ci.yml

name: CI

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

permissions:
  contents: read

# A new push to a pull request makes the previous run pointless.
concurrency:
  group: ci-${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: ${{ github.event_name == 'pull_request' }}

env:
  CARGO_TERM_COLOR: always

jobs:
  # The crate has a build script that reads `presets/`, but it only needs the
  # checked-out tree, so a stock toolchain is enough on every platform.
  test:
    name: test (${{ matrix.os }})
    runs-on: ${{ matrix.os }}
    strategy:
      fail-fast: false
      matrix:
        os: [ubuntu-latest, windows-latest, macos-latest]
    steps:
      - uses: actions/checkout@v7

      - uses: dtolnay/rust-toolchain@stable
        with:
          components: clippy

      - uses: Swatinem/rust-cache@v2

      - name: Build
        run: cargo build --locked

      - name: Test
        run: cargo test --locked

      - name: Clippy
        run: cargo clippy --locked --lib --bins --tests -- -D warnings

  fmt:
    name: rustfmt
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v7

      - uses: dtolnay/rust-toolchain@stable
        with:
          components: rustfmt

      - name: Check formatting
        run: cargo fmt --check

  # `cargo deny` reads the lockfile and the advisory database; it never builds
  # the crate, so this finishes long before the test matrix does.
  deny:
    name: cargo-deny
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v7

      - uses: EmbarkStudios/cargo-deny-action@v2
        with:
          command: check

  # `rust-version` in Cargo.toml is a promise. This is the only thing that keeps
  # it true, since a stable toolchain will happily accept newer syntax.
  msrv:
    name: msrv
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v7

      - id: msrv
        shell: bash
        run: |
          set -euo pipefail
          version=$(awk -F' *= *' '
            /^\[/ { section = $0 }
            section == "[package]" && $1 == "rust-version" { gsub(/"/, "", $2); print $2; exit }
          ' Cargo.toml)
          if [ -z "$version" ]; then
            echo "::error::Cargo.toml has no [package] rust-version"
            exit 1
          fi
          echo "version=$version" >> "$GITHUB_OUTPUT"
          echo "MSRV is $version"

      - uses: dtolnay/rust-toolchain@master
        with:
          toolchain: ${{ steps.msrv.outputs.version }}

      - uses: Swatinem/rust-cache@v2
        with:
          key: msrv-${{ steps.msrv.outputs.version }}

      # `check`, not `build`: this asks whether the declared MSRV can still
      # compile the tree, and does not need to produce a binary to answer.
      - name: Check against the declared MSRV
        run: cargo check --locked --all-targets