src/tools/miri/tests/pass/issues/issue-miri-2068.rs

#![feature(noop_waker)]

use std::future::Future;
use std::pin::Pin;
use std::task::{Context, Poll, Waker};

pub fn fuzzing_block_on<O, F: Future<Output = O>>(fut: F) -> O {
    let mut fut = std::pin::pin!(fut);
    let mut context = Context::from_waker(Waker::noop());
    loop {
        match fut.as_mut().poll(&mut context) {
            Poll::Ready(v) => return v,
            Poll::Pending => {}
        }
    }
}

pub struct LastFuture<S> {
    last: S,
}

impl<S> Future for LastFuture<S>
where
    Self: Unpin,
    S: Unpin + Copy,
{
    type Output = S;

    fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
        return Poll::Ready(self.last);
    }
}

fn main() {
    fuzzing_block_on(async {
        LastFuture { last: &0u32 }.await;
        LastFuture { last: Option::<u32>::None }.await;
    });
}