Typing updates for recent mypy versions (#481)

* Remove redunant casts

A version of mypy has been released which includes
python/typeshed#6150. (Typeshed is vendored with mypy these days.) We
can now remove the redundant cast.

* Mark logging handler as a generic logging handler.

Since python/typeshed#5681 (vendored in recent mypy releases),
StreamHandler is now generic over its stream. This causes us pain:

> Missing type parameters for generic type "StreamHandler"

And I couldn't find a satisfactory type parameter that worked here.

- a `TimedRotatingFileHandler` instance is a `FileHandler` which is a
`StreamHandler[TextIOWrapper]`. - the instance `StreamHandler()` (which
writes to stdout) is overloaded to be a `StreamHandler[TextIO]`

`handler: StreamHandler[TextIO]` didn't work. I don't fully understand
the difference between the concrete TextIOWrapper and the abstract
TextIO (the former looks to be compatible with the latter?). I think the
StreamHandler type parameter would need to be covariant for this to
work.

In any case, we're not making use of any of the stream or file specific
attributes here. So let's just mark it as a general `Handler`.

changelog.d/481.misc

@@ -0,0 +1 @@
+Update type annotations to ensure Sydent typechecks with recent mypy versions.

sydent/db/accounts.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import TYPE_CHECKING, Optional, Tuple, cast
+from typing import TYPE_CHECKING, Optional, Tuple
 
 from sydent.users.accounts import Account
 
@@ -104,7 +104,6 @@ def delToken(self, token: str) -> int:
             "delete from tokens where token = ?",
             (token,),
         )
-        # Cast safety: DBAPI-2 says this is a "number"; c.f. python/typeshed#6150
-        deleted = cast(int, cur.rowcount)
+        deleted = cur.rowcount
         self.sydent.db.commit()
         return deleted

sydent/db/invite_tokens.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import time
-from typing import TYPE_CHECKING, Dict, List, Optional, Tuple, cast
+from typing import TYPE_CHECKING, Dict, List, Optional, Tuple
 
 if TYPE_CHECKING:
     from sydent.sydent import Sydent
@@ -137,9 +137,7 @@ def validateEphemeralPublicKey(self, publicKey: str) -> bool:
             (publicKey,),
         )
         self.sydent.db.commit()
-        # Cast safety: DBAPI-2 says this is a "number"; c.f. python/typeshed#6150
-        rows = cast(int, cur.rowcount)
-        return rows > 0
+        return cur.rowcount > 0
 
     def getSenderForToken(self, token: str) -> Optional[str]:
         """

sydent/sydent.py

@@ -339,8 +339,9 @@ def setup_logging(config: SydentConfig) -> None:
     log_format = "%(asctime)s - %(name)s - %(lineno)d - %(levelname)s" " - %(message)s"
     formatter = logging.Formatter(log_format)
 
+    handler: logging.Handler
     if log_path != "":
-        handler: logging.StreamHandler = logging.handlers.TimedRotatingFileHandler(
+        handler = logging.handlers.TimedRotatingFileHandler(
             log_path, when="midnight", backupCount=365
         )
         handler.setFormatter(formatter)