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//@ 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.
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() {}
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