50 lines
1.0 KiB
Rust
50 lines
1.0 KiB
Rust
//@ check-pass
|
|
//@ edition: 2021
|
|
|
|
// Make sure that we infer the args of an async closure even if it's passed to
|
|
// a function that requires the async closure implement `Fn*` but does *not* have
|
|
// a `Future` bound on the return type.
|
|
|
|
#![feature(async_closure)]
|
|
|
|
use std::future::Future;
|
|
|
|
trait TryStream {
|
|
type Ok;
|
|
type Err;
|
|
}
|
|
|
|
trait TryFuture {
|
|
type Ok;
|
|
type Err;
|
|
}
|
|
|
|
impl<F, T, E> TryFuture for F where F: Future<Output = Result<T, E>> {
|
|
type Ok = T;
|
|
type Err = E;
|
|
}
|
|
|
|
trait TryStreamExt: TryStream {
|
|
fn try_for_each<F, Fut>(&self, f: F)
|
|
where
|
|
F: FnMut(Self::Ok) -> Fut,
|
|
Fut: TryFuture<Ok = (), Err = Self::Err>;
|
|
}
|
|
|
|
impl<S> TryStreamExt for S where S: TryStream {
|
|
fn try_for_each<F, Fut>(&self, f: F)
|
|
where
|
|
F: FnMut(Self::Ok) -> Fut,
|
|
Fut: TryFuture<Ok = (), Err = Self::Err>,
|
|
{ }
|
|
}
|
|
|
|
fn test(stream: impl TryStream<Ok = &'static str, Err = ()>) {
|
|
stream.try_for_each(async |s| {
|
|
s.trim(); // Make sure we know the type of `s` at this point.
|
|
Ok(())
|
|
});
|
|
}
|
|
|
|
fn main() {}
|