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-march=native + Clang occasional "invalid feature combination" AVX10.1 error on Ubuntu 24.04 #14296

Description

@tzcnt

Description

Failed job link: https://github.com/tzcnt/TooManyCooks/actions/runs/28302440587/job/83853001861

I'm not setting any AVX specific flags in these builds; only -march=native. But I'm getting error: invalid feature combination: +avx10.1-256; will be promoted to avx10.1-512. This failure has occurred infrequently (maybe ~5 times total) in the past months so it's probably due to the specific machine that a runner is assigned to.

CMake configure step (succeeds):

cmake -G "Unix Makefiles" -DTMC_AS_SUBMODULE=ON -DTMC_COPY_COMPILE_COMMANDS=OFF -DTMC_USE_HWLOC=ON -DTMC_WORK_ITEM=FUNCORO  -DCMD_COMPILE_FLAGS='-Werror;-fprofile-instr-generate;-fcoverage-mapping' -DCMD_LINK_FLAGS='-Wl,--build-id;-fprofile-instr-generate;-fcoverage-mapping' --preset clang-linux-debug .
Preset CMake variables:

  CMAKE_BUILD_TYPE="Debug"
  CMAKE_CXX_COMPILER="clang++"
  CMAKE_CXX_FLAGS="-march=native"
  CMAKE_C_COMPILER="clang"
  CMAKE_C_FLAGS="-march=native"
  CMAKE_EXPORT_COMPILE_COMMANDS="ON"
  CMAKE_INSTALL_PREFIX:PATH="/home/runner/work/TooManyCooks/TooManyCooks/install/clang-linux-debug"

-- The C compiler identification is Clang 18.1.3
-- The CXX compiler identification is Clang 18.1.3
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/clang - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/clang++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- CMD_COMPILE_FLAGS: -Werror;-fprofile-instr-generate;-fcoverage-mapping
-- CMD_LINK_FLAGS: -Wl,--build-id;-fprofile-instr-generate;-fcoverage-mapping
-- TooManyCooks: Found hwloc: /usr/lib/x86_64-linux-gnu/libhwloc.so
-- CPM: Adding package asio@1.28.1 (asio-1-28-1)
-- CPM: Adding package googletest@1.15.2 (v1.15.2)
-- Configuring done (8.0s)
-- Generating done (0.0s)
-- Build files have been written to: /home/runner/work/TooManyCooks/TooManyCooks/build/clang-linux-debug

CMake build step (fails):

cmake --build ./build/clang-linux-debug --parallel $(nproc) --target all
[  0%] Building CXX object CMakeFiles/alignment.dir/examples/alignment.cpp.o
[  1%] Building CXX object CMakeFiles/external_callback_awaitable.dir/examples/external/callback_awaitable.cpp.o
[  1%] Building CXX object CMakeFiles/external_coro.dir/examples/external/external_coro.cpp.o
[  2%] Building CXX object CMakeFiles/external_executor.dir/examples/external/external_executor.cpp.o
error: error: error: invalid feature combination:  +avx10.1-256; will be promoted to avx10.1-512 [-Werror,-Winvalid-feature-combination]
invalid feature combination:  +avx10.1-256; will be promoted to avx10.1-512 [-Werror,-Winvalid-feature-combination]
invalid feature combination:  +avx10.1-256; will be promoted to avx10.1-512 [-Werror,-Winvalid-feature-combination]

Platforms affected

  • Azure DevOps
  • GitHub Actions - Standard Runners
  • GitHub Actions - Larger Runners

Runner images affected

  • Ubuntu 22.04
  • Ubuntu 22.04 Arm64
  • Ubuntu 24.04
  • Ubuntu 24.04 Arm64
  • Ubuntu 26.04
  • Ubuntu 26.04 Arm64
  • Ubuntu Slim
  • macOS 14
  • macOS 14 Arm64
  • macOS 15
  • macOS 15 Arm64
  • macOS 26
  • macOS 26 Arm64
  • Windows Server 2022
  • Windows Server 2025
  • Windows Server 2025 with Visual Studio 2026
  • Windows Desktop 11
  • Windows Desktop 11 with Visual Studio 2026

Image version and build link

Image: ubuntu-24.04
Version: 20260622.220.1
Failed Job: https://github.com/tzcnt/TooManyCooks/actions/runs/28302440587/job/83853001861

Is it regression?

I don't know - behavior started happening sometime in 2026

Expected behavior

The build should not error when passed -march=native.

Actual behavior

Build fails with warning (promoted to error per my build settings):

error: invalid feature combination: +avx10.1-256; will be promoted to avx10.1-512 [-Werror,-Winvalid-feature-combination]

Repro steps

Run job with -march=native build on Clang on Ubuntu 24.04 runner

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Area: OtherOS: Ubuntubug reportinvestigateCollect additional information, like space on disk, other tool incompatibilities etc.

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