#[derive(Debug)]
struct A {
    x: u8,
    y: u8,
}

fn set_x(mut a: A) {
    println!("{:p}", &a);
    a.x = 22;
}

fn main() {
    let a = A { x: 10, y: 20 };
    println!("{:p}", &a);
    set_x(a);
}