Wrong type casting leads to wrong value

bitwise-u16

use std::io::println;

fn main() {
  let m : [u8, ..1] = [ 0u8 ];
  println(format!("{}",  ((m[0] >> 8) | 0) as u16));
  println(format!("{}",  ((m[0] >> 8) | m[0]) as u16));
  assert!((((m[0] >> 8) | 0) as u16) == 0);
  assert!((((m[0] >> 8) | m[0]) as u16) == 255);
}