https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70704
--- Comment #35 from David Edelsohn <dje at gcc dot gnu.org> --- Flex 2.6.0 works with --enable-checking=yes, but may not work with --enable-checking=release. I believe that Flex may be the culprit. If the current bootstrap confirms that, I am going to bootstrap with gengtype-lex.c compiled with -fsigned-char.
