typed enum not supported ? enum NAME : _type_ {}

[ivanbrug]

        template <typename _Ty>
        struct __vcrt_va_list_is_reference
        {
            enum : bool { __the_value = false };
        };

error

partition_rowoperations.i(4398): syntax error at token enum
partition_rowoperations.i(4398): trying to match class_block_item_list at 'enum'
partition_rowoperations.i(4404): syntax error at token enum
partition_rowoperations.i(4404): trying to match class_block_item_list at 'enum'
partition_rowoperations.i(4405): syntax error at token }
partition_rowoperations.i(4405): trying to match start at '}'

tried to fix

enum_definition : 
	 ( anonymous_enum_definition )?
	 | named_enum_definition	 
	 ;

anonymous_enum_definition :
	    ENUM brace_block opt_instance_list SEMICOLON
	  ;

named_enum_definition :
<<int startLine=LT(1)->getLine(); >>
	  ENUM id:IDENTIFIER **( COLON type[d1,d2,d3])?** brace_block SEMICOLON
	<<
		ps->record_module_extent(startLine,startLine,
					$id->getText(),"enum",
					 "definition",utDEFINITION);
	>>
	;

but did not compile