clang incorrectly accepts ::template S<...>

[zygoloid]

Bugzilla Link	11245
Resolution	FIXED
Resolved on	Oct 17, 2012 11:47
Version	unspecified
OS	Linux
CC	@DougGregor

Extended Description

clang accepts this in C++11 mode, and with a warning in C++98 mode:

template struct S {};
::template S s;

This is not legal in either language (and not legal even within a template in C++98). The grammar for elaborated-type-specifiers requires a nested-name-specifier before the 'template' keyword in this context, and :: is not one.

[zygoloid]

Sorry, I meant simple-type-specifiers, not elaborated-type-specifiers, obviously. (The latter doesn't accept just "::" in C++11 either, but that appears to be a bug introduced by the C++11 nested-name-specifier refactoring.)

[zygoloid]

In the same class of issues, this is ill-formed in both C++98 and C++11:

typedef int I;
template struct S {
using typename ::I; // typename not allowed with no nested-name-specifier
};

[zygoloid]

Fixed by core issue 1411.