gcc/testsuite/gcc.dg/spellcheck-identifiers-4a.c

/* { dg-options "" } */

extern double sqrt (double);

void test (float pf, float inff)
{
  assert (pf == inff); /* { dg-bogus "sqrt" } */
  /* { dg-error "implicit declaration of function 'assert'" "" { target *-*-* } .-1 } */
  /* { dg-message "header '<assert.h>'" "" { target *-*-* } .-2 } */
}