refactor(core): Extract deno_core (#19658)

`deno_core` is moving out! You'll find it at
https://github.com/denoland/deno_core/ once this PR lands.

1 files changed, 0 insertions, 793 deletions

diff --git a/core/async_cancel.rs b/core/async_cancel.rs
deleted file mode 100644
index 5573e543d..000000000
--- a/core/async_cancel.rs
+++ /dev/null
@@ -1,793 +0,0 @@
-// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
-
-use std::any::type_name;
-use std::borrow::Cow;
-use std::error::Error;
-use std::fmt;
-use std::fmt::Display;
-use std::fmt::Formatter;
-use std::io;
-use std::pin::Pin;
-use std::rc::Rc;
-
-use futures::future::FusedFuture;
-use futures::future::Future;
-use futures::future::TryFuture;
-use futures::task::Context;
-use futures::task::Poll;
-use pin_project::pin_project;
-
-use crate::RcLike;
-use crate::Resource;
-
-use self::internal as i;
-
-#[derive(Debug, Default)]
-pub struct CancelHandle {
-  node: i::Node,
-}
-
-impl CancelHandle {
-  pub fn new() -> Self {
-    Default::default()
-  }
-
-  pub fn new_rc() -> Rc<Self> {
-    Rc::new(Self::new())
-  }
-
-  /// Cancel all cancelable futures that are bound to this handle. Note that
-  /// this method does not require a mutable reference to the `CancelHandle`.
-  pub fn cancel(&self) {
-    self.node.cancel();
-  }
-
-  pub fn is_canceled(&self) -> bool {
-    self.node.is_canceled()
-  }
-}
-
-#[pin_project(project = CancelableProjection)]
-#[derive(Debug)]
-pub enum Cancelable<F> {
-  Pending {
-    #[pin]
-    future: F,
-    #[pin]
-    registration: i::Registration,
-  },
-  Terminated,
-}
-
-impl<F: Future> Future for Cancelable<F> {
-  type Output = Result<F::Output, Canceled>;
-
-  fn poll(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
-    let poll_result = match self.as_mut().project() {
-      CancelableProjection::Pending {
-        future,
-        registration,
-      } => Self::poll_pending(future, registration, cx),
-      CancelableProjection::Terminated => {
-        panic!("{}::poll() called after completion", type_name::<Self>())
-      }
-    };
-    // Fuse: if this Future is completed or canceled, make sure the inner
-    // `future` and `registration` fields are dropped in order to unlink it from
-    // its cancel handle.
-    if matches!(poll_result, Poll::Ready(_)) {
-      self.set(Cancelable::Terminated)
-    }
-    poll_result
-  }
-}
-
-impl<F: Future> FusedFuture for Cancelable<F> {
-  fn is_terminated(&self) -> bool {
-    matches!(self, Self::Terminated)
-  }
-}
-
-impl Resource for CancelHandle {
-  fn name(&self) -> Cow<str> {
-    "cancellation".into()
-  }
-
-  fn close(self: Rc<Self>) {
-    self.cancel();
-  }
-}
-
-#[pin_project(project = TryCancelableProjection)]
-#[derive(Debug)]
-pub struct TryCancelable<F> {
-  #[pin]
-  inner: Cancelable<F>,
-}
-
-impl<F, T, E> Future for TryCancelable<F>
-where
-  F: Future<Output = Result<T, E>>,
-  Canceled: Into<E>,
-{
-  type Output = F::Output;
-
-  fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
-    let TryCancelableProjection { inner } = self.project();
-    match inner.poll(cx) {
-      Poll::Pending => Poll::Pending,
-      Poll::Ready(Ok(result)) => Poll::Ready(result),
-      Poll::Ready(Err(err)) => Poll::Ready(Err(err.into())),
-    }
-  }
-}
-
-impl<F, T, E> FusedFuture for TryCancelable<F>
-where
-  F: Future<Output = Result<T, E>>,
-  Canceled: Into<E>,
-{
-  fn is_terminated(&self) -> bool {
-    self.inner.is_terminated()
-  }
-}
-
-pub trait CancelFuture
-where
-  Self: Future + Sized,
-{
-  fn or_cancel<H: RcLike<CancelHandle>>(
-    self,
-    cancel_handle: H,
-  ) -> Cancelable<Self> {
-    Cancelable::new(self, cancel_handle.into())
-  }
-}
-
-impl<F> CancelFuture for F where F: Future {}
-
-pub trait CancelTryFuture
-where
-  Self: TryFuture + Sized,
-  Canceled: Into<Self::Error>,
-{
-  fn try_or_cancel<H: RcLike<CancelHandle>>(
-    self,
-    cancel_handle: H,
-  ) -> TryCancelable<Self> {
-    TryCancelable::new(self, cancel_handle.into())
-  }
-}
-
-impl<F> CancelTryFuture for F
-where
-  F: TryFuture,
-  Canceled: Into<F::Error>,
-{
-}
-
-#[derive(Copy, Clone, Default, Debug, Eq, Hash, PartialEq)]
-pub struct Canceled;
-
-impl Display for Canceled {
-  fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-    write!(f, "operation canceled")
-  }
-}
-
-impl Error for Canceled {}
-
-impl From<Canceled> for io::Error {
-  fn from(_: Canceled) -> Self {
-    io::Error::new(io::ErrorKind::Interrupted, Canceled)
-  }
-}
-
-mod internal {
-  use super::CancelHandle;
-  use super::Cancelable;
-  use super::Canceled;
-  use super::TryCancelable;
-  use crate::RcRef;
-  use futures::future::Future;
-  use futures::task::Context;
-  use futures::task::Poll;
-  use futures::task::Waker;
-  use pin_project::pin_project;
-  use std::any::Any;
-  use std::cell::UnsafeCell;
-  use std::marker::PhantomPinned;
-  use std::mem::replace;
-  use std::pin::Pin;
-  use std::ptr::NonNull;
-  use std::rc::Rc;
-  use std::rc::Weak;
-
-  impl<F: Future> Cancelable<F> {
-    pub(super) fn new(future: F, cancel_handle: RcRef<CancelHandle>) -> Self {
-      let head_node = RcRef::map(cancel_handle, |r| &r.node);
-      let registration = Registration::WillRegister { head_node };
-      Self::Pending {
-        future,
-        registration,
-      }
-    }
-
-    pub(super) fn poll_pending(
-      future: Pin<&mut F>,
-      mut registration: Pin<&mut Registration>,
-      cx: &mut Context,
-    ) -> Poll<Result<F::Output, Canceled>> {
-      // Do a cancellation check _before_ polling the inner future. If it has
-      // already been canceled the inner future will not be polled.
-      let node = match &*registration {
-        Registration::WillRegister { head_node } => head_node,
-        Registration::Registered { node } => node,
-      };
-      if node.is_canceled() {
-        return Poll::Ready(Err(Canceled));
-      }
-
-      match future.poll(cx) {
-        Poll::Ready(res) => return Poll::Ready(Ok(res)),
-        Poll::Pending => {}
-      }
-
-      // Register this future with its `CancelHandle`, saving the `Waker` that
-      // can be used to make the runtime poll this future when it is canceled.
-      // When already registered, update the stored `Waker` if necessary.
-      let head_node = match &*registration {
-        Registration::WillRegister { .. } => {
-          match registration.as_mut().project_replace(Default::default()) {
-            RegistrationProjectionOwned::WillRegister { head_node } => {
-              Some(head_node)
-            }
-            _ => unreachable!(),
-          }
-        }
-        _ => None,
-      };
-      let node = match registration.project() {
-        RegistrationProjection::Registered { node } => node,
-        _ => unreachable!(),
-      };
-      node.register(cx.waker(), head_node)?;
-
-      Poll::Pending
-    }
-  }
-
-  impl<F: Future> TryCancelable<F> {
-    pub(super) fn new(future: F, cancel_handle: RcRef<CancelHandle>) -> Self {
-      Self {
-        inner: Cancelable::new(future, cancel_handle),
-      }
-    }
-  }
-
-  #[pin_project(project = RegistrationProjection,
-                project_replace = RegistrationProjectionOwned)]
-  #[derive(Debug)]
-  pub enum Registration {
-    WillRegister {
-      head_node: RcRef<Node>,
-    },
-    Registered {
-      #[pin]
-      node: Node,
-    },
-  }
-
-  impl Default for Registration {
-    fn default() -> Self {
-      Self::Registered {
-        node: Default::default(),
-      }
-    }
-  }
-
-  #[derive(Debug)]
-  pub struct Node {
-    inner: UnsafeCell<NodeInner>,
-    _pin: PhantomPinned,
-  }
-
-  impl Node {
-    /// If necessary, register a `Cancelable` node with a `CancelHandle`, and
-    /// save or update the `Waker` that can wake with this cancelable future.
-    pub fn register(
-      &self,
-      waker: &Waker,
-      head_rc: Option<RcRef<Node>>,
-    ) -> Result<(), Canceled> {
-      match head_rc.as_ref().map(RcRef::split) {
-        Some((head, rc)) => {
-          // Register this `Cancelable` node with a `CancelHandle` head node.
-          assert_ne!(self, head);
-          // TODO(piscisaureus): safety comment
-          #[allow(clippy::undocumented_unsafe_blocks)]
-          let self_inner = unsafe { &mut *self.inner.get() };
-          // TODO(piscisaureus): safety comment
-          #[allow(clippy::undocumented_unsafe_blocks)]
-          let head_inner = unsafe { &mut *head.inner.get() };
-          self_inner.link(waker, head_inner, rc)
-        }
-        None => {
-          // This `Cancelable` has already been linked to a `CancelHandle` head
-          // node; just update our stored `Waker` if necessary.
-          // TODO(piscisaureus): safety comment
-          #[allow(clippy::undocumented_unsafe_blocks)]
-          let inner = unsafe { &mut *self.inner.get() };
-          inner.update_waker(waker)
-        }
-      }
-    }
-
-    pub fn cancel(&self) {
-      // TODO(piscisaureus): safety comment
-      #[allow(clippy::undocumented_unsafe_blocks)]
-      let inner = unsafe { &mut *self.inner.get() };
-      inner.cancel();
-    }
-
-    pub fn is_canceled(&self) -> bool {
-      // TODO(piscisaureus): safety comment
-      #[allow(clippy::undocumented_unsafe_blocks)]
-      let inner = unsafe { &mut *self.inner.get() };
-      inner.is_canceled()
-    }
-  }
-
-  impl Default for Node {
-    fn default() -> Self {
-      Self {
-        inner: UnsafeCell::new(NodeInner::Unlinked),
-        _pin: PhantomPinned,
-      }
-    }
-  }
-
-  impl Drop for Node {
-    fn drop(&mut self) {
-      // TODO(piscisaureus): safety comment
-      #[allow(clippy::undocumented_unsafe_blocks)]
-      let inner = unsafe { &mut *self.inner.get() };
-      inner.unlink();
-    }
-  }
-
-  impl PartialEq for Node {
-    fn eq(&self, other: &Self) -> bool {
-      std::ptr::eq(self, other)
-    }
-  }
-
-  #[derive(Debug)]
-  enum NodeInner {
-    Unlinked,
-    Linked {
-      kind: NodeKind,
-      prev: NonNull<NodeInner>,
-      next: NonNull<NodeInner>,
-    },
-    Canceled,
-  }
-
-  impl NodeInner {
-    fn as_non_null(&mut self) -> NonNull<Self> {
-      NonNull::from(self)
-    }
-
-    fn link(
-      &mut self,
-      waker: &Waker,
-      head: &mut Self,
-      rc_pin: &Rc<dyn Any>,
-    ) -> Result<(), Canceled> {
-      // The future should not have been linked to a cancel handle before.
-      assert!(matches!(self, NodeInner::Unlinked));
-
-      match head {
-        NodeInner::Unlinked => {
-          *head = NodeInner::Linked {
-            kind: NodeKind::head(rc_pin),
-            prev: self.as_non_null(),
-            next: self.as_non_null(),
-          };
-          *self = NodeInner::Linked {
-            kind: NodeKind::item(waker),
-            prev: head.as_non_null(),
-            next: head.as_non_null(),
-          };
-          Ok(())
-        }
-        NodeInner::Linked {
-          kind: NodeKind::Head { .. },
-          prev: next_prev_nn,
-          ..
-        } => {
-          // TODO(piscisaureus): safety comment
-          #[allow(clippy::undocumented_unsafe_blocks)]
-          let prev = unsafe { &mut *next_prev_nn.as_ptr() };
-          match prev {
-            NodeInner::Linked {
-              kind: NodeKind::Item { .. },
-              next: prev_next_nn,
-              ..
-            } => {
-              *self = NodeInner::Linked {
-                kind: NodeKind::item(waker),
-                prev: replace(next_prev_nn, self.as_non_null()),
-                next: replace(prev_next_nn, self.as_non_null()),
-              };
-              Ok(())
-            }
-            _ => unreachable!(),
-          }
-        }
-        NodeInner::Canceled => Err(Canceled),
-        _ => unreachable!(),
-      }
-    }
-
-    fn update_waker(&mut self, new_waker: &Waker) -> Result<(), Canceled> {
-      match self {
-        NodeInner::Unlinked => Ok(()),
-        NodeInner::Linked {
-          kind: NodeKind::Item { waker },
-          ..
-        } => {
-          if !waker.will_wake(new_waker) {
-            *waker = new_waker.clone();
-          }
-          Ok(())
-        }
-        NodeInner::Canceled => Err(Canceled),
-        _ => unreachable!(),
-      }
-    }
-
-    /// If this node is linked to other nodes, remove it from the chain. This
-    /// method is called (only) by the drop handler for `Node`. It is suitable
-    /// for both 'head' and 'item' nodes.
-    fn unlink(&mut self) {
-      if let NodeInner::Linked {
-        prev: mut prev_nn,
-        next: mut next_nn,
-        ..
-      } = replace(self, NodeInner::Unlinked)
-      {
-        if prev_nn == next_nn {
-          // There were only two nodes in this chain; after unlinking ourselves
-          // the other node is no longer linked.
-          // TODO(piscisaureus): safety comment
-          #[allow(clippy::undocumented_unsafe_blocks)]
-          let other = unsafe { prev_nn.as_mut() };
-          *other = NodeInner::Unlinked;
-        } else {
-          // The chain had more than two nodes.
-          // TODO(piscisaureus): safety comment
-          #[allow(clippy::undocumented_unsafe_blocks)]
-          match unsafe { prev_nn.as_mut() } {
-            NodeInner::Linked {
-              next: prev_next_nn, ..
-            } => {
-              *prev_next_nn = next_nn;
-            }
-            _ => unreachable!(),
-          }
-          // TODO(piscisaureus): safety comment
-          #[allow(clippy::undocumented_unsafe_blocks)]
-          match unsafe { next_nn.as_mut() } {
-            NodeInner::Linked {
-              prev: next_prev_nn, ..
-            } => {
-              *next_prev_nn = prev_nn;
-            }
-            _ => unreachable!(),
-          }
-        }
-      }
-    }
-
-    /// Mark this node and all linked nodes for cancellation. Note that `self`
-    /// must refer to a head (`CancelHandle`) node.
-    fn cancel(&mut self) {
-      let mut head_nn = NonNull::from(self);
-
-      // TODO(piscisaureus): safety comment
-      #[allow(clippy::undocumented_unsafe_blocks)]
-      // Mark the head node as canceled.
-      let mut item_nn =
-        match replace(unsafe { head_nn.as_mut() }, NodeInner::Canceled) {
-          NodeInner::Linked {
-            kind: NodeKind::Head { .. },
-            next: next_nn,
-            ..
-          } => next_nn,
-          NodeInner::Unlinked | NodeInner::Canceled => return,
-          _ => unreachable!(),
-        };
-
-      // Cancel all item nodes in the chain, waking each stored `Waker`.
-      while item_nn != head_nn {
-        // TODO(piscisaureus): safety comment
-        #[allow(clippy::undocumented_unsafe_blocks)]
-        match replace(unsafe { item_nn.as_mut() }, NodeInner::Canceled) {
-          NodeInner::Linked {
-            kind: NodeKind::Item { waker },
-            next: next_nn,
-            ..
-          } => {
-            waker.wake();
-            item_nn = next_nn;
-          }
-          _ => unreachable!(),
-        }
-      }
-    }
-
-    /// Returns true if this node has been marked for cancellation. This method
-    /// may be used with both head (`CancelHandle`) and item (`Cancelable`)
-    /// nodes.
-    fn is_canceled(&self) -> bool {
-      match self {
-        NodeInner::Unlinked | NodeInner::Linked { .. } => false,
-        NodeInner::Canceled => true,
-      }
-    }
-  }
-
-  #[derive(Debug)]
-  enum NodeKind {
-    /// In a chain of linked nodes, the "head" node is owned by the
-    /// `CancelHandle`. A chain usually contains at most one head node; however
-    /// when a `CancelHandle` is dropped before the futures associated with it
-    /// are dropped, a chain may temporarily contain no head node at all.
-    Head {
-      /// The `weak_pin` field adds adds a weak reference to the `Rc` guarding
-      /// the heap allocation that contains the `CancelHandle`. Without this
-      /// extra weak reference, `Rc::get_mut()` might succeed and allow the
-      /// `CancelHandle` to be moved when it isn't safe to do so.
-      _weak_pin: Weak<dyn Any>,
-    },
-    /// All item nodes in a chain are associated with a `Cancelable` head node.
-    Item {
-      /// If this future indeed does get canceled, the waker is needed to make
-      /// sure that the canceled future gets polled as soon as possible.
-      waker: Waker,
-    },
-  }
-
-  impl NodeKind {
-    fn head(rc_pin: &Rc<dyn Any>) -> Self {
-      let _weak_pin = Rc::downgrade(rc_pin);
-      Self::Head { _weak_pin }
-    }
-
-    fn item(waker: &Waker) -> Self {
-      let waker = waker.clone();
-      Self::Item { waker }
-    }
-  }
-}
-
-#[cfg(test)]
-mod tests {
-  use super::*;
-  use anyhow::Error;
-  use futures::future::pending;
-  use futures::future::poll_fn;
-  use futures::future::ready;
-  use futures::future::FutureExt;
-  use futures::future::TryFutureExt;
-  use futures::pending;
-  use futures::select;
-  use futures::task::noop_waker_ref;
-  use futures::task::Context;
-  use futures::task::Poll;
-  use std::convert::Infallible as Never;
-  use std::io;
-  use tokio::net::TcpStream;
-  use tokio::spawn;
-  use tokio::task::yield_now;
-
-  fn box_fused<'a, F: FusedFuture + 'a>(
-    future: F,
-  ) -> Pin<Box<dyn FusedFuture<Output = F::Output> + 'a>> {
-    Box::pin(future)
-  }
-
-  async fn ready_in_n(name: &str, count: usize) -> &str {
-    let mut remaining = count as isize;
-    poll_fn(|_| {
-      assert!(remaining >= 0);
-      if remaining == 0 {
-        Poll::Ready(name)
-      } else {
-        remaining -= 1;
-        Poll::Pending
-      }
-    })
-    .await
-  }
-
-  #[test]
-  fn cancel_future() {
-    let cancel_now = CancelHandle::new_rc();
-    let cancel_at_0 = CancelHandle::new_rc();
-    let cancel_at_1 = CancelHandle::new_rc();
-    let cancel_at_4 = CancelHandle::new_rc();
-    let cancel_never = CancelHandle::new_rc();
-
-    cancel_now.cancel();
-
-    let mut futures = vec![
-      box_fused(ready("A").or_cancel(&cancel_now)),
-      box_fused(ready("B").or_cancel(&cancel_at_0)),
-      box_fused(ready("C").or_cancel(&cancel_at_1)),
-      box_fused(
-        ready_in_n("D", 0)
-          .or_cancel(&cancel_never)
-          .try_or_cancel(&cancel_now),
-      ),
-      box_fused(
-        ready_in_n("E", 1)
-          .or_cancel(&cancel_at_1)
-          .try_or_cancel(&cancel_at_1),
-      ),
-      box_fused(ready_in_n("F", 2).or_cancel(&cancel_at_1)),
-      box_fused(ready_in_n("G", 3).or_cancel(&cancel_at_4)),
-      box_fused(ready_in_n("H", 4).or_cancel(&cancel_at_4)),
-      box_fused(ready_in_n("I", 5).or_cancel(&cancel_at_4)),
-      box_fused(ready_in_n("J", 5).map(Ok)),
-      box_fused(ready_in_n("K", 5).or_cancel(cancel_never)),
-    ];
-
-    let mut cx = Context::from_waker(noop_waker_ref());
-
-    for i in 0..=5 {
-      match i {
-        0 => cancel_at_0.cancel(),
-        1 => cancel_at_1.cancel(),
-        4 => cancel_at_4.cancel(),
-        2 | 3 | 5 => {}
-        _ => unreachable!(),
-      }
-
-      let results = futures
-        .iter_mut()
-        .filter(|fut| !fut.is_terminated())
-        .filter_map(|fut| match fut.poll_unpin(&mut cx) {
-          Poll::Pending => None,
-          Poll::Ready(res) => Some(res),
-        })
-        .collect::<Vec<_>>();
-
-      match i {
-        0 => assert_eq!(
-          results,
-          [Err(Canceled), Err(Canceled), Ok("C"), Err(Canceled)]
-        ),
-        1 => assert_eq!(results, [Err(Canceled), Err(Canceled)]),
-        2 => assert_eq!(results, []),
-        3 => assert_eq!(results, [Ok("G")]),
-        4 => assert_eq!(results, [Err(Canceled), Err(Canceled)]),
-        5 => assert_eq!(results, [Ok("J"), Ok("K")]),
-        _ => unreachable!(),
-      }
-    }
-
-    assert!(!futures.into_iter().any(|fut| !fut.is_terminated()));
-
-    let cancel_handles = [cancel_now, cancel_at_0, cancel_at_1, cancel_at_4];
-    assert!(!cancel_handles.iter().any(|c| !c.is_canceled()));
-  }
-
-  #[tokio::test]
-  async fn cancel_try_future() {
-    {
-      // Cancel a spawned task before it actually runs.
-      let cancel_handle = Rc::new(CancelHandle::new());
-      let future = spawn(async { panic!("the task should not be spawned") })
-        .map_err(Error::from)
-        .try_or_cancel(&cancel_handle);
-      cancel_handle.cancel();
-      let error = future.await.unwrap_err();
-      assert!(error.downcast_ref::<Canceled>().is_some());
-      assert_eq!(error.to_string().as_str(), "operation canceled");
-    }
-
-    {
-      // Cancel a network I/O future right after polling it.
-      let cancel_handle = Rc::new(CancelHandle::new());
-      let result = loop {
-        select! {
-          r = TcpStream::connect("1.2.3.4:12345")
-            .try_or_cancel(&cancel_handle) => break r,
-          default => cancel_handle.cancel(),
-        };
-      };
-      let error = result.unwrap_err();
-      assert_eq!(error.kind(), io::ErrorKind::Interrupted);
-      assert_eq!(error.to_string().as_str(), "operation canceled");
-    }
-  }
-
-  #[tokio::test]
-  async fn future_cancels_itself_before_completion() {
-    // A future cancels itself before it reaches completion. This future should
-    // indeed get canceled and should not be polled again.
-    let cancel_handle = CancelHandle::new_rc();
-    let result = async {
-      cancel_handle.cancel();
-      yield_now().await;
-      unreachable!();
-    }
-    .or_cancel(&cancel_handle)
-    .await;
-    assert_eq!(result.unwrap_err(), Canceled);
-  }
-
-  #[tokio::test]
-  async fn future_cancels_itself_and_hangs() {
-    // A future cancels itself, after which it returns `Poll::Pending` without
-    // setting up a waker that would allow it to make progress towards
-    // completion. Nevertheless, the `Cancelable` wrapper future must finish.
-    let cancel_handle = CancelHandle::new_rc();
-    let result = async {
-      yield_now().await;
-      cancel_handle.cancel();
-      pending!();
-      unreachable!();
-    }
-    .or_cancel(&cancel_handle)
-    .await;
-    assert_eq!(result.unwrap_err(), Canceled);
-  }
-
-  #[tokio::test]
-  async fn future_cancels_itself_and_completes() {
-    // A TryFuture attempts to cancel itself while it is getting polled, and
-    // yields a result from the very same `poll()` call. Because this future
-    // actually reaches completion, the attempted cancellation has no effect.
-    let cancel_handle = CancelHandle::new_rc();
-    let result = async {
-      yield_now().await;
-      cancel_handle.cancel();
-      Ok::<_, io::Error>("done")
-    }
-    .try_or_cancel(&cancel_handle)
-    .await;
-    assert_eq!(result.unwrap(), "done");
-  }
-
-  #[test]
-  fn cancel_handle_pinning() {
-    let mut cancel_handle = CancelHandle::new_rc();
-
-    // There is only one reference to `cancel_handle`, so `Rc::get_mut()` should
-    // succeed.
-    assert!(Rc::get_mut(&mut cancel_handle).is_some());
-
-    let mut future = pending::<Never>().or_cancel(&cancel_handle);
-    // SAFETY: `Cancelable` pins the future
-    let future = unsafe { Pin::new_unchecked(&mut future) };
-
-    // There are two `Rc<CancelHandle>` references now, so this fails.
-    assert!(Rc::get_mut(&mut cancel_handle).is_none());
-
-    let mut cx = Context::from_waker(noop_waker_ref());
-    assert!(future.poll(&mut cx).is_pending());
-
-    // Polling `future` has established a link between the future and
-    // `cancel_handle`, so both values should be pinned at this point.
-    assert!(Rc::get_mut(&mut cancel_handle).is_none());
-
-    cancel_handle.cancel();
-
-    // Canceling or dropping the associated future(s) unlinks them from the
-    // cancel handle, therefore `cancel_handle` can now safely be moved again.
-    assert!(Rc::get_mut(&mut cancel_handle).is_some());
-  }
-}