Fix loading of cyclic scenes from GDScript

godotengine · Jun 18, 2024 · d8169fd · d8169fd
1 parent 7b63ac4
commit d8169fd
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Showing 3 changed files with 32 additions and 4 deletions.
diff --git a/core/io/resource_loader.cpp b/core/io/resource_loader.cpp
@@ -454,6 +454,25 @@ Ref<Resource> ResourceLoader::load(const String &p_path, const String &p_type_hi
 	return res;
 }
 
+// Returns a shallow reference of the loading resource.
+// Will fail if the resource is not loading.
+Ref<Resource> ResourceLoader::get_loading_resource(const String &p_path, Error *r_error) {
+	ERR_FAIL_COND_V(r_error == nullptr, nullptr);
+	*r_error = OK;
+
+	String local_path = _validate_local_path(p_path);
+	{
+		MutexLock thread_load_lock(thread_load_mutex);
+
+		if (!thread_load_tasks.has(local_path)) {
+			*r_error = FAILED;
+			return nullptr;
+		}
+
+		return thread_load_tasks[local_path].resource;
+	}
+}
+
 Ref<ResourceLoader::LoadToken> ResourceLoader::_load_start(const String &p_path, const String &p_type_hint, LoadThreadMode p_thread_mode, ResourceFormatLoader::CacheMode p_cache_mode) {
 	String local_path = _validate_local_path(p_path);
 

diff --git a/core/io/resource_loader.h b/core/io/resource_loader.h
@@ -204,6 +204,7 @@ class ResourceLoader {
 	static bool is_within_load() { return load_nesting > 0; };
 
 	static Ref<Resource> load(const String &p_path, const String &p_type_hint = "", ResourceFormatLoader::CacheMode p_cache_mode = ResourceFormatLoader::CACHE_MODE_REUSE, Error *r_error = nullptr);
+	static Ref<Resource> get_loading_resource(const String &p_path, Error *r_error);
 	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);

diff --git a/modules/gdscript/gdscript_analyzer.cpp b/modules/gdscript/gdscript_analyzer.cpp
@@ -4296,20 +4296,28 @@ void GDScriptAnalyzer::reduce_preload(GDScriptParser::PreloadNode *p_preload) {
 			}
 		} else {
 			// TODO: Don't load if validating: use completion cache.
+			String resource_type = ResourceLoader::get_resource_type(p_preload->resolved_path);
 
 			// Must load GDScript separately to permit cyclic references
 			// as ResourceLoader::load() detects and rejects those.
-			if (ResourceLoader::get_resource_type(p_preload->resolved_path) == "GDScript") {
+			if (resource_type == "GDScript") {
 				Error err = OK;
 				Ref<GDScript> res = GDScriptCache::get_shallow_script(p_preload->resolved_path, err, parser->script_path);
 				p_preload->resource = res;
 				if (err != OK) {
 					push_error(vformat(R"(Could not preload resource script "%s".)", p_preload->resolved_path), p_preload->path);
 				}
 			} else {
-				p_preload->resource = ResourceLoader::load(p_preload->resolved_path);
-				if (p_preload->resource.is_null()) {
-					push_error(vformat(R"(Could not preload resource file "%s".)", p_preload->resolved_path), p_preload->path);
+				// Permit cyclic loading if `ResourceLoader` is currently loading that resource.
+				Error err = OK;
+				Ref<PackedScene> res = ResourceLoader::get_loading_resource(p_preload->resolved_path, &err);
+				if (err == OK) {
+					p_preload->resource = res;
+				} else {
+					p_preload->resource = ResourceLoader::load(p_preload->resolved_path);
+					if (p_preload->resource.is_null()) {
+						push_error(vformat(R"(Could not preload resource file "%s".)", p_preload->resolved_path), p_preload->path);
+					}
 				}
 			}
 		}