Improve type hints in storage classes. (#11652)

By using cast and making ignores more specific.

1 files changed, 2 insertions, 2 deletions

diff --git a/synapse/storage/databases/main/deviceinbox.py b/synapse/storage/databases/main/deviceinbox.py

index b410eefdc7..3682cb6a81 100644
--- a/synapse/storage/databases/main/deviceinbox.py
+++ b/synapse/storage/databases/main/deviceinbox.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 
 import logging
-from typing import TYPE_CHECKING, List, Optional, Tuple
+from typing import TYPE_CHECKING, List, Optional, Tuple, cast
 
 from synapse.logging import issue9533_logger
 from synapse.logging.opentracing import log_kv, set_tag, trace
@@ -673,7 +673,7 @@ class DeviceInboxBackgroundUpdateStore(SQLBaseStore):
                 # There's a type mismatch here between how we want to type the row and
                 # what fetchone says it returns, but we silence it because we know that
                 # res can't be None.
-                res: Tuple[Optional[int]] = txn.fetchone()  # type: ignore[assignment]
+                res = cast(Tuple[Optional[int]], txn.fetchone())
                 if res[0] is None:
                     # this can only happen if the `device_inbox` table is empty, in which
                     # case we have no work to do.