llvm-gcc-4.2/gcc/testsuite/gcc.c-torture/execute/builtins/lib/strcspn.c

extern void abort (void);
extern int inside_main;

__SIZE_TYPE__
strcspn (const char *s1, const char *s2)
{
  const char *p, *q;

#ifdef __OPTIMIZE__
  if (inside_main)
    abort();
#endif

  for (p = s1; *p; p++)
    for (q = s2; *q; q++)
      if (*p == *q)
	goto found;

 found:
  return p - s1;
}