[1/3] rust: add missing zlib and zstd dependencies

From: Peter Tatrai <peter.tatrai.ext@siemens.com>

Use WRAPPER_TARGET_EXTRALD to pass '-lz -lzstd' to the target linker wrapper,

Rust's internal LLVM requires zlib and zstd compression libraries when
building rustc_codegen_llvm and other compiler components.
Without these dependencies, building Rust for PowerPC target fails
with linker errors:

  error: linking with `target-rust-ccld` failed: exit status: 1
  = note: undefined reference to `compress2'
  = note: undefined reference to `uncompress'
  = note: undefined reference to `ZSTD_decompress'
  = note: undefined reference to `ZSTD_isError'
  = note: undefined reference to `ZSTD_compress2'
  = note: undefined reference to `crc32'

This manifested in oe-selftest failure on qemuppc:
  oe-selftest -r rust.RustSelfTestSystemEmulated.test_rust

Fix rust-common.bbclass wrapper generation to properly split EXTRALD flags
into separate arguments (extend instead of append), making the wrapper
mechanism work correctly for multi-flag values like '-lz -lzstd'.

Signed-off-by: Peter Tatrai <peter.tatrai.ext@siemens.com>
---
 meta/classes-recipe/rust-common.bbclass   | 2 +-
 meta/recipes-devtools/rust/rust_1.90.0.bb | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

On Mon, 2025-10-27 at 11:28 +0100, Tatrai, Peter via lists.openembedded.org wrote:
> From: Peter Tatrai <peter.tatrai.ext@siemens.com>
> 
> Use WRAPPER_TARGET_EXTRALD to pass '-lz -lzstd' to the target linker wrapper,
> 
> Rust's internal LLVM requires zlib and zstd compression libraries when
> building rustc_codegen_llvm and other compiler components.
> Without these dependencies, building Rust for PowerPC target fails
> with linker errors:
> 
>   error: linking with `target-rust-ccld` failed: exit status: 1
>   = note: undefined reference to `compress2'
>   = note: undefined reference to `uncompress'
>   = note: undefined reference to `ZSTD_decompress'
>   = note: undefined reference to `ZSTD_isError'
>   = note: undefined reference to `ZSTD_compress2'
>   = note: undefined reference to `crc32'
> 
> This manifested in oe-selftest failure on qemuppc:
>   oe-selftest -r rust.RustSelfTestSystemEmulated.test_rust
> 
> Fix rust-common.bbclass wrapper generation to properly split EXTRALD flags
> into separate arguments (extend instead of append), making the wrapper
> mechanism work correctly for multi-flag values like '-lz -lzstd'.
> 
> Signed-off-by: Peter Tatrai <peter.tatrai.ext@siemens.com>
> ---
>  meta/classes-recipe/rust-common.bbclass   | 2 +-
>  meta/recipes-devtools/rust/rust_1.90.0.bb | 5 +++++
>  2 files changed, 6 insertions(+), 1 deletion(-)

Why do we only see this on powerpc?

Cheers,

Richard

On 27 Oct 2025, at 10:28, Tatrai, Peter via lists.openembedded.org <peter.tatrai.ext=siemens.com@lists.openembedded.org> wrote:
> 
> Rust's internal LLVM requires zlib and zstd compression libraries when
> building rustc_codegen_llvm and other compiler components.
> Without these dependencies, building Rust for PowerPC target fails
> with linker errors:

Is this still the case after we dropped rust-llvm and now use the same llvm as clang?

Notably, the patch to switch from rust-llvm to llvm included this:

-    export RUSTFLAGS="${RUST_DEBUG_REMAP}"
+    export RUSTFLAGS="${RUST_DEBUG_REMAP} -Clink-arg=-lz -Clink-arg=-lzstd"

Ross

> > Rust's internal LLVM requires zlib and zstd compression libraries when 
> > building rustc_codegen_llvm and other compiler components.
> > Without these dependencies, building Rust for PowerPC target fails 
> > with linker errors:

> Is this still the case after we dropped rust-llvm and now use the same llvm as clang?

Dropping rust-llvm has introduced this issue. It worked before because rust-llvm was configured with "-DLLVM_ENABLE_ZLIB=OFF -DLLVM_ENABLE_ZSTD=OFF"

> Notably, the patch to switch from rust-llvm to llvm included this:

> -    export RUSTFLAGS="${RUST_DEBUG_REMAP}"
> +    export RUSTFLAGS="${RUST_DEBUG_REMAP} -Clink-arg=-lz -Clink-arg=-lzstd"

These arguments don't help when compiling test binaries. Providing -lz -lzstd works. Also notable is that on other platforms, it's not needed to add libz and libzstd .so files into the qemu image used for testing.

Peter.

> Notably, the patch to switch from rust-llvm to llvm included this:
> 
> -    export RUSTFLAGS="${RUST_DEBUG_REMAP}"
> +    export RUSTFLAGS="${RUST_DEBUG_REMAP} -Clink-arg=-lz -Clink-arg=-lzstd"

I realized that these RUSTFLAGS exported at the recipe level don't propagate 
to the rust self-test. The test directly runs 'python3 src/bootstrap/bootstrap.py test 
--target' in an environment where recipe-level variables aren't visible.

I'm sending a v2 that fixes this specifically in the selftest harness 
(meta/lib/oeqa/selftest/cases/rust.py) by passing the link args via RUSTFLAGS 
in the test command itself, plus adding libzstd to the QEMU test image.

This approach is more targeted and only affects the selftest execution.

Peter