#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::ptr;
fn swap<T>(a: &mut T, b: &mut T) {
    unsafe {
        let tmp = ptr::read(a);
        ptr::copy_nonoverlapping(b, a, 1);
        ptr::write(b, tmp);
    }
}
fn main() {
    let mut foo = "foo".to_owned();
    let mut bar = "bar".to_owned();
    swap(&mut foo, &mut bar);
    assert_eq!(foo, "bar");
    assert_eq!(bar, "foo");
}