Pin, Unpin, and why Rust needs them

This is good info, but I don't fully understand why pinning makes self-references safe. I thought the problem with self-references was that they interfere with single-ownership, which is required for automatic deallocation?

I guess maybe if direct self-referencing is a distinct case from indirect self-referencing then it might not be problematic for single-ownership?

Using the `async fn` syntax, this whole wrapper becomes:

    async fn time_future<Fut: Future>(fut: Fut) -> (Fut::Output, Duration) {
        let start = Instant::now();
        let result = fut.await;
        (result, start.elapsed())
    }