.github/workflows/libcxx-build-and-test.yaml

# This file defines pre-commit CI for libc++, libc++abi, and libunwind (on Github).
#
# We split the configurations in multiple stages with the intent of saving compute time
# when a job fails early in the pipeline. This is why the jobs are marked as `continue-on-error: false`.
# We try to run the CI configurations with the most signal in the first stage.
#
# Stages 1 & 2 are meant to be "smoke tests", and are meant to catch most build/test failures quickly and without using
# too many resources.
# Stage 3 is "everything else", and is meant to catch breakages on more niche or unique configurations.
#
# Therefore, we "fail-fast" for any failures during stages 1 & 2, meaning any job failing cancels all other running jobs,
# under the assumption that if the "smoke tests" fail, then the other configurations will likely fail in the same way.
# However, stage 3 does not fail fast, as it's more likely that any one job failing is a flake or a configuration-specific
#
name: Build and Test libc++
on:
  pull_request:
    paths:
      - 'libcxx/**'
      - 'libcxxabi/**'
      - 'libunwind/**'
      - 'runtimes/**'
      - 'cmake/**'
      - '.github/workflows/libcxx-build-and-test.yaml'
  schedule:
    # Run nightly at 08:00 UTC (aka 00:00 Pacific, aka 03:00 Eastern)
    - cron: '0 8 * * *'

permissions:
  contents: read # Default everything to read-only

concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
  cancel-in-progress: true

jobs:
  stage1:
    if: github.repository_owner == 'llvm'
    runs-on: llvm-premerge-libcxx-runners
    continue-on-error: false
    strategy:
      fail-fast: false
      matrix:
        config: [
          'frozen-cxx03-headers',
          'generic-cxx03',
          'generic-cxx26',
          'generic-modules'
        ]
        cc: [  'clang-22' ]
        cxx: [ 'clang++-22' ]
        include:
          - config: 'generic-gcc'
            cc: 'gcc-15'
            cxx: 'g++-15'
    steps:
      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
      - name: ${{ matrix.config }}.${{ matrix.cxx }}
        run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
        env:
          CC: ${{ matrix.cc }}
          CXX: ${{ matrix.cxx }}
      - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
        if: always()
        with:
          name: ${{ matrix.config }}-${{ matrix.cxx }}-results
          path: |
            **/test-results.xml
            **/*.abilist
            **/CMakeConfigureLog.yaml
            **/CMakeError.log
            **/CMakeOutput.log
            **/crash_diagnostics/*
  stage2:
    if: github.repository_owner == 'llvm'
    runs-on: llvm-premerge-libcxx-runners
    needs: [ stage1 ]
    continue-on-error: false
    strategy:
      fail-fast: false
      matrix:
        config: [
          'generic-cxx11',
          'generic-cxx14',
          'generic-cxx17',
          'generic-cxx20',
          'generic-cxx23'
        ]
        cc: [ 'clang-22' ]
        cxx: [ 'clang++-22' ]
        include:
          - config: 'generic-gcc-cxx11'
            cc: 'gcc-15'
            cxx: 'g++-15'
          - config: 'generic-cxx26'
            cc: 'clang-21'
            cxx: 'clang++-21'
          - config: 'generic-cxx26'
            cc: 'clang-20'
            cxx: 'clang++-20'
    steps:
      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
      - name: ${{ matrix.config }}
        run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
        env:
          CC: ${{ matrix.cc }}
          CXX: ${{ matrix.cxx }}
      - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
        if: always()  # Upload artifacts even if the build or test suite fails
        with:
          name: ${{ matrix.config }}-${{ matrix.cxx }}-results
          path: |
            **/test-results.xml
            **/*.abilist
            **/CMakeConfigureLog.yaml
            **/CMakeError.log
            **/CMakeOutput.log
            **/crash_diagnostics/*
  stage3:
    if: github.repository_owner == 'llvm'
    needs: [ stage2 ]
    continue-on-error: false
    strategy:
      fail-fast: false
      max-parallel: 8
      matrix:
        config: [
          'generic-abi-unstable',
          'generic-hardening-mode-debug',
          'generic-hardening-mode-extensive',
          'generic-hardening-mode-extensive-observe-semantic',
          'generic-hardening-mode-fast',
          'generic-hardening-mode-fast-with-abi-breaks',
          'generic-merged',
          'generic-modules-cxx17-lsv',
          'generic-no-exceptions',
          'generic-no-experimental',
          'generic-no-filesystem',
          'generic-no-localization',
          'generic-no-terminal',
          'generic-no-random_device',
          'generic-no-threads',
          'generic-no-tzdb',
          'generic-no-unicode',
          'generic-no-wide-characters',
          'generic-no-rtti',
          'generic-optimized-speed',
          'generic-static',
          'bootstrapping-build'
        ]
        machine: [ 'llvm-premerge-libcxx-runners' ]
        include:
        - config: 'generic-cxx26'
          machine: llvm-premerge-libcxx-runners
        - config: 'generic-asan'
          machine: llvm-premerge-libcxx-runners
        - config: 'generic-tsan'
          machine: llvm-premerge-libcxx-runners
        - config: 'generic-ubsan'
          machine: llvm-premerge-libcxx-runners
        # Use a larger machine for MSAN to avoid timeout and memory allocation issues.
        - config: 'generic-msan'
          machine: llvm-premerge-libcxx-runners
    runs-on: ${{ matrix.machine }}
    steps:
      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
      - name: ${{ matrix.config }}
        run: libcxx/utils/ci/run-buildbot ${{ matrix.config }}
        env:
          CC: clang-22
          CXX: clang++-22
      - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
        if: always()
        with:
          name: ${{ matrix.config }}-results
          path: |
            **/test-results.xml
            **/*.abilist
            **/CMakeConfigureLog.yaml
            **/CMakeError.log
            **/CMakeOutput.log
            **/crash_diagnostics/*

  macos:
    needs: [ stage2 ]
    strategy:
      fail-fast: false
      matrix:
        include:
        - config: generic-cxx03
          os: macos-15
        - config: generic-cxx23
          os: macos-15
        - config: generic-modules
          os: macos-15
        - config: apple-configuration
          os: macos-15
        # TODO: These jobs are intended to test back-deployment (building against ToT libc++ but running against an
        #       older system-provided libc++.dylib). Doing this properly would require building the test suite on a
        #       recent macOS using a recent Clang (hence recent Xcode), and then running the actual test suite on an
        #       older mac. We could do that by e.g. sharing artifacts between the two jobs.
        #
        #       However, our Lit configuration currently doesn't provide a good way to do that in a batch, so our only
        #       alternative is to actually build on the same host that we're going to run on. Sadly, that doesn't work
        #       since older macOSes don't support newer Xcodes. For now, we run the "backdeployment" jobs on recent
        #       macOS versions as a way to avoid rotting that configuration, but it doesn't provide a lot of additional
        #       coverage.
        - config: apple-system
          os: macos-15
        - config: apple-system-hardened
          os: macos-15
    runs-on: ${{ matrix.os }}
    steps:
      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
      - uses: maxim-lobanov/setup-xcode@60606e260d2fc5762a71e64e74b2174e8ea3c8bd # v1.6.0
        with:
          # https://github.com/actions/runner-images/blob/main/images/macos/macos-15-Readme.md
          xcode-version: '26.0'
      - uses: seanmiddleditch/gha-setup-ninja@3b1f8f94a2f8254bd26914c4ab9474d4f0015f67 # v6
      - name: Build and test
        run: |
          python3 -m venv .venv
          source .venv/bin/activate
          python -m pip install psutil
          xcrun bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
        env:
          CC: clang
          CXX: clang++
      - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
        if: always()  # Upload artifacts even if the build or test suite fails
        with:
          name: macos-${{ matrix.config }}-results
          path: |
            **/test-results.xml
            **/*.abilist
            **/CMakeConfigureLog.yaml
            **/CMakeError.log
            **/CMakeOutput.log
            **/crash_diagnostics/*

  windows:
    needs: [ stage2 ]
    strategy:
      fail-fast: false
      matrix:
        include:
        - { config: clang-cl-dll,             mingw: false, cc: clang-cl, cxx: clang-cl }
        - { config: clang-cl-static,          mingw: false, cc: clang-cl, cxx: clang-cl }
        - { config: clang-cl-no-vcruntime,    mingw: false, cc: clang-cl, cxx: clang-cl }
        - { config: clang-cl-debug,           mingw: false, cc: clang-cl, cxx: clang-cl }
        - { config: clang-cl-static-crt,      mingw: false, cc: clang-cl, cxx: clang-cl }
        - { config: mingw-dll,                mingw: true,  cc: cc,       cxx: c++ }
        - { config: mingw-dll,                mingw: true,  cc: i686-w64-mingw32-clang, cxx: i686-w64-mingw32-clang++ }
        - { config: mingw-static,             mingw: true,  cc: cc,       cxx: c++ }
        - { config: mingw-incomplete-sysroot, mingw: true,  cc: cc,       cxx: c++ }
        - { config: mingw-static,             mingw: true,  cc: cc,       cxx: c++, runner: windows-11-arm }
    runs-on: ${{ matrix.runner != '' && matrix.runner || 'windows-2022' }}
    steps:
      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
      - name: Install dependencies
        run: |
          pip install psutil
      - name: Install a current LLVM
        if: ${{ matrix.mingw != true }}
        run: |
          choco install -y llvm --version=20.1.8 --allow-downgrade
      - name: Install llvm-mingw
        if: ${{ matrix.mingw == true }}
        run: |
          curl -LO https://github.com/mstorsjo/llvm-mingw/releases/download/20250709/llvm-mingw-20250709-ucrt-${{ matrix.runner == 'windows-11-arm' && 'aarch64' || 'x86_64' }}.zip
          powershell Expand-Archive llvm-mingw*.zip -DestinationPath .
          del llvm-mingw*.zip
          mv llvm-mingw* c:\llvm-mingw
          echo "c:\llvm-mingw\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
      - name: Simulate a from-scratch build of llvm-mingw
        if: ${{ matrix.config == 'mingw-incomplete-sysroot' }}
        run: |
          rm -r c:\llvm-mingw\include\c++
          rm -r c:\llvm-mingw\*-w64-mingw32\lib\libc++*
          rm -r c:\llvm-mingw\*-w64-mingw32\lib\libunwind*
      - name: Add Git Bash to the path
        run: |
          echo "c:\Program Files\Git\usr\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
      - name: Set up the MSVC dev environment
        if: ${{ matrix.mingw != true }}
        uses: ilammy/msvc-dev-cmd@0b201ec74fa43914dc39ae48a89fd1d8cb592756 # v1.13.0
      - name: Add the installed Clang at the start of the path
        if: ${{ matrix.mingw != true }}
        run: |
          echo "c:\Program Files\LLVM\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
      - name: Build and test
        run: bash libcxx/utils/ci/run-buildbot ${{ matrix.config }}
        env:
          CC: ${{ matrix.cc }}
          CXX: ${{ matrix.cxx }}