From c7ce343d9bf1a329056a4dd5b32ea8cc43b55e15 Mon Sep 17 00:00:00 2001
From: GrizzlT <13691001+GrizzlT@users.noreply.github.com>
Date: Wed, 24 Jan 2024 11:30:39 +0100
Subject: [PATCH] home-manager: add extendModules attribute

The `home-manager.lib.homeManagerConfiguration` function now has an
additional attribute that can be used to extend a Home Manager
configuration with additional modules outside the project tree.

It works similar to the result of `lib.nixosSystem` from Nixpkgs
---
 modules/default.nix | 44 +++++++++++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/modules/default.nix b/modules/default.nix
index ba43fec5c..ad0e67646 100644
--- a/modules/default.nix
+++ b/modules/default.nix
@@ -28,28 +28,34 @@ let
     specialArgs = { modulesPath = builtins.toString ./.; } // extraSpecialArgs;
   };
 
-  module = showWarnings (let
-    failed = collectFailed rawModule.config;
-    failedStr = concatStringsSep "\n" (map (x: "- ${x}") failed);
-  in if failed == [ ] then
-    rawModule
-  else
-    throw ''
+  moduleChecks = raw:
+    showWarnings (let
+      failed = collectFailed raw.config;
+      failedStr = concatStringsSep "\n" (map (x: "- ${x}") failed);
+    in if failed == [ ] then
+      raw
+    else
+      throw ''
 
-      Failed assertions:
-      ${failedStr}'');
+        Failed assertions:
+        ${failedStr}'');
 
-in {
-  inherit (module) options config;
+  withExtraAttrs = rawModule:
+    let module = moduleChecks rawModule;
+    in {
+      inherit (module) options config;
 
-  activationPackage = module.config.home.activationPackage;
+      activationPackage = module.config.home.activationPackage;
 
-  # For backwards compatibility. Please use activationPackage instead.
-  activation-script = module.config.home.activationPackage;
+      # For backwards compatibility. Please use activationPackage instead.
+      activation-script = module.config.home.activationPackage;
 
-  newsDisplay = rawModule.config.news.display;
-  newsEntries = sort (a: b: a.time > b.time)
-    (filter (a: a.condition) rawModule.config.news.entries);
+      newsDisplay = rawModule.config.news.display;
+      newsEntries = sort (a: b: a.time > b.time)
+        (filter (a: a.condition) rawModule.config.news.entries);
 
-  inherit (module._module.args) pkgs;
-}
+      inherit (module._module.args) pkgs;
+
+      extendModules = args: withExtraAttrs (rawModule.extendModules args);
+    };
+in withExtraAttrs rawModule