Add type hints to app.__init__.

mypy.ini

@@ -25,7 +25,6 @@ exclude = (?x)
   ^(
    |synapse/_scripts/register_new_matrix_user.py
    |synapse/_scripts/review_recent_signups.py
-   |synapse/app/__init__.py
    |synapse/storage/databases/__init__.py
    |synapse/storage/databases/main/__init__.py
    |synapse/storage/databases/main/account_data.py

synapse/app/__init__.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 import logging
 import sys
+from typing import Container
 
 from synapse import python_dependencies  # noqa: E402
 
@@ -27,7 +28,9 @@ except python_dependencies.DependencyException as e:
     sys.exit(1)
 
 
-def check_bind_error(e, address, bind_addresses):
+def check_bind_error(
+    e: Exception, address: str, bind_addresses: Container[str]
+) -> None:
     """
     This method checks an exception occurred while binding on 0.0.0.0.
     If :: is specified in the bind addresses a warning is shown.
@@ -38,9 +41,9 @@ def check_bind_error(e, address, bind_addresses):
     When binding on 0.0.0.0 after :: this can safely be ignored.
 
     Args:
-        e (Exception): Exception that was caught.
-        address (str): Address on which binding was attempted.
-        bind_addresses (list): Addresses on which the service listens.
+        e: Exception that was caught.
+        address: Address on which binding was attempted.
+        bind_addresses: Addresses on which the service listens.
     """
     if address == "0.0.0.0" and "::" in bind_addresses:
         logger.warning(

synapse/app/_base.py

@@ -27,6 +27,7 @@ from typing import (
     Any,
     Awaitable,
     Callable,
+    Collection,
     Dict,
     Iterable,
     List,
@@ -256,7 +257,7 @@ def listen_metrics(bind_addresses: Iterable[str], port: int) -> None:
 
 
 def listen_manhole(
-    bind_addresses: Iterable[str],
+    bind_addresses: Collection[str],
     port: int,
     manhole_settings: ManholeConfig,
     manhole_globals: dict,
@@ -280,7 +281,7 @@ def listen_manhole(
 
 
 def listen_tcp(
-    bind_addresses: Iterable[str],
+    bind_addresses: Collection[str],
     port: int,
     factory: ServerFactory,
     # mypy can't figure out what the default reactor is.
@@ -306,7 +307,7 @@ def listen_tcp(
 
 
 def listen_ssl(
-    bind_addresses: Iterable[str],
+    bind_addresses: Collection[str],
     port: int,
     factory: ServerFactory,
     context_factory: IOpenSSLContextFactory,