https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78868
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution|--- |INVALID --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- > printf("%d, %d\n", __builtin_va_arg(args,int), __builtin_va_arg(args,int)); The order of execution here is not specified in the C standard. So either of the var_arg could be executed first.