This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 111d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
[Moved to DR at the November, 2014 meeting.]
According to 11.4.10 [class.bit] paragraph 2,
Unnamed bit-fields are not members and cannot be initialized.
However, the rules defining standard-layout classes in Clause 11 [class] paragraph 7 do not account for the fact that a class containing an unnamed bit-field has associated storage.
See also issue 1813 for a related question about standard-layout classes.
Proposed resolution (June, 2014):
This issue is resolved by the resolution of issue 1813.