diff mbox series

[meta-oe,118/128] android-tools: fix build with libstdc++ and current C++ frontends

Message ID 20260628162222.4081517-18-khem.raj@oss.qualcomm.com
State New
Headers show
Series None | expand

Commit Message

Khem Raj June 28, 2026, 4:22 p.m. UTC 
From: Khem Raj <raj.khem@gmail.com>

Two build failures occur with the default clang/lld toolchain (and with
gcc) when compiling android-tools 35.0.2:

1. The bundled fmtlib 10.2.0 validates FMT_STRING() inside a consteval
   basic_format_string constructor whose parse path evaluates
   "format_str_.remove_prefix(detail::to_unsigned(it - begin()))". Current
   C++ frontends reject that iterator subtraction as a non-constant
   subexpression:

     error: call to consteval function
       'fmt::basic_format_string<...>::basic_format_string<FMT_COMPILE_STRING,0>'
       is not a constant expression

   Define FMT_CONSTEVAL to empty so fmt drops the consteval qualifier and
   validates format strings via its runtime path instead.

2. adb's IOVector::coalesce() static_asserts that its Block collection type
   is standard-layout. Block holds a std::unique_ptr<char[]>, which is
   standard-layout under LLVM libc++ (AOSP's runtime) but not under GNU
   libstdc++, so the assertion fails for libstdc++ based toolchains:

     packages/modules/adb/types.h:235:27: error: static assertion failed due
     to requirement 'std::is_standard_layout<Block>()'

   The assertion does not protect the memcpy it guards (which writes into
   plain char storage), so drop it.

Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 ...ortable-is_standard_layout-assertion.patch | 42 +++++++++++++++++++
 .../android-tools/android-tools_35.0.2.bb     |  8 +++-
 2 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 meta-oe/recipes-devtools/android-tools/android-tools/0011-adb-drop-non-portable-is_standard_layout-assertion.patch
diff mbox series

Patch

diff --git a/meta-oe/recipes-devtools/android-tools/android-tools/0011-adb-drop-non-portable-is_standard_layout-assertion.patch b/meta-oe/recipes-devtools/android-tools/android-tools/0011-adb-drop-non-portable-is_standard_layout-assertion.patch
new file mode 100644
index 0000000000..c8316a48fa
--- /dev/null
+++ b/meta-oe/recipes-devtools/android-tools/android-tools/0011-adb-drop-non-portable-is_standard_layout-assertion.patch
@@ -0,0 +1,42 @@ 
+From 1cbe4eb212f9be35e89eb7f43160c7e0ec35524c Mon Sep 17 00:00:00 2001
+From: Khem Raj <raj.khem@gmail.com>
+Date: Wed, 24 Jun 2026 17:50:54 -0700
+Subject: [PATCH] adb: drop non-portable std::is_standard_layout assertion in
+ IOVector::coalesce
+
+IOVector::coalesce() asserts that the destination collection type is
+standard-layout before memcpy'ing the coalesced payload into it:
+
+  static_assert(std::is_standard_layout<decltype(result)>());
+
+The default collection type is Block, which holds a std::unique_ptr<char[]>
+member. unique_ptr is standard-layout in LLVM libc++ (what AOSP builds
+against) but not in GNU libstdc++, so the assertion fails for any
+libstdc++ based toolchain (gcc, or clang with the default C++ runtime):
+
+  packages/modules/adb/types.h:235:27: error: static assertion failed due
+  to requirement 'std::is_standard_layout<Block>()'
+
+The assertion does not protect the memcpy, which only writes into the
+contiguous char storage exposed via Block::operator[]; Block being
+standard-layout is irrelevant to its correctness. Drop the assertion so
+the code builds with libstdc++.
+
+Upstream-Status: Pending
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+---
+ packages/modules/adb/types.h | 1 -
+ 1 file changed, 1 deletion(-)
+
+diff --git a/packages/modules/adb/types.h b/packages/modules/adb/types.h
+index 18c8e13..2ed006a 100644
+--- a/packages/modules/adb/types.h
++++ b/packages/modules/adb/types.h
+@@ -232,7 +232,6 @@ struct IOVector {
+ 
+         size_t offset = 0;
+         iterate_blocks([&offset, &result](const char* data, size_t len) {
+-            static_assert(std::is_standard_layout<decltype(result)>());
+             memcpy(&result[offset], data, len);
+             offset += len;
+         });
diff --git a/meta-oe/recipes-devtools/android-tools/android-tools_35.0.2.bb b/meta-oe/recipes-devtools/android-tools/android-tools_35.0.2.bb
index 3a277cd4b5..5a3ff3a6dd 100644
--- a/meta-oe/recipes-devtools/android-tools/android-tools_35.0.2.bb
+++ b/meta-oe/recipes-devtools/android-tools/android-tools_35.0.2.bb
@@ -55,6 +55,7 @@  SRC_URI = "https://deb.debian.org/debian/pool/main/a/android-platform-tools/andr
            file://0008-adb-GCC-compatibility-fixes-for-usb_linux-and-sysdep.patch \
            file://0009-libbase-include-stdint.h-in-hex.cpp.patch \
            file://0010-adbd-make-systemd-sd_notify-conditional-on-HAVE_SYSTEMD.patch \
+           file://0011-adb-drop-non-portable-is_standard_layout-assertion.patch \
            "
 
 SRC_URI[orig.md5sum] = "352376965cdef7bd7505d8fefdd43d50"
@@ -79,7 +80,12 @@  SYSTEMD_PACKAGES = "${PN}-adbd"
 SYSTEMD_SERVICE:${PN}-adbd = "android-tools-adbd.service"
 
 CFLAGS:append = " -fPIC -std=gnu2x"
-CXXFLAGS:append = " -fPIC -std=gnu++20 -D_Nonnull= -D_Nullable= -I${STAGING_INCDIR}/boringssl"
+# The bundled fmtlib 10.2.0 validates FMT_STRING() inside a consteval
+# basic_format_string constructor whose parse path evaluates "it - begin()",
+# which current C++ frontends reject as a non-constant subexpression. Define
+# FMT_CONSTEVAL to empty so format-string checking falls back to fmt's runtime
+# path instead of the broken compile-time one.
+CXXFLAGS:append = " -fPIC -std=gnu++20 -D_Nonnull= -D_Nullable= -I${STAGING_INCDIR}/boringssl -DFMT_CONSTEVAL="
 LDFLAGS:append = " -fPIC -L${STAGING_LIBDIR}/android"