gcc/testsuite/gcc.dg/c2x-digit-separators-3.c

/* Test C2x digit separators.  Test token pasting avoided for preprocessed
   output.  */
/* { dg-do compile } */
/* { dg-options "-std=c2x -save-temps" } */

#define ZERO 0

int
f (void)
{
  return ZERO'0'0; /* { dg-error "expected" } */
}