Fix reloading scripts already in use

core/object/script_language.cpp

@@ -191,7 +191,14 @@ void Script::reload_from_file() {
 	set_source_code(rel->get_source_code());
 	set_last_modified_time(rel->get_last_modified_time());
 
-	reload();
+	if (Engine::get_singleton()->is_editor_hint() && is_tool()) {
+		get_language()->reload_tool_script(this, true);
+	} else {
+		// It's important to set p_keep_state to true in order to manage reloading scripts
+		// that are currently instantiated.
+		reload(true);
+	}
+
 #else
 	Resource::reload_from_file();
 #endif

editor/editor_file_system.cpp

@@ -1973,18 +1973,16 @@ void EditorFileSystem::_update_script_documentation() {
 		for (int i = 0; i < ScriptServer::get_language_count(); i++) {
 			ScriptLanguage *lang = ScriptServer::get_language(i);
 			if (lang->supports_documentation() && efd->files[index]->type == lang->get_type()) {
-				// Reloading the script from disk if resource already in memory. Otherwise, the
-				// ResourceLoader::load will return the last loaded version of the script (without the modifications).
-				// The only have the script already loaded here is to edit the script outside the
-				// editor without being connected to the LSP server.
-				Ref<Resource> res = ResourceCache::get_ref(path);
-				if (res.is_valid()) {
-					res->reload_from_file();
-				}
+				bool should_reload_script = _should_reload_script(path);
 				Ref<Script> scr = ResourceLoader::load(path);
 				if (scr.is_null()) {
 					continue;
 				}
+				if (should_reload_script) {
+					// Reloading the script from disk. Otherwise, the ResourceLoader::load will
+					// return the last loaded version of the script (without the modifications).
+					scr->reload_from_file();
+				}
 				Vector<DocData::ClassDoc> docs = scr->get_documentation();
 				for (int j = 0; j < docs.size(); j++) {
 					EditorHelp::get_doc_data()->add_doc(docs[j]);
@@ -2006,6 +2004,36 @@ void EditorFileSystem::_update_script_documentation() {
 	update_script_paths_documentation.clear();
 }
 
+bool EditorFileSystem::_should_reload_script(const String &p_path) {
+	if (first_scan) {
+		return false;
+	}
+
+	Ref<Resource> res = ResourceCache::get_ref(p_path);
+	if (res.is_null()) {
+		// Script not already loaded.
+		return false;
+	}
+
+	Ref<Script> scr = res;
+	if (scr.is_null()) {
+		// Not a script.
+		return false;
+	}
+
+	// Scripts are reloaded via the script editor if they are currently opened.
+	if (ScriptEditor::get_singleton()->get_open_scripts().has(scr)) {
+		return false;
+	}
+
+	if (res->get_last_modified_time() == FileAccess::get_modified_time(p_path)) {
+		// Already up to date.
+		return false;
+	}
+
+	return true;
+}
+
 void EditorFileSystem::_process_update_pending() {
 	_update_script_classes();
 	// Parse documentation second, as it requires the class names to be loaded

editor/editor_file_system.h

@@ -295,6 +295,7 @@ class EditorFileSystem : public Node {
 	void _update_script_documentation();
 	void _process_update_pending();
 	void _process_removed_files(const HashSet<String> &p_processed_files);
+	bool _should_reload_script(const String &p_path);
 
 	Mutex update_scene_mutex;
 	HashSet<String> update_scene_paths;

editor/editor_node.cpp

@@ -944,6 +944,12 @@ void EditorNode::_resources_changed(const Vector<String> &p_resources) {
 			continue;
 		}
 
+		if (res->get_last_modified_time() == FileAccess::get_modified_time(res->get_path())) {
+			// Already up to date. That prevents reloading a script already reloaded for documentation
+			// in EditorFileSystem::_update_script_documentation.
+			continue;
+		}
+
 		changed.push_back(res);
 	}