https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122107
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- So this is a bug also for -d which does not show up in --help=common either. So the bug itself is much older. Looks like for --help Common does not override the language marker. Let me see if there is a bug filed for -d.
