https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82611
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |INVALID
Status|UNCONFIRMED |RESOLVED
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
https://gcc.gnu.org/pipermail/gcc-patches/2011-June/315878.html
So basically GCC decided to make it a warning rather than a hard error even
though the standard says it is illformed.