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// check-pass
// edition:2018
#![feature(arbitrary_self_types)]
use std::task::{self, Poll};
use std::future::Future;
use std::marker::Unpin;
use std::pin::Pin;
// This is a regression test for an ICE/unbounded recursion issue relating to async-await.
#[derive(Debug)]
#[must_use = "futures do nothing unless polled"]
pub struct Lazy<F> {
f: Option<F>
}
impl<F> Unpin for Lazy<F> {}
pub fn lazy<F, R>(f: F) -> Lazy<F>
where F: FnOnce(&mut task::Context) -> R,
{
Lazy { f: Some(f) }
}
impl<R, F> Future for Lazy<F>
where F: FnOnce(&mut task::Context) -> R,
{
type Output = R;
fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context) -> Poll<R> {
Poll::Ready((self.f.take().unwrap())(cx))
}
}
async fn __receive<WantFn, Fut>(want: WantFn) -> ()
where Fut: Future<Output = ()>, WantFn: Fn(&Box<dyn Send + 'static>) -> Fut,
{
lazy(|_| ()).await;
}
pub fn basic_spawn_receive() {
async { __receive(|_| async { () }).await };
}
fn main() {}
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