Implement Future for SmallBox<F> where F: Future

[PonasKovas]

Previously discussed in #38

Additionally I ran cargo fmt in the repository.

I am pretty certain that this is safe and sound, but if you want to discuss this further I will gladly do so.

Closes #38

[andylokandy]

would you like to add an example demonstrating how SmallBox can be uesd in async context?

[PonasKovas]

You mean demonstrate to you, or add it to the repository somewhere? To the readme?

[PonasKovas]

It's really pretty simple, similar to the std Box in user-facing code, but doesn't need to be pinned with Box::pin

Here's a simple example:

async fn foo() {
    let fut = async {
        sleep(Duration::from_secs(1)).await;
        println!("finished");
    };

    let boxed_fut: SmallBox<_, S1> = SmallBox::new(fut);

    let erased = boxed_fut as SmallBox<dyn Future<Output = ()>, S1>;

    erased.await;
}

[andylokandy]

Looks good to me. And would you like to add the async example into the unit tests, to ensure the impl Future works?

[PonasKovas]

@andylokandy I could, but then I would need to pull in some dev-dependencies, either some framework like tokio or futures crate. Tell me if that's okay.

Personally I don't think this needs any testing since this feature is pretty much a compile time thing.

[andylokandy]

is pollster sufficient?

[PonasKovas]

Yes. I will do it with pollster then

[andylokandy]

There is a conflict in the commit. I'll merge once it's resolved.

[PonasKovas]

Hmm probably pollster doesn't support this MSRV

Yep, pollster's MSRV is 1.69, while this project is 1.56

[PonasKovas]

I can switch to futures crate, it's MSRV is also 1.56

[andylokandy]

Released 0.8.6 #41