https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80916
--- Comment #1 from Davin McCall <davmac at davmac dot org> --- (Does not actually require -Wno-invalid-offsetof to reproduce; that was just me copying my command line literally. Problem first appears in GCC 6.1, not in 5.x, still present in 7.1).
