workflows: use Nix in CI.

.github/workflows/zig.yml

@@ -5,35 +5,22 @@ on:
   pull_request:
 
 jobs:
-  test-linux:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-        with:
-          submodules: recursive
-      - uses: goto-bus-stop/setup-zig@v1
-        with:
-          version: 0.11.0
-      - run: zig build
-      - run: zig build test
-  test-macos:
-    runs-on: macos-latest
+  test-nix:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v2
-        with:
-          submodules: recursive
-      - uses: goto-bus-stop/setup-zig@v1
-        with:
-          version: 0.11.0
-      - run: brew install pcre
-      - run: zig build
-      - run: zig build test
+      - uses: actions/checkout@v3
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@v4
+      - name: Run the Magic Nix Cache
+        uses: DeterminateSystems/magic-nix-cache-action@v2
+      - run: nix build -L
   test-windows:
     runs-on: windows-latest
     steps:
-      - uses: actions/checkout@v2
-        with:
-          submodules: recursive
+      - uses: actions/checkout@v3
       - uses: goto-bus-stop/setup-zig@v1
         with:
           version: 0.11.0
@@ -45,10 +32,9 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-        with:
-          submodules: recursive
-      - uses: goto-bus-stop/setup-zig@v1
-        with:
-          version: 0.11.0
-      - run: zig fmt --check build.zig src/*.zig
+      - uses: actions/checkout@v3
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@v4
+      - name: Run the Magic Nix Cache
+        uses: DeterminateSystems/magic-nix-cache-action@v2
+      - run: nix develop --command zig fmt --check src/*.zig

flake.nix

@@ -9,10 +9,22 @@
       pkgs = nixpkgs.legacyPackages.${system};
       inherit (pkgs) lib;
     in rec {
-      formatter = pkgs.alejandra;
+      packages.default = pkgs.stdenv.mkDerivation {
+        name = "libpcre.zig-build";
+
+        src = ./.;
 
-      devShells.default = pkgs.mkShell {
         nativeBuildInputs = [pkgs.zig pkgs.pcre];
+
+        buildPhase = ''
+          export ZIG_GLOBAL_CACHE_DIR="$TMPDIR/zig"
+          zig build test
+          touch $out
+        '';
+
+        dontInstall = true;
       };
+
+      formatter = pkgs.alejandra;
     });
 }