http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48814
--- Comment #4 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2011-04-29 12:13:46 UTC --- I think the relevant wording in the C1X DIS is "With respect to an indeterminately-sequenced function call, the operation of postfix ++ is a single evaluation."; C++ N3291 has the same wording.
