static int *a[4][5];
char b;
long c;
long d[4];
short e;
int main() {
  int **f = &a[0][0];
  *f = a[3][2];
  c = 0;
  for (; c <= 1; c++) {
    b = 1;
    for (; b >= 0; b--) {
      e = 0;
      for (; e <= 2; e++)
        a[e][c + 1] = 0;
      d[e] = 0;
    }
  }
}

$ gcc -O2 a.c && ./a.out
$ 
$ bisheng/clang -O0 a.c && ./a.out
$ 
$  bisheng/clang -O2 a.c && ./a.out
Segmentation fault
$  bisheng/clang -O3 a.c && ./a.out
Segmentation fault