https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66777
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- -Waggressive-loop-optimizations, but it doesn't warn for me in this case. Of course we warn about t.c: In function ‘main’: t.c:8:26: warning: ‘a[0]’ is used uninitialized in this function [-Wuninitialized] for (i = 0; a[i] && i < 5; i++) ^