7 files changed, 24 insertions, 12 deletions
diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index 91118a8d84..d475fe7ae5 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -462,7 +462,7 @@ class FrozenEvent(EventBase):
         # Signatures is a dict of dicts, and this is faster than doing a
         # copy.deepcopy
         signatures = {
-            name: {sig_id: sig for sig_id, sig in sigs.items()}
+            name: dict(sigs.items())
             for name, sigs in event_dict.pop("signatures", {}).items()
         }
 
@@ -510,7 +510,7 @@ class FrozenEventV2(EventBase):
         # Signatures is a dict of dicts, and this is faster than doing a
         # copy.deepcopy
         signatures = {
-            name: {sig_id: sig for sig_id, sig in sigs.items()}
+            name: dict(sigs.items())
             for name, sigs in event_dict.pop("signatures", {}).items()
         }
 
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index e41c7a4b83..c14c7791db 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -355,7 +355,7 @@ def serialize_event(
     time_now_ms = int(time_now_ms)
 
     # Should this strip out None's?
-    d = {k: v for k, v in e.get_dict().items()}
+    d = dict(e.get_dict().items())
 
     d["event_id"] = e.event_id
 
diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index fec4ae5b97..226ccc1671 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -1504,8 +1504,8 @@ class DatabasePool:
         self.engine.lock_table(txn, "user_ips")
 
         for keyv, valv in zip(key_values, value_values):
-            _keys = {x: y for x, y in zip(key_names, keyv)}
-            _vals = {x: y for x, y in zip(value_names, valv)}
+            _keys = dict(zip(key_names, keyv))
+            _vals = dict(zip(value_names, valv))
 
             self.simple_upsert_txn_emulated(txn, table, _keys, _vals, lock=False)
 
diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index 193959b250..ccd9f9d141 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -27,6 +27,7 @@ from typing import (
     Optional,
     Set,
     Tuple,
+    cast,
 )
 
 import attr
@@ -1348,9 +1349,7 @@ class PersistEventsStore:
             [event.event_id for event, _ in events_and_contexts],
         )
 
-        have_persisted: Dict[str, bool] = {
-            event_id: outlier for event_id, outlier in txn
-        }
+        have_persisted = dict(cast(Iterable[Tuple[str, bool]], txn))
 
         logger.debug(
             "_update_outliers_txn: events=%s have_persisted=%s",
diff --git a/synapse/storage/databases/main/pusher.py b/synapse/storage/databases/main/pusher.py
index ab76b754e0..aeb6034f46 100644
--- a/synapse/storage/databases/main/pusher.py
+++ b/synapse/storage/databases/main/pusher.py
@@ -518,7 +518,7 @@ class PusherBackgroundUpdatesStore(SQLBaseStore):
         def set_device_id_for_pushers_txn(txn: LoggingTransaction) -> int:
             txn.execute(
                 """
-                    SELECT 
+                    SELECT
                         p.id AS pusher_id,
                         p.device_id AS pusher_device_id,
                         at.device_id AS token_device_id
diff --git a/synapse/storage/databases/main/stats.py b/synapse/storage/databases/main/stats.py
index d3393d8e49..97c4dc2603 100644
--- a/synapse/storage/databases/main/stats.py
+++ b/synapse/storage/databases/main/stats.py
@@ -16,7 +16,17 @@
 import logging
 from enum import Enum
 from itertools import chain
-from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple, Union, cast
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Dict,
+    Iterable,
+    List,
+    Optional,
+    Tuple,
+    Union,
+    cast,
+)
 
 from typing_extensions import Counter
 
@@ -523,7 +533,7 @@ class StatsStore(StateDeltasStore):
                 """,
                 (room_id,),
             )
-            membership_counts = {membership: cnt for membership, cnt in txn}
+            membership_counts = dict(cast(Iterable[Tuple[str, int]], txn))
 
             txn.execute(
                 """
diff --git a/synapse/storage/databases/main/stream.py b/synapse/storage/databases/main/stream.py
index 2b8779bbb8..92cbe262a6 100644
--- a/synapse/storage/databases/main/stream.py
+++ b/synapse/storage/databases/main/stream.py
@@ -41,6 +41,7 @@ from typing import (
     Any,
     Collection,
     Dict,
+    Iterable,
     List,
     Optional,
     Set,
@@ -1343,7 +1344,9 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
             GROUP BY type
         """
         txn.execute(sql)
-        min_positions = {typ: pos for typ, pos in txn}  # Map from type -> min position
+        min_positions = dict(
+            cast(Iterable[Tuple[str, int]], txn)
+        )  # Map from type -> min position
 
         # Ensure we do actually have some values here
         assert set(min_positions) == {"federation", "events"}