use std::thread;

struct A {
    i: u8,
}

pub struct User<'a> {
    src: &'a mut A,
}

impl<'a> User<'a> {
    pub fn new(src: &'a mut A) -> Self {
        Self { src }
    }

    pub fn f(&self) -> u8 {
        self.src.i + 1
    }
}

fn main() {
    let mut a = A { i: 0 };
    let u = User::new(&mut a);
    println!("{}", u.f());

    let t = thread::spawn(move || {
        println!("{}", u.f());
    });

    t.join().unwrap();
}