http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48973
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-05-12 07:29:37 UTC --- extern void abort (void); struct S { int f : 1; } s; int v = -1; void foo (unsigned int x) { if (x != -1U) abort (); } int main () { s.f = (v & 1) > 0; foo (s.f); return 0; } Smaller testcase which failed already in 4.2, apparently introduced in between r97500 and r98750.