https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92798
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Joseph Tilahun from comment #4) > Is there a reason why the _Rb_tree_color > enum does not have an explicit underlying type? Yes because it has to work with C++98 while enums with underlying types was only added for C++11. Again -fshort-enums changes the ABI so you can't use that option unless you compile everything with it.