Build failure: pkgsCross.arm-embedded.clangStdenv

[RossSmyth]

Nixpkgs version

• Unstable (25.05)

Steps to reproduce

1. nix build github:nixos/nixpkgs/nixos-unstable#pkgsCross.arm-embedded.clangStdenv

Can Hydra reproduce this build failure?

No, Hydra cannot reproduce this build failure.

Link to Hydra build job

No response

Relevant log output

compiler-rt-libc-arm-none-eabi> [100/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/popcountti2.c.obj
compiler-rt-libc-arm-none-eabi> [101/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/subdf3.c.obj
compiler-rt-libc-arm-none-eabi> [102/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/powidf2.c.obj
compiler-rt-libc-arm-none-eabi> [103/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/subvti3.c.obj
compiler-rt-libc-arm-none-eabi> [104/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/powisf2.c.obj
compiler-rt-libc-arm-none-eabi> [105/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/subsf3.c.obj
compiler-rt-libc-arm-none-eabi> [106/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/trampoline_setup.c.obj
compiler-rt-libc-arm-none-eabi> [107/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/subvsi3.c.obj
compiler-rt-libc-arm-none-eabi> [108/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/subvdi3.c.obj
compiler-rt-libc-arm-none-eabi> [109/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/ucmpti2.c.obj
compiler-rt-libc-arm-none-eabi> [110/167] Building ASM object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_4.S.obj
compiler-rt-libc-arm-none-eabi> FAILED: lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_4.S.obj
compiler-rt-libc-arm-none-eabi> /nix/store/j8g3lsngxhpdabgwayaiify2ygxrprm0-arm-none-eabi-gcc-wrapper-14-20241116/bin/arm-none-eabi-gcc -DVISIBILITY_HIDDEN  -O3 -DNDEBUG -fno-lto -Werror=array-bounds -Werror=uninitialized -Werror=shadow -Werror=empty-body -Werror=sizeof-pointer-memaccess -Werror=sizeof-array-argument -Wformat -std=c11 -Werror=builtin-declaration-mismatch -fPIC -fno-builtin -fvisibility=hidden -fomit-frame-pointer -MD -MT lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_4.S.obj -MF lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_4.S.obj.d -o lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_4.S.obj -c /build/compiler-rt-src-19.1.7/compiler-rt/lib/builtins/arm/sync_fetch_and_add_4.S
compiler-rt-libc-arm-none-eabi> In file included from /build/compiler-rt-src-19.1.7/compiler-rt/lib/builtins/arm/sync_fetch_and_add_4.S:14:
compiler-rt-libc-arm-none-eabi> /build/compiler-rt-src-19.1.7/compiler-rt/lib/builtins/arm/sync-ops.h:22:2: error: #error DMB is only supported on ARMv6+
compiler-rt-libc-arm-none-eabi>    22 | #error DMB is only supported on ARMv6+
compiler-rt-libc-arm-none-eabi>       |  ^~~~~
compiler-rt-libc-arm-none-eabi> [111/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/ucmpdi2.c.obj
compiler-rt-libc-arm-none-eabi> [112/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/udivmodti4.c.obj
compiler-rt-libc-arm-none-eabi> [113/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/udivti3.c.obj
compiler-rt-libc-arm-none-eabi> [114/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/umodti3.c.obj
compiler-rt-libc-arm-none-eabi> [115/167] Building ASM object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_8.S.obj
compiler-rt-libc-arm-none-eabi> FAILED: lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_8.S.obj
compiler-rt-libc-arm-none-eabi> /nix/store/j8g3lsngxhpdabgwayaiify2ygxrprm0-arm-none-eabi-gcc-wrapper-14-20241116/bin/arm-none-eabi-gcc -DVISIBILITY_HIDDEN  -O3 -DNDEBUG -fno-lto -Werror=array-bounds -Werror=uninitialized -Werror=shadow -Werror=empty-body -Werror=sizeof-pointer-memaccess -Werror=sizeof-array-argument -Wformat -std=c11 -Werror=builtin-declaration-mismatch -fPIC -fno-builtin -fvisibility=hidden -fomit-frame-pointer -MD -MT lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_8.S.obj -MF lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_8.S.obj.d -o lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_8.S.obj -c /build/compiler-rt-src-19.1.7/compiler-rt/lib/builtins/arm/sync_fetch_and_add_8.S
compiler-rt-libc-arm-none-eabi> In file included from /build/compiler-rt-src-19.1.7/compiler-rt/lib/builtins/arm/sync_fetch_and_add_8.S:14:
compiler-rt-libc-arm-none-eabi> /build/compiler-rt-src-19.1.7/compiler-rt/lib/builtins/arm/sync-ops.h:22:2: error: #error DMB is only supported on ARMv6+
compiler-rt-libc-arm-none-eabi>    22 | #error DMB is only supported on ARMv6+
compiler-rt-libc-arm-none-eabi>       |  ^~~~~
compiler-rt-libc-arm-none-eabi> [116/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/truncdfsf2.c.obj
compiler-rt-libc-arm-none-eabi> [117/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/clear_cache.c.obj
compiler-rt-libc-arm-none-eabi> [118/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/truncsfhf2.c.obj
compiler-rt-libc-arm-none-eabi> [119/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/truncdfhf2.c.obj
compiler-rt-libc-arm-none-eabi> [120/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/udivdi3.c.obj
compiler-rt-libc-arm-none-eabi> [121/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/umoddi3.c.obj
compiler-rt-libc-arm-none-eabi> [122/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/udivmoddi4.c.obj
compiler-rt-libc-arm-none-eabi> [123/167] Building C object lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/gcc_personality_v0.c.obj
compiler-rt-libc-arm-none-eabi> ninja: build stopped: subcommand failed.

Additional context

Clang is a cross-compiler by default so this is a little annoying. It seems nix builds compiler_rt for each platform on demand it seems, which is fine, but it fails at building it.

System metadata

• system: "x86_64-linux"
• host os: Linux 5.15.167.4-microsoft-standard-WSL2, NixOS, 25.05 (Warbler), 25.05.20250315.c80f6a7
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.24.12
• nixpkgs: /nix/store/alzxn3hjisc84hrlv44x6hni48crww26-source

Notify maintainers

@NixOS/llvm @NixOS/exotic-platform-maintainers (?)

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Note for maintainers: Please tag this issue in your pull request description. (i.e. Resolves #ISSUE.)

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• I assert that this is a bug and not a support request.
• I assert that this is not a duplicate of an existing issue.
• I assert that I have read the NixOS Code of Conduct and agree to abide by it.

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[concatime]

pkgsCross.armhf-embedded.clangStdenv also fails to compile with the same error.

[concatime]

Looking at the compiler arguments, compiler-rt's CMake does not pass any argument specifying the targeted ARM architecture profile.

/nix/store/j8g3lsngxhpdabgwayaiify2ygxrprm0-arm-none-eabi-gcc-wrapper-14-20241116/bin/arm-none-eabi-gcc \
  -DVISIBILITY_HIDDEN  -O3 -DNDEBUG -fno-lto -Werror=array-bounds \
  -Werror=uninitialized -Werror=shadow -Werror=empty-body -Werror=sizeof-pointer-memaccess -Werror=sizeof-array-argument -Wformat -std=c11 -Werror=builtin-declaration-mismatch\
 -fPIC -fno-builtin -fvisibility=hidden -fomit-frame-pointer \
  -MD -MT lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_4.S.obj -MF lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_4.S.obj.d \
  -o lib/builtins/CMakeFiles/clang_rt.builtins-arm.dir/arm/sync_fetch_and_add_4.S.obj \
  -c /build/compiler-rt-src-19.1.7/compiler-rt/lib/builtins/arm/sync_fetch_and_add_4.S

By default, arm-none-eabi-gcc targets ARM v4T (-mcpu=arm7tdmi). So the compilation error is expected.

compiler-rt-libc-arm-none-eabi> /build/compiler-rt-src-19.1.7/compiler-rt/lib/builtins/arm/sync-ops.h:22:2: error: #error DMB is only supported on ARMv6+

What bothers me is how was it working before??

[concatime]

The target specified to CMake is correct.

-- cmake c compiler target: arm-none-eabi

arm-none-eabi is an alias to armv4t-none-eabi in Clang from my tests.

clang -v --target=arm-none-eabi
...
-cc1 -triple armv4t-unknown-none-eabi

I tried to hardcode the target in pkgs/development/compilers/llvm/common/compiler-rt/default.nix like this:

  cmakeFlags =
    [
      "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"
      # "-DCMAKE_C_COMPILER_TARGET=${stdenv.hostPlatform.config}"
      "-DCMAKE_C_COMPILER_TARGET=armv4t-none-eabi"
      # "-DCMAKE_ASM_COMPILER_TARGET=${stdenv.hostPlatform.config}"
      "-DCMAKE_ASM_COMPILER_TARGET=armv4t-none-eabi"
    ]

And it compiled.

That means the issue is that compiler-rt's CMake does not interpret arm-none-eabi as armv4t-none-eabi like Clang and Rust.

[concatime]

Here are the relevant part of compiler-rt's CMake:

set(arm_sync_SOURCES
  arm/sync_fetch_and_add_4.S
  # ...
)
# ...
if(MINGW)
  # ...
elseif(NOT WIN32)
  # TODO the EABI sources should only be added to EABI targets
  set(arm_SOURCES
    ${arm_or_thumb2_base_SOURCES}
    ${arm_sync_SOURCES}
    ${arm_EABI_SOURCES}
    ${arm_Thumb1_SOURCES}
  )
  # ...
endif()
# ...
set(armv4t_SOURCES ${arm_min_SOURCES})
set(armv5te_SOURCES ${arm_min_SOURCES})
set(armv6_SOURCES ${arm_min_SOURCES})
set(armhf_SOURCES ${arm_SOURCES})
set(armv7_SOURCES ${arm_SOURCES})
set(armv7s_SOURCES ${arm_SOURCES})
set(armv7k_SOURCES ${arm_SOURCES})

My guess is that, when the target is arm-none-eabi, arm_SOURCES gets selected instead of armv4t_SOURCES. And arm_SOURCES depends on arm_sync_SOURCES, which lists our failing source file. I don't know if the LLVM team expects this behavior or not.

[concatime]

Well, looking at this test, it seems that this behavior is expected from the LLVM team.

        test_target_arch(arm "" "-march=armv7-a" "-mfloat-abi=soft")