build(nix): add formatting checks

Signed-off-by: seth <getchoo@tuta.io>

flake.nix

@@ -54,6 +54,14 @@
       nixpkgsFor = forAllSystems (system: nixpkgs.legacyPackages.${system});
     in
     {
+      checks = forAllSystems (
+        system:
+        let
+          checks' = nixpkgsFor.${system}.callPackage ./nix/checks.nix { inherit self; };
+        in
+        lib.filterAttrs (_: lib.isDerivation) checks'
+      );
+
       devShells = forAllSystems (
         system:
         let
@@ -88,12 +96,17 @@
         let
           pkgs = nixpkgsFor.${system};
 
+          # Build a scope from our overlay
           prismPackages = lib.makeScope pkgs.newScope (final: self.overlays.default final pkgs);
+
+          # Grab our packages from it and set the default
+          packages = {
+            inherit (prismPackages) prismlauncher-unwrapped prismlauncher;
+            default = prismPackages.prismlauncher;
+          };
         in
-        {
+        # Only output them if they're available on the current system
-          inherit (prismPackages) prismlauncher-unwrapped prismlauncher;
+        lib.filterAttrs (_: lib.meta.availableOn pkgs.stdenv.hostPlatform) packages
-          default = prismPackages.prismlauncher;
-        }
       );
     };
 }

nix/checks.nix

@@ -0,0 +1,42 @@
+{
+  runCommand,
+  deadnix,
+  llvmPackages_18,
+  markdownlint-cli,
+  nixfmt-rfc-style,
+  statix,
+  self,
+}:
+{
+  formatting =
+    runCommand "check-formatting"
+      {
+        nativeBuildInputs = [
+          deadnix
+          llvmPackages_18.clang-tools
+          markdownlint-cli
+          nixfmt-rfc-style
+          statix
+        ];
+      }
+      ''
+        cd ${self}
+
+        echo "Running clang-format...."
+        clang-format -i --style='file' --Werror */**.{c,cc,cpp,h,hh,hpp}
+
+        echo "Running deadnix..."
+        deadnix --fail
+
+        echo "Running markdownlint..."
+        markdownlint --dot .
+
+        echo "Running nixfmt..."
+        nixfmt --check .
+
+        echo "Running statix"
+        statix check .
+
+        touch $out
+      '';
+}