2 files changed, 168 insertions, 0 deletions
diff --git a/src/test/ui/async-await/drop-tracking-unresolved-typeck-results.rs b/src/test/ui/async-await/drop-tracking-unresolved-typeck-results.rs
new file mode 100644
index 00000000000..7f729429581
--- /dev/null
+++ b/src/test/ui/async-await/drop-tracking-unresolved-typeck-results.rs
@@ -0,0 +1,106 @@
+// compile-flags: -Zdrop-tracking
+// incremental
+// edition: 2021
+
+use std::future::*;
+use std::marker::PhantomData;
+use std::pin::Pin;
+use std::task::*;
+
+fn send<T: Send>(_: T) {}
+
+pub trait Stream {
+    type Item;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>>;
+}
+
+struct Empty<T>(PhantomData<fn() -> T>);
+
+impl<T> Stream for Empty<T> {
+    type Item = T;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        todo!()
+    }
+}
+
+pub trait FnOnce1<A> {
+    type Output;
+    fn call_once(self, arg: A) -> Self::Output;
+}
+
+impl<T, A, R> FnOnce1<A> for T
+where
+    T: FnOnce(A) -> R,
+{
+    type Output = R;
+    fn call_once(self, arg: A) -> R {
+        self(arg)
+    }
+}
+
+pub trait FnMut1<A>: FnOnce1<A> {
+    fn call_mut(&mut self, arg: A) -> Self::Output;
+}
+
+impl<T, A, R> FnMut1<A> for T
+where
+    T: FnMut(A) -> R,
+{
+    fn call_mut(&mut self, arg: A) -> R {
+        self(arg)
+    }
+}
+
+struct Map<St, F>(St, F);
+
+impl<St, F> Stream for Map<St, F>
+where
+    St: Stream,
+    F: FnMut1<St::Item>,
+{
+    type Item = F::Output;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        todo!()
+    }
+}
+
+struct FuturesOrdered<T: Future>(PhantomData<fn() -> T::Output>);
+
+pub struct Buffered<St: Stream>(St, FuturesOrdered<St::Item>, usize)
+where
+    St::Item: Future;
+
+impl<St> Stream for Buffered<St>
+where
+    St: Stream,
+    St::Item: Future,
+{
+    type Item = <St::Item as Future>::Output;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        todo!()
+    }
+}
+
+struct Next<'a, T: ?Sized>(&'a T);
+
+impl<St: ?Sized + Stream + Unpin> Future for Next<'_, St> {
+    type Output = Option<St::Item>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        todo!()
+    }
+}
+
+fn main() {
+    send(async {
+        //~^ ERROR implementation of `FnOnce` is not general enough
+        //~| ERROR implementation of `FnOnce` is not general enough
+        //~| ERROR implementation of `FnOnce` is not general enough
+        //~| ERROR implementation of `FnOnce` is not general enough
+        Next(&Buffered(Map(Empty(PhantomData), ready::<&()>), FuturesOrdered(PhantomData), 0)).await
+    });
+}
diff --git a/src/test/ui/async-await/drop-tracking-unresolved-typeck-results.stderr b/src/test/ui/async-await/drop-tracking-unresolved-typeck-results.stderr
new file mode 100644
index 00000000000..aa9a22e9e72
--- /dev/null
+++ b/src/test/ui/async-await/drop-tracking-unresolved-typeck-results.stderr
@@ -0,0 +1,62 @@
+error: implementation of `FnOnce` is not general enough
+  --> $DIR/drop-tracking-unresolved-typeck-results.rs:99:5
+   |
+LL | /     send(async {
+LL | |
+LL | |
+LL | |
+LL | |
+LL | |         Next(&Buffered(Map(Empty(PhantomData), ready::<&()>), FuturesOrdered(PhantomData), 0)).await
+LL | |     });
+   | |______^ implementation of `FnOnce` is not general enough
+   |
+   = note: `fn(&'0 ()) -> std::future::Ready<&'0 ()> {std::future::ready::<&'0 ()>}` must implement `FnOnce<(&'1 (),)>`, for any two lifetimes `'0` and `'1`...
+   = note: ...but it actually implements `FnOnce<(&(),)>`
+
+error: implementation of `FnOnce` is not general enough
+  --> $DIR/drop-tracking-unresolved-typeck-results.rs:99:5
+   |
+LL | /     send(async {
+LL | |
+LL | |
+LL | |
+LL | |
+LL | |         Next(&Buffered(Map(Empty(PhantomData), ready::<&()>), FuturesOrdered(PhantomData), 0)).await
+LL | |     });
+   | |______^ implementation of `FnOnce` is not general enough
+   |
+   = note: `fn(&'0 ()) -> std::future::Ready<&'0 ()> {std::future::ready::<&'0 ()>}` must implement `FnOnce<(&'1 (),)>`, for any two lifetimes `'0` and `'1`...
+   = note: ...but it actually implements `FnOnce<(&(),)>`
+
+error: implementation of `FnOnce` is not general enough
+  --> $DIR/drop-tracking-unresolved-typeck-results.rs:99:5
+   |
+LL | /     send(async {
+LL | |
+LL | |
+LL | |
+LL | |
+LL | |         Next(&Buffered(Map(Empty(PhantomData), ready::<&()>), FuturesOrdered(PhantomData), 0)).await
+LL | |     });
+   | |______^ implementation of `FnOnce` is not general enough
+   |
+   = note: `fn(&'0 ()) -> std::future::Ready<&'0 ()> {std::future::ready::<&'0 ()>}` must implement `FnOnce<(&'1 (),)>`, for any two lifetimes `'0` and `'1`...
+   = note: ...but it actually implements `FnOnce<(&(),)>`
+
+error: implementation of `FnOnce` is not general enough
+  --> $DIR/drop-tracking-unresolved-typeck-results.rs:99:5
+   |
+LL | /     send(async {
+LL | |
+LL | |
+LL | |
+LL | |
+LL | |         Next(&Buffered(Map(Empty(PhantomData), ready::<&()>), FuturesOrdered(PhantomData), 0)).await
+LL | |     });
+   | |______^ implementation of `FnOnce` is not general enough
+   |
+   = note: `fn(&'0 ()) -> std::future::Ready<&'0 ()> {std::future::ready::<&'0 ()>}` must implement `FnOnce<(&'1 (),)>`, for any two lifetimes `'0` and `'1`...
+   = note: ...but it actually implements `FnOnce<(&(),)>`
+
+error: aborting due to 4 previous errors
+