Duplicating code due to strange Rust error.

src/stream/stream/merge.rs

@@ -45,26 +45,25 @@ where
     fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
         let this = self.project();
         if utils::random(1) == 1 {
-            poll_next_in_order(cx, this.left, this.right)
+            match this.left.poll_next(cx) {
+                Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
+                Poll::Ready(None) => this.right.poll_next(cx),
+                Poll::Pending => match this.right.poll_next(cx) {
+                    Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
+                    Poll::Ready(None) => Poll::Pending,
+                    Poll::Pending => Poll::Pending,
+                },
+            }
         } else {
-            poll_next_in_order(cx, this.right, this.left)
+            match this.right.poll_next(cx) {
+                Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
+                Poll::Ready(None) => this.left.poll_next(cx),
+                Poll::Pending => match this.left.poll_next(cx) {
+                    Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
+                    Poll::Ready(None) => Poll::Pending,
+                    Poll::Pending => Poll::Pending,
+                },
+            }
         }
     }
 }
-
-/// Pools the next item, trying in order, first the first item, then the second one.
-fn poll_next_in_order<F, S, T>(cx: &mut Context<'_>, first: F, second: S) -> Poll<Option<T>>
-where
-    F: Stream<Item = T>,
-    S: Stream<Item = T>,
-{
-    match first.poll_next(cx) {
-        Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
-        Poll::Ready(None) => second.poll_next(cx),
-        Poll::Pending => match second.poll_next(cx) {
-            Poll::Ready(Some(item)) => Poll::Ready(Some(item)),
-            Poll::Ready(None) => Poll::Pending,
-            Poll::Pending => Poll::Pending,
-        },
-    }
-}