io, stream: make ext trait futures !Unpin (#2910)

Make these future `!Unpin` for compatibility with async trait methods.

1 files changed, 10 insertions, 2 deletions

diff --git a/tokio/src/stream/collect.rs b/tokio/src/stream/collect.rs
index a2b5169f..3f91a6f2 100644
--- a/tokio/src/stream/collect.rs
+++ b/tokio/src/stream/collect.rs
@@ -2,6 +2,7 @@ use crate::stream::Stream;
 
 use bytes::{Buf, BufMut, Bytes, BytesMut};
 use core::future::Future;
+use core::marker::PhantomPinned;
 use core::mem;
 use core::pin::Pin;
 use core::task::{Context, Poll};
@@ -10,7 +11,7 @@ use pin_project_lite::pin_project;
 // Do not export this struct until `FromStream` can be unsealed.
 pin_project! {
     /// Future returned by the [`collect`](super::StreamExt::collect) method.
-    #[must_use = "streams do nothing unless polled"]
+    #[must_use = "futures do nothing unless you `.await` or poll them"]
     #[derive(Debug)]
     pub struct Collect<T, U>
     where
@@ -20,6 +21,9 @@ pin_project! {
         #[pin]
         stream: T,
         collection: U::InternalCollection,
+        // Make this future `!Unpin` for compatibility with async trait methods.
+        #[pin]
+        _pin: PhantomPinned,
     }
 }
 
@@ -44,7 +48,11 @@ where
         let (lower, upper) = stream.size_hint();
         let collection = U::initialize(sealed::Internal, lower, upper);
 
-        Collect { stream, collection }
+        Collect {
+            stream,
+            collection,
+            _pin: PhantomPinned,
+        }
     }
 }