http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54487 --- Comment #25 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-09-11 18:58:59 UTC --- Indeed, seems http://gcc.gnu.org/ml/gcc-patches/2003-05/msg00571.html has introduced use of that macro, but didn't bother to actually define it anywhere.