8 files changed, 2300 insertions, 0 deletions
diff --git a/third_party/rust/async-task/tests/basic.rs b/third_party/rust/async-task/tests/basic.rs
new file mode 100644
index 0000000000..c2230434aa
--- /dev/null
+++ b/third_party/rust/async-task/tests/basic.rs
@@ -0,0 +1,299 @@
+use std::future::Future;
+use std::pin::Pin;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::task::{Context, Poll};
+
+use async_task::Runnable;
+use smol::future;
+
+// Creates a future with event counters.
+//
+// Usage: `future!(f, POLL, DROP)`
+//
+// The future `f` always returns `Poll::Ready`.
+// When it gets polled, `POLL` is incremented.
+// When it gets dropped, `DROP` is incremented.
+macro_rules! future {
+    ($name:pat, $poll:ident, $drop:ident) => {
+        static $poll: AtomicUsize = AtomicUsize::new(0);
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+
+        let $name = {
+            struct Fut(Box<i32>);
+
+            impl Future for Fut {
+                type Output = Box<i32>;
+
+                fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+                    $poll.fetch_add(1, Ordering::SeqCst);
+                    Poll::Ready(Box::new(0))
+                }
+            }
+
+            impl Drop for Fut {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            Fut(Box::new(0))
+        };
+    };
+}
+
+// Creates a schedule function with event counters.
+//
+// Usage: `schedule!(s, SCHED, DROP)`
+//
+// The schedule function `s` does nothing.
+// When it gets invoked, `SCHED` is incremented.
+// When it gets dropped, `DROP` is incremented.
+macro_rules! schedule {
+    ($name:pat, $sched:ident, $drop:ident) => {
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static $sched: AtomicUsize = AtomicUsize::new(0);
+
+        let $name = {
+            struct Guard(Box<i32>);
+
+            impl Drop for Guard {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            let guard = Guard(Box::new(0));
+            move |_runnable| {
+                let _ = &guard;
+                $sched.fetch_add(1, Ordering::SeqCst);
+            }
+        };
+    };
+}
+
+fn try_await<T>(f: impl Future<Output = T>) -> Option<T> {
+    future::block_on(future::poll_once(f))
+}
+
+#[test]
+fn drop_and_detach() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    drop(runnable);
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    task.detach();
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn detach_and_drop() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    task.detach();
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    drop(runnable);
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn detach_and_run() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    task.detach();
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn run_and_detach() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    task.detach();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn cancel_and_run() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    drop(task);
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn run_and_cancel() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    drop(task);
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn cancel_join() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, mut task) = async_task::spawn(f, s);
+
+    assert!(try_await(&mut task).is_none());
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    assert!(try_await(&mut task).is_some());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    drop(task);
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn schedule() {
+    let (s, r) = flume::unbounded();
+    let schedule = move |runnable| s.send(runnable).unwrap();
+    let (runnable, _task) = async_task::spawn(future::poll_fn(|_| Poll::<()>::Pending), schedule);
+
+    assert!(r.is_empty());
+    runnable.schedule();
+
+    let runnable = r.recv().unwrap();
+    assert!(r.is_empty());
+    runnable.schedule();
+
+    let runnable = r.recv().unwrap();
+    assert!(r.is_empty());
+    runnable.schedule();
+
+    r.recv().unwrap();
+}
+
+#[test]
+fn schedule_counter() {
+    static COUNT: AtomicUsize = AtomicUsize::new(0);
+
+    let (s, r) = flume::unbounded();
+    let schedule = move |runnable: Runnable| {
+        COUNT.fetch_add(1, Ordering::SeqCst);
+        s.send(runnable).unwrap();
+    };
+    let (runnable, _task) = async_task::spawn(future::poll_fn(|_| Poll::<()>::Pending), schedule);
+    runnable.schedule();
+
+    r.recv().unwrap().schedule();
+    r.recv().unwrap().schedule();
+    assert_eq!(COUNT.load(Ordering::SeqCst), 3);
+    r.recv().unwrap();
+}
+
+#[test]
+fn drop_inside_schedule() {
+    struct DropGuard(AtomicUsize);
+    impl Drop for DropGuard {
+        fn drop(&mut self) {
+            self.0.fetch_add(1, Ordering::SeqCst);
+        }
+    }
+    let guard = DropGuard(AtomicUsize::new(0));
+
+    let (runnable, _) = async_task::spawn(async {}, move |runnable| {
+        assert_eq!(guard.0.load(Ordering::SeqCst), 0);
+        drop(runnable);
+        assert_eq!(guard.0.load(Ordering::SeqCst), 0);
+    });
+    runnable.schedule();
+}
+
+#[test]
+fn waker() {
+    let (s, r) = flume::unbounded();
+    let schedule = move |runnable| s.send(runnable).unwrap();
+    let (runnable, _task) = async_task::spawn(future::poll_fn(|_| Poll::<()>::Pending), schedule);
+
+    assert!(r.is_empty());
+    let waker = runnable.waker();
+    runnable.run();
+    waker.wake_by_ref();
+
+    let runnable = r.recv().unwrap();
+    runnable.run();
+    waker.wake();
+    r.recv().unwrap();
+}
diff --git a/third_party/rust/async-task/tests/cancel.rs b/third_party/rust/async-task/tests/cancel.rs
new file mode 100644
index 0000000000..0fe7c72120
--- /dev/null
+++ b/third_party/rust/async-task/tests/cancel.rs
@@ -0,0 +1,183 @@
+use std::future::Future;
+use std::pin::Pin;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::task::{Context, Poll};
+use std::thread;
+use std::time::Duration;
+
+use async_task::Runnable;
+use easy_parallel::Parallel;
+use smol::future;
+
+// Creates a future with event counters.
+//
+// Usage: `future!(f, POLL, DROP_F, DROP_T)`
+//
+// The future `f` outputs `Poll::Ready`.
+// When it gets polled, `POLL` is incremented.
+// When it gets dropped, `DROP_F` is incremented.
+// When the output gets dropped, `DROP_T` is incremented.
+macro_rules! future {
+    ($name:pat, $poll:ident, $drop_f:ident, $drop_t:ident) => {
+        static $poll: AtomicUsize = AtomicUsize::new(0);
+        static $drop_f: AtomicUsize = AtomicUsize::new(0);
+        static $drop_t: AtomicUsize = AtomicUsize::new(0);
+
+        let $name = {
+            struct Fut(Box<i32>);
+
+            impl Future for Fut {
+                type Output = Out;
+
+                fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+                    $poll.fetch_add(1, Ordering::SeqCst);
+                    thread::sleep(ms(400));
+                    Poll::Ready(Out(Box::new(0), true))
+                }
+            }
+
+            impl Drop for Fut {
+                fn drop(&mut self) {
+                    $drop_f.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            #[derive(Default)]
+            struct Out(Box<i32>, bool);
+
+            impl Drop for Out {
+                fn drop(&mut self) {
+                    if self.1 {
+                        $drop_t.fetch_add(1, Ordering::SeqCst);
+                    }
+                }
+            }
+
+            Fut(Box::new(0))
+        };
+    };
+}
+
+// Creates a schedule function with event counters.
+//
+// Usage: `schedule!(s, SCHED, DROP)`
+//
+// The schedule function `s` does nothing.
+// When it gets invoked, `SCHED` is incremented.
+// When it gets dropped, `DROP` is incremented.
+macro_rules! schedule {
+    ($name:pat, $sched:ident, $drop:ident) => {
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static $sched: AtomicUsize = AtomicUsize::new(0);
+
+        let $name = {
+            struct Guard(Box<i32>);
+
+            impl Drop for Guard {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            let guard = Guard(Box::new(0));
+            move |runnable: Runnable| {
+                let _ = &guard;
+                runnable.schedule();
+                $sched.fetch_add(1, Ordering::SeqCst);
+            }
+        };
+    };
+}
+
+fn ms(ms: u64) -> Duration {
+    Duration::from_millis(ms)
+}
+
+#[test]
+fn run_and_cancel() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    assert!(future::block_on(task.cancel()).is_some());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn cancel_and_run() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            thread::sleep(ms(200));
+            runnable.run();
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 0);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+            thread::sleep(ms(200));
+
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            assert!(future::block_on(task.cancel()).is_none());
+
+            thread::sleep(ms(200));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 0);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+            thread::sleep(ms(200));
+
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .run();
+}
+
+#[test]
+fn cancel_during_run() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            runnable.run();
+
+            thread::sleep(ms(200));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            assert!(future::block_on(task.cancel()).is_none());
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .run();
+}
diff --git a/third_party/rust/async-task/tests/join.rs b/third_party/rust/async-task/tests/join.rs
new file mode 100644
index 0000000000..2ac7b8d37b
--- /dev/null
+++ b/third_party/rust/async-task/tests/join.rs
@@ -0,0 +1,386 @@
+use std::cell::Cell;
+use std::future::Future;
+use std::panic::{catch_unwind, AssertUnwindSafe};
+use std::pin::Pin;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::task::{Context, Poll};
+use std::thread;
+use std::time::Duration;
+
+use async_task::Runnable;
+use easy_parallel::Parallel;
+use smol::future;
+
+// Creates a future with event counters.
+//
+// Usage: `future!(f, POLL, DROP_F, DROP_T)`
+//
+// The future `f` outputs `Poll::Ready`.
+// When it gets polled, `POLL` is incremented.
+// When it gets dropped, `DROP_F` is incremented.
+// When the output gets dropped, `DROP_T` is incremented.
+macro_rules! future {
+    ($name:pat, $poll:ident, $drop_f:ident, $drop_t:ident) => {
+        static $poll: AtomicUsize = AtomicUsize::new(0);
+        static $drop_f: AtomicUsize = AtomicUsize::new(0);
+        static $drop_t: AtomicUsize = AtomicUsize::new(0);
+
+        let $name = {
+            struct Fut(Box<i32>);
+
+            impl Future for Fut {
+                type Output = Out;
+
+                fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+                    $poll.fetch_add(1, Ordering::SeqCst);
+                    Poll::Ready(Out(Box::new(0), true))
+                }
+            }
+
+            impl Drop for Fut {
+                fn drop(&mut self) {
+                    $drop_f.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            #[derive(Default)]
+            struct Out(Box<i32>, bool);
+
+            impl Drop for Out {
+                fn drop(&mut self) {
+                    if self.1 {
+                        $drop_t.fetch_add(1, Ordering::SeqCst);
+                    }
+                }
+            }
+
+            Fut(Box::new(0))
+        };
+    };
+}
+
+// Creates a schedule function with event counters.
+//
+// Usage: `schedule!(s, SCHED, DROP)`
+//
+// The schedule function `s` does nothing.
+// When it gets invoked, `SCHED` is incremented.
+// When it gets dropped, `DROP` is incremented.
+macro_rules! schedule {
+    ($name:pat, $sched:ident, $drop:ident) => {
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static $sched: AtomicUsize = AtomicUsize::new(0);
+
+        let $name = {
+            struct Guard(Box<i32>);
+
+            impl Drop for Guard {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            let guard = Guard(Box::new(0));
+            move |runnable: Runnable| {
+                let _ = &guard;
+                runnable.schedule();
+                $sched.fetch_add(1, Ordering::SeqCst);
+            }
+        };
+    };
+}
+
+fn ms(ms: u64) -> Duration {
+    Duration::from_millis(ms)
+}
+
+#[test]
+fn drop_and_join() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+    drop(runnable);
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+    assert!(catch_unwind(|| future::block_on(task)).is_err());
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+}
+
+#[test]
+fn run_and_join() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+    runnable.run();
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+    assert!(catch_unwind(|| future::block_on(task)).is_ok());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn detach_and_run() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+    task.detach();
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn join_twice() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, mut task) = async_task::spawn(f, s);
+
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+    runnable.run();
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+    future::block_on(&mut task);
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+
+    assert!(catch_unwind(AssertUnwindSafe(|| future::block_on(&mut task))).is_err());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+
+    task.detach();
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn join_and_cancel() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            thread::sleep(ms(200));
+            drop(runnable);
+
+            thread::sleep(ms(400));
+            assert_eq!(POLL.load(Ordering::SeqCst), 0);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            assert!(catch_unwind(|| future::block_on(task)).is_err());
+            assert_eq!(POLL.load(Ordering::SeqCst), 0);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+
+            thread::sleep(ms(200));
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .run();
+}
+
+#[test]
+fn join_and_run() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            thread::sleep(ms(400));
+
+            runnable.run();
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+
+            thread::sleep(ms(200));
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            future::block_on(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+
+            thread::sleep(ms(200));
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .run();
+}
+
+#[test]
+fn try_join_and_run_and_join() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, mut task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            thread::sleep(ms(400));
+
+            runnable.run();
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+
+            thread::sleep(ms(200));
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            future::block_on(future::or(&mut task, future::ready(Default::default())));
+            assert_eq!(POLL.load(Ordering::SeqCst), 0);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+            future::block_on(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+
+            thread::sleep(ms(200));
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .run();
+}
+
+#[test]
+fn try_join_and_cancel_and_run() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, mut task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            thread::sleep(ms(200));
+
+            runnable.run();
+            assert_eq!(POLL.load(Ordering::SeqCst), 0);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            future::block_on(future::or(&mut task, future::ready(Default::default())));
+            assert_eq!(POLL.load(Ordering::SeqCst), 0);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+            drop(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 0);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+        })
+        .run();
+}
+
+#[test]
+fn try_join_and_run_and_cancel() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, mut task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            thread::sleep(ms(200));
+
+            runnable.run();
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+        })
+        .add(|| {
+            future::block_on(future::or(&mut task, future::ready(Default::default())));
+            assert_eq!(POLL.load(Ordering::SeqCst), 0);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+            thread::sleep(ms(400));
+
+            drop(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+        })
+        .run();
+}
+
+#[test]
+fn await_output() {
+    struct Fut<T>(Cell<Option<T>>);
+
+    impl<T> Fut<T> {
+        fn new(t: T) -> Fut<T> {
+            Fut(Cell::new(Some(t)))
+        }
+    }
+
+    impl<T> Future for Fut<T> {
+        type Output = T;
+
+        fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+            Poll::Ready(self.0.take().unwrap())
+        }
+    }
+
+    for i in 0..10 {
+        let (runnable, task) = async_task::spawn(Fut::new(i), drop);
+        runnable.run();
+        assert_eq!(future::block_on(task), i);
+    }
+
+    for i in 0..10 {
+        let (runnable, task) = async_task::spawn(Fut::new(vec![7; i]), drop);
+        runnable.run();
+        assert_eq!(future::block_on(task), vec![7; i]);
+    }
+
+    let (runnable, task) = async_task::spawn(Fut::new("foo".to_string()), drop);
+    runnable.run();
+    assert_eq!(future::block_on(task), "foo");
+}
diff --git a/third_party/rust/async-task/tests/panic.rs b/third_party/rust/async-task/tests/panic.rs
new file mode 100644
index 0000000000..09ffb28512
--- /dev/null
+++ b/third_party/rust/async-task/tests/panic.rs
@@ -0,0 +1,234 @@
+use std::future::Future;
+use std::panic::catch_unwind;
+use std::pin::Pin;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::task::{Context, Poll};
+use std::thread;
+use std::time::Duration;
+
+use async_task::Runnable;
+use easy_parallel::Parallel;
+use smol::future;
+
+// Creates a future with event counters.
+//
+// Usage: `future!(f, POLL, DROP)`
+//
+// The future `f` sleeps for 200 ms and then panics.
+// When it gets polled, `POLL` is incremented.
+// When it gets dropped, `DROP` is incremented.
+macro_rules! future {
+    ($name:pat, $poll:ident, $drop:ident) => {
+        static $poll: AtomicUsize = AtomicUsize::new(0);
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+
+        let $name = {
+            struct Fut(Box<i32>);
+
+            impl Future for Fut {
+                type Output = ();
+
+                fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+                    $poll.fetch_add(1, Ordering::SeqCst);
+                    thread::sleep(ms(400));
+                    panic!()
+                }
+            }
+
+            impl Drop for Fut {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            Fut(Box::new(0))
+        };
+    };
+}
+
+// Creates a schedule function with event counters.
+//
+// Usage: `schedule!(s, SCHED, DROP)`
+//
+// The schedule function `s` does nothing.
+// When it gets invoked, `SCHED` is incremented.
+// When it gets dropped, `DROP` is incremented.
+macro_rules! schedule {
+    ($name:pat, $sched:ident, $drop:ident) => {
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static $sched: AtomicUsize = AtomicUsize::new(0);
+
+        let $name = {
+            struct Guard(Box<i32>);
+
+            impl Drop for Guard {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            let guard = Guard(Box::new(0));
+            move |_runnable: Runnable| {
+                let _ = &guard;
+                $sched.fetch_add(1, Ordering::SeqCst);
+            }
+        };
+    };
+}
+
+fn ms(ms: u64) -> Duration {
+    Duration::from_millis(ms)
+}
+
+#[test]
+fn cancel_during_run() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            assert!(catch_unwind(|| runnable.run()).is_err());
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            drop(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+        })
+        .run();
+}
+
+#[test]
+fn run_and_join() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    assert!(catch_unwind(|| runnable.run()).is_err());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    assert!(catch_unwind(|| future::block_on(task)).is_err());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn try_join_and_run_and_join() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, mut task) = async_task::spawn(f, s);
+
+    future::block_on(future::or(&mut task, future::ready(Default::default())));
+    assert_eq!(POLL.load(Ordering::SeqCst), 0);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    assert!(catch_unwind(|| runnable.run()).is_err());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    assert!(catch_unwind(|| future::block_on(task)).is_err());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn join_during_run() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            assert!(catch_unwind(|| runnable.run()).is_err());
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+
+            thread::sleep(ms(200));
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            assert!(catch_unwind(|| future::block_on(task)).is_err());
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+
+            thread::sleep(ms(200));
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .run();
+}
+
+#[test]
+fn try_join_during_run() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, mut task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            assert!(catch_unwind(|| runnable.run()).is_err());
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            future::block_on(future::or(&mut task, future::ready(Default::default())));
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            drop(task);
+        })
+        .run();
+}
+
+#[test]
+fn detach_during_run() {
+    future!(f, POLL, DROP_F);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            assert!(catch_unwind(|| runnable.run()).is_err());
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            task.detach();
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+        })
+        .run();
+}
diff --git a/third_party/rust/async-task/tests/ready.rs b/third_party/rust/async-task/tests/ready.rs
new file mode 100644
index 0000000000..e3455651f3
--- /dev/null
+++ b/third_party/rust/async-task/tests/ready.rs
@@ -0,0 +1,225 @@
+use std::future::Future;
+use std::pin::Pin;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::task::{Context, Poll};
+use std::thread;
+use std::time::Duration;
+
+use async_task::Runnable;
+use easy_parallel::Parallel;
+use smol::future;
+
+// Creates a future with event counters.
+//
+// Usage: `future!(f, POLL, DROP_F, DROP_T)`
+//
+// The future `f` sleeps for 200 ms and outputs `Poll::Ready`.
+// When it gets polled, `POLL` is incremented.
+// When it gets dropped, `DROP_F` is incremented.
+// When the output gets dropped, `DROP_T` is incremented.
+macro_rules! future {
+    ($name:pat, $poll:ident, $drop_f:ident, $drop_t:ident) => {
+        static $poll: AtomicUsize = AtomicUsize::new(0);
+        static $drop_f: AtomicUsize = AtomicUsize::new(0);
+        static $drop_t: AtomicUsize = AtomicUsize::new(0);
+
+        let $name = {
+            struct Fut(Box<i32>);
+
+            impl Future for Fut {
+                type Output = Out;
+
+                fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> {
+                    $poll.fetch_add(1, Ordering::SeqCst);
+                    thread::sleep(ms(400));
+                    Poll::Ready(Out(Box::new(0), true))
+                }
+            }
+
+            impl Drop for Fut {
+                fn drop(&mut self) {
+                    $drop_f.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            #[derive(Default)]
+            struct Out(Box<i32>, bool);
+
+            impl Drop for Out {
+                fn drop(&mut self) {
+                    if self.1 {
+                        $drop_t.fetch_add(1, Ordering::SeqCst);
+                    }
+                }
+            }
+
+            Fut(Box::new(0))
+        };
+    };
+}
+
+// Creates a schedule function with event counters.
+//
+// Usage: `schedule!(s, SCHED, DROP)`
+//
+// The schedule function `s` does nothing.
+// When it gets invoked, `SCHED` is incremented.
+// When it gets dropped, `DROP` is incremented.
+macro_rules! schedule {
+    ($name:pat, $sched:ident, $drop:ident) => {
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static $sched: AtomicUsize = AtomicUsize::new(0);
+
+        let $name = {
+            struct Guard(Box<i32>);
+
+            impl Drop for Guard {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            let guard = Guard(Box::new(0));
+            move |_runnable: Runnable| {
+                let _ = &guard;
+                $sched.fetch_add(1, Ordering::SeqCst);
+            }
+        };
+    };
+}
+
+fn ms(ms: u64) -> Duration {
+    Duration::from_millis(ms)
+}
+
+#[test]
+fn cancel_during_run() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            runnable.run();
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+            drop(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+
+            thread::sleep(ms(400));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+        })
+        .run();
+}
+
+#[test]
+fn join_during_run() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            runnable.run();
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+
+            thread::sleep(ms(200));
+
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            future::block_on(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+
+            thread::sleep(ms(200));
+
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+        })
+        .run();
+}
+
+#[test]
+fn try_join_during_run() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, mut task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            runnable.run();
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            future::block_on(future::or(&mut task, future::ready(Default::default())));
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+            drop(task);
+        })
+        .run();
+}
+
+#[test]
+fn detach_during_run() {
+    future!(f, POLL, DROP_F, DROP_T);
+    schedule!(s, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    Parallel::new()
+        .add(|| {
+            runnable.run();
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 1);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            task.detach();
+            assert_eq!(POLL.load(Ordering::SeqCst), 1);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_T.load(Ordering::SeqCst), 0);
+        })
+        .run();
+}
diff --git a/third_party/rust/async-task/tests/waker_panic.rs b/third_party/rust/async-task/tests/waker_panic.rs
new file mode 100644
index 0000000000..7a7792ed55
--- /dev/null
+++ b/third_party/rust/async-task/tests/waker_panic.rs
@@ -0,0 +1,330 @@
+use std::cell::Cell;
+use std::future::Future;
+use std::panic::{catch_unwind, AssertUnwindSafe};
+use std::pin::Pin;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::task::{Context, Poll};
+use std::thread;
+use std::time::Duration;
+
+use async_task::Runnable;
+use atomic_waker::AtomicWaker;
+use easy_parallel::Parallel;
+use smol::future;
+
+// Creates a future with event counters.
+//
+// Usage: `future!(f, get_waker, POLL, DROP)`
+//
+// The future `f` always sleeps for 200 ms, and panics the second time it is polled.
+// When it gets polled, `POLL` is incremented.
+// When it gets dropped, `DROP` is incremented.
+//
+// Every time the future is run, it stores the waker into a global variable.
+// This waker can be extracted using the `get_waker()` function.
+macro_rules! future {
+    ($name:pat, $get_waker:pat, $poll:ident, $drop:ident) => {
+        static $poll: AtomicUsize = AtomicUsize::new(0);
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static WAKER: AtomicWaker = AtomicWaker::new();
+
+        let ($name, $get_waker) = {
+            struct Fut(Cell<bool>, Box<i32>);
+
+            impl Future for Fut {
+                type Output = ();
+
+                fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+                    WAKER.register(cx.waker());
+                    $poll.fetch_add(1, Ordering::SeqCst);
+                    thread::sleep(ms(400));
+
+                    if self.0.get() {
+                        panic!()
+                    } else {
+                        self.0.set(true);
+                        Poll::Pending
+                    }
+                }
+            }
+
+            impl Drop for Fut {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            (Fut(Cell::new(false), Box::new(0)), || WAKER.take().unwrap())
+        };
+    };
+}
+
+// Creates a schedule function with event counters.
+//
+// Usage: `schedule!(s, chan, SCHED, DROP)`
+//
+// The schedule function `s` pushes the task into `chan`.
+// When it gets invoked, `SCHED` is incremented.
+// When it gets dropped, `DROP` is incremented.
+//
+// Receiver `chan` extracts the task when it is scheduled.
+macro_rules! schedule {
+    ($name:pat, $chan:pat, $sched:ident, $drop:ident) => {
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static $sched: AtomicUsize = AtomicUsize::new(0);
+
+        let ($name, $chan) = {
+            let (s, r) = flume::unbounded();
+
+            struct Guard(Box<i32>);
+
+            impl Drop for Guard {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            let guard = Guard(Box::new(0));
+            let sched = move |runnable: Runnable| {
+                let _ = &guard;
+                $sched.fetch_add(1, Ordering::SeqCst);
+                s.send(runnable).unwrap();
+            };
+
+            (sched, r)
+        };
+    };
+}
+
+fn ms(ms: u64) -> Duration {
+    Duration::from_millis(ms)
+}
+
+fn try_await<T>(f: impl Future<Output = T>) -> Option<T> {
+    future::block_on(future::poll_once(f))
+}
+
+#[test]
+fn wake_during_run() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    let waker = get_waker();
+    waker.wake_by_ref();
+    let runnable = chan.recv().unwrap();
+
+    Parallel::new()
+        .add(|| {
+            assert!(catch_unwind(|| runnable.run()).is_err());
+            drop(get_waker());
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            waker.wake();
+            task.detach();
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            thread::sleep(ms(400));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .run();
+}
+
+#[test]
+fn cancel_during_run() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    let waker = get_waker();
+    waker.wake();
+    let runnable = chan.recv().unwrap();
+
+    Parallel::new()
+        .add(|| {
+            assert!(catch_unwind(|| runnable.run()).is_err());
+            drop(get_waker());
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            drop(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            thread::sleep(ms(400));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .run();
+}
+
+#[test]
+fn wake_and_cancel_during_run() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    let waker = get_waker();
+    waker.wake_by_ref();
+    let runnable = chan.recv().unwrap();
+
+    Parallel::new()
+        .add(|| {
+            assert!(catch_unwind(|| runnable.run()).is_err());
+            drop(get_waker());
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            waker.wake();
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            drop(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            thread::sleep(ms(400));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .run();
+}
+
+#[flaky_test::flaky_test]
+fn cancel_and_wake_during_run() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    POLL.store(0, Ordering::SeqCst);
+    DROP_F.store(0, Ordering::SeqCst);
+    SCHEDULE.store(0, Ordering::SeqCst);
+    DROP_S.store(0, Ordering::SeqCst);
+
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    let waker = get_waker();
+    waker.wake_by_ref();
+    let runnable = chan.recv().unwrap();
+
+    Parallel::new()
+        .add(|| {
+            assert!(catch_unwind(|| runnable.run()).is_err());
+            drop(get_waker());
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            drop(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            waker.wake();
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            thread::sleep(ms(400));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .run();
+}
+
+#[test]
+fn panic_and_poll() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    get_waker().wake();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    let mut task = task;
+    assert!(try_await(&mut task).is_none());
+
+    let runnable = chan.recv().unwrap();
+    assert!(catch_unwind(|| runnable.run()).is_err());
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    assert!(catch_unwind(AssertUnwindSafe(|| try_await(&mut task))).is_err());
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+
+    drop(get_waker());
+    drop(task);
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
diff --git a/third_party/rust/async-task/tests/waker_pending.rs b/third_party/rust/async-task/tests/waker_pending.rs
new file mode 100644
index 0000000000..9c95cba06b
--- /dev/null
+++ b/third_party/rust/async-task/tests/waker_pending.rs
@@ -0,0 +1,365 @@
+use std::future::Future;
+use std::pin::Pin;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::task::{Context, Poll};
+use std::thread;
+use std::time::Duration;
+
+use async_task::Runnable;
+use atomic_waker::AtomicWaker;
+use easy_parallel::Parallel;
+
+// Creates a future with event counters.
+//
+// Usage: `future!(f, get_waker, POLL, DROP)`
+//
+// The future `f` always sleeps for 200 ms and returns `Poll::Pending`.
+// When it gets polled, `POLL` is incremented.
+// When it gets dropped, `DROP` is incremented.
+//
+// Every time the future is run, it stores the waker into a global variable.
+// This waker can be extracted using the `get_waker()` function.
+macro_rules! future {
+    ($name:pat, $get_waker:pat, $poll:ident, $drop:ident) => {
+        static $poll: AtomicUsize = AtomicUsize::new(0);
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static WAKER: AtomicWaker = AtomicWaker::new();
+
+        let ($name, $get_waker) = {
+            struct Fut(Box<i32>);
+
+            impl Future for Fut {
+                type Output = ();
+
+                fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+                    WAKER.register(cx.waker());
+                    $poll.fetch_add(1, Ordering::SeqCst);
+                    thread::sleep(ms(400));
+                    Poll::Pending
+                }
+            }
+
+            impl Drop for Fut {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            (Fut(Box::new(0)), || WAKER.take().unwrap())
+        };
+    };
+}
+
+// Creates a schedule function with event counters.
+//
+// Usage: `schedule!(s, chan, SCHED, DROP)`
+//
+// The schedule function `s` pushes the task into `chan`.
+// When it gets invoked, `SCHED` is incremented.
+// When it gets dropped, `DROP` is incremented.
+//
+// Receiver `chan` extracts the task when it is scheduled.
+macro_rules! schedule {
+    ($name:pat, $chan:pat, $sched:ident, $drop:ident) => {
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static $sched: AtomicUsize = AtomicUsize::new(0);
+
+        let ($name, $chan) = {
+            let (s, r) = flume::unbounded();
+
+            struct Guard(Box<i32>);
+
+            impl Drop for Guard {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            let guard = Guard(Box::new(0));
+            let sched = move |runnable: Runnable| {
+                let _ = &guard;
+                $sched.fetch_add(1, Ordering::SeqCst);
+                s.send(runnable).unwrap();
+            };
+
+            (sched, r)
+        };
+    };
+}
+
+fn ms(ms: u64) -> Duration {
+    Duration::from_millis(ms)
+}
+
+#[test]
+fn wake_during_run() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, _task) = async_task::spawn(f, s);
+
+    runnable.run();
+    let waker = get_waker();
+    waker.wake_by_ref();
+    let runnable = chan.recv().unwrap();
+
+    Parallel::new()
+        .add(|| {
+            runnable.run();
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 2);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 1);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            waker.wake_by_ref();
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            thread::sleep(ms(400));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 2);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 1);
+        })
+        .run();
+
+    chan.recv().unwrap();
+    drop(get_waker());
+}
+
+#[test]
+fn cancel_during_run() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    let waker = get_waker();
+    waker.wake();
+    let runnable = chan.recv().unwrap();
+
+    Parallel::new()
+        .add(|| {
+            runnable.run();
+            drop(get_waker());
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            drop(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            thread::sleep(ms(400));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .run();
+}
+
+#[test]
+fn wake_and_cancel_during_run() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    let waker = get_waker();
+    waker.wake_by_ref();
+    let runnable = chan.recv().unwrap();
+
+    Parallel::new()
+        .add(|| {
+            runnable.run();
+            drop(get_waker());
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            waker.wake();
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            drop(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            thread::sleep(ms(400));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .run();
+}
+
+#[test]
+fn cancel_and_wake_during_run() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    let waker = get_waker();
+    waker.wake_by_ref();
+    let runnable = chan.recv().unwrap();
+
+    Parallel::new()
+        .add(|| {
+            runnable.run();
+            drop(get_waker());
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .add(|| {
+            thread::sleep(ms(200));
+
+            drop(task);
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            waker.wake();
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+            assert_eq!(chan.len(), 0);
+
+            thread::sleep(ms(400));
+
+            assert_eq!(POLL.load(Ordering::SeqCst), 2);
+            assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+            assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+            assert_eq!(chan.len(), 0);
+        })
+        .run();
+}
+
+#[test]
+fn drop_last_waker() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    let waker = get_waker();
+
+    task.detach();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    drop(waker);
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 1);
+
+    chan.recv().unwrap().run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+    assert_eq!(chan.len(), 0);
+}
+
+#[test]
+fn cancel_last_task() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    drop(get_waker());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    drop(task);
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 1);
+
+    chan.recv().unwrap().run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+    assert_eq!(chan.len(), 0);
+}
+
+#[test]
+fn drop_last_task() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+
+    runnable.run();
+    drop(get_waker());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    task.detach();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 1);
+
+    chan.recv().unwrap().run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+    assert_eq!(chan.len(), 0);
+}
diff --git a/third_party/rust/async-task/tests/waker_ready.rs b/third_party/rust/async-task/tests/waker_ready.rs
new file mode 100644
index 0000000000..10d38cb256
--- /dev/null
+++ b/third_party/rust/async-task/tests/waker_ready.rs
@@ -0,0 +1,278 @@
+use std::cell::Cell;
+use std::future::Future;
+use std::pin::Pin;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::task::{Context, Poll};
+use std::thread;
+use std::time::Duration;
+
+use async_task::Runnable;
+use atomic_waker::AtomicWaker;
+
+// Creates a future with event counters.
+//
+// Usage: `future!(f, get_waker, POLL, DROP)`
+//
+// The future `f` always sleeps for 200 ms, and returns `Poll::Ready` the second time it is polled.
+// When it gets polled, `POLL` is incremented.
+// When it gets dropped, `DROP` is incremented.
+//
+// Every time the future is run, it stores the waker into a global variable.
+// This waker can be extracted using the `get_waker()` function.
+macro_rules! future {
+    ($name:pat, $get_waker:pat, $poll:ident, $drop:ident) => {
+        static $poll: AtomicUsize = AtomicUsize::new(0);
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static WAKER: AtomicWaker = AtomicWaker::new();
+
+        let ($name, $get_waker) = {
+            struct Fut(Cell<bool>, Box<i32>);
+
+            impl Future for Fut {
+                type Output = Box<i32>;
+
+                fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+                    WAKER.register(cx.waker());
+                    $poll.fetch_add(1, Ordering::SeqCst);
+                    thread::sleep(ms(200));
+
+                    if self.0.get() {
+                        Poll::Ready(Box::new(0))
+                    } else {
+                        self.0.set(true);
+                        Poll::Pending
+                    }
+                }
+            }
+
+            impl Drop for Fut {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            (Fut(Cell::new(false), Box::new(0)), || WAKER.take().unwrap())
+        };
+    };
+}
+
+// Creates a schedule function with event counters.
+//
+// Usage: `schedule!(s, chan, SCHED, DROP)`
+//
+// The schedule function `s` pushes the task into `chan`.
+// When it gets invoked, `SCHED` is incremented.
+// When it gets dropped, `DROP` is incremented.
+//
+// Receiver `chan` extracts the task when it is scheduled.
+macro_rules! schedule {
+    ($name:pat, $chan:pat, $sched:ident, $drop:ident) => {
+        static $drop: AtomicUsize = AtomicUsize::new(0);
+        static $sched: AtomicUsize = AtomicUsize::new(0);
+
+        let ($name, $chan) = {
+            let (s, r) = flume::unbounded();
+
+            struct Guard(Box<i32>);
+
+            impl Drop for Guard {
+                fn drop(&mut self) {
+                    $drop.fetch_add(1, Ordering::SeqCst);
+                }
+            }
+
+            let guard = Guard(Box::new(0));
+            let sched = move |runnable: Runnable| {
+                let _ = &guard;
+                $sched.fetch_add(1, Ordering::SeqCst);
+                s.send(runnable).unwrap();
+            };
+
+            (sched, r)
+        };
+    };
+}
+
+fn ms(ms: u64) -> Duration {
+    Duration::from_millis(ms)
+}
+
+#[test]
+fn wake() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (mut runnable, task) = async_task::spawn(f, s);
+    task.detach();
+
+    assert!(chan.is_empty());
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    get_waker().wake();
+    runnable = chan.recv().unwrap();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    get_waker().wake();
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+    assert_eq!(chan.len(), 0);
+}
+
+#[test]
+fn wake_by_ref() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (mut runnable, task) = async_task::spawn(f, s);
+    task.detach();
+
+    assert!(chan.is_empty());
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    get_waker().wake_by_ref();
+    runnable = chan.recv().unwrap();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    get_waker().wake_by_ref();
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+    assert_eq!(chan.len(), 0);
+}
+
+#[test]
+fn clone() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (mut runnable, task) = async_task::spawn(f, s);
+    task.detach();
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    let w2 = get_waker().clone();
+    let w3 = w2.clone();
+    let w4 = w3.clone();
+    w4.wake();
+
+    runnable = chan.recv().unwrap();
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    w3.wake();
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    drop(w2);
+    drop(get_waker());
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+}
+
+#[test]
+fn wake_dropped() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+    task.detach();
+
+    runnable.run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    let waker = get_waker();
+
+    waker.wake_by_ref();
+    drop(chan.recv().unwrap());
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    waker.wake();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+    assert_eq!(chan.len(), 0);
+}
+
+#[test]
+fn wake_completed() {
+    future!(f, get_waker, POLL, DROP_F);
+    schedule!(s, chan, SCHEDULE, DROP_S);
+    let (runnable, task) = async_task::spawn(f, s);
+    task.detach();
+
+    runnable.run();
+    let waker = get_waker();
+    assert_eq!(POLL.load(Ordering::SeqCst), 1);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 0);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    waker.wake();
+    chan.recv().unwrap().run();
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 0);
+    assert_eq!(chan.len(), 0);
+
+    get_waker().wake();
+    assert_eq!(POLL.load(Ordering::SeqCst), 2);
+    assert_eq!(SCHEDULE.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_F.load(Ordering::SeqCst), 1);
+    assert_eq!(DROP_S.load(Ordering::SeqCst), 1);
+    assert_eq!(chan.len(), 0);
+}