cargo.yml

on: [push, pull_request, merge_group]

name: Cargo

jobs:
  fmt:
    name: Fmt
    runs-on: ubuntu-latest

    steps:
      - name: Checkout sources
        uses: actions/checkout@v4

      - name: Install toolchain
        uses: dtolnay/rust-toolchain@v1
        with:
          toolchain: 1.78.0 # MSRV
          components: rustfmt

      - name: Run cargo fmt
        run: cargo fmt --check

  check:
    name: Check
    runs-on: ubuntu-latest
    strategy:
      matrix:
        rust:
          - 1.78.0 # MSRV
          - stable
          - beta

    steps:
      - name: Checkout sources
        uses: actions/checkout@v4

      - name: Install toolchain
        uses: dtolnay/rust-toolchain@v1
        with:
          toolchain: ${{ matrix.rust }}

      - uses: swatinem/rust-cache@v2
        with:
          shared-key: "ci"

      - name: Run cargo check
        run: cargo check --all-targets

  test:
    needs: [check]
    name: Test
    runs-on: ubuntu-latest
    strategy:
      matrix:
        rust:
          - 1.78.0 # MSRV
          - stable
          - beta
    steps:
      - name: Checkout sources
        uses: actions/checkout@v4

      - name: Install toolchain
        uses: dtolnay/rust-toolchain@v1
        with:
          toolchain: ${{ matrix.rust }}

      - uses: swatinem/rust-cache@v2
        with:
          shared-key: "ci"

      - name: Run cargo test
        run: cargo test

  deny:
    name: Deny
    runs-on: ubuntu-latest
    strategy:
      matrix:
        checks:
          - advisories
          - bans licenses sources

    # Prevent sudden announcement of a new advisory from failing ci:
    continue-on-error: ${{ matrix.checks == 'advisories' }}

    steps:
      - uses: actions/checkout@v4
      - uses: EmbarkStudios/cargo-deny-action@v1
        with:
          command: check ${{ matrix.checks }}

  clippy:
    needs: [check]
    name: Clippy
    runs-on: ubuntu-latest
    continue-on-error: ${{ matrix.optional }}
    strategy:
      fail-fast: false
      matrix:
        include:
          - rust: 1.78.0 # MSRV
            optional: false
          - rust: beta
            optional: true
    steps:
      - uses: actions/checkout@v4
      - uses: dtolnay/rust-toolchain@v1
        with:
          toolchain: ${{ matrix.rust }}
          components: clippy
      - uses: swatinem/rust-cache@v2
        with:
          shared-key: "ci"
      - name: cargo clippy
        run: cargo clippy --all-targets -- -D warnings

  # This "accumulation" job is used as the required CI check for PRs.
  # We could require multiple jobs but the MSRV is subject to change and makes
  # it into the job names when using the matrix strategy (e.g., "Check (1.65.0)").
  # This approach seems to be the easiest solution for now.
  # Ideally, it would be enough to set "needs" accordingly but GitHub will
  # accept the "skipped" status as a "success" when merging (which is very
  # bad!). Therefore, we need to always run this job and have to manually check
  # if all required jobs did return "success".
  result:
    name: Result
    if: ${{ always() }}
    runs-on: ubuntu-latest
    needs:
      - fmt
      - check
      - test
      - deny
      - clippy
    steps:
      - run: |
          echo "Error: A required CI check failed!" >&2
          exit 1
        if: >-
          ${{
            contains(needs.*.result, 'failure') ||
            contains(needs.*.result, 'cancelled') ||
            contains(needs.*.result, 'skipped')
          }}