[macOS] Add `create_instance` function to spawn editor copies.

[macOS] Modify `create_project` function to detect and run app bundles using NSWorkspace to ensure app window is registered and activated correctly.

core/core_bind.cpp

@@ -235,6 +235,19 @@ int OS::execute(const String &p_path, const Vector<String> &p_arguments, Array r
 	return exitcode;
 }
 
+int OS::create_instance(const Vector<String> &p_arguments) {
+	List<String> args;
+	for (int i = 0; i < p_arguments.size(); i++) {
+		args.push_back(p_arguments[i]);
+	}
+	::OS::ProcessID pid = 0;
+	Error err = ::OS::get_singleton()->create_instance(args, &pid);
+	if (err != OK) {
+		return -1;
+	}
+	return pid;
+}
+
 int OS::create_process(const String &p_path, const Vector<String> &p_arguments) {
 	List<String> args;
 	for (int i = 0; i < p_arguments.size(); i++) {
@@ -537,6 +550,7 @@ void OS::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_executable_path"), &OS::get_executable_path);
 	ClassDB::bind_method(D_METHOD("execute", "path", "arguments", "output", "read_stderr"), &OS::execute, DEFVAL(Array()), DEFVAL(false));
 	ClassDB::bind_method(D_METHOD("create_process", "path", "arguments"), &OS::create_process);
+	ClassDB::bind_method(D_METHOD("create_instance", "arguments"), &OS::create_instance);
 	ClassDB::bind_method(D_METHOD("kill", "pid"), &OS::kill);
 	ClassDB::bind_method(D_METHOD("shell_open", "uri"), &OS::shell_open);
 	ClassDB::bind_method(D_METHOD("get_process_id"), &OS::get_process_id);

core/core_bind.h

@@ -165,6 +165,7 @@ public:
 	String get_executable_path() const;
 	int execute(const String &p_path, const Vector<String> &p_arguments, Array r_output = Array(), bool p_read_stderr = false);
 	int create_process(const String &p_path, const Vector<String> &p_arguments);
+	int create_instance(const Vector<String> &p_arguments);
 	Error kill(int p_pid);
 	Error shell_open(String p_uri);
 

core/os/os.h

@@ -151,6 +151,7 @@ public:
 	virtual String get_executable_path() const;
 	virtual Error execute(const String &p_path, const List<String> &p_arguments, String *r_pipe = nullptr, int *r_exitcode = nullptr, bool read_stderr = false, Mutex *p_pipe_mutex = nullptr) = 0;
 	virtual Error create_process(const String &p_path, const List<String> &p_arguments, ProcessID *r_child_id = nullptr) = 0;
+	virtual Error create_instance(const List<String> &p_arguments, ProcessID *r_child_id = nullptr) { return create_process(get_executable_path(), p_arguments, r_child_id); };
 	virtual Error kill(const ProcessID &p_pid) = 0;
 	virtual int get_process_id() const;
 	virtual void vibrate_handheld(int p_duration_ms = 500);

doc/classes/OS.xml

@@ -31,12 +31,21 @@
 				[b]Note:[/b] This method is implemented on Linux, macOS and Windows.
 			</description>
 		</method>
+		<method name="create_instance">
+			<return type="int" />
+			<argument index="0" name="arguments" type="PackedStringArray" />
+			<description>
+				Creates a new instance of Godot that runs independently. The [code]arguments[/code] are used in the given order and separated by a space.
+				If the process creation succeeds, the method will return the new process ID, which you can use to monitor the process (and potentially terminate it with [method kill]). If the process creation fails, the method will return [code]-1[/code].
+				[b]Note:[/b] This method is implemented on Android, iOS, Linux, macOS and Windows.
+			</description>
+		</method>
 		<method name="create_process">
 			<return type="int" />
 			<argument index="0" name="path" type="String" />
 			<argument index="1" name="arguments" type="PackedStringArray" />
 			<description>
-				Creates a new process that runs independently of Godot. It will not terminate if Godot terminates. The file specified in [code]path[/code] must exist and be executable. Platform path resolution will be used. The [code]arguments[/code] are used in the given order and separated by a space.
+				Creates a new process that runs independently of Godot. It will not terminate if Godot terminates. The path specified in [code]path[/code] must exist and be executable file or macOS .app bundle. Platform path resolution will be used. The [code]arguments[/code] are used in the given order and separated by a space.
 				If the process creation succeeds, the method will return the new process ID, which you can use to monitor the process (and potentially terminate it with [method kill]). If the process creation fails, the method will return [code]-1[/code].
 				For example, running another instance of the project:
 				[codeblocks]
@@ -49,7 +58,7 @@
 				[/codeblocks]
 				See [method execute] if you wish to run an external command and retrieve the results.
 				[b]Note:[/b] This method is implemented on Android, iOS, Linux, macOS and Windows.
-				[b]Note:[/b] On macOS, sandboxed applications are limited to run only embedded helper executables, specified during export.
+				[b]Note:[/b] On macOS, sandboxed applications are limited to run only embedded helper executables, specified during export or system .app bundle, system .app bundles will ignore arguments.
 			</description>
 		</method>
 		<method name="delay_msec" qualifiers="const">
@@ -201,6 +210,7 @@
 			<return type="String" />
 			<description>
 				Returns the path to the current engine executable.
+				[b]Note:[/b] On macOS, always use [method create_instance] instead of relying on executable path.
 			</description>
 		</method>
 		<method name="get_granted_permissions" qualifiers="const">

editor/editor_node.cpp

@@ -3059,7 +3059,7 @@ void EditorNode::_discard_changes(const String &p_str) {
 			args.push_back(exec.get_base_dir());
 			args.push_back("--project-manager");
 
-			Error err = OS::get_singleton()->create_process(exec, args);
+			Error err = OS::get_singleton()->create_instance(args);
 			ERR_FAIL_COND(err);
 		} break;
 	}
@@ -5420,8 +5420,7 @@ void EditorNode::_global_menu_new_window(const Variant &p_tag) {
 	if (OS::get_singleton()->get_main_loop()) {
 		List<String> args;
 		args.push_back("-p");
-		String exec = OS::get_singleton()->get_executable_path();
-		OS::get_singleton()->create_process(exec, args);
+		OS::get_singleton()->create_instance(args);
 	}
 }
 

editor/editor_run.cpp

@@ -236,7 +236,7 @@ Error EditorRun::run(const String &p_scene, const String &p_custom_args, const L
 	int instances = EditorSettings::get_singleton()->get_project_metadata("debug_options", "run_debug_instances", 1);
 	for (int i = 0; i < instances; i++) {
 		OS::ProcessID pid = 0;
-		Error err = OS::get_singleton()->create_process(exec, args, &pid);
+		Error err = OS::get_singleton()->create_instance(args, &pid);
 		ERR_FAIL_COND_V(err, err);
 		pids.push_back(pid);
 	}

editor/project_manager.cpp

@@ -1304,8 +1304,7 @@ void ProjectList::update_dock_menu() {
 void ProjectList::_global_menu_new_window(const Variant &p_tag) {
 	List<String> args;
 	args.push_back("-p");
-	String exec = OS::get_singleton()->get_executable_path();
-	OS::get_singleton()->create_process(exec, args);
+	OS::get_singleton()->create_instance(args);
 }
 
 void ProjectList::_global_menu_open_project(const Variant &p_tag) {
@@ -1315,8 +1314,7 @@ void ProjectList::_global_menu_open_project(const Variant &p_tag) {
 		String conf = _projects[idx].path.plus_file("project.godot");
 		List<String> args;
 		args.push_back(conf);
-		String exec = OS::get_singleton()->get_executable_path();
-		OS::get_singleton()->create_process(exec, args);
+		OS::get_singleton()->create_instance(args);
 	}
 }
 
@@ -2062,8 +2060,7 @@ void ProjectManager::_open_selected_projects() {
 			args.push_back("--single-window");
 		}
 
-		String exec = OS::get_singleton()->get_executable_path();
-		Error err = OS::get_singleton()->create_process(exec, args);
+		Error err = OS::get_singleton()->create_instance(args);
 		ERR_FAIL_COND(err);
 	}
 
@@ -2148,8 +2145,7 @@ void ProjectManager::_run_project_confirm() {
 			args.push_back("--disable-crash-handler");
 		}
 
-		String exec = OS::get_singleton()->get_executable_path();
-		Error err = OS::get_singleton()->create_process(exec, args);
+		Error err = OS::get_singleton()->create_instance(args);
 		ERR_FAIL_COND(err);
 	}
 }
@@ -2278,8 +2274,7 @@ void ProjectManager::_language_selected(int p_id) {
 
 void ProjectManager::_restart_confirm() {
 	List<String> args = OS::get_singleton()->get_cmdline_args();
-	String exec = OS::get_singleton()->get_executable_path();
-	Error err = OS::get_singleton()->create_process(exec, args);
+	Error err = OS::get_singleton()->create_instance(args);
 	ERR_FAIL_COND(err);
 
 	_dim_window();

main/main.cpp

@@ -2848,9 +2848,8 @@ void Main::cleanup(bool p_force) {
 
 	if (OS::get_singleton()->is_restart_on_exit_set()) {
 		//attempt to restart with arguments
-		String exec = OS::get_singleton()->get_executable_path();
 		List<String> args = OS::get_singleton()->get_restart_on_exit_arguments();
-		OS::get_singleton()->create_process(exec, args);
+		OS::get_singleton()->create_instance(args);
 		OS::get_singleton()->set_restart_on_exit(false, List<String>()); //clear list (uses memory)
 	}
 

platform/osx/os_osx.h

@@ -92,6 +92,8 @@ public:
 	String get_locale() const override;
 
 	virtual String get_executable_path() const override;
+	virtual Error create_process(const String &p_path, const List<String> &p_arguments, ProcessID *r_child_id = nullptr) override;
+	virtual Error create_instance(const List<String> &p_arguments, ProcessID *r_child_id = nullptr) override;
 
 	virtual String get_unique_id() const override; //++
 

platform/osx/os_osx.mm

@@ -491,6 +491,64 @@ String OS_OSX::get_executable_path() const {
 	}
 }
 
+Error OS_OSX::create_instance(const List<String> &p_arguments, ProcessID *r_child_id) {
+	// If executable is bundled, always execute editor instances as an app bundle to ensure app window is registered and activated correctly.
+	NSString *nsappname = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleName"];
+	if (nsappname != nil) {
+		String path;
+		path.parse_utf8([[[NSBundle mainBundle] bundlePath] UTF8String]);
+		return create_process(path, p_arguments, r_child_id);
+	} else {
+		return create_process(get_executable_path(), p_arguments, r_child_id);
+	}
+}
+
+Error OS_OSX::create_process(const String &p_path, const List<String> &p_arguments, ProcessID *r_child_id) {
+	if (@available(macOS 10.15, *)) {
+		// Use NSWorkspace if path is an .app bundle.
+		NSURL *url = [NSURL fileURLWithPath:@(p_path.utf8().get_data())];
+		NSBundle *bundle = [NSBundle bundleWithURL:url];
+		if (bundle) {
+			NSMutableArray *arguments = [[NSMutableArray alloc] init];
+			for (const List<String>::Element *E = p_arguments.front(); E; E = E->next()) {
+				[arguments addObject:[NSString stringWithUTF8String:E->get().utf8().get_data()]];
+			}
+			NSWorkspaceOpenConfiguration *configuration = [[NSWorkspaceOpenConfiguration alloc] init];
+			[configuration setArguments:arguments];
+			[configuration setCreatesNewApplicationInstance:YES];
+			__block dispatch_semaphore_t lock = dispatch_semaphore_create(0);
+			__block Error err = ERR_TIMEOUT;
+			__block pid_t pid = 0;
+			[[NSWorkspace sharedWorkspace] openApplicationAtURL:url
+												  configuration:configuration
+											  completionHandler:^(NSRunningApplication *app, NSError *error) {
+												  if (error) {
+													  err = ERR_CANT_FORK;
+													  NSLog(@"Failed to execute: %@", error.localizedDescription);
+												  } else {
+													  pid = [app processIdentifier];
+													  err = OK;
+												  }
+												  dispatch_semaphore_signal(lock);
+											  }];
+			dispatch_semaphore_wait(lock, dispatch_time(DISPATCH_TIME_NOW, 20000000000)); // 20 sec timeout, wait for app to launch.
+			dispatch_release(lock);
+
+			if (err == OK) {
+				if (r_child_id) {
+					*r_child_id = (ProcessID)pid;
+				}
+			}
+
+			return err;
+		} else {
+			return OS_Unix::create_process(p_path, p_arguments, r_child_id);
+		}
+	} else {
+		return OS_Unix::create_process(p_path, p_arguments, r_child_id);
+	}
+}
+
 void OS_OSX::run() {
 	force_quit = false;