check_pr_code.yml

name: PR code check

on:
  pull_request:

jobs:
  code_checks:
    uses: ./.github/workflows/_code_checks.yml

  count_commits:
    needs: code_checks
    runs-on: ubuntu-latest
    outputs:
      n_commits: ${{ steps.count_commits.outputs.n_commits }}
    steps:
      - name: checkout current branch
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: count commits from main
        id: count_commits
        run: |
          git fetch
          N_COMMITS=$(git rev-list origin/main.. --count)
          echo "n_commits=${N_COMMITS}" >> $GITHUB_OUTPUT

  add_empty_commit_if_only_one:
    needs: count_commits
    runs-on: ubuntu-latest
    # 2 commits because the PR code gets merged into a temp commit on main
    if: ${{ (!!needs.count_commits.outputs.n_commits) && needs.count_commits.outputs.n_commits <= 2 }}
    steps:

      - name: checkout current branch
        uses: actions/checkout@v4
        with:
          repository: ${{ github.event.pull_request.head.repo.full_name }}
          ref: ${{ github.event.pull_request.head.ref }}

      - uses: EndBug/add-and-commit@v8
        with:
          default_author: github_actions
          message: 'Add empty commit to force use PR title during squash merge'
          commit: --allow-empty
          add: '.'  # working tree should be clean
          push: true