haskell.yml

name: CI

on:
  # Build every pull request, to check for regressions.
  pull_request:
    types: [opened, synchronize]

  # Build when a PR is merged, to update the README's CI badge.
  push:
    branches: [main]

  # Build once a month, to detect missing upper bounds.
  schedule:
    - cron: '0 0 1 * *'

jobs:
  stack:
    name: ${{ matrix.name }}
    runs-on: ubuntu-latest
    strategy:
      matrix:
        include:
          # Check that the build passes with the recommended snapshot.
          - name: stable
            stack_yaml: "stack.yaml"
            os: ubuntu-latest

          # Check that the lower bounds are still correct by building with the
          # lowest-supported version of everything, including our dependencies.
          - name: oldest
            stack_yaml: "oldest-supported-lts.yaml"
            os: ubuntu-latest

    steps:
    - uses: actions/checkout@v2

    - uses: actions/cache@v2
      name: Cache Stack Artifacts
      with:
        path: |
          ~/.stack
          .stack-work
        key: ${{ runner.os }}-stack-${{ hashFiles(matrix.stack_yaml) }}

    - uses: haskell/actions/setup@v1
      id: setup-haskell-stack
      name: Setup Stack
      with:
        enable-stack: true
        stack-setup-ghc: true
        stack-no-global: true
        ghc-version: ${{ matrix.ghc }}

    - name: Build
      run: |
        stack --stack-yaml=${{ matrix.stack_yaml }} build --test --bench --no-run-tests --no-run-benchmarks

    - name: Test
      run: |
        stack --stack-yaml=${{ matrix.stack_yaml }} test

  cabal:
    name: ${{ matrix.name }}
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        include:
          # The purpose of that section is two-fold. First, because we are
          # using cabal and not stack, cabal will pick the most recent version
          # of our dependencies which has been released. This way, if a
          # dependency releases a breaking change, the next monthly CI will
          # pick that version and notify us if we are affected by the change.
          #
          # Second, since this project is a ghc plugin, we rely on details of
          # the GHC library which change between versions. It is thus quite
          # easy to accidentally make a change which works for the latest
          # version of GHC but not with older versions. CI should thus test all
          # the supported GHC versions.
          - name: ghc-8.10
            ghc: "8.10.7"
            os: ubuntu-latest
          - name: ghc-9.0
            ghc: "9.0.2"
            os: ubuntu-latest

    steps:
    - uses: actions/checkout@v2

    - uses: haskell/actions/setup@v1
      id: setup-haskell-cabal
      name: Setup Cabal
      with:
        ghc-version: ${{ matrix.ghc }}
        cabal-version: ${{ matrix.cabal }}

    # This freeze file is regenerated on every build, so we will always test
    # with the most recent version of our dependencies allowed by our upper
    # bounds.
    - name: Freeze
      run: |
        cabal configure --enable-tests --enable-benchmarks --test-show-details=direct
        cabal freeze

    # Only reuse the cached copy of our dependencies if our freeze file matches
    # the cache's copy.
    - uses: actions/cache@v2
      name: Cache Cabal Artifacts
      with:
        path: |
          ${{ steps.setup-haskell-cabal.outputs.cabal-store }}
          dist-newstyle
        key: ${{ runner.os }}-cabal-${{ hashFiles('cabal.project.freeze') }}

    - name: Build
      run: |
        cabal build all

    - name: Test
      run: |
        cabal test all

  # a separate job just to check the error messages, because that requires
  # building several failing projects and so the test framework is more complex.
  error-messages:
    name: Error Messages
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        include:
          - ghc: "9.0"
            os: ubuntu-latest

    steps:
    - uses: actions/checkout@v2

    # ./test/error-messages/Test.hs is a cabal script, so we need Cabal.
    - uses: haskell/actions/setup@v1
      id: setup-haskell-cabal
      name: Setup Cabal
      with:
        ghc-version: ${{ matrix.ghc }}
        enable-stack: false

    # ./test/error-messages/Test.hs runs some stack projects, so we also need stack.
    - uses: haskell/actions/setup@v1
      id: setup-haskell-stack
      name: Setup Stack
      with:
        ghc-version: ${{ matrix.ghc }}
        enable-stack: true

    - uses: actions/cache@v2
      id: cache-stack-and-cabal
      name: Cache Stack and Cabal Artifacts
      with:
        # store the whole ~/.cabal, not just ~/.cabal/store, so we don't have to re-run 'cabal update'.
        path: |
          ~/.cabal
          dist-newstyle
          ~/.stack
          **/.stack-work
        key: ${{ runner.os }}-${{ matrix.ghc }}-error-messages-${{ hashFiles('stack.yaml') }}

    # For some reason setup-haskell-cabal sometimes doesn't run 'cabal update'.
    - name: Initialize Cabal
      if: steps.cache-stack-and-cabal.outputs.cache-hit != 'true'
      run: |
        cabal update

    - name: Test Error Messages
      run: |
        ./test/error-messages/Test.hs `pwd`