Identifier expression syntax 1 %unqualified_id 1 %qualified_id unqualified_id: 1 identifier 1 operator_function_id 1 conversion_function_id 1 ~ class_name 1 template_id qualified_id: 1 :: 1.1 identifier 1.1 operator_function_id 1.1 template_id 1? :: 1.1+ 1.1? class_or_namespace :: 1.1.1? template 1.1.2 class_or_namespace :: 1.1.3? template 1.1.4 unqualified_id