Nix flake checks #15

	name: "Nix flake checks"

	on:
	pull_request:
	push:

	permissions:
	contents: read

	jobs:
	nix-matrix:
	runs-on: ubuntu-latest
	outputs:
	matrix: ${{ steps.set-matrix.outputs.matrix }}
	steps:
	- uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
	with:
	persist-credentials: false
	- uses: cachix/install-nix-action@3715ab1a11cac9e991980d7b4a28d80c7ebdd8f9 # v27
	- id: set-matrix
	name: Generate Nix checks matrix
	run: \|
	set -Eeu
	matrix="$(nix eval --json '.#githubActions.matrix')"
	echo "matrix=$matrix" >> "$GITHUB_OUTPUT"

	nix-build:
	name: ${{ matrix.name }} (${{ matrix.system }})
	needs: nix-matrix
	runs-on: ${{ matrix.os }}
	permissions:
	actions: write
	env:
	CHECK_ATTR: ${{ matrix.attr }}
	strategy:
	matrix: ${{fromJSON(needs.nix-matrix.outputs.matrix)}}
	steps:
	- uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
	with:
	persist-credentials: false
	- uses: nixbuild/nix-quick-install-action@25aff27c252e0c8cdda3264805f7b6bcd92c8718 # v29
	- uses: nix-community/cache-nix-action@8351fb9f51c580c96c509987ebb99e38aed956ce # v5.2.1
	with:
	primary-key: build-${{ runner.os }}-${{ matrix.id }}-${{ hashFiles('.github/workflows/build-checks.yml', 'flake.lock') }}
	purge: true
	purge-last-accessed: 2629800 # 1 month
	purge-primary-key: never
	- run: nix build -L ".#${CHECK_ATTR}"

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