   return detail::get_iterator(buf, out);
+ }
+ 
+ template <typename OutputIt, typename S, typename... T,
+-          typename Char = char_t<S>,
+-          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
+-                            detail::is_exotic_char<Char>::value)>
++          typename Char = detail::format_string_char_t<S>,
++          FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value &&
++                        !std::is_same<Char, char>::value &&
++                        !std::is_same<Char, wchar_t>::value)>
+ inline auto format_to(OutputIt out, const S& fmt, T&&... args) -> OutputIt {
+   return vformat_to(out, detail::to_string_view(fmt),
+-                    fmt::make_format_args<buffer_context<Char>>(args...));
++                    fmt::make_format_args<buffered_context<Char>>(args...));
+ }
+ 
+ template <typename Locale, typename S, typename OutputIt, typename... Args,
+-          typename Char = char_t<S>,
++          typename Char = detail::format_string_char_t<S>,
+           FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
+                             detail::is_locale<Locale>::value&&
+                                 detail::is_exotic_char<Char>::value)>
+-inline auto vformat_to(
+-    OutputIt out, const Locale& loc, const S& format_str,
+-    basic_format_args<buffer_context<type_identity_t<Char>>> args) -> OutputIt {
++inline auto vformat_to(OutputIt out, const Locale& loc, const S& fmt,
++                       typename detail::vformat_args<Char>::type args)
++    -> OutputIt {
+   auto&& buf = detail::get_buffer<Char>(out);
+-  vformat_to(buf, detail::to_string_view(format_str), args,
+-             detail::locale_ref(loc));
++  vformat_to(buf, detail::to_string_view(fmt), args, detail::locale_ref(loc));
+   return detail::get_iterator(buf, out);
+ }
+ 
+-template <
+-    typename OutputIt, typename Locale, typename S, typename... T,
+-    typename Char = char_t<S>,
+-    bool enable = detail::is_output_iterator<OutputIt, Char>::value&&
+-        detail::is_locale<Locale>::value&& detail::is_exotic_char<Char>::value>
+-inline auto format_to(OutputIt out, const Locale& loc, const S& format_str,
++template <typename Locale, typename OutputIt, typename S, typename... T,
++          typename Char = detail::format_string_char_t<S>,
++          bool enable = detail::is_output_iterator<OutputIt, Char>::value &&
++                        detail::is_locale<Locale>::value &&
++                        detail::is_exotic_char<Char>::value>
++inline auto format_to(OutputIt out, const Locale& loc, const S& fmt,
+                       T&&... args) ->
+     typename std::enable_if<enable, OutputIt>::type {
+-  return vformat_to(out, loc, detail::to_string_view(format_str),
+-                    fmt::make_format_args<buffer_context<Char>>(args...));
++  return vformat_to(out, loc, detail::to_string_view(fmt),
++                    fmt::make_format_args<buffered_context<Char>>(args...));
+ }
+ 
+ template <typename OutputIt, typename Char, typename... Args,
+           FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
+                             detail::is_exotic_char<Char>::value)>
+-inline auto vformat_to_n(
+-    OutputIt out, size_t n, basic_string_view<Char> format_str,
+-    basic_format_args<buffer_context<type_identity_t<Char>>> args)
++inline auto vformat_to_n(OutputIt out, size_t n, basic_string_view<Char> fmt,
++                         typename detail::vformat_args<Char>::type args)
+     -> format_to_n_result<OutputIt> {
+   using traits = detail::fixed_buffer_traits;
+   auto buf = detail::iterator_buffer<OutputIt, Char, traits>(out, n);
+-  detail::vformat_to(buf, format_str, args);
++  detail::vformat_to(buf, fmt, args);
+   return {buf.out(), buf.count()};
+ }
+ 
+ template <typename OutputIt, typename S, typename... T,
+-          typename Char = char_t<S>,
++          typename Char = detail::format_string_char_t<S>,
+           FMT_ENABLE_IF(detail::is_output_iterator<OutputIt, Char>::value&&
+                             detail::is_exotic_char<Char>::value)>
+ inline auto format_to_n(OutputIt out, size_t n, const S& fmt, T&&... args)
+     -> format_to_n_result<OutputIt> {
+-  return vformat_to_n(out, n, detail::to_string_view(fmt),
+-                      fmt::make_format_args<buffer_context<Char>>(args...));
++  return vformat_to_n(out, n, fmt::basic_string_view<Char>(fmt),
++                      fmt::make_format_args<buffered_context<Char>>(args...));
+ }
+ 
+-template <typename S, typename... T, typename Char = char_t<S>,
++template <typename S, typename... T,
++          typename Char = detail::format_string_char_t<S>,
+           FMT_ENABLE_IF(detail::is_exotic_char<Char>::value)>
+ inline auto formatted_size(const S& fmt, T&&... args) -> size_t {
+   auto buf = detail::counting_buffer<Char>();
+   detail::vformat_to(buf, detail::to_string_view(fmt),
+-                     fmt::make_format_args<buffer_context<Char>>(args...));
++                     fmt::make_format_args<buffered_context<Char>>(args...));
+   return buf.count();
+ }
+ 
+@@ -246,9 +322,48 @@ template <typename... T> void println(wformat_string<T...> fmt, T&&... args) {
+   return print(L"{}\n", fmt::format(fmt, std::forward<T>(args)...));
+ }
+ 
+-/**
+-  Converts *value* to ``std::wstring`` using the default format for type *T*.
+- */
++inline auto vformat(text_style ts, wstring_view fmt, wformat_args args)
++    -> std::wstring {
++  auto buf = wmemory_buffer();
++  detail::vformat_to(buf, ts, fmt, args);
++  return {buf.data(), buf.size()};
++}
++
++template <typename... T>
++inline auto format(text_style ts, wformat_string<T...> fmt, T&&... args)
++    -> std::wstring {
++  return fmt::vformat(ts, fmt, fmt::make_wformat_args(args...));
++}
++
++template <typename... T>
++FMT_DEPRECATED void print(std::FILE* f, text_style ts, wformat_string<T...> fmt,
++                          const T&... args) {
++  vprint(f, ts, fmt, fmt::make_wformat_args(args...));
++}
++
++template <typename... T>
++FMT_DEPRECATED void print(text_style ts, wformat_string<T...> fmt,
++                          const T&... args) {
++  return print(stdout, ts, fmt, args...);
++}
++
++inline void vprint(std::wostream& os, wstring_view fmt, wformat_args args) {
++  auto buffer = basic_memory_buffer<wchar_t>();
++  detail::vformat_to(buffer, fmt, args);
++  detail::write_buffer(os, buffer);
++}
++
++template <typename... T>
++void print(std::wostream& os, wformat_string<T...> fmt, T&&... args) {
++  vprint(os, fmt, fmt::make_format_args<buffered_context<wchar_t>>(args...));
++}
++
++template <typename... T>
++void println(std::wostream& os, wformat_string<T...> fmt, T&&... args) {
++  print(os, L"{}\n", fmt::format(fmt, std::forward<T>(args)...));
++}
++
++/// Converts `value` to `std::wstring` using the default format for type `T`.
+ template <typename T> inline auto to_wstring(const T& value) -> std::wstring {
+   return format(FMT_STRING(L"{}"), value);
+ }
diff --git a/meta-oe/recipes-support/btop/btop_1.4.0.bb b/meta-oe/recipes-support/btop/btop_1.4.0.bb
index adfb2418b0..8afda1c5d3 100644
--- a/meta-oe/recipes-support/btop/btop_1.4.0.bb
+++ b/meta-oe/recipes-support/btop/btop_1.4.0.bb
@@ -4,7 +4,9 @@  LICENSE = "Apache-2.0"
 LIC_FILES_CHKSUM = "file://LICENSE;md5=3b83ef96387f14655fc854ddc3c6bd57"
 SECTION = "console/utils"
 
-SRC_URI = "git://github.com/aristocratos/btop.git;protocol=https;branch=main"
+SRC_URI = "git://github.com/aristocratos/btop.git;protocol=https;branch=main \
+           file://0001-fmt-Update-headers-from-11.1.4.patch \
+           "
 SRCREV = "6c0cedd8912785f0f353af389e72a0ffc69984a2"
 
 S = "${WORKDIR}/git"