#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::ptr::NonNull;
fn main() {
    let mut x = 0u32;
    let mut ptr = NonNull::new(&mut x).expect("null pointer");
    let x_ref = unsafe { ptr.as_mut() };
    assert_eq!(* x_ref, 0);
    *x_ref += 2;
    assert_eq!(* x_ref, 2);
}