https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72855
--- Comment #12 from Bill Schmidt <wschmidt at gcc dot gnu.org> --- Last night before I ran out of time, I built a debug compiler on gcc-6-branch, and flag_checking was always 0, and I didn't have the compile time issue. So it appears to be something that only occurs with a bootstrap compiler, which isn't going to be very helpful for running this down. :/
