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//@ build-fail
//@ edition: 2021
use std::future::Future;
use std::pin::pin;
use std::task::*;
pub fn block_on<T>(fut: impl Future<Output = T>) -> T {
let mut fut = pin!(fut);
// Poll loop, just to test the future...
let ctx = &mut Context::from_waker(Waker::noop());
loop {
match fut.as_mut().poll(ctx) {
Poll::Pending => {}
Poll::Ready(t) => break t,
}
}
}
trait Blah {
async fn iter<T>(&mut self, iterator: T)
where
T: IntoIterator<Item = ()>;
}
impl Blah for () {
async fn iter<T>(&mut self, iterator: T)
//~^ ERROR recursion in an async fn requires boxing
where
T: IntoIterator<Item = ()>,
{
Blah::iter(self, iterator).await
}
}
struct Wrap<T: Blah> {
t: T,
}
impl<T: Blah> Wrap<T>
where
T: Blah,
{
async fn ice(&mut self) {
let arr: [(); 0] = [];
self.t.iter(arr.into_iter()).await;
}
}
fn main() {
block_on(async {
let mut t = Wrap { t: () };
t.ice();
})
}
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