This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115c. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-09-25
The example in 11.5 [class.union] paragraph 8 reads,
union U {
int x = 0;
union { };
union {
int z;
int y = 1; // error: initialization for second variant member of U
};
};
The empty anonymous union appears to be a violation of the requirement in 11.4 [class.mem] paragraph 1,
Except when used to declare friends (11.8.4 [class.friend]), to declare an unnamed bit-field (11.4.10 [class.bit]), or to introduce the name of a member of a base class into a derived class (9.9 [namespace.udecl]), or when the declaration is an empty-declaration, member-declarations declare members of the class, and each such member-declaration shall declare at least one member name of the class.
Additional note, February, 2021:
The issue was resolved editorially.