CI: Try building Serenity with Clang

.github/workflows/cmake.yml

@@ -21,12 +21,15 @@ jobs:
  debug-options: ['ALL_DEBUG', 'NORMAL_DEBUG']
  os: [ubuntu-20.04]
  arch: ['i686', 'x86_64']
+ compiler: ['GCC', 'Clang']
  # If ccache is broken and you would like to bust the ccache cache on Github Actions, increment this:
  ccache-mark: [0]
  exclude:
  # We currently manually disable the ALL_DEBUG build on x86_64 for sake of saving CI time, as it is not our main target right now
  - debug-options: 'ALL_DEBUG'
  arch: 'x86_64'
+ - debug-options: 'ALL_DEBUG'
+ compiler: 'Clang'
 
  steps:
  - uses: actions/checkout@v2
@@ -83,9 +86,13 @@ jobs:
  # This assumes that *ALL* LibC and LibPthread headers have an impact on the Toolchain.
  # This is wrong, and causes more Toolchain rebuilds than necessary.
  # However, we want to avoid false cache hits at all costs.
- key: ${{ runner.os }}-toolchain-${{ matrix.arch }}-${{ steps.stamps.outputs.libc_headers }}
- - name: Restore or regenerate Toolchain
+ key: ${{ runner.os }}-toolchain-${{ matrix.arch }}-${{ matrix.compiler }}-${{ steps.stamps.outputs.libc_headers }}
+ - name: Restore or regenerate GCC Toolchain
  run: TRY_USE_LOCAL_TOOLCHAIN=y ARCH="${{ matrix.arch }}" ${{ github.workspace }}/Toolchain/BuildIt.sh
+ if: ${{ matrix.compiler == 'GCC' }}
+ - name: Restore or regenerate Clang Toolchain
+ run: TRY_USE_LOCAL_TOOLCHAIN=y ARCH="${{ matrix.arch }}" ${{ github.workspace }}/Toolchain/BuildClang.sh
+ if: ${{ matrix.compiler == 'Clang' }}
  - name: ccache(1) cache
  # Pull the ccache *after* building the toolchain, in case building the Toolchain somehow interferes.
  # TODO: Change the version to the released version when https://github.com/actions/cache/pull/489 (or 571) is merged.
@@ -99,10 +106,10 @@ jobs:
  # This is achieved by using the "prefix-timestamp" format,
  # and permitting the restore-key "prefix-" without specifying a timestamp.
  # For this trick to work, the timestamp *must* come last, and it *must* be missing in 'restore-keys'.
- key: ${{ runner.os }}-ccache-${{ matrix.arch }}-v${{ matrix.ccache-mark }}-D${{ matrix.debug-options }}-toolchain_${{steps.stamps.outputs.libc_headers}}-time${{ steps.stamps.outputs.time }}
+ key: ${{ runner.os }}-ccache-${{ matrix.arch }}-${{ matrix.compiler }}-v${{ matrix.ccache-mark }}-D${{ matrix.debug-options }}-toolchain_${{steps.stamps.outputs.libc_headers}}-time${{ steps.stamps.outputs.time }}
  # IMPORTANT: Keep these two in sync!
  restore-keys: |
- ${{ runner.os }}-ccache-${{ matrix.arch }}-v${{ matrix.ccache-mark }}-D${{ matrix.debug-options }}-toolchain_${{steps.stamps.outputs.libc_headers}}-
+ ${{ runner.os }}-ccache-${{ matrix.arch }}-${{ matrix.compiler }}-v${{ matrix.ccache-mark }}-D${{ matrix.debug-options }}-toolchain_${{steps.stamps.outputs.libc_headers}}-
  - name: Show ccache stats before build and configure
  run: |
  # We only have 5 GiB of cache available *in total*. Beyond that, GitHub deletes caches.
@@ -127,13 +134,13 @@ jobs:
  working-directory: ${{ github.workspace }}/Build
  # Build the entire project with all available debug options turned on, to prevent code rot.
  # However, it is unweildy and slow to run tests with them enabled, so we will build twice.
- run: cmake .. -GNinja -DSERENITY_ARCH=${{ matrix.arch }} -DBUILD_LAGOM=ON -DENABLE_ALL_DEBUG_FACILITIES=ON -DENABLE_PCI_IDS_DOWNLOAD=OFF -DENABLE_USB_IDS_DOWNLOAD=OFF -DCMAKE_C_COMPILER=gcc-10 -DCMAKE_CXX_COMPILER=g++-10
+ run: cmake .. -GNinja -DSERENITY_ARCH=${{ matrix.arch }} -DUSE_CLANG_TOOLCHAIN=${{ matrix.compiler == 'Clang' }} -DBUILD_LAGOM=ON -DENABLE_ALL_DEBUG_FACILITIES=ON -DENABLE_PCI_IDS_DOWNLOAD=OFF -DENABLE_USB_IDS_DOWNLOAD=OFF -DCMAKE_C_COMPILER=gcc-10 -DCMAKE_CXX_COMPILER=g++-10
  if: ${{ matrix.debug-options == 'ALL_DEBUG' }}
  - name: Create build environment
  working-directory: ${{ github.workspace }}/Build
  # Note that we do not set BUILD_LAGOM for the normal debug build
  # We build and run the Lagom tests in a separate job, and sanitizer builds take a good while longer than non-sanitized.
- run: cmake .. -GNinja -DSERENITY_ARCH=${{ matrix.arch }} -DENABLE_UNDEFINED_SANITIZER=ON -DENABLE_PCI_IDS_DOWNLOAD=OFF -DENABLE_USB_IDS_DOWNLOAD=OFF -DCMAKE_C_COMPILER=gcc-10 -DCMAKE_CXX_COMPILER=g++-10
+ run: cmake .. -GNinja -DSERENITY_ARCH=${{ matrix.arch }} -DUSE_CLANG_TOOLCHAIN=${{ matrix.compiler == 'Clang' }} -DENABLE_UNDEFINED_SANITIZER=ON -DENABLE_PCI_IDS_DOWNLOAD=OFF -DENABLE_USB_IDS_DOWNLOAD=OFF -DCMAKE_C_COMPILER=gcc-10 -DCMAKE_CXX_COMPILER=g++-10
  if: ${{ matrix.debug-options == 'NORMAL_DEBUG' }}
 
  # === ACTUALLY BUILD ===