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

Ensure good comprehension hygiene using flake8-comprehensions.

2 files changed, 9 insertions, 9 deletions

diff --git a/synapse/state/v1.py b/synapse/state/v1.py
index 24b7c0faef..9bf98d06f2 100644
--- a/synapse/state/v1.py
+++ b/synapse/state/v1.py
@@ -69,9 +69,9 @@ def resolve_events_with_store(
 
     unconflicted_state, conflicted_state = _seperate(state_sets)
 
-    needed_events = set(
+    needed_events = {
         event_id for event_ids in itervalues(conflicted_state) for event_id in event_ids
-    )
+    }
     needed_event_count = len(needed_events)
     if event_map is not None:
         needed_events -= set(iterkeys(event_map))
@@ -261,11 +261,11 @@ def _resolve_state_events(conflicted_state, auth_events):
 
 
 def _resolve_auth_events(events, auth_events):
-    reverse = [i for i in reversed(_ordered_events(events))]
+    reverse = list(reversed(_ordered_events(events)))
 
-    auth_keys = set(
+    auth_keys = {
         key for event in events for key in event_auth.auth_types_for_event(event)
-    )
+    }
 
     new_auth_events = {}
     for key in auth_keys:
diff --git a/synapse/state/v2.py b/synapse/state/v2.py
index 75fe58305a..0ffe6d8c14 100644
--- a/synapse/state/v2.py
+++ b/synapse/state/v2.py
@@ -105,7 +105,7 @@ def resolve_events_with_store(
                 % (room_id, event.event_id, event.room_id,)
             )
 
-    full_conflicted_set = set(eid for eid in full_conflicted_set if eid in event_map)
+    full_conflicted_set = {eid for eid in full_conflicted_set if eid in event_map}
 
     logger.debug("%d full_conflicted_set entries", len(full_conflicted_set))
 
@@ -233,7 +233,7 @@ def _get_auth_chain_difference(state_sets, event_map, state_res_store):
 
     auth_sets = []
     for state_set in state_sets:
-        auth_ids = set(
+        auth_ids = {
             eid
             for key, eid in iteritems(state_set)
             if (
@@ -246,7 +246,7 @@ def _get_auth_chain_difference(state_sets, event_map, state_res_store):
                 )
             )
             and eid not in common
-        )
+        }
 
         auth_chain = yield state_res_store.get_auth_chain(auth_ids, common)
         auth_ids.update(auth_chain)
@@ -275,7 +275,7 @@ def _seperate(state_sets):
     conflicted_state = {}
 
     for key in set(itertools.chain.from_iterable(state_sets)):
-        event_ids = set(state_set.get(key) for state_set in state_sets)
+        event_ids = {state_set.get(key) for state_set in state_sets}
         if len(event_ids) == 1:
             unconflicted_state[key] = event_ids.pop()
         else: