https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70704
--- Comment #36 from David Edelsohn <dje at gcc dot gnu.org> --- It definitely is Flex. gcc-6-branch r235040 and r235340 fail when built with Flex 2.6.0. gcc-6.0.1-RC-20160415 fails using the supplied gengtype-lex.c created with Flex 2.5.37.
