#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::future::Future;
use std::pin::Pin;
use std::sync::{Arc, Mutex};
use std::task::{Context, Poll, Waker};
struct Waiter {
    shared: Arc<Mutex<Shared>>,
}
struct Shared {
    waker: Waker,
}
impl Future for Waiter {
    type Output = ();
    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()> {
        let mut shared = self.shared.lock().unwrap();
        shared.waker.clone_from(cx.waker());
        Poll::Ready(())
    }
}
fn main() {}