ci,nix: added nix flake check to ci

Author: lromor

.github/workflows/ci.yml

@@ -89,6 +89,15 @@ jobs:
           clang-tidy-18 --version
           CLANG_TIDY=clang-tidy-18 scripts/run-clang-tidy-cached.cc \
             || ( cat fpga-assembler_clang-tidy.out ; exit 1)
+  NixCheck:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v25
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+      - run: |
+          nix flake check
   NixBuild:
     runs-on: ubuntu-latest
     steps:

flake.lock

@@ -43,34 +43,23 @@
               programs.yamlfmt.enable = true;
               programs.nixfmt.enable = true;
             };
-            devShells.default =
-              let
-                # There is too much volatility between even micro-versions of
-                # newer clang-format. Use slightly older version for now.
-                clang_for_formatting = pkgs.llvmPackages_17.clang-tools;
-
-                # clang tidy: use latest.
-                clang_for_tidy = pkgs.llvmPackages_18.clang-tools;
-              in
-              with pkgs;
-              pkgs.mkShell {
-                packages = with pkgs; [
+            devShells.default = with pkgs; mkShell {
+                packages = [
                   git
                   bazel_7
                   jdk
                   bash
                   gdb
 
                   # For clang-tidy and clang-format.
-                  clang_for_formatting
-                  clang_for_tidy
+                  clang-tools
 
                   # For buildifier, buildozer.
                   bazel-buildtools
                   bant
 
                   # Profiling and sanitizers.
-                  linuxPackages_latest.perf
+                  perf
                   pprof
                   perf_data_converter
                   valgrind
@@ -79,12 +68,8 @@
                   openfpgaloader
                 ];
 
-                CLANG_TIDY = "${clang_for_tidy}/bin/clang-tidy";
-                CLANG_FORMAT = "${clang_for_formatting}/bin/clang-format";
-
-                shellHook = ''
-                  exec bash
-                '';
+                CLANG_TIDY = "${clang-tools}/bin/clang-tidy";
+                CLANG_FORMAT = "${clang-tools}/bin/clang-format";
               };
 
             # Package fpga-assembler.