Add support for specifying a build arch.

nix/configuration/hosts/odo/default.nix

@@ -30,6 +30,7 @@
     me.optimizations = {
       enable = true;
       arch = "znver4";
+      # build_arch = "x86-64-v3";
       system_features = [
         "gccarch-znver4"
         "gccarch-skylake"

nix/configuration/hosts/quark/default.nix

@@ -28,6 +28,7 @@
     me.optimizations = {
       enable = true;
       arch = "znver4";
+      # build_arch = "x86-64-v3";
       system_features = [
         "gccarch-znver4"
         "gccarch-znver5"

nix/configuration/roles/optimized_build/default.nix

@@ -24,6 +24,13 @@
       description = "The CPU arch for which programs should be optimized.";
     };
 
+    optimizations.build_arch = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      example = "znver4";
+      description = "The CPU arch for which programs should be optimized.";
+    };
+
     optimizations.system_features = lib.mkOption {
       type = lib.types.listOf lib.types.str;
       default = [ ];
@@ -61,14 +68,6 @@
             system = "x86_64-linux";
           };
 
-          # Uncomment on of these to enable cross compiling:
-          # nixpkgs.buildPlatform = builtins.currentSystem;
-          # nixpkgs.buildPlatform = {
-          #   gcc.arch = "znver4";
-          #   gcc.tune = "znver4";
-          #   system = "x86_64-linux";
-          # };
-
           nixpkgs.overlays = [
             (
               final: prev:
@@ -108,6 +107,18 @@
         }
       ]
     ))
+    (lib.mkIf (config.me.optimizations.build_arch != null) (
+      lib.mkMerge [
+        {
+          # Enable cross-compiling
+          nixpkgs.buildPlatform = {
+            gcc.arch = config.me.optimizations.build_arch;
+            gcc.tune = "generic";
+            system = "x86_64-linux";
+          };
+        }
+      ]
+    ))
     (lib.mkIf (config.me.optimizations.system_features != [ ]) (
       lib.mkMerge [
         {

nix/configuration/roles/waybar/default.nix

@@ -171,7 +171,7 @@ in
         waybar = pkgs.symlinkJoin {
           name = prev.waybar.name;
           paths = [ prev.waybar ];
-          buildInputs = [ pkgs.makeWrapper ];
+          nativeBuildInputs = [ pkgs.makeWrapper ];
           postBuild = ''
             wrapProgram $out/bin/waybar --prefix PATH : ${
               lib.makeBinPath [