1 files changed, 45 insertions, 0 deletions
diff --git a/third_party/rust/futures-util/src/stream/pending.rs b/third_party/rust/futures-util/src/stream/pending.rs
new file mode 100644
index 0000000000..d7030ff3cc
--- /dev/null
+++ b/third_party/rust/futures-util/src/stream/pending.rs
@@ -0,0 +1,45 @@
+use super::assert_stream;
+use core::marker;
+use core::pin::Pin;
+use futures_core::stream::{FusedStream, Stream};
+use futures_core::task::{Context, Poll};
+
+/// Stream for the [`pending()`] function.
+#[derive(Debug)]
+#[must_use = "streams do nothing unless polled"]
+pub struct Pending<T> {
+    _data: marker::PhantomData<T>,
+}
+
+/// Creates a stream which never returns any elements.
+///
+/// The returned stream will always return `Pending` when polled.
+pub fn pending<T>() -> Pending<T> {
+    assert_stream::<T, _>(Pending { _data: marker::PhantomData })
+}
+
+impl<T> Unpin for Pending<T> {}
+
+impl<T> FusedStream for Pending<T> {
+    fn is_terminated(&self) -> bool {
+        true
+    }
+}
+
+impl<T> Stream for Pending<T> {
+    type Item = T;
+
+    fn poll_next(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        Poll::Pending
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (0, Some(0))
+    }
+}
+
+impl<T> Clone for Pending<T> {
+    fn clone(&self) -> Self {
+        pending()
+    }
+}