gnome: use overlay.nix

Author: awwpotato

modules/gnome/nixos.nix

@@ -4,14 +4,6 @@
   config,
   ...
 }:
-
-let
-  theme = pkgs.callPackage ./theme.nix {
-    inherit (config.lib.stylix) colors;
-    inherit (config.stylix) inputs;
-  };
-
-in
 {
   options.stylix.targets.gnome.enable =
     config.lib.stylix.mkEnableTarget "GNOME and GDM" true;
@@ -34,25 +26,6 @@ in
         # which will then download the pack regardless of its exclusion below.
         environment.gnome.excludePackages = [ pkgs.gnome-backgrounds ];
 
-        nixpkgs.overlays = [
-          (_: super: {
-            gnome-shell = super.gnome-shell.overrideAttrs (oldAttrs: {
-              # Themes are usually applied via an extension, but extensions are
-              # not available on the login screen. The only way to change the
-              # theme there is by replacing the default.
-              postFixup =
-                (oldAttrs.postFixup or "")
-                + ''
-                  cp ${theme}/share/gnome-shell/gnome-shell-theme.gresource \
-                    $out/share/gnome-shell/gnome-shell-theme.gresource
-                '';
-              patches = (oldAttrs.patches or [ ]) ++ [
-                ./shell_remove_dark_mode.patch
-              ];
-            });
-          })
-        ];
-
         # Cursor settings are usually applied via Home Manager,
         # but the login screen uses a separate database.
         environment.systemPackages = lib.mkIf (config.stylix.cursor != null) [

modules/gnome/overlay.nix

@@ -0,0 +1,37 @@
+{
+  lib,
+  config,
+  pkgs,
+  ...
+}:
+{
+  overlay =
+    lib.mkIf (config.stylix.enable && config.stylix.targets.gnome.enable or false)
+      (
+        _: super: {
+          gnome-shell = super.gnome-shell.overrideAttrs (
+            oldAttrs:
+            let
+              theme = pkgs.callPackage ./theme.nix {
+                inherit (config.lib.stylix) colors;
+                inherit (config.stylix) inputs;
+              };
+            in
+            {
+              # Themes are usually applied via an extension, but extensions are
+              # not available on the login screen. The only way to change the
+              # theme there is by replacing the default.
+              postFixup =
+                (oldAttrs.postFixup or "")
+                + ''
+                  cp ${theme}/share/gnome-shell/gnome-shell-theme.gresource \
+                    $out/share/gnome-shell/gnome-shell-theme.gresource
+                '';
+              patches = (oldAttrs.patches or [ ]) ++ [
+                ./shell_remove_dark_mode.patch
+              ];
+            }
+          );
+        }
+      );
+}