Fix support for older versions of zope-interface (#19274)

Fixes #19269 

Versions of zope-interface from RHEL, Ubuntu LTS 22 & 24 and OpenSuse
don't support the new python union `X | Y` syntax for interfaces. This
PR partially reverts the change over to fully use the new syntax, adds a
minimum supported version of zope-interface to Synapse's dependency
list, and removes the linter auto-upgrades which prefer the newer
syntax.

### Pull Request Checklist

<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->

* [X] Pull request is based on the develop branch
* [X] Pull request includes a [changelog
file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog).
The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
  - Use markdown where necessary, mostly for `code blocks`.
  - End with either a period (.) or an exclamation mark (!).
  - Start with a capital letter.
- Feel free to credit yourself, by adding a sentence "Contributed by
@github_username." or "Contributed by [Your Name]." to the end of the
entry.
* [X] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct (run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))

---------

Co-authored-by: Andrew Morgan <[email protected]>

Author: devonh

changelog.d/19274.bugfix

@@ -0,0 +1 @@
+Fix bug introduced in 1.143.0 that broke support for versions of `zope-interface` older than 6.2.

poetry.lock

@@ -109,7 +109,12 @@ dependencies = [
     "pyrsistent>=0.18.0",  # via jsonschema
     "requests>=2.16.0", # 2.16.0+ no longer vendors urllib3, avoiding Python 3.10+ incompatibility
     "urllib3>=1.26.5", # via treq; 1.26.5 fixes Python 3.10+ collections.abc compatibility
-    "zope-interface>=6.2", # via twisted
+    # 5.2 is the current version in Debian oldstable. If we don't care to support that, then 5.4 is
+    # the minimum version from Ubuntu 22.04 and RHEL 9. (as of 2025-12)
+    # When bumping this version to 6.2 or above, refer to https://github.com/element-hq/synapse/pull/19274
+    # for details of Synapse improvements that may be unlocked. Particularly around the use of `|`
+    # syntax with zope interface types.
+    "zope-interface>=5.2", # via twisted
 ]
 
 [project.optional-dependencies]
@@ -383,15 +388,10 @@ select = [
     "G",
     # pyupgrade
     "UP006",
-    "UP007",
-    "UP045",
 ]
 extend-safe-fixes = [
     # pyupgrade rules compatible with Python >= 3.9
     "UP006",
-    "UP007",
-    # pyupgrade rules compatible with Python >= 3.10
-    "UP045",
     # Allow ruff to automatically fix trailing spaces within a multi-line string/comment.
     "W293"
 ]

pyproject.toml

@@ -36,6 +36,7 @@
     Awaitable,
     Callable,
     NoReturn,
+    Optional,
     cast,
 )
 from wsgiref.simple_server import WSGIServer
@@ -455,7 +456,7 @@ def listen_http(
     root_resource: Resource,
     version_string: str,
     max_request_body_size: int,
-    context_factory: IOpenSSLContextFactory | None,
+    context_factory: Optional[IOpenSSLContextFactory],
     reactor: ISynapseReactor = reactor,
 ) -> list[Port]:
     """

synapse/app/_base.py

@@ -24,7 +24,7 @@
 import os
 import sys
 import tempfile
-from typing import Mapping, Sequence
+from typing import Mapping, Optional, Sequence
 
 from twisted.internet import defer, task
 
@@ -291,7 +291,7 @@ def load_config(argv_options: list[str]) -> tuple[HomeServerConfig, argparse.Nam
 
 def create_homeserver(
     config: HomeServerConfig,
-    reactor: ISynapseReactor | None = None,
+    reactor: Optional[ISynapseReactor] = None,
 ) -> AdminCmdServer:
     """
     Create a homeserver instance for the Synapse admin command process.

synapse/app/admin_cmd.py

@@ -21,6 +21,7 @@
 #
 import logging
 import sys
+from typing import Optional
 
 from twisted.web.resource import Resource
 
@@ -335,7 +336,7 @@ def load_config(argv_options: list[str]) -> HomeServerConfig:
 
 def create_homeserver(
     config: HomeServerConfig,
-    reactor: ISynapseReactor | None = None,
+    reactor: Optional[ISynapseReactor] = None,
 ) -> GenericWorkerServer:
     """
     Create a homeserver instance for the Synapse worker process.

synapse/app/generic_worker.py

@@ -22,7 +22,7 @@
 import logging
 import os
 import sys
-from typing import Iterable
+from typing import Iterable, Optional
 
 from twisted.internet.tcp import Port
 from twisted.web.resource import EncodingResourceWrapper, Resource
@@ -350,7 +350,7 @@ def load_or_generate_config(argv_options: list[str]) -> HomeServerConfig:
 
 def create_homeserver(
     config: HomeServerConfig,
-    reactor: ISynapseReactor | None = None,
+    reactor: Optional[ISynapseReactor] = None,
 ) -> SynapseHomeServer:
     """
     Create a homeserver instance for the Synapse main process.

synapse/app/homeserver.py

@@ -13,7 +13,7 @@
 #
 
 import logging
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 
 from twisted.internet.interfaces import IDelayedCall
 
@@ -74,7 +74,7 @@ def __init__(self, hs: "HomeServer"):
             cfg=self._config.ratelimiting.rc_delayed_event_mgmt,
         )
 
-        self._next_delayed_event_call: IDelayedCall | None = None
+        self._next_delayed_event_call: Optional[IDelayedCall] = None
 
         # The current position in the current_state_delta stream
         self._event_pos: int | None = None

synapse/handlers/delayed_events.py

@@ -22,7 +22,7 @@
 import logging
 import random
 from http import HTTPStatus
-from typing import TYPE_CHECKING, Any, Mapping, Sequence
+from typing import TYPE_CHECKING, Any, Mapping, Optional, Sequence
 
 from canonicaljson import encode_canonical_json
 
@@ -111,7 +111,7 @@ def __init__(self, hs: "HomeServer"):
 
         # The scheduled call to self._expire_event. None if no call is currently
         # scheduled.
-        self._scheduled_expiry: IDelayedCall | None = None
+        self._scheduled_expiry: Optional[IDelayedCall] = None
 
         if not hs.config.worker.worker_app:
             self.hs.run_as_background_process(

synapse/handlers/message.py

@@ -21,7 +21,7 @@
 
 import logging
 from http import HTTPStatus
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 
 from twisted.internet.interfaces import IDelayedCall
 
@@ -125,7 +125,7 @@ def __init__(self, hs: "HomeServer"):
         # Guard to ensure we only have one process for refreshing remote profiles
         self._is_refreshing_remote_profiles = False
         # Handle to cancel the `call_later` of `kick_off_remote_profile_refresh_process`
-        self._refresh_remote_profiles_call_later: IDelayedCall | None = None
+        self._refresh_remote_profiles_call_later: Optional[IDelayedCall] = None
 
         # Guard to ensure we only have one process for refreshing remote profiles
         # for the given servers.