This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115f. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-12-06
[Voted into the WP at the March, 2011 meeting as part of paper N3262.]
Given
template <const char *N> struct A { static const char *p; }; template <class T> struct B { static const char c[1]; typedef A<B<T>::c> C; }; template <class T> struct D { static const char c[1]; typedef A<c> C; };
13.8.3.5 [temp.dep.temp] says that B<T>::c is dependent because it is used as a non-integral non-type template argument and it is a qualified-id with a nested-name-specifier that names a dependent type.
There doesn't seem to be anything to say that c in the definition of D<T>::C is dependent, which suggests that D<T>::C is the same type for all T, which is clearly false.
Instead of this special rule in 13.8.3.5 [temp.dep.temp], 13.8.3.4 [temp.dep.constexpr] should say that the address of a member of a dependent type is value-dependent, regardless of whether the address is written with a qualified-id.
Proposed resolution (November, 2010) [SUPERSEDED]:
Add a new paragraph at the end of 13.8.3.4 [temp.dep.constexpr]:
An id-expression is value-dependent if it names a member of an unknown specialization.
Change 13.8.3.5 [temp.dep.temp] paragraphs 2-3 as follows:
An integralA non-type template-argument is dependent if its type is dependent or the constant expression it specifies is value-dependent.
A non-integralFurthermore, a non-type template-argument is dependent ifits type is dependent or it has either of the following forms
qualified-id
& qualified-id
and contains a nested-name-specifier which specifies a class-name that names a dependent typethe corresponding non-type template-parameter is of reference or pointer type and the template-argument designates or points to a member of the current instantiation or a member of a dependent type.