http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53013
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-04-16 22:10:29 UTC --- >IOW, "undefined" means the standard deliberately refuses to make a statement about a real thing, it does not mean that the thing is not real. That is unspecified behavior and not undefined behavior.