feat: support submodule longhand

lib/src/modules/default.test.nix

@@ -454,5 +454,44 @@ in {
       };
     in
       evaluated.config.aux.x.message == expected;
+
+    "submodules without shorthand" = let
+      expected = "Hello, World!";
+      evaluated = lib.modules.run {
+        modules = [
+          {
+            options = {
+              aux = lib.options.create {
+                type = lib.types.submodules.of {
+                  shorthand = false;
+                  modules = [
+                    {
+                      options.message = lib.options.create {
+                        type = lib.types.string;
+                      };
+                    }
+                  ];
+                };
+              };
+            };
+            config = {
+              aux = {
+                options = {
+                  message2 = lib.options.create {
+                    type = lib.types.string;
+                  };
+                };
+
+                config = {
+                  message = expected;
+                  message2 = expected;
+                };
+              };
+            };
+          }
+        ];
+      };
+    in
+      evaluated.config.aux.message == evaluated.config.aux.message2;
   };
 }

lib/src/types/default.nix

@@ -761,10 +761,11 @@ lib: {
         modules,
         args ? {},
         description ? null,
+        shorthand ? true,
       }: let
         getModules = builtins.map (
           definition:
-            if builtins.isAttrs definition
+            if shorthand && builtins.isAttrs definition
             then {
               __file__ = definition.__file__;
               config = definition.value;
@@ -816,7 +817,7 @@ lib: {
           getSubModules = modules;
           withSubModules = modules:
             lib.types.submodules.of {
-              inherit args description modules;
+              inherit args description modules shorthand;
             };
           children = lib.attrs.when (freeform != null) {
             inherit freeform;
@@ -826,7 +827,7 @@ lib: {
             // {
               type = lib.types.submodules.of;
               payload = {
-                inherit modules args description;
+                inherit modules args description shorthand;
               };
               merge = x: y: {
                 modules = x.modules ++ y.modules;