Merging upstream version 1.68.2+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

8 files changed, 1222 insertions, 0 deletions

diff --git a/tests/ui/async-await/drop-order/auxiliary/arc_wake.rs b/tests/ui/async-await/drop-order/auxiliary/arc_wake.rs
new file mode 100644
index 000000000..c21886f26
--- /dev/null
+++ b/tests/ui/async-await/drop-order/auxiliary/arc_wake.rs
@@ -0,0 +1,64 @@
+// edition:2018
+
+use std::sync::Arc;
+use std::task::{
+    Waker, RawWaker, RawWakerVTable,
+};
+
+macro_rules! waker_vtable {
+    ($ty:ident) => {
+        &RawWakerVTable::new(
+            clone_arc_raw::<$ty>,
+            wake_arc_raw::<$ty>,
+            wake_by_ref_arc_raw::<$ty>,
+            drop_arc_raw::<$ty>,
+        )
+    };
+}
+
+pub trait ArcWake {
+    fn wake(self: Arc<Self>);
+
+    fn wake_by_ref(arc_self: &Arc<Self>) {
+        arc_self.clone().wake()
+    }
+
+    fn into_waker(wake: Arc<Self>) -> Waker where Self: Sized
+    {
+        let ptr = Arc::into_raw(wake) as *const ();
+
+        unsafe {
+            Waker::from_raw(RawWaker::new(ptr, waker_vtable!(Self)))
+        }
+    }
+}
+
+unsafe fn increase_refcount<T: ArcWake>(data: *const ()) {
+    // Retain Arc by creating a copy
+    let arc: Arc<T> = Arc::from_raw(data as *const T);
+    let arc_clone = arc.clone();
+    // Forget the Arcs again, so that the refcount isn't decrased
+    let _ = Arc::into_raw(arc);
+    let _ = Arc::into_raw(arc_clone);
+}
+
+unsafe fn clone_arc_raw<T: ArcWake>(data: *const ()) -> RawWaker {
+    increase_refcount::<T>(data);
+    RawWaker::new(data, waker_vtable!(T))
+}
+
+unsafe fn drop_arc_raw<T: ArcWake>(data: *const ()) {
+    // Drop Arc
+    let _: Arc<T> = Arc::from_raw(data as *const T);
+}
+
+unsafe fn wake_arc_raw<T: ArcWake>(data: *const ()) {
+    let arc: Arc<T> = Arc::from_raw(data as *const T);
+    ArcWake::wake(arc);
+}
+
+unsafe fn wake_by_ref_arc_raw<T: ArcWake>(data: *const ()) {
+    let arc: Arc<T> = Arc::from_raw(data as *const T);
+    ArcWake::wake_by_ref(&arc);
+    let _ = Arc::into_raw(arc);
+}
diff --git a/tests/ui/async-await/drop-order/drop-order-for-async-fn-parameters-by-ref-binding.rs b/tests/ui/async-await/drop-order/drop-order-for-async-fn-parameters-by-ref-binding.rs
new file mode 100644
index 000000000..9817d377a
--- /dev/null
+++ b/tests/ui/async-await/drop-order/drop-order-for-async-fn-parameters-by-ref-binding.rs
@@ -0,0 +1,270 @@
+// aux-build:arc_wake.rs
+// edition:2018
+// run-pass
+
+#![allow(unused_variables)]
+
+// Test that the drop order for parameters in a fn and async fn matches up. Also test that
+// parameters (used or unused) are not dropped until the async fn completes execution.
+// See also #54716.
+
+extern crate arc_wake;
+
+use arc_wake::ArcWake;
+use std::cell::RefCell;
+use std::future::Future;
+use std::marker::PhantomData;
+use std::sync::Arc;
+use std::rc::Rc;
+use std::task::Context;
+
+struct EmptyWaker;
+
+impl ArcWake for EmptyWaker {
+    fn wake(self: Arc<Self>) {}
+}
+
+#[derive(Debug, Eq, PartialEq)]
+enum DropOrder {
+    Function,
+    Val(&'static str),
+}
+
+type DropOrderListPtr = Rc<RefCell<Vec<DropOrder>>>;
+
+struct D(&'static str, DropOrderListPtr);
+
+impl Drop for D {
+    fn drop(&mut self) {
+        self.1.borrow_mut().push(DropOrder::Val(self.0));
+    }
+}
+
+/// Check that unused bindings are dropped after the function is polled.
+async fn foo_async(ref mut x: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn foo_sync(ref mut x: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns are dropped after the function is polled.
+async fn bar_async(ref mut x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn bar_sync(ref mut x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns within more complex patterns are dropped after the function
+/// is polled.
+async fn baz_async((ref mut x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn baz_sync((ref mut x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore and unused bindings within and outwith more complex patterns are dropped
+/// after the function is polled.
+async fn foobar_async(ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn foobar_sync(ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+struct Foo;
+
+impl Foo {
+    /// Check that unused bindings are dropped after the method is polled.
+    async fn foo_async(ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foo_sync(ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method is polled.
+    async fn bar_async(ref mut x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn bar_sync(ref mut x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns within more complex patterns are dropped after the method
+    /// is polled.
+    async fn baz_async((ref mut x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn baz_sync((ref mut x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore and unused bindings within and outwith more complex patterns are
+    /// dropped after the method is polled.
+    async fn foobar_async(
+        ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foobar_sync(
+        ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+struct Bar<'a>(PhantomData<&'a ()>);
+
+impl<'a> Bar<'a> {
+    /// Check that unused bindings are dropped after the method with self is polled.
+    async fn foo_async(&'a self, ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foo_sync(&'a self, ref mut x: D, ref mut _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method with self is polled.
+    async fn bar_async(&'a self, ref mut x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn bar_sync(&'a self, ref mut x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns within more complex patterns are dropped after the method
+    /// with self is polled.
+    async fn baz_async(&'a self, (ref mut x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn baz_sync(&'a self, (ref mut x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore and unused bindings within and outwith more complex patterns are
+    /// dropped after the method with self is polled.
+    async fn foobar_async(
+        &'a self, ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foobar_sync(
+        &'a self, ref mut x: D, (ref mut a, _, ref mut _c): (D, D, D), _: D, ref mut _y: D,
+    ) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+fn assert_drop_order_after_poll<Fut: Future<Output = ()>>(
+    f: impl FnOnce(DropOrderListPtr) -> Fut,
+    g: impl FnOnce(DropOrderListPtr),
+) {
+    let empty = Arc::new(EmptyWaker);
+    let waker = ArcWake::into_waker(empty);
+    let mut cx = Context::from_waker(&waker);
+
+    let actual_order = Rc::new(RefCell::new(Vec::new()));
+    let mut fut = Box::pin(f(actual_order.clone()));
+    let _ = fut.as_mut().poll(&mut cx);
+
+    let expected_order = Rc::new(RefCell::new(Vec::new()));
+    g(expected_order.clone());
+
+    assert_eq!(*actual_order.borrow(), *expected_order.borrow());
+}
+
+fn main() {
+    // Free functions (see doc comment on function for what it tests).
+    assert_drop_order_after_poll(|l| foo_async(D("x", l.clone()), D("_y", l.clone())),
+                                 |l| foo_sync(D("x", l.clone()), D("_y", l.clone())));
+    assert_drop_order_after_poll(|l| bar_async(D("x", l.clone()), D("_", l.clone())),
+                                 |l| bar_sync(D("x", l.clone()), D("_", l.clone())));
+    assert_drop_order_after_poll(|l| baz_async((D("x", l.clone()), D("_", l.clone()))),
+                                 |l| baz_sync((D("x", l.clone()), D("_", l.clone()))));
+    assert_drop_order_after_poll(
+        |l| {
+            foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+
+    // Methods w/out self (see doc comment on function for what it tests).
+    assert_drop_order_after_poll(|l| Foo::foo_async(D("x", l.clone()), D("_y", l.clone())),
+                                 |l| Foo::foo_sync(D("x", l.clone()), D("_y", l.clone())));
+    assert_drop_order_after_poll(|l| Foo::bar_async(D("x", l.clone()), D("_", l.clone())),
+                                 |l| Foo::bar_sync(D("x", l.clone()), D("_", l.clone())));
+    assert_drop_order_after_poll(|l| Foo::baz_async((D("x", l.clone()), D("_", l.clone()))),
+                                 |l| Foo::baz_sync((D("x", l.clone()), D("_", l.clone()))));
+    assert_drop_order_after_poll(
+        |l| {
+            Foo::foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            Foo::foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+
+    // Methods (see doc comment on function for what it tests).
+    let b = Bar(Default::default());
+    assert_drop_order_after_poll(|l| b.foo_async(D("x", l.clone()), D("_y", l.clone())),
+                                 |l| b.foo_sync(D("x", l.clone()), D("_y", l.clone())));
+    assert_drop_order_after_poll(|l| b.bar_async(D("x", l.clone()), D("_", l.clone())),
+                                 |l| b.bar_sync(D("x", l.clone()), D("_", l.clone())));
+    assert_drop_order_after_poll(|l| b.baz_async((D("x", l.clone()), D("_", l.clone()))),
+                                 |l| b.baz_sync((D("x", l.clone()), D("_", l.clone()))));
+    assert_drop_order_after_poll(
+        |l| {
+            b.foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            b.foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+}
diff --git a/tests/ui/async-await/drop-order/drop-order-for-async-fn-parameters.rs b/tests/ui/async-await/drop-order/drop-order-for-async-fn-parameters.rs
new file mode 100644
index 000000000..6c10ead36
--- /dev/null
+++ b/tests/ui/async-await/drop-order/drop-order-for-async-fn-parameters.rs
@@ -0,0 +1,265 @@
+// aux-build:arc_wake.rs
+// edition:2018
+// run-pass
+
+// revisions: default nomiropt
+//[nomiropt]compile-flags: -Z mir-opt-level=0
+
+#![allow(unused_variables)]
+
+// Test that the drop order for parameters in a fn and async fn matches up. Also test that
+// parameters (used or unused) are not dropped until the async fn completes execution.
+// See also #54716.
+
+extern crate arc_wake;
+
+use arc_wake::ArcWake;
+use std::cell::RefCell;
+use std::future::Future;
+use std::marker::PhantomData;
+use std::sync::Arc;
+use std::rc::Rc;
+use std::task::Context;
+
+struct EmptyWaker;
+
+impl ArcWake for EmptyWaker {
+    fn wake(self: Arc<Self>) {}
+}
+
+#[derive(Debug, Eq, PartialEq)]
+enum DropOrder {
+    Function,
+    Val(&'static str),
+}
+
+type DropOrderListPtr = Rc<RefCell<Vec<DropOrder>>>;
+
+struct D(&'static str, DropOrderListPtr);
+
+impl Drop for D {
+    fn drop(&mut self) {
+        self.1.borrow_mut().push(DropOrder::Val(self.0));
+    }
+}
+
+/// Check that unused bindings are dropped after the function is polled.
+async fn foo_async(x: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn foo_sync(x: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns are dropped after the function is polled.
+async fn bar_async(x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn bar_sync(x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns within more complex patterns are dropped after the function
+/// is polled.
+async fn baz_async((x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn baz_sync((x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore and unused bindings within and outwith more complex patterns are dropped
+/// after the function is polled.
+async fn foobar_async(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+fn foobar_sync(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+struct Foo;
+
+impl Foo {
+    /// Check that unused bindings are dropped after the method is polled.
+    async fn foo_async(x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foo_sync(x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method is polled.
+    async fn bar_async(x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn bar_sync(x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns within more complex patterns are dropped after the method
+    /// is polled.
+    async fn baz_async((x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn baz_sync((x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore and unused bindings within and outwith more complex patterns are
+    /// dropped after the method is polled.
+    async fn foobar_async(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foobar_sync(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+struct Bar<'a>(PhantomData<&'a ()>);
+
+impl<'a> Bar<'a> {
+    /// Check that unused bindings are dropped after the method with self is polled.
+    async fn foo_async(&'a self, x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foo_sync(&'a self, x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method with self is polled.
+    async fn bar_async(&'a self, x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn bar_sync(&'a self, x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns within more complex patterns are dropped after the method
+    /// with self is polled.
+    async fn baz_async(&'a self, (x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn baz_sync(&'a self, (x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore and unused bindings within and outwith more complex patterns are
+    /// dropped after the method with self is polled.
+    async fn foobar_async(&'a self, x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    fn foobar_sync(&'a self, x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+fn assert_drop_order_after_poll<Fut: Future<Output = ()>>(
+    f: impl FnOnce(DropOrderListPtr) -> Fut,
+    g: impl FnOnce(DropOrderListPtr),
+) {
+    let empty = Arc::new(EmptyWaker);
+    let waker = ArcWake::into_waker(empty);
+    let mut cx = Context::from_waker(&waker);
+
+    let actual_order = Rc::new(RefCell::new(Vec::new()));
+    let mut fut = Box::pin(f(actual_order.clone()));
+    let _ = fut.as_mut().poll(&mut cx);
+
+    let expected_order = Rc::new(RefCell::new(Vec::new()));
+    g(expected_order.clone());
+
+    assert_eq!(*actual_order.borrow(), *expected_order.borrow());
+}
+
+fn main() {
+    // Free functions (see doc comment on function for what it tests).
+    assert_drop_order_after_poll(|l| foo_async(D("x", l.clone()), D("_y", l.clone())),
+                                 |l| foo_sync(D("x", l.clone()), D("_y", l.clone())));
+    assert_drop_order_after_poll(|l| bar_async(D("x", l.clone()), D("_", l.clone())),
+                                 |l| bar_sync(D("x", l.clone()), D("_", l.clone())));
+    assert_drop_order_after_poll(|l| baz_async((D("x", l.clone()), D("_", l.clone()))),
+                                 |l| baz_sync((D("x", l.clone()), D("_", l.clone()))));
+    assert_drop_order_after_poll(
+        |l| {
+            foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+
+    // Methods w/out self (see doc comment on function for what it tests).
+    assert_drop_order_after_poll(|l| Foo::foo_async(D("x", l.clone()), D("_y", l.clone())),
+                                 |l| Foo::foo_sync(D("x", l.clone()), D("_y", l.clone())));
+    assert_drop_order_after_poll(|l| Foo::bar_async(D("x", l.clone()), D("_", l.clone())),
+                                 |l| Foo::bar_sync(D("x", l.clone()), D("_", l.clone())));
+    assert_drop_order_after_poll(|l| Foo::baz_async((D("x", l.clone()), D("_", l.clone()))),
+                                 |l| Foo::baz_sync((D("x", l.clone()), D("_", l.clone()))));
+    assert_drop_order_after_poll(
+        |l| {
+            Foo::foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            Foo::foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+
+    // Methods (see doc comment on function for what it tests).
+    let b = Bar(Default::default());
+    assert_drop_order_after_poll(|l| b.foo_async(D("x", l.clone()), D("_y", l.clone())),
+                                 |l| b.foo_sync(D("x", l.clone()), D("_y", l.clone())));
+    assert_drop_order_after_poll(|l| b.bar_async(D("x", l.clone()), D("_", l.clone())),
+                                 |l| b.bar_sync(D("x", l.clone()), D("_", l.clone())));
+    assert_drop_order_after_poll(|l| b.baz_async((D("x", l.clone()), D("_", l.clone()))),
+                                 |l| b.baz_sync((D("x", l.clone()), D("_", l.clone()))));
+    assert_drop_order_after_poll(
+        |l| {
+            b.foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            b.foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+}
diff --git a/tests/ui/async-await/drop-order/drop-order-for-locals-when-cancelled.rs b/tests/ui/async-await/drop-order/drop-order-for-locals-when-cancelled.rs
new file mode 100644
index 000000000..15cc9fbc8
--- /dev/null
+++ b/tests/ui/async-await/drop-order/drop-order-for-locals-when-cancelled.rs
@@ -0,0 +1,176 @@
+// aux-build:arc_wake.rs
+// edition:2018
+// run-pass
+
+#![deny(dead_code)]
+#![allow(unused_variables)]
+#![allow(unused_must_use)]
+#![allow(path_statements)]
+
+// Test that the drop order for locals in a fn and async fn matches up.
+extern crate arc_wake;
+
+use arc_wake::ArcWake;
+use std::cell::RefCell;
+use std::future::Future;
+use std::pin::Pin;
+use std::rc::Rc;
+use std::sync::Arc;
+use std::task::{Context, Poll};
+
+struct EmptyWaker;
+
+impl ArcWake for EmptyWaker {
+    fn wake(self: Arc<Self>) {}
+}
+
+#[derive(Debug, Eq, PartialEq)]
+enum DropOrder {
+    Function,
+    Val(&'static str),
+}
+
+type DropOrderListPtr = Rc<RefCell<Vec<DropOrder>>>;
+
+struct D(&'static str, DropOrderListPtr);
+
+impl Drop for D {
+    fn drop(&mut self) {
+        self.1.borrow_mut().push(DropOrder::Val(self.0));
+    }
+}
+
+struct NeverReady;
+
+impl Future for NeverReady {
+    type Output = ();
+    fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
+        Poll::Pending
+    }
+}
+
+async fn simple_variable_declaration_async(l: DropOrderListPtr) {
+    l.borrow_mut().push(DropOrder::Function);
+    let x = D("x", l.clone());
+    let y = D("y", l.clone());
+    NeverReady.await;
+}
+
+fn simple_variable_declaration_sync(l: DropOrderListPtr) {
+    l.borrow_mut().push(DropOrder::Function);
+    let x = D("x", l.clone());
+    let y = D("y", l.clone());
+}
+
+async fn varable_completely_contained_within_block_async(l: DropOrderListPtr) {
+    l.borrow_mut().push(DropOrder::Function);
+    async {
+        let x = D("x", l.clone());
+    }
+        .await;
+    let y = D("y", l.clone());
+    NeverReady.await;
+}
+
+fn varable_completely_contained_within_block_sync(l: DropOrderListPtr) {
+    l.borrow_mut().push(DropOrder::Function);
+    {
+        let x = D("x", l.clone());
+    }
+    let y = D("y", l.clone());
+}
+
+async fn variables_moved_into_separate_blocks_async(l: DropOrderListPtr) {
+    l.borrow_mut().push(DropOrder::Function);
+    let x = D("x", l.clone());
+    let y = D("y", l.clone());
+    async move { x }.await;
+    async move { y }.await;
+    NeverReady.await;
+}
+
+fn variables_moved_into_separate_blocks_sync(l: DropOrderListPtr) {
+    l.borrow_mut().push(DropOrder::Function);
+    let x = D("x", l.clone());
+    let y = D("y", l.clone());
+    {
+        x
+    };
+    {
+        y
+    };
+}
+
+async fn variables_moved_into_same_block_async(l: DropOrderListPtr) {
+    l.borrow_mut().push(DropOrder::Function);
+    let x = D("x", l.clone());
+    let y = D("y", l.clone());
+    async move {
+        x;
+        y;
+    };
+    NeverReady.await;
+}
+
+fn variables_moved_into_same_block_sync(l: DropOrderListPtr) {
+    l.borrow_mut().push(DropOrder::Function);
+    let x = D("x", l.clone());
+    let y = D("y", l.clone());
+    {
+        x;
+        y;
+    };
+    return;
+}
+
+async fn move_after_current_await_doesnt_affect_order(l: DropOrderListPtr) {
+    l.borrow_mut().push(DropOrder::Function);
+    let x = D("x", l.clone());
+    let y = D("y", l.clone());
+    NeverReady.await;
+    async move {
+        x;
+        y;
+    };
+}
+
+fn assert_drop_order_after_cancel<Fut: Future<Output = ()>>(
+    f: impl FnOnce(DropOrderListPtr) -> Fut,
+    g: impl FnOnce(DropOrderListPtr),
+) {
+    let empty = Arc::new(EmptyWaker);
+    let waker = ArcWake::into_waker(empty);
+    let mut cx = Context::from_waker(&waker);
+
+    let actual_order = Rc::new(RefCell::new(Vec::new()));
+    let mut fut = Box::pin(f(actual_order.clone()));
+    let _ = fut.as_mut().poll(&mut cx);
+    drop(fut);
+
+    let expected_order = Rc::new(RefCell::new(Vec::new()));
+    g(expected_order.clone());
+    assert_eq!(*actual_order.borrow(), *expected_order.borrow());
+}
+
+fn main() {
+    assert_drop_order_after_cancel(
+        simple_variable_declaration_async,
+        simple_variable_declaration_sync,
+    );
+    assert_drop_order_after_cancel(
+        varable_completely_contained_within_block_async,
+        varable_completely_contained_within_block_sync,
+    );
+    assert_drop_order_after_cancel(
+        variables_moved_into_separate_blocks_async,
+        variables_moved_into_separate_blocks_sync,
+    );
+    assert_drop_order_after_cancel(
+        variables_moved_into_same_block_async,
+        variables_moved_into_same_block_sync,
+    );
+    assert_drop_order_after_cancel(
+        move_after_current_await_doesnt_affect_order,
+        simple_variable_declaration_sync,
+    );
+}
diff --git a/tests/ui/async-await/drop-order/drop-order-for-temporary-in-tail-return-expr.rs b/tests/ui/async-await/drop-order/drop-order-for-temporary-in-tail-return-expr.rs
new file mode 100644
index 000000000..edfecb910
--- /dev/null
+++ b/tests/ui/async-await/drop-order/drop-order-for-temporary-in-tail-return-expr.rs
@@ -0,0 +1,98 @@
+// aux-build:arc_wake.rs
+// edition:2018
+// run-pass
+
+// revisions: default nomiropt
+//[nomiropt]compile-flags: -Z mir-opt-level=0
+
+#![allow(unused_variables)]
+
+// Test the drop order for parameters relative to local variables and
+// temporaries created in the tail return expression of the function
+// body. In particular, check that this drop order is the same between
+// an `async fn` and an ordinary `fn`. See #64512.
+
+extern crate arc_wake;
+
+use arc_wake::ArcWake;
+use std::cell::RefCell;
+use std::future::Future;
+use std::sync::Arc;
+use std::rc::Rc;
+use std::task::Context;
+
+struct EmptyWaker;
+
+impl ArcWake for EmptyWaker {
+    fn wake(self: Arc<Self>) {}
+}
+
+#[derive(Debug, Eq, PartialEq)]
+enum DropOrder {
+    Function,
+    Val(&'static str),
+}
+
+type DropOrderListPtr = Rc<RefCell<Vec<DropOrder>>>;
+
+struct D(&'static str, DropOrderListPtr);
+
+impl Drop for D {
+    fn drop(&mut self) {
+        self.1.borrow_mut().push(DropOrder::Val(self.0));
+    }
+}
+
+/// Check drop order of temporary "temp" as compared to `x`, `y`, and `z`.
+///
+/// Expected order:
+/// - `z`
+/// - temp
+/// - `y`
+/// - `x`
+async fn foo_async(x: D, _y: D) {
+    let l = x.1.clone();
+    let z = D("z", l.clone());
+    l.borrow_mut().push(DropOrder::Function);
+    helper_async(&D("temp", l)).await
+}
+
+async fn helper_async(v: &D) { }
+
+fn foo_sync(x: D, _y: D) {
+    let l = x.1.clone();
+    let z = D("z", l.clone());
+    l.borrow_mut().push(DropOrder::Function);
+    helper_sync(&D("temp", l))
+}
+
+fn helper_sync(v: &D) { }
+
+fn assert_drop_order_after_poll<Fut: Future<Output = ()>>(
+    f: impl FnOnce(DropOrderListPtr) -> Fut,
+    g: impl FnOnce(DropOrderListPtr),
+) {
+    let empty = Arc::new(EmptyWaker);
+    let waker = ArcWake::into_waker(empty);
+    let mut cx = Context::from_waker(&waker);
+
+    let actual_order = Rc::new(RefCell::new(Vec::new()));
+    let mut fut = Box::pin(f(actual_order.clone()));
+    let r = fut.as_mut().poll(&mut cx);
+
+    assert!(match r {
+        std::task::Poll::Ready(()) => true,
+        _ => false,
+    });
+
+    let expected_order = Rc::new(RefCell::new(Vec::new()));
+    g(expected_order.clone());
+
+    assert_eq!(*actual_order.borrow(), *expected_order.borrow());
+}
+
+fn main() {
+    // Free functions (see doc comment on function for what it tests).
+    assert_drop_order_after_poll(|l| foo_async(D("x", l.clone()), D("_y", l.clone())),
+                                 |l| foo_sync(D("x", l.clone()), D("_y", l.clone())));
+}
diff --git a/tests/ui/async-await/drop-order/drop-order-locals-are-hidden.rs b/tests/ui/async-await/drop-order/drop-order-locals-are-hidden.rs
new file mode 100644
index 000000000..79dedb1ba
--- /dev/null
+++ b/tests/ui/async-await/drop-order/drop-order-locals-are-hidden.rs
@@ -0,0 +1,13 @@
+// edition:2018
+
+async fn foobar_async(x: u32, (a, _, _c): (u32, u32, u32), _: u32, _y: u32) {
+    assert_eq!(__arg1, (1, 2, 3)); //~ ERROR cannot find value `__arg1` in this scope [E0425]
+    assert_eq!(__arg2, 4); //~ ERROR cannot find value `__arg2` in this scope [E0425]
+}
+
+async fn baz_async(ref mut x: u32, ref y: u32) {
+    assert_eq!(__arg0, 1); //~ ERROR cannot find value `__arg0` in this scope [E0425]
+    assert_eq!(__arg1, 2); //~ ERROR cannot find value `__arg1` in this scope [E0425]
+}
+
+fn main() {}
diff --git a/tests/ui/async-await/drop-order/drop-order-locals-are-hidden.stderr b/tests/ui/async-await/drop-order/drop-order-locals-are-hidden.stderr
new file mode 100644
index 000000000..aa04a613f
--- /dev/null
+++ b/tests/ui/async-await/drop-order/drop-order-locals-are-hidden.stderr
@@ -0,0 +1,27 @@
+error[E0425]: cannot find value `__arg1` in this scope
+  --> $DIR/drop-order-locals-are-hidden.rs:4:16
+   |
+LL |     assert_eq!(__arg1, (1, 2, 3));
+   |                ^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `__arg2` in this scope
+  --> $DIR/drop-order-locals-are-hidden.rs:5:16
+   |
+LL |     assert_eq!(__arg2, 4);
+   |                ^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `__arg0` in this scope
+  --> $DIR/drop-order-locals-are-hidden.rs:9:16
+   |
+LL |     assert_eq!(__arg0, 1);
+   |                ^^^^^^ not found in this scope
+
+error[E0425]: cannot find value `__arg1` in this scope
+  --> $DIR/drop-order-locals-are-hidden.rs:10:16
+   |
+LL |     assert_eq!(__arg1, 2);
+   |                ^^^^^^ not found in this scope
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0425`.
diff --git a/tests/ui/async-await/drop-order/drop-order-when-cancelled.rs b/tests/ui/async-await/drop-order/drop-order-when-cancelled.rs
new file mode 100644
index 000000000..cfd68bc0d
--- /dev/null
+++ b/tests/ui/async-await/drop-order/drop-order-when-cancelled.rs
@@ -0,0 +1,309 @@
+// aux-build:arc_wake.rs
+// edition:2018
+// run-pass
+
+// revisions: default nomiropt
+//[nomiropt]compile-flags: -Z mir-opt-level=0
+
+// Test that the drop order for parameters in a fn and async fn matches up. Also test that
+// parameters (used or unused) are not dropped until the async fn is cancelled.
+// This file is mostly copy-pasted from drop-order-for-async-fn-parameters.rs
+
+#![allow(unused_variables)]
+
+extern crate arc_wake;
+
+use arc_wake::ArcWake;
+use std::cell::RefCell;
+use std::future::Future;
+use std::marker::PhantomData;
+use std::pin::Pin;
+use std::rc::Rc;
+use std::sync::Arc;
+use std::task::{Context, Poll};
+
+struct EmptyWaker;
+
+impl ArcWake for EmptyWaker {
+    fn wake(self: Arc<Self>) {}
+}
+
+#[derive(Debug, Eq, PartialEq)]
+enum DropOrder {
+    Function,
+    Val(&'static str),
+}
+
+type DropOrderListPtr = Rc<RefCell<Vec<DropOrder>>>;
+
+struct D(&'static str, DropOrderListPtr);
+
+impl Drop for D {
+    fn drop(&mut self) {
+        self.1.borrow_mut().push(DropOrder::Val(self.0));
+    }
+}
+
+struct NeverReady;
+
+impl Future for NeverReady {
+    type Output = ();
+    fn poll(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Self::Output> {
+        Poll::Pending
+    }
+}
+
+/// Check that unused bindings are dropped after the function is polled.
+async fn foo_async(x: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+    NeverReady.await;
+}
+
+fn foo_sync(x: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns are dropped after the function is polled.
+async fn bar_async(x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+    NeverReady.await;
+}
+
+fn bar_sync(x: D, _: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore patterns within more complex patterns are dropped after the function
+/// is polled.
+async fn baz_async((x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+    NeverReady.await;
+}
+
+fn baz_sync((x, _): (D, D)) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+/// Check that underscore and unused bindings within and outwith more complex patterns are dropped
+/// after the function is polled.
+async fn foobar_async(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+    NeverReady.await;
+}
+
+fn foobar_sync(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+    x.1.borrow_mut().push(DropOrder::Function);
+}
+
+struct Foo;
+
+impl Foo {
+    /// Check that unused bindings are dropped after the method is polled.
+    async fn foo_async(x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn foo_sync(x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method is polled.
+    async fn bar_async(x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn bar_sync(x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns within more complex patterns are dropped after the method
+    /// is polled.
+    async fn baz_async((x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn baz_sync((x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore and unused bindings within and outwith more complex patterns are
+    /// dropped after the method is polled.
+    async fn foobar_async(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn foobar_sync(x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+struct Bar<'a>(PhantomData<&'a ()>);
+
+impl<'a> Bar<'a> {
+    /// Check that unused bindings are dropped after the method with self is polled.
+    async fn foo_async(&'a self, x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn foo_sync(&'a self, x: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns are dropped after the method with self is polled.
+    async fn bar_async(&'a self, x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn bar_sync(&'a self, x: D, _: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore patterns within more complex patterns are dropped after the method
+    /// with self is polled.
+    async fn baz_async(&'a self, (x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn baz_sync(&'a self, (x, _): (D, D)) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+
+    /// Check that underscore and unused bindings within and outwith more complex patterns are
+    /// dropped after the method with self is polled.
+    async fn foobar_async(&'a self, x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+        NeverReady.await;
+    }
+
+    fn foobar_sync(&'a self, x: D, (a, _, _c): (D, D, D), _: D, _y: D) {
+        x.1.borrow_mut().push(DropOrder::Function);
+    }
+}
+
+fn assert_drop_order_after_cancel<Fut: Future<Output = ()>>(
+    f: impl FnOnce(DropOrderListPtr) -> Fut,
+    g: impl FnOnce(DropOrderListPtr),
+) {
+    let empty = Arc::new(EmptyWaker);
+    let waker = ArcWake::into_waker(empty);
+    let mut cx = Context::from_waker(&waker);
+
+    let actual_order = Rc::new(RefCell::new(Vec::new()));
+    let mut fut = Box::pin(f(actual_order.clone()));
+    let _ = fut.as_mut().poll(&mut cx);
+
+    // Parameters are never dropped until the future completes.
+    assert_eq!(*actual_order.borrow(), vec![DropOrder::Function]);
+
+    drop(fut);
+
+    let expected_order = Rc::new(RefCell::new(Vec::new()));
+    g(expected_order.clone());
+    assert_eq!(*actual_order.borrow(), *expected_order.borrow());
+}
+
+fn main() {
+    // Free functions (see doc comment on function for what it tests).
+    assert_drop_order_after_cancel(
+        |l| foo_async(D("x", l.clone()), D("_y", l.clone())),
+        |l| foo_sync(D("x", l.clone()), D("_y", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| bar_async(D("x", l.clone()), D("_", l.clone())),
+        |l| bar_sync(D("x", l.clone()), D("_", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| baz_async((D("x", l.clone()), D("_", l.clone()))),
+        |l| baz_sync((D("x", l.clone()), D("_", l.clone()))),
+    );
+    assert_drop_order_after_cancel(
+        |l| {
+            foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+
+    // Methods w/out self (see doc comment on function for what it tests).
+    assert_drop_order_after_cancel(
+        |l| Foo::foo_async(D("x", l.clone()), D("_y", l.clone())),
+        |l| Foo::foo_sync(D("x", l.clone()), D("_y", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| Foo::bar_async(D("x", l.clone()), D("_", l.clone())),
+        |l| Foo::bar_sync(D("x", l.clone()), D("_", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| Foo::baz_async((D("x", l.clone()), D("_", l.clone()))),
+        |l| Foo::baz_sync((D("x", l.clone()), D("_", l.clone()))),
+    );
+    assert_drop_order_after_cancel(
+        |l| {
+            Foo::foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            Foo::foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+
+    // Methods (see doc comment on function for what it tests).
+    let b = Bar(Default::default());
+    assert_drop_order_after_cancel(
+        |l| b.foo_async(D("x", l.clone()), D("_y", l.clone())),
+        |l| b.foo_sync(D("x", l.clone()), D("_y", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| b.bar_async(D("x", l.clone()), D("_", l.clone())),
+        |l| b.bar_sync(D("x", l.clone()), D("_", l.clone())),
+    );
+    assert_drop_order_after_cancel(
+        |l| b.baz_async((D("x", l.clone()), D("_", l.clone()))),
+        |l| b.baz_sync((D("x", l.clone()), D("_", l.clone()))),
+    );
+    assert_drop_order_after_cancel(
+        |l| {
+            b.foobar_async(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+        |l| {
+            b.foobar_sync(
+                D("x", l.clone()),
+                (D("a", l.clone()), D("_", l.clone()), D("_c", l.clone())),
+                D("_", l.clone()),
+                D("_y", l.clone()),
+            )
+        },
+    );
+}