rust-pin

When Pin is Needed

1. async/await Futures

use std::pin::Pin;
use std::task::{Context, Poll};
use std::future::Future;

struct MyFuture {
    state: State,
}

impl Future for MyFuture {
    type Output = ();

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        // self is pinned, guaranteed not to move