166 lines
3.4 KiB
Rust
166 lines
3.4 KiB
Rust
|
// check-pass
|
||
|
// edition:2018
|
||
|
|
||
|
// This is a regression test for https://github.com/rust-lang/rust/issues/105501.
|
||
|
// It was minified from the published `msf-ice:0.2.1` crate which failed in a crater run.
|
||
|
// A faulty compiler was triggering a `higher-ranked lifetime error`:
|
||
|
//
|
||
|
// > could not prove `[async block@...]: Send`
|
||
|
|
||
|
use mini_futures::Stream;
|
||
|
|
||
|
fn is_send(_: impl Send) {}
|
||
|
|
||
|
pub fn main() {
|
||
|
let fut = async {
|
||
|
let mut stream = mini_futures::iter([()])
|
||
|
.then(|_| async {})
|
||
|
.map(|_| async { None })
|
||
|
.buffered()
|
||
|
.filter_map(std::future::ready);
|
||
|
|
||
|
stream.next().await
|
||
|
};
|
||
|
|
||
|
is_send(async move {
|
||
|
let _: Option<()> = fut.await;
|
||
|
});
|
||
|
}
|
||
|
|
||
|
// this is a simplified subset of `futures::StreamExt` and related types
|
||
|
mod mini_futures {
|
||
|
use std::future::Future;
|
||
|
use std::pin::Pin;
|
||
|
use std::task::{Context, Poll};
|
||
|
|
||
|
pub fn iter<I>(_: I) -> Iter<I::IntoIter>
|
||
|
where
|
||
|
I: IntoIterator,
|
||
|
{
|
||
|
todo!()
|
||
|
}
|
||
|
|
||
|
pub trait Stream {
|
||
|
type Item;
|
||
|
|
||
|
fn then<Fut, F>(self, _: F) -> Then<Self, Fut, F>
|
||
|
where
|
||
|
F: FnMut(Self::Item) -> Fut,
|
||
|
Fut: Future,
|
||
|
Self: Sized,
|
||
|
{
|
||
|
todo!()
|
||
|
}
|
||
|
|
||
|
fn map<T, F>(self, _: F) -> Map<Self, F>
|
||
|
where
|
||
|
F: FnMut(Self::Item) -> T,
|
||
|
Self: Sized,
|
||
|
{
|
||
|
todo!()
|
||
|
}
|
||
|
|
||
|
fn buffered(self) -> Buffered<Self>
|
||
|
where
|
||
|
Self::Item: Future,
|
||
|
Self: Sized,
|
||
|
{
|
||
|
todo!()
|
||
|
}
|
||
|
|
||
|
fn filter_map<Fut, T, F>(self, _: F) -> FilterMap<Self, Fut, F>
|
||
|
where
|
||
|
F: FnMut(Self::Item) -> Fut,
|
||
|
Fut: Future<Output = Option<T>>,
|
||
|
Self: Sized,
|
||
|
{
|
||
|
todo!()
|
||
|
}
|
||
|
|
||
|
fn next(&mut self) -> Next<'_, Self> {
|
||
|
todo!()
|
||
|
}
|
||
|
}
|
||
|
|
||
|
pub struct Iter<I> {
|
||
|
__: I,
|
||
|
}
|
||
|
impl<I> Stream for Iter<I>
|
||
|
where
|
||
|
I: Iterator,
|
||
|
{
|
||
|
type Item = I::Item;
|
||
|
}
|
||
|
|
||
|
pub struct Then<St, Fut, F> {
|
||
|
__: (St, Fut, F),
|
||
|
}
|
||
|
impl<St, Fut, F> Stream for Then<St, Fut, F>
|
||
|
where
|
||
|
St: Stream,
|
||
|
F: FnMut(St::Item) -> Fut,
|
||
|
Fut: Future,
|
||
|
{
|
||
|
type Item = Fut::Output;
|
||
|
}
|
||
|
|
||
|
pub struct Map<St, F> {
|
||
|
__: (St, F),
|
||
|
}
|
||
|
impl<St, F> Stream for Map<St, F>
|
||
|
where
|
||
|
St: Stream,
|
||
|
F: FnMut1<St::Item>,
|
||
|
{
|
||
|
type Item = F::Output;
|
||
|
}
|
||
|
|
||
|
pub trait FnMut1<A> {
|
||
|
type Output;
|
||
|
}
|
||
|
impl<T, A, R> FnMut1<A> for T
|
||
|
where
|
||
|
T: FnMut(A) -> R,
|
||
|
{
|
||
|
type Output = R;
|
||
|
}
|
||
|
|
||
|
pub struct Buffered<St>
|
||
|
where
|
||
|
St: Stream,
|
||
|
St::Item: Future,
|
||
|
{
|
||
|
__: (St, St::Item),
|
||
|
}
|
||
|
impl<St> Stream for Buffered<St>
|
||
|
where
|
||
|
St: Stream,
|
||
|
St::Item: Future,
|
||
|
{
|
||
|
type Item = <St::Item as Future>::Output;
|
||
|
}
|
||
|
|
||
|
pub struct FilterMap<St, Fut, F> {
|
||
|
__: (St, Fut, F),
|
||
|
}
|
||
|
impl<St, Fut, F, T> Stream for FilterMap<St, Fut, F>
|
||
|
where
|
||
|
St: Stream,
|
||
|
F: FnMut1<St::Item, Output = Fut>,
|
||
|
Fut: Future<Output = Option<T>>,
|
||
|
{
|
||
|
type Item = T;
|
||
|
}
|
||
|
|
||
|
pub struct Next<'a, St: ?Sized> {
|
||
|
__: &'a mut St,
|
||
|
}
|
||
|
impl<St: ?Sized + Stream> Future for Next<'_, St> {
|
||
|
type Output = Option<St::Item>;
|
||
|
|
||
|
fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Self::Output> {
|
||
|
todo!()
|
||
|
}
|
||
|
}
|
||
|
}
|