Clarify list/set/dict/tuple comprehensions and enforce via flake8 (#6957)

Ensure good comprehension hygiene using flake8-comprehensions.

1 files changed, 2 insertions, 2 deletions

diff --git a/synapse/visibility.py b/synapse/visibility.py

index d0abd8f04f..e60d9756b7 100644
--- a/synapse/visibility.py
+++ b/synapse/visibility.py
@@ -75,7 +75,7 @@ def filter_events_for_client(
     """
     # Filter out events that have been soft failed so that we don't relay them
     # to clients.
-    events = list(e for e in events if not e.internal_metadata.is_soft_failed())
+    events = [e for e in events if not e.internal_metadata.is_soft_failed()]
 
     types = ((EventTypes.RoomHistoryVisibility, ""), (EventTypes.Member, user_id))
     event_id_to_state = yield storage.state.get_state_for_events(
@@ -97,7 +97,7 @@ def filter_events_for_client(
     erased_senders = yield storage.main.are_users_erased((e.sender for e in events))
 
     if apply_retention_policies:
-        room_ids = set(e.room_id for e in events)
+        room_ids = {e.room_id for e in events}
         retention_policies = {}
 
         for room_id in room_ids: