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 grammar for alignment-specifier in 9.12.1 [dcl.attr.grammar] paragraph 1 is:
There is no such nonterminal as alignment-expression; it should be assignment-expression instead.
Rationale (August, 2011)
This is an editorial issue that has been transmitted to the project editor.