Refactor a bit

synapse/visibility.py

@@ -118,26 +118,28 @@ def filter_events_for_client(
 
                the original event if they can see it as normal.
         """
-        if event.type == "org.matrix.dummy_event" and filter_send_to_client:
+        # Only run some checks if these events aren't about to be sent to clients. This is
+        # because, if this is not the case, we're probably only checking if the users can
+        # see events in the room at that point in the DAG, and that shouldn't be decided
+        # on those checks.
+        if filter_send_to_client:
+            if event.type == "org.matrix.dummy_event":
                 return None
 
-        if (
-            not event.is_state()
-            and event.sender in ignore_list
-            and filter_send_to_client
-        ):
+            if not event.is_state() and event.sender in ignore_list:
                 return None
 
             # Until MSC2261 has landed we can't redact malicious alias events, so for
             # now we temporarily filter out m.room.aliases entirely to mitigate
             # abuse, while we spec a better solution to advertising aliases
             # on rooms.
-        if event.type == EventTypes.Aliases and filter_send_to_client:
+            if event.type == EventTypes.Aliases:
                 return None
 
-        # Don't try to apply the room's retention policy if the event is a state event, as
-        # MSC1763 states that retention is only considered for non-state events.
-        if filter_send_to_client and not event.is_state():
+            # Don't try to apply the room's retention policy if the event is a state
+            # event, as MSC1763 states that retention is only considered for non-state
+            # events.
+            if not event.is_state():
                 retention_policy = retention_policies[event.room_id]
                 max_lifetime = retention_policy.get("max_lifetime")