Simple async wrapper doubles the size of a future

[jimblandy]

I'm using the following wrapper function:

pub async fn log_error<F>(future: F)
where
    F: Future<Output = Result<(), Box<dyn Error + Send + Sync + 'static>>>
{
    if let Err(err) = future.await {
        print_error(err);
    }
}

Using std::mem::size_of_val, the size of any future returned by this function is a bit more than twice the size of the future passed to it. This is a pretty severe penalty for a simple helper function.

[jonas-schievink]

Duplicate of #62958