impl Clone for stream::{Empty, Pending, Repeat} (#2248)

Author: taiki-e

futures-util/src/stream/empty.rs

@@ -38,3 +38,9 @@ impl<T> Stream for Empty<T> {
         (0, Some(0))
     }
 }
+
+impl<T> Clone for Empty<T> {
+    fn clone(&self) -> Self {
+        empty()
+    }
+}

futures-util/src/stream/pending.rs

@@ -36,3 +36,9 @@ impl<T> Stream for Pending<T> {
         (0, Some(0))
     }
 }
+
+impl<T> Clone for Pending<T> {
+    fn clone(&self) -> Self {
+        pending()
+    }
+}

futures-util/src/stream/repeat.rs

@@ -3,7 +3,7 @@ use futures_core::stream::{Stream, FusedStream};
 use futures_core::task::{Context, Poll};
 
 /// Stream for the [`repeat`] function.
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 #[must_use = "streams do nothing unless polled"]
 pub struct Repeat<T> {
     item: T,