https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87656
--- Comment #11 from David Binderman <dcb314 at hotmail dot com> --- -Wold-style-definition KnR style function definitions have been deprecated for about 35 years. Yes, there is a warning for it in gcc, but that warning isn't in either -Wall or -Wextra. Also, switching on -std=c2x only makes it a warning, not an error. That doesn't sound correct to me. AFAIK KnR is removed from c2x.
