https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117124
Sam James <sjames at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |sjames at gcc dot gnu.org --- Comment #1 from Sam James <sjames at gcc dot gnu.org> --- It's UB to redefine keywords like that. The standard headers are free to clobber. Also, please use text rather than screenshots as they're not accessible. You should be able to do inspection with gcc -E or -save-temps and resultant .i.