version-check.yml

name: Version Check

# Every PR must bump the root VERSION file (plain "x.y.z"). Release tags it on
# merge. Used by repos with no package manifest (Go, C++, Shell).
on:
  pull_request:
    branches: ["main"]
    types: [opened, synchronize, reopened]

permissions:
  contents: read

jobs:
  version-bumped:
    name: version bumped
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6
        with:
          fetch-depth: 0 # need the base branch to diff the version
          persist-credentials: false
      - name: Read versions
        id: v
        run: |
          git fetch --no-tags --depth=1 origin "${{ github.base_ref }}"
          pr=$(tr -d ' \r\n' < VERSION)
          # If VERSION doesn't exist on the base yet (the PR that introduces it),
          # treat the base as 0.0.0 so any real version passes the bump check.
          base=$(git show "origin/${{ github.base_ref }}:VERSION" 2>/dev/null | tr -d ' \r\n' || true)
          base=${base:-0.0.0}
          echo "pr=$pr" >> "$GITHUB_OUTPUT"
          echo "base=$base" >> "$GITHUB_OUTPUT"
      - name: Compare
        env:
          PR: ${{ steps.v.outputs.pr }}
          BASE: ${{ steps.v.outputs.base }}
        run: |
          echo "base=$BASE  pr=$PR"
          if [ "$PR" = "$BASE" ]; then
            echo "::error::VERSION not bumped (still $BASE)."
            exit 1
          fi
          greater=$(printf '%s\n%s\n' "$BASE" "$PR" | sort -V | tail -n1)
          if [ "$greater" != "$PR" ]; then
            echo "::error::VERSION $PR is lower than base $BASE."
            exit 1
          fi
          echo "Version bumped $BASE -> $PR ✓"