specify installing arm64 gcc in nix

Signed-off-by: Thing-han, Lim <[email protected]>

flake.nix

@@ -16,17 +16,21 @@
     flake-parts.lib.mkFlake { inherit inputs; } {
       imports = [ ];
       systems = [ "x86_64-linux" "aarch64-linux" "aarch64-darwin" "x86_64-darwin" ];
-      perSystem = { pkgs, ... }:
+      perSystem = { pkgs, system, ... }:
         let
-          core = builtins.attrValues {
-            inherit (pkgs)
-              gcc13
-
-              # formatter & linters
-              astyle# 3.4.10
-              nixpkgs-fmt
-              shfmt;
-          };
+          # NOTE: For installing pkgs specific for aarch64 (not sure if there is any better way of doing this)
+          aarch64-system = "aarch64-" + pkgs.lib.lists.last (pkgs.lib.strings.splitString "-" system);
+          aarch64-pkgs = inputs.nixpkgs.legacyPackages.${aarch64-system};
+          core = builtins.attrValues
+            {
+              inherit (pkgs)
+                # formatter & linters
+                astyle# 3.4.10
+                nixpkgs-fmt
+                shfmt;
+            }
+          ++ [ (aarch64-pkgs.gcc13.override { propagateDoc = true; isGNU = true; }) ];
+
         in
         {
           devShells.default = pkgs.mkShellNoCC {