This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 110c. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2023-02-07


1161. Dependent nested-name-specifier in a pointer-to-member declarator

Section: 13.8  [temp.res]     Status: C++11     Submitter: GB     Date: 2010-08-03

[Voted into the WP at the November, 2010 meeting.]

N3092 comment GB 44

It is not clear from the current wording of 13.8 [temp.res] whether the following is well-formed or not:

    template<typename T> struct id { typedef T type; };
    template<typename T> void f() { int id<T>::type::*p = 0; }
    struct A { };
    int main() { f<A>(); }

If typename is required before the use of id<T>::type, it is not permitted by the current syntax.

Proposed resolution (August, 2010):

Change 13.8 [temp.res] paragraph 5 as follows:

A qualified name used as the name in a mem-initializer-id, a base-specifier, or an elaborated-type-specifier is implicitly assumed to name a type, without the use of the typename keyword. In a nested-name-specifier that immediately contains a nested-name-specifier that depends on a template parameter, the identifier or simple-template-id is implicitly assumed to name a type, without the use of the typename keyword. [Note: the typename keyword is not permitted by the syntax of these constructs. —end note]