https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97952
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- That is for the C case replace: auto Skip_f skip_zero, skip_one_half, skip_one, command_skip_zero, command_skip, skip; With: inline auto Skip_f skip_zero, skip_one_half, skip_one, command_skip_zero, command_skip, skip; And you get closer code due to there is an implicit inline for the C++ case already.