[saghm]

Ah, I guess I did misunderstand then. I see now rereading that the "don't treat as a mutable borrow until first write" is already how things behave today and have since NLL.

[k1t]

That's not really true. If it were, this would compile since there are no writes.

  fn main() {
    let mut x = [1,2,3,4,5];
    let y = &mut x[0];
    let z = &x[1];
    println!("y {}... z {} ", y,  z);
  }

But it doesn't.