# Evaluates the Nix flake (no build, about a minute): `nix build` / `nix develop` stop at evaluation
# when Cargo.lock gains something nix/package.nix can't vendor, and nothing else would notice.
name: Nix

on:
  push:
    branches: [main]
    paths: ["flake.nix", "flake.lock", "nix/**", "Cargo.lock", ".github/workflows/nix.yml"]
  pull_request:
    paths: ["flake.nix", "flake.lock", "nix/**", "Cargo.lock", ".github/workflows/nix.yml"]
  workflow_dispatch:

permissions:
  contents: read

concurrency:
  group: nix-${{ github.ref }}
  cancel-in-progress: true

jobs:
  eval:
    runs-on: ubuntu-latest
    timeout-minutes: 15
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
      - uses: cachix/install-nix-action@13d8dd58da0234aa297dedd986986ccb8e7f3e24 # v31.11.1
      - name: nix flake check --no-build
        run: |
          if [ -f flake.nix ]; then
            nix flake check --no-build --all-systems
          else
            echo "No flake.nix present in this repository; skipping check."
          fi