Remove Unpin bound from SelectAll
-#![allow(dead_code)]
-
use core::future::Future;
use core::pin::Pin;
use core::task::{Context, Poll};
-use futures::future::FutureExt;
-
/// Future for the [`select_all`] function.
#[derive(Debug)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
@@ -24,9 +20,9 @@ impl<Fut: Unpin, const N: usize> Unpin for SelectAll<Fut, N> {}
/// # Panics
///
/// This function will panic if the array specified contains no items.
-pub fn select_all<Fut: Future + Unpin, const N: usize>(arr: [Fut; N]) -> Option<SelectAll<Fut, N>> {
+pub fn select_all<Fut: Future, const N: usize>(arr: [Fut; N]) -> SelectAll<Fut, N> {
assert!(N > 0);
- Some(SelectAll { inner: arr })
+ SelectAll { inner: arr }
}
impl<Fut, const N: usize> SelectAll<Fut, N> {
@@ -36,18 +32,24 @@ impl<Fut, const N: usize> SelectAll<Fut, N> {
}
}
-impl<Fut: Future + Unpin, const N: usize> Future for SelectAll<Fut, N> {
+impl<Fut: Future, const N: usize> Future for SelectAll<Fut, N> {
type Output = (Fut::Output, usize);
- fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
- let item = self
+ fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+ // Safety: Since `self` is pinned, `inner` cannot move. Since `inner` cannot move,
+ // its elements also cannot move. Therefore it is safe to access `inner` and pin
+ // references to the contained futures.
+ let item = unsafe {
+ self.get_unchecked_mut()
.inner
.iter_mut()
.enumerate()
- .find_map(|(i, f)| match f.poll_unpin(cx) {
+ .find_map(|(i, f)| match Pin::new_unchecked(f).poll(cx) {
Poll::Pending => None,
Poll::Ready(e) => Some((i, e)),
- });
+ })
+ };
+
match item {
Some((idx, res)) => Poll::Ready((res, idx)),
None => Poll::Pending,
