syntax-checks.yaml

name: Syntactic checks
on:
  pull_request:
    branches: [ main ]

jobs:
  # This job takes approximately 1 minute
  check-clang-format:
    runs-on: ubuntu-24.04
    steps:
      - uses: actions/checkout@v4
        with:
          submodules: recursive
          fetch-depth: 0
      - name: Fetch dependencies
        env:
          # This is needed in addition to -yq to prevent apt-get from asking for
          # user input
          DEBIAN_FRONTEND: noninteractive
        run: |
          sudo apt-get update
          sudo apt-get install --no-install-recommends -yq clang-format-15
      - name: Check updated lines of code match clang-format-15 style
        env:
          BASE_BRANCH: ${{ github.base_ref }}
          MERGE_BRANCH: ${{ github.ref }}
        run: |
          # Log information about the run of this check.
          echo "Pull request's base branch is: ${BASE_BRANCH}"
          echo "Pull request's merge branch is: ${MERGE_BRANCH}"
          echo "Pull request's source branch is: ${GITHUB_HEAD_REF}"
          clang-format-15 --version

          # The checkout action leaves us in detatched head state. The following line
          # names the checked out commit, for simpler reference later.
          git checkout -b ${MERGE_BRANCH}

          # Make sure we can refer to ${BASE_BRANCH} by name
          git checkout ${BASE_BRANCH}
          git checkout ${MERGE_BRANCH}

          # Find the commit on which the PR is based.
          MERGE_BASE=$(git merge-base ${BASE_BRANCH} ${MERGE_BRANCH})
          echo "Checking for formatting errors introduced since $MERGE_BASE"

          # Do the checking. "eval" is used so that quotes (as inserted into $EXCLUDES
          # above) are not interpreted as parts of file names.
          git-clang-format-15 --binary clang-format-15 $MERGE_BASE
          git diff > formatted.diff
          if [[ -s formatted.diff ]] ; then
            echo 'Formatting error! The following diff shows the required changes'
            echo 'Use the raw log to get a version of the diff that preserves spacing'
            cat formatted.diff
            exit 1
          fi
          echo 'No formatting errors found'