Add String.is_valid_unicode_identifier()

- Adds `is_valid_unicode_identifier()`
- Adds `is_valid_ascii_identifier()`
- Deprecates `is_valid_identifier()`
- Renames `validate_identifier()` to `validate_ascii_identifier()`

core/core_bind.cpp

@@ -1768,7 +1768,7 @@ Object *Engine::get_singleton_object(const StringName &p_name) const {
 
 void Engine::register_singleton(const StringName &p_name, Object *p_object) {
 	ERR_FAIL_COND_MSG(has_singleton(p_name), "Singleton already registered: " + String(p_name));
-	ERR_FAIL_COND_MSG(!String(p_name).is_valid_identifier(), "Singleton name is not a valid identifier: " + p_name);
+	ERR_FAIL_COND_MSG(!String(p_name).is_valid_ascii_identifier(), "Singleton name is not a valid identifier: " + p_name);
 	::Engine::Singleton s;
 	s.class_name = p_name;
 	s.name = p_name;

core/extension/gdextension.cpp

@@ -355,7 +355,7 @@ void GDExtension::_register_extension_class_internal(GDExtensionClassLibraryPtr
 
 	StringName class_name = *reinterpret_cast<const StringName *>(p_class_name);
 	StringName parent_class_name = *reinterpret_cast<const StringName *>(p_parent_class_name);
-	ERR_FAIL_COND_MSG(!String(class_name).is_valid_identifier(), "Attempt to register extension class '" + class_name + "', which is not a valid class identifier.");
+	ERR_FAIL_COND_MSG(!String(class_name).is_valid_ascii_identifier(), "Attempt to register extension class '" + class_name + "', which is not a valid class identifier.");
 	ERR_FAIL_COND_MSG(ClassDB::class_exists(class_name), "Attempt to register extension class '" + class_name + "', which appears to be already registered.");
 
 	Extension *parent_extension = nullptr;

core/object/object.cpp

@@ -997,7 +997,7 @@ void Object::set_meta(const StringName &p_name, const Variant &p_value) {
 	if (E) {
 		E->value = p_value;
 	} else {
-		ERR_FAIL_COND_MSG(!p_name.operator String().is_valid_identifier(), "Invalid metadata identifier: '" + p_name + "'.");
+		ERR_FAIL_COND_MSG(!p_name.operator String().is_valid_ascii_identifier(), "Invalid metadata identifier: '" + p_name + "'.");
 		Variant *V = &metadata.insert(p_name, p_value)->value;
 
 		const String &sname = p_name;

core/string/ustring.cpp

@@ -4624,7 +4624,7 @@ bool String::is_absolute_path() const {
 	}
 }
 
-String String::validate_identifier() const {
+String String::validate_ascii_identifier() const {
 	if (is_empty()) {
 		return "_"; // Empty string is not a valid identifier;
 	}
@@ -4647,7 +4647,7 @@ String String::validate_identifier() const {
 	return result;
 }
 
-bool String::is_valid_identifier() const {
+bool String::is_valid_ascii_identifier() const {
 	int len = length();
 
 	if (len == 0) {
@@ -4669,6 +4669,26 @@ bool String::is_valid_identifier() const {
 	return true;
 }
 
+bool String::is_valid_unicode_identifier() const {
+	const char32_t *str = ptr();
+	int len = length();
+
+	if (len == 0) {
+		return false; // Empty string.
+	}
+
+	if (!is_unicode_identifier_start(str[0])) {
+		return false;
+	}
+
+	for (int i = 1; i < len; i++) {
+		if (!is_unicode_identifier_continue(str[i])) {
+			return false;
+		}
+	}
+	return true;
+}
+
 bool String::is_valid_string() const {
 	int l = length();
 	const char32_t *src = get_data();

core/string/ustring.h

@@ -459,10 +459,11 @@ public:
 	// node functions
 	static String get_invalid_node_name_characters(bool p_allow_internal = false);
 	String validate_node_name() const;
-	String validate_identifier() const;
+	String validate_ascii_identifier() const;
 	String validate_filename() const;
 
-	bool is_valid_identifier() const;
+	bool is_valid_ascii_identifier() const;
+	bool is_valid_unicode_identifier() const;
 	bool is_valid_int() const;
 	bool is_valid_float() const;
 	bool is_valid_hex_number(bool p_with_prefix) const;
@@ -470,6 +471,9 @@ public:
 	bool is_valid_ip_address() const;
 	bool is_valid_filename() const;
 
+	// Use `is_valid_ascii_identifier()` instead. Kept for compatibility.
+	bool is_valid_identifier() const { return is_valid_ascii_identifier(); }
+
 	/**
 	 * The constructors must not depend on other overloads
 	 */

core/variant/variant_call.cpp

@@ -1724,6 +1724,8 @@ static void _register_variant_builtin_methods_string() {
 	bind_string_method(validate_node_name, sarray(), varray());
 	bind_string_method(validate_filename, sarray(), varray());
 
+	bind_string_method(is_valid_ascii_identifier, sarray(), varray());
+	bind_string_method(is_valid_unicode_identifier, sarray(), varray());
 	bind_string_method(is_valid_identifier, sarray(), varray());
 	bind_string_method(is_valid_int, sarray(), varray());
 	bind_string_method(is_valid_float, sarray(), varray());