#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::{
    future::Future, pin::pin, task::{Context, Poll},
    thread,
};
use std::{sync::Arc, task::Wake, thread::Thread};
/// A waker that wakes up the current thread when called.
struct ThreadWaker(Thread);
impl Wake for ThreadWaker {
    fn wake(self: Arc<Self>) {
        self.0.unpark();
    }
}
/// Runs a future to completion.
fn block_on<Fut: Future>(fut: Fut) -> Fut::Output {
    let waker_that_unparks_thread = Arc::new(ThreadWaker(thread::current())).into();
    let mut cx = Context::from_waker(&waker_that_unparks_thread);
    let mut pinned_fut = pin!(fut);
    loop {
        match pinned_fut.as_mut().poll(&mut cx) {
            Poll::Pending => thread::park(),
            Poll::Ready(res) => return res,
        }
    }
}
fn main() {
    assert_eq!(42, block_on(async { 42 }));
}