Use sort_by() instead of sort_by_key().

client/src/room/event.rs

@@ -327,11 +327,6 @@ mod tests {
     assert_eq!(request, ServerRequest::RoomListRequest);
   }
 
-  // Cannot get the compiler to be satisfied when borrowing the name...
-  fn room_name(pair: &(String, RoomState)) -> String {
-    pair.0.clone()
-  }
-
   #[test]
   fn handle_list_request_sends_immediate_response() {
     let mut options = ContextOptions::default();
@@ -360,7 +355,12 @@ mod tests {
       _ => panic!("Unexpected control response: {:?}", response),
     };
 
-    rooms.sort_by_key(room_name);
+    // `sort_by_key()` cannot handle an extractor function that returns
+    // references, so we use `sort_by()` instead.
+    // See: https://github.com/rust-lang/rust/issues/34162
+    rooms.sort_unstable_by(|(ref lhs_name, _), (ref rhs_name, _)| {
+      lhs_name.cmp(rhs_name)
+    });
 
     assert_eq!(
       rooms,