Fix editor potentially having multiple instances of the same subresource

Author: RandomShaper

core/io/resource_loader.cpp

@@ -336,6 +336,10 @@ void ResourceLoader::_remove_from_loading_map_and_thread(const String &p_path, T
 }
 
 RES ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p_no_cache, Error *r_error) {
+	return load(p_path, p_type_hint, p_no_cache, false, r_error);
+}
+
+RES ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p_no_cache, bool p_no_subresources_cache, Error *r_error) {
 	if (r_error) {
 		*r_error = ERR_CANT_OPEN;
 	}
@@ -386,7 +390,7 @@ RES ResourceLoader::load(const String &p_path, const String &p_type_hint, bool p
 	}
 
 	print_verbose("Loading resource: " + path);
-	RES res = _load(path, local_path, p_type_hint, p_no_cache, r_error);
+	RES res = _load(path, local_path, p_type_hint, p_no_subresources_cache, r_error);
 
 	if (res.is_null()) {
 		if (!p_no_cache) {
@@ -453,6 +457,10 @@ bool ResourceLoader::exists(const String &p_path, const String &p_type_hint) {
 }
 
 Ref<ResourceInteractiveLoader> ResourceLoader::load_interactive(const String &p_path, const String &p_type_hint, bool p_no_cache, Error *r_error) {
+	return load_interactive(p_path, p_type_hint, p_no_cache, p_no_cache, r_error);
+}
+
+Ref<ResourceInteractiveLoader> ResourceLoader::load_interactive(const String &p_path, const String &p_type_hint, bool p_no_cache, bool p_no_subresources_cache, Error *r_error) {
 	if (r_error) {
 		*r_error = ERR_CANT_OPEN;
 	}
@@ -497,7 +505,7 @@ Ref<ResourceInteractiveLoader> ResourceLoader::load_interactive(const String &p_
 			continue;
 		}
 		found = true;
-		Ref<ResourceInteractiveLoader> ril = loader[i]->load_interactive(path, local_path, r_error, p_no_cache);
+		Ref<ResourceInteractiveLoader> ril = loader[i]->load_interactive(path, local_path, r_error, p_no_subresources_cache);
 		if (ril.is_null()) {
 			continue;
 		}

core/io/resource_loader.h

@@ -143,7 +143,9 @@ class ResourceLoader {
 
 public:
 	static Ref<ResourceInteractiveLoader> load_interactive(const String &p_path, const String &p_type_hint = "", bool p_no_cache = false, Error *r_error = nullptr);
+	static Ref<ResourceInteractiveLoader> load_interactive(const String &p_path, const String &p_type_hint, bool p_no_cache, bool p_no_subresources_cache, Error *r_error = nullptr);
 	static RES load(const String &p_path, const String &p_type_hint = "", bool p_no_cache = false, Error *r_error = nullptr);
+	static RES load(const String &p_path, const String &p_type_hint, bool p_no_cache, bool p_no_subresources_cache, Error *r_error = nullptr);
 	static bool exists(const String &p_path, const String &p_type_hint = "");
 
 	static void get_recognized_extensions_for_type(const String &p_type, List<String> *p_extensions);

editor/editor_node.cpp

@@ -1002,7 +1002,7 @@ Error EditorNode::load_resource(const String &p_resource, bool p_ignore_broken_d
 	dependency_errors.clear();
 
 	Error err;
-	RES res = ResourceLoader::load(p_resource, "", false, &err);
+	RES res = ResourceLoader::load(p_resource, "", false, false, &err);
 	ERR_FAIL_COND_V(!res.is_valid(), ERR_CANT_OPEN);
 
 	if (!p_ignore_broken_deps && dependency_errors.has(p_resource)) {
@@ -3686,7 +3686,10 @@ Error EditorNode::load_scene(const String &p_scene, bool p_ignore_broken_deps, b
 	dependency_errors.clear();
 
 	Error err;
-	Ref<PackedScene> sdata = ResourceLoader::load(lpath, "", true, &err);
+	// Subresources must use cache since they may already be referenced by other scenes.
+	// Otherwise, main and inherited scenes would contain different instances of the same
+	// resource, leading to superfluously saved subresources in derived scenes.
+	Ref<PackedScene> sdata = ResourceLoader::load(lpath, "", true, false, &err);
 	if (!sdata.is_valid()) {
 		_dialog_display_load_error(lpath, err);
 		opening_prev = false;