CountDownLatch::wait should return WaitFuture rather than impl Future<Output = ()>

[tomshackell]

Currently CountDownLatch::wait is defined as:

  pub fn wait(&self) -> impl Future<Output = ()> {
        WaitFuture {
            latch: self.clone(),
            state_lock: None,
        }
    }

Unfortunately, I need to put this future in a struct and currently that requires using unstable to use an impl type alias. It would be much easier (with no loss of functionality) if this method were instead defined as:

  pub fn wait(&self) -> WaitFuture {
        WaitFuture {
            latch: self.clone(),
            state_lock: None,
        }
    }

And WaitFuture made pub so that it can be used as a named type.

[wolf4ood]

Hi @tomshackell

thanks for raising this, it should be fine i think, if you some time to spare could you provide a PR for this?

Thanks