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.
(The originally reported ambiguity between simple-declaration and empty-declaration does not seem to exist.)
There is a grammar ambiguity between
member-declaration : attribute-specifier-seqopt decl-specifier-seqopt member-declarator-listopt ; ... empty-declaration