3 files changed, 23 insertions, 10 deletions
diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index 7a91544119..b700cbbfa1 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -22,7 +22,7 @@ from synapse.events import EventBase
 from synapse.types import JsonDict, StateMap
 
 if TYPE_CHECKING:
-    from synapse.storage import Storage
+    from synapse.storage.controllers import StorageControllers
     from synapse.storage.databases.main import DataStore
     from synapse.storage.state import StateFilter
 
@@ -84,7 +84,7 @@ class EventContext:
             incomplete state.
     """
 
-    _storage: "Storage"
+    _storage: "StorageControllers"
     rejected: Union[Literal[False], str] = False
     _state_group: Optional[int] = None
     state_group_before_event: Optional[int] = None
@@ -97,7 +97,7 @@ class EventContext:
 
     @staticmethod
     def with_state(
-        storage: "Storage",
+        storage: "StorageControllers",
         state_group: Optional[int],
         state_group_before_event: Optional[int],
         state_delta_due_to_event: Optional[StateMap[str]],
@@ -117,7 +117,7 @@ class EventContext:
 
     @staticmethod
     def for_outlier(
-        storage: "Storage",
+        storage: "StorageControllers",
     ) -> "EventContext":
         """Return an EventContext instance suitable for persisting an outlier event"""
         return EventContext(storage=storage)
@@ -147,7 +147,7 @@ class EventContext:
         }
 
     @staticmethod
-    def deserialize(storage: "Storage", input: JsonDict) -> "EventContext":
+    def deserialize(storage: "StorageControllers", input: JsonDict) -> "EventContext":
         """Converts a dict that was produced by `serialize` back into a
         EventContext.
 
diff --git a/synapse/events/spamcheck.py b/synapse/events/spamcheck.py
index 1048b4c825..d2e06c754e 100644
--- a/synapse/events/spamcheck.py
+++ b/synapse/events/spamcheck.py
@@ -21,6 +21,7 @@ from typing import (
     Awaitable,
     Callable,
     Collection,
+    Dict,
     List,
     Optional,
     Tuple,
@@ -41,12 +42,17 @@ if TYPE_CHECKING:
 
 logger = logging.getLogger(__name__)
 
-
 CHECK_EVENT_FOR_SPAM_CALLBACK = Callable[
     ["synapse.events.EventBase"],
     Awaitable[
         Union[
             str,
+            Codes,
+            # Highly experimental, not officially part of the spamchecker API, may
+            # disappear without warning depending on the results of ongoing
+            # experiments.
+            # Use this to return additional information as part of an error.
+            Tuple[Codes, Dict],
             # Deprecated
             bool,
         ]
@@ -267,7 +273,9 @@ class SpamChecker:
         if check_media_file_for_spam is not None:
             self._check_media_file_for_spam_callbacks.append(check_media_file_for_spam)
 
-    async def check_event_for_spam(self, event: "synapse.events.EventBase") -> str:
+    async def check_event_for_spam(
+        self, event: "synapse.events.EventBase"
+    ) -> Union[Tuple[Codes, Dict], str]:
         """Checks if a given event is considered "spammy" by this server.
 
         If the server considers an event spammy, then it will be rejected if
@@ -303,7 +311,7 @@ class SpamChecker:
                     # mypy complains that we can't reach this code because of the
                     # return type in CHECK_EVENT_FOR_SPAM_CALLBACK, but we don't know
                     # for sure that the module actually returns it.
-                    logger.warning(  # type: ignore[unreachable]
+                    logger.warning(
                         "Module returned invalid value, rejecting message as spam"
                     )
                     res = "This message has been rejected as probable spam"
diff --git a/synapse/events/validator.py b/synapse/events/validator.py
index 360d24274a..29fa9b3880 100644
--- a/synapse/events/validator.py
+++ b/synapse/events/validator.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import collections.abc
-from typing import Iterable, Type, Union
+from typing import Iterable, Type, Union, cast
 
 import jsonschema
 
@@ -103,7 +103,12 @@ class EventValidator:
             except jsonschema.ValidationError as e:
                 if e.path:
                     # example: "users_default": '0' is not of type 'integer'
-                    message = '"' + e.path[-1] + '": ' + e.message  # noqa: B306
+                    # cast safety: path entries can be integers, if we fail to validate
+                    # items in an array. However the POWER_LEVELS_SCHEMA doesn't expect
+                    # to see any arrays.
+                    message = (
+                        '"' + cast(str, e.path[-1]) + '": ' + e.message  # noqa: B306
+                    )
                     # jsonschema.ValidationError.message is a valid attribute
                 else:
                     # example: '0' is not of type 'integer'