force-rebase.yml

name: Force rebased

on: [pull_request]

jobs:
  force-rebase:
    runs-on: ubuntu-latest
    steps:

      - name: 'PR commits + 1'
        id: pr_commits
        run: echo "pr_fetch_depth=$(( ${{ github.event.pull_request.commits }} + 1 ))" >> "${GITHUB_OUTPUT}"

      - name: 'Checkout PR branch and all PR commits'
        uses: actions/checkout@v4
        with:
          ref: ${{ github.event.pull_request.head.sha }}
          fetch-depth: ${{ steps.pr_commits.outputs.pr_fetch_depth }}

      - name: Check if PR branch is rebased on target branch
        shell: bash
        run: |
          git merge-base --is-ancestor ${{ github.event.pull_request.base.sha }} HEAD

      - name: Check if PR branch contains merge commits
        shell: bash
        run: |
          merges=$(git log --oneline HEAD~${{ github.event.pull_request.commits }}...HEAD --merges ); \
          echo "--- Merges ---"; \
          echo ${merges}; \
          [[ -z "${merges}" ]]