Make editor language setting default to Auto

doc/classes/EditorInterface.xml

@@ -96,6 +96,12 @@
 				Returns the edited (current) scene's root [Node].
 			</description>
 		</method>
+		<method name="get_editor_language" qualifiers="const">
+			<return type="String" />
+			<description>
+				Returns the language currently used for the editor interface.
+			</description>
+		</method>
 		<method name="get_editor_main_screen" qualifiers="const">
 			<return type="VBoxContainer" />
 			<description>

doc/classes/EditorSettings.xml

@@ -880,7 +880,7 @@
 			During a drag-and-drop, this is how long to wait over a UI element before it triggers a reaction (e.g. a section unfolds to show nested items).
 		</member>
 		<member name="interface/editor/editor_language" type="String" setter="" getter="">
-			The language to use for the editor interface.
+			The language to use for the editor interface. If set to [b]Auto[/b], the language is automatically determined based on the system locale. See also [method EditorInterface.get_editor_language].
 			Translations are provided by the community. If you spot a mistake, [url=https://contributing.godotengine.org/en/latest/documentation/translation/index.html]contribute to editor translations on Weblate![/url]
 		</member>
 		<member name="interface/editor/editor_screen" type="int" setter="" getter="">

editor/editor_interface.cpp

@@ -442,6 +442,10 @@ float EditorInterface::get_editor_scale() const {
 	return EDSCALE;
 }
 
+String EditorInterface::get_editor_language() const {
+	return EditorSettings::get_singleton()->get_language();
+}
+
 bool EditorInterface::is_node_3d_snap_enabled() const {
 	return Node3DEditor::get_singleton()->is_snap_enabled();
 }
@@ -846,6 +850,7 @@ void EditorInterface::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("is_multi_window_enabled"), &EditorInterface::is_multi_window_enabled);
 
 	ClassDB::bind_method(D_METHOD("get_editor_scale"), &EditorInterface::get_editor_scale);
+	ClassDB::bind_method(D_METHOD("get_editor_language"), &EditorInterface::get_editor_language);
 
 	ClassDB::bind_method(D_METHOD("is_node_3d_snap_enabled"), &EditorInterface::is_node_3d_snap_enabled);
 	ClassDB::bind_method(D_METHOD("get_node_3d_translate_snap"), &EditorInterface::get_node_3d_translate_snap);

editor/editor_interface.h

@@ -131,6 +131,7 @@ public:
 	bool is_multi_window_enabled() const;
 
 	float get_editor_scale() const;
+	String get_editor_language() const;
 
 	bool is_node_3d_snap_enabled() const;
 	real_t get_node_3d_translate_snap() const;

editor/inspector/editor_property_name_processor.cpp

@@ -59,7 +59,7 @@ EditorPropertyNameProcessor::Style EditorPropertyNameProcessor::get_tooltip_styl
 }
 
 bool EditorPropertyNameProcessor::is_localization_available() {
-	return EditorSettings::get_singleton() && EDITOR_GET("interface/editor/editor_language") != "en";
+	return EditorSettings::get_singleton() && EditorSettings::get_singleton()->get_language() != "en";
 }
 
 String EditorPropertyNameProcessor::_capitalize_name(const String &p_name) const {

editor/settings/editor_settings.cpp

@@ -363,6 +363,28 @@ void EditorSettings::_set_initialized() {
 	initialized = true;
 }
 
+static LocalVector<String> _get_skipped_locales() {
+	// Skip locales if Text server lack required features.
+	LocalVector<String> locales_to_skip;
+	if (!TS->has_feature(TextServer::FEATURE_BIDI_LAYOUT) || !TS->has_feature(TextServer::FEATURE_SHAPING)) {
+		locales_to_skip.push_back("ar"); // Arabic.
+		locales_to_skip.push_back("fa"); // Persian.
+		locales_to_skip.push_back("ur"); // Urdu.
+	}
+	if (!TS->has_feature(TextServer::FEATURE_BIDI_LAYOUT)) {
+		locales_to_skip.push_back("he"); // Hebrew.
+	}
+	if (!TS->has_feature(TextServer::FEATURE_SHAPING)) {
+		locales_to_skip.push_back("bn"); // Bengali.
+		locales_to_skip.push_back("hi"); // Hindi.
+		locales_to_skip.push_back("ml"); // Malayalam.
+		locales_to_skip.push_back("si"); // Sinhala.
+		locales_to_skip.push_back("ta"); // Tamil.
+		locales_to_skip.push_back("te"); // Telugu.
+	}
+	return locales_to_skip;
+}
+
 void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 	_THREAD_SAFE_METHOD_
 // Sets up the editor setting with a default value and hint PropertyInfo.
@@ -381,36 +403,18 @@ void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 	/* Languages */
 
 	{
-		String lang_hint = ";en/[en] English";
+		String lang_hint;
-		String host_lang = OS::get_singleton()->get_locale();
+		const String host_lang = OS::get_singleton()->get_locale();
-
-		// Skip locales if Text server lack required features.
-		Vector<String> locales_to_skip;
-		if (!TS->has_feature(TextServer::FEATURE_BIDI_LAYOUT) || !TS->has_feature(TextServer::FEATURE_SHAPING)) {
-			locales_to_skip.push_back("ar"); // Arabic
-			locales_to_skip.push_back("fa"); // Persian
-			locales_to_skip.push_back("ur"); // Urdu
-		}
-		if (!TS->has_feature(TextServer::FEATURE_BIDI_LAYOUT)) {
-			locales_to_skip.push_back("he"); // Hebrew
-		}
-		if (!TS->has_feature(TextServer::FEATURE_SHAPING)) {
-			locales_to_skip.push_back("bn"); // Bengali
-			locales_to_skip.push_back("hi"); // Hindi
-			locales_to_skip.push_back("ml"); // Malayalam
-			locales_to_skip.push_back("si"); // Sinhala
-			locales_to_skip.push_back("ta"); // Tamil
-			locales_to_skip.push_back("te"); // Telugu
-		}
 
+		// Skip locales which we can't render properly.
+		const LocalVector<String> locales_to_skip = _get_skipped_locales();
 		if (!locales_to_skip.is_empty()) {
 			WARN_PRINT("Some locales are not properly supported by selected Text Server and are disabled.");
 		}
 
-		String best;
+		String best = "en";
 		int best_score = 0;
 		for (const String &locale : get_editor_locales()) {
-			// Skip locales which we can't render properly (see above comment).
 			// Test against language code without regional variants (e.g. ur_PK).
 			String lang_code = locale.get_slicec('_', 0);
 			if (locales_to_skip.has(lang_code)) {
@@ -427,11 +431,9 @@ void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 				best_score = score;
 			}
 		}
-		if (best_score == 0) {
+		lang_hint = vformat(";auto/Auto (%s);en/[en] English", TranslationServer::get_singleton()->get_locale_name(best)) + lang_hint;
-			best = "en";
-		}
 
-		EDITOR_SETTING_USAGE(Variant::STRING, PROPERTY_HINT_ENUM, "interface/editor/editor_language", best, lang_hint, PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED | PROPERTY_USAGE_EDITOR_BASIC_SETTING);
+		EDITOR_SETTING_USAGE(Variant::STRING, PROPERTY_HINT_ENUM, "interface/editor/editor_language", "auto", lang_hint, PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED | PROPERTY_USAGE_EDITOR_BASIC_SETTING);
 	}
 
 	// Asset library
@@ -1329,7 +1331,7 @@ fail:
 }
 
 void EditorSettings::setup_language(bool p_initial_setup) {
-	String lang = _EDITOR_GET("interface/editor/editor_language");
+	String lang = get_language();
 	if (p_initial_setup) {
 		String lang_ov = Main::get_locale_override();
 		if (!lang_ov.is_empty()) {
@@ -1851,6 +1853,37 @@ float EditorSettings::get_auto_display_scale() {
 #endif // defined(MACOS_ENABLED) || defined(ANDROID_ENABLED)
 }
 
+String EditorSettings::get_language() const {
+	const String language = has_setting("interface/editor/editor_language") ? get("interface/editor/editor_language") : "auto";
+	if (language != "auto") {
+		return language;
+	}
+
+	if (auto_language.is_empty()) {
+		// Skip locales which we can't render properly.
+		const LocalVector<String> locales_to_skip = _get_skipped_locales();
+		const String host_lang = OS::get_singleton()->get_locale();
+
+		String best = "en";
+		int best_score = 0;
+		for (const String &locale : get_editor_locales()) {
+			// Test against language code without regional variants (e.g. ur_PK).
+			String lang_code = locale.get_slicec('_', 0);
+			if (locales_to_skip.has(lang_code)) {
+				continue;
+			}
+
+			int score = TranslationServer::get_singleton()->compare_locales(host_lang, locale);
+			if (score > 0 && score >= best_score) {
+				best = locale;
+				best_score = score;
+			}
+		}
+		auto_language = best;
+	}
+	return auto_language;
+}
+
 // Shortcuts
 
 void EditorSettings::_add_shortcut_default(const String &p_name, const Ref<Shortcut> &p_shortcut) {

editor/settings/editor_settings.h

@@ -89,6 +89,7 @@ private:
 	static Ref<EditorSettings> singleton;
 
 	HashSet<String> changed_settings;
+	mutable String auto_language;
 
 	mutable Ref<ConfigFile> project_metadata;
 	HashMap<String, PropertyInfo> hints;
@@ -186,6 +187,7 @@ public:
 	Vector<String> get_script_templates(const String &p_extension, const String &p_custom_path = String());
 	String get_editor_layouts_config() const;
 	static float get_auto_display_scale();
+	String get_language() const;
 
 	void _add_shortcut_default(const String &p_name, const Ref<Shortcut> &p_shortcut);
 	void add_shortcut(const String &p_name, const Ref<Shortcut> &p_shortcut);

modules/mono/editor/GodotTools/GodotTools/Build/BuildSystem.cs

@@ -41,7 +41,7 @@ namespace GodotTools.Build
             startInfo.UseShellExecute = false;
             startInfo.CreateNoWindow = true;
             startInfo.EnvironmentVariables["DOTNET_CLI_UI_LANGUAGE"]
-                = ((string)editorSettings.GetSetting("interface/editor/editor_language")).Replace('_', '-');
+                = ((string)EditorInterface.Singleton.GetEditorLanguage()).Replace('_', '-');
 
             if (OperatingSystem.IsWindows())
             {
@@ -111,7 +111,7 @@ namespace GodotTools.Build
             startInfo.RedirectStandardError = true;
             startInfo.UseShellExecute = false;
             startInfo.EnvironmentVariables["DOTNET_CLI_UI_LANGUAGE"]
-                = ((string)editorSettings.GetSetting("interface/editor/editor_language")).Replace('_', '-');
+                = ((string)EditorInterface.Singleton.GetEditorLanguage()).Replace('_', '-');
 
             if (OperatingSystem.IsWindows())
             {