This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 112e. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
[Resolved editorially by editorial issue 2353.]
According to 11.4 [class.mem] paragraph 1,
A member shall not be declared twice in the member-specification, except that a nested class or member class template can be declared and then later defined, and except that an enumeration can be introduced with an opaque-enum-declaration and later redeclared with an enum-specifier.
However, the grammar for member-declaration does not have a production that allows an opaque-enum-declaration.