nixpkgs-ci.yml

name: "nixpkgs CI"

on:
  workflow_dispatch:
  push:
    branches: [ master ]
  pull_request:
    branches: [ master ]

jobs:
  get-ghc-versions:
    name: Determine GHC versions to test
    runs-on: ubuntu-latest
    outputs:
      versions: ${{ steps.get-ghc-versions-step.outputs.versions }}

    steps:
      - uses: actions/checkout@v4.2.2
      - uses: cachix/install-nix-action@v30
        with:
          nix_path: nixpkgs=channel:nixos-unstable
      - name: Get GHC Versions from ci.nix
        id: get-ghc-versions-step
        run: |
          echo -n "versions=" >> "$GITHUB_OUTPUT"
          nix-instantiate --eval --strict --json -E "builtins.attrNames (import ./ci.nix { })" >> "$GITHUB_OUTPUT"

  nix-build:
    runs-on: ubuntu-latest
    needs:
      - get-ghc-versions

    strategy:
      matrix:
        version: ${{ fromJSON(needs.get-ghc-versions.outputs.versions) }}

    steps:
      - uses: actions/checkout@v4.2.2
      - uses: cachix/install-nix-action@v30
        with:
          nix_path: nixpkgs=channel:nixos-unstable
      - name: nix-build ci.nix -A ${{ matrix.version }}
        env:
          ATTR: ${{ matrix.version }}
        run: |
          nix-build ci.nix -A "$ATTR"