https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116123
--- Comment #4 from Sam James <sjames at gcc dot gnu.org> --- (In reply to Andrew Pinski from comment #1) > flex is required for building GCC from git even without m2. > > gengtype-lex.l needs to be processed by flex. Yes, I was surprised to see FX ask for this because it's definitely needed... (ref. https://inbox.sourceware.org/gcc/f2b9e804-0226-4851-969c-2ec584b62...@gmail.com/). See also PR106899. But really, I don't see how needing flex is a big problem.
