This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-10-26
During the discussion of issue 1918, it was decided that the last part of the issue should be split off into a separate issue. According to 13.7.5 [temp.friend] paragraph 5,
A member of a class template may be declared to be a friend of a non-template class.
Does this make the example from issue 1918,
template<typename T> struct A { class B { class C {}; }; }; class X { static int x; template <typename T> friend class A<T>::B::C; }; template<> struct A<int> { typedef struct Q B; }; struct Q { class C { int f() { return X::x; } }; };
ill-formed because the friend declaration does not refer to a member of a class template? This does not appear to be the interpretation chosen by most implementations.
Additional note (January, 2024)
The example is ill-formed per the resolution of issue 1862 (adopted in November, 2017).