can't move variable into closure in special case

[FH0]

use futures::Future;
use tokio::sync::mpsc::channel;

fn foo<F, S>(mut f: F)
where
    F: FnMut() -> S,
    S: Future,
{
    f();
}

#[tokio::main]
async fn main() {
    let (tx, mut rx) = channel::<bool>(1);
    foo(move || async move {
        let _ = rx.recv().await;
    });
}

I want to move rx into closure but failed.

I checked a lot of information but still can't solve it.

• https://github.com/hyperium/hyper/blob/master/examples/http_proxy.rs#L30-#L33
• Cannot assign to captured outer variable in an FnMut closure diagnostic #41790
• https://stackoverflow.com/questions/53038935/cannot-move-out-of-captured-variables-in-an-fnmut-closure
• https://docs.rs/hyper/0.14.9/hyper/service/fn.service_fn.html

[fee1-dead]

You expect the closure to be FnMut, but it can't. This is because you can't call it multiple times, since calling it moves rx into an async block.

[FH0]

I did some attempts and it can only be called once. Finally I solved the problem using macros.