gcc/testsuite/g++.dg/coroutines/co-return-syntax-07-vararg.C

//  { dg-additional-options "-fsyntax-only -w" }

#include "coro.h"

int
bar (int x, ...)
{
  co_return 1; // { dg-error "cannot be used in a varargs function" }
}

int main (int ac, char *av[]) {
  bar (5, ac);
  return 0;
}