https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79818
--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> --- We have ++c on signed char, which gcc turns into c=c+1, still on signed char, where overflow is undefined behavior. The problem is long before the transformation of the comparison. If ++c means c=(signed char)((int)c+1), it should be lowered to that, or to an unsigned char addition.
