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
[Accepted at the July, 2019 meeting as part of paper P1099R5 (Using enum).]
A using-declaration cannot name a scoped enumerator, according to 9.9 [namespace.udecl] paragraph 7. This is presumably because a scoped enumerator belongs to an enumeration scope and thus logically cannot belong to the non-enumeration scope in which the using-declaration appears. It seems inconsistent, however, to permit using-declarations to name unscoped enumerators but not scoped enumerators.
Also, 9.9 [namespace.udecl] paragraph 3 says,
In a using-declaration used as a member-declaration, the nested-name-specifier shall name a base class of the class being defined.
The consequence of this is that
enum E { e0 }; void f() { using E::e0; }
is well-formed, but
struct B { enum E { e0 }; }; struct D : B { using B::E::e0; };
is not. Again, this seems inconsistent. Should these rules be relaxed?