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.
In 22.214.171.124 [class.copy.ctor] paragraph 25, a move assignment operator is defined as deleted if it has any direct or indirect virtual base class. This could be relaxed to apply only if a virtual base is derived from more than once in the DAG.
Rationale (August, 2010):
CWG felt that there was insufficient motivation to change this at this time.