auto-release.yml

name: Auto Release

# Merging a branch named vX.Y.Z into master tags the merge commit and kicks
# off the tag-gated release pipeline in build.yml. The Build run is dispatched
# explicitly because tags pushed with GITHUB_TOKEN never trigger on-push
# workflows.

on:
  pull_request:
    types: [closed]
    branches: [master]

jobs:
  tag-and-release:
    if: github.event.pull_request.merged == true &&
        startsWith(github.event.pull_request.head.ref, 'v')
    runs-on: ubuntu-24.04
    permissions:
      contents: write
      actions: write
    env:
      TAG: ${{ github.event.pull_request.head.ref }}
      MERGE_SHA: ${{ github.event.pull_request.merge_commit_sha }}
    steps:
      - name: Validate release branch name
        id: check
        run: |
          if [[ "$TAG" =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
            echo "release=true" >> "$GITHUB_OUTPUT"
          else
            echo "Branch '$TAG' is not vX.Y.Z; skipping release"
          fi

      - uses: actions/checkout@v7
        if: steps.check.outputs.release == 'true'
        with:
          ref: ${{ env.MERGE_SHA }}

      # same guard as build.yml: a tag that disagrees with project(VERSION)
      # would bake the wrong version into every artifact
      - name: Check branch matches project version
        if: steps.check.outputs.release == 'true'
        run: |
          VER=$(sed -n 's/^ *VERSION \([0-9.]*\)$/\1/p' CMakeLists.txt | head -1)
          if [ "${TAG#v}" != "$VER" ]; then
            echo "::error::Branch ${TAG} != project VERSION ${VER} in CMakeLists.txt"
            exit 1
          fi

      - name: Create and push tag
        if: steps.check.outputs.release == 'true'
        run: |
          if git ls-remote --tags origin "refs/tags/${TAG}" | grep -q .; then
            echo "::error::Tag ${TAG} already exists"
            exit 1
          fi
          git tag "$TAG" "$MERGE_SHA"
          git push origin "refs/tags/${TAG}"

      - name: Dispatch release build
        if: steps.check.outputs.release == 'true'
        env:
          GH_TOKEN: ${{ github.token }}
        run: gh workflow run build.yml --ref "refs/tags/${TAG}" -R "$GITHUB_REPOSITORY"