Deprecating bit flags export with no hint text

modules/gdscript/gdscript_parser.cpp

@@ -3918,14 +3918,15 @@ void GDScriptParser::_parse_class(ClassNode *p_class) {
 
 									if (tokenizer->get_token() == GDScriptTokenizer::TK_IDENTIFIER && tokenizer->get_token_identifier() == "FLAGS") {
 
-										//current_export.hint=PROPERTY_HINT_ALL_FLAGS;
 										tokenizer->advance();
 
 										if (tokenizer->get_token() == GDScriptTokenizer::TK_PARENTHESIS_CLOSE) {
+											ERR_EXPLAIN("Exporting bit flags hint requires string constants.");
+											WARN_DEPRECATED
 											break;
 										}
 										if (tokenizer->get_token() != GDScriptTokenizer::TK_COMMA) {
-											_set_error("Expected ')' or ',' in bit flags hint.");
+											_set_error("Expected ',' in bit flags hint.");
 											return;
 										}