2 files changed, 16 insertions, 5 deletions
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 5c06073901..6f7963df43 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -859,6 +859,7 @@ class DeviceHandler(DeviceWorkerHandler):
         known_hosts_at_join = await self.store.get_partial_state_servers_at_join(
             room_id
         )
+        assert known_hosts_at_join is not None
         potentially_changed_hosts.difference_update(known_hosts_at_join)
 
         potentially_changed_hosts.discard(self.server_name)
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index dc1cbf5c3d..7f64130e0a 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -20,7 +20,17 @@ import itertools
 import logging
 from enum import Enum
 from http import HTTPStatus
-from typing import TYPE_CHECKING, Dict, Iterable, List, Optional, Set, Tuple, Union
+from typing import (
+    TYPE_CHECKING,
+    AbstractSet,
+    Dict,
+    Iterable,
+    List,
+    Optional,
+    Set,
+    Tuple,
+    Union,
+)
 
 import attr
 from prometheus_client import Histogram
@@ -169,7 +179,7 @@ class FederationHandler:
         # A dictionary mapping room IDs to (initial destination, other destinations)
         # tuples.
         self._partial_state_syncs_maybe_needing_restart: Dict[
-            str, Tuple[Optional[str], StrCollection]
+            str, Tuple[Optional[str], AbstractSet[str]]
         ] = {}
         # A lock guarding the partial state flag for rooms.
         # When the lock is held for a given room, no other concurrent code may
@@ -1720,7 +1730,7 @@ class FederationHandler:
     def _start_partial_state_room_sync(
         self,
         initial_destination: Optional[str],
-        other_destinations: StrCollection,
+        other_destinations: AbstractSet[str],
         room_id: str,
     ) -> None:
         """Starts the background process to resync the state of a partial state room,
@@ -1802,7 +1812,7 @@ class FederationHandler:
     async def _sync_partial_state_room(
         self,
         initial_destination: Optional[str],
-        other_destinations: StrCollection,
+        other_destinations: AbstractSet[str],
         room_id: str,
     ) -> None:
         """Background process to resync the state of a partial-state room
@@ -1939,7 +1949,7 @@ class FederationHandler:
 
 def _prioritise_destinations_for_partial_state_resync(
     initial_destination: Optional[str],
-    other_destinations: StrCollection,
+    other_destinations: AbstractSet[str],
     room_id: str,
 ) -> StrCollection:
     """Work out the order in which we should ask servers to resync events.