no better solution to allocating other than nesting

src/api/client_server/sync.rs

@@ -289,15 +289,13 @@ async fn sync_helper(
     }
 
     let mut left_rooms = BTreeMap::new();
-    let all_left_rooms: Vec<_> = if filter.room.include_leave {
-        services()
+    if filter.room.include_leave {
+        let all_left_rooms: Vec<_> = services()
             .rooms
             .state_cache
             .rooms_left(&sender_user)
-            .collect()
-    } else {
-        Vec::default()
-    };
+            .collect();
+
         for result in all_left_rooms {
             let (room_id, _) = result?;
 
@@ -462,6 +460,7 @@ async fn sync_helper(
                 },
             );
         }
+    }
 
     let mut invited_rooms = BTreeMap::new();
     let all_invited_rooms: Vec<_> = services()