Add type hints to synapse.events.*. (#11066)

Except `synapse/events/__init__.py`, which will be done in a follow-up.

1 files changed, 11 insertions, 10 deletions

diff --git a/synapse/events/presence_router.py b/synapse/events/presence_router.py
index 68b8b19024..a58f313e8b 100644
--- a/synapse/events/presence_router.py
+++ b/synapse/events/presence_router.py
@@ -14,6 +14,7 @@
 import logging
 from typing import (
     TYPE_CHECKING,
+    Any,
     Awaitable,
     Callable,
     Dict,
@@ -33,14 +34,13 @@ if TYPE_CHECKING:
 GET_USERS_FOR_STATES_CALLBACK = Callable[
     [Iterable[UserPresenceState]], Awaitable[Dict[str, Set[UserPresenceState]]]
 ]
-GET_INTERESTED_USERS_CALLBACK = Callable[
-    [str], Awaitable[Union[Set[str], "PresenceRouter.ALL_USERS"]]
-]
+# This must either return a set of strings or the constant PresenceRouter.ALL_USERS.
+GET_INTERESTED_USERS_CALLBACK = Callable[[str], Awaitable[Union[Set[str], str]]]
 
 logger = logging.getLogger(__name__)
 
 
-def load_legacy_presence_router(hs: "HomeServer"):
+def load_legacy_presence_router(hs: "HomeServer") -> None:
     """Wrapper that loads a presence router module configured using the old
     configuration, and registers the hooks they implement.
     """
@@ -69,9 +69,10 @@ def load_legacy_presence_router(hs: "HomeServer"):
         if f is None:
             return None
 
-        def run(*args, **kwargs):
-            # mypy doesn't do well across function boundaries so we need to tell it
-            # f is definitely not None.
+        def run(*args: Any, **kwargs: Any) -> Awaitable:
+            # Assertion required because mypy can't prove we won't change `f`
+            # back to `None`. See
+            # https://mypy.readthedocs.io/en/latest/common_issues.html#narrowing-and-inner-functions
             assert f is not None
 
             return maybe_awaitable(f(*args, **kwargs))
@@ -104,7 +105,7 @@ class PresenceRouter:
         self,
         get_users_for_states: Optional[GET_USERS_FOR_STATES_CALLBACK] = None,
         get_interested_users: Optional[GET_INTERESTED_USERS_CALLBACK] = None,
-    ):
+    ) -> None:
         # PresenceRouter modules are required to implement both of these methods
         # or neither of them as they are assumed to act in a complementary manner
         paired_methods = [get_users_for_states, get_interested_users]
@@ -142,7 +143,7 @@ class PresenceRouter:
             # Don't include any extra destinations for presence updates
             return {}
 
-        users_for_states = {}
+        users_for_states: Dict[str, Set[UserPresenceState]] = {}
         # run all the callbacks for get_users_for_states and combine the results
         for callback in self._get_users_for_states_callbacks:
             try:
@@ -171,7 +172,7 @@ class PresenceRouter:
 
         return users_for_states
 
-    async def get_interested_users(self, user_id: str) -> Union[Set[str], ALL_USERS]:
+    async def get_interested_users(self, user_id: str) -> Union[Set[str], str]:
         """
         Retrieve a list of users that `user_id` is interested in receiving the
         presence of. This will be in addition to those they share a room with.