961203-1.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

struct s {
  char a[0x32100000];
  int x:30, y:30;
};

int
main ()
{
  struct s* p;

  p = (struct s*) 0;
  if (p->x == p->y)
    exit (1);
}