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 <1342360+anoadragon453@users.noreply.github.com>

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

@@ -3542,4 +3542,4 @@ url-preview = ["lxml"]
 [metadata]
 lock-version = "2.1"
 python-versions = ">=3.10.0,<4.0.0"
-content-hash = "abbbdff591a306b56cc8890dbb2f477ac5f1a2d328baa6409e01084abc655bbf"
+content-hash = "1caa5072f6304122c89377420f993a54f54587f3618ccc8094ec31642264592c"

pyproject.toml

@@ -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"
 ]

synapse/app/_base.py

@@ -36,6 +36,7 @@ from typing import (
     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/admin_cmd.py

@@ -24,7 +24,7 @@ import logging
 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/generic_worker.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/homeserver.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/handlers/delayed_events.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 @@ class DelayedEventsHandler:
             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/message.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 @@ class MessageHandler:
 
         # 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/user_directory.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 @@ class UserDirectoryHandler(StateDeltasHandler):
         # 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.

synapse/http/client.py

@@ -28,6 +28,7 @@ from typing import (
     BinaryIO,
     Callable,
     Mapping,
+    Optional,
     Protocol,
 )
 
@@ -313,7 +314,7 @@ class BlocklistingAgentWrapper(Agent):
         method: bytes,
         uri: bytes,
         headers: Headers | None = None,
-        bodyProducer: IBodyProducer | None = None,
+        bodyProducer: Optional[IBodyProducer] = None,
     ) -> defer.Deferred:
         h = urllib.parse.urlparse(uri.decode("ascii"))
 
@@ -1033,7 +1034,7 @@ class BodyExceededMaxSize(Exception):
 class _DiscardBodyWithMaxSizeProtocol(protocol.Protocol):
     """A protocol which immediately errors upon receiving data."""
 
-    transport: ITCPTransport | None = None
+    transport: Optional[ITCPTransport] = None
 
     def __init__(self, deferred: defer.Deferred):
         self.deferred = deferred
@@ -1075,7 +1076,7 @@ class _MultipartParserProtocol(protocol.Protocol):
     Protocol to read and parse a MSC3916 multipart/mixed response
     """
 
-    transport: ITCPTransport | None = None
+    transport: Optional[ITCPTransport] = None
 
     def __init__(
         self,
@@ -1188,7 +1189,7 @@ class _MultipartParserProtocol(protocol.Protocol):
 class _ReadBodyWithMaxSizeProtocol(protocol.Protocol):
     """A protocol which reads body to a stream, erroring if the body exceeds a maximum size."""
 
-    transport: ITCPTransport | None = None
+    transport: Optional[ITCPTransport] = None
 
     def __init__(
         self, stream: ByteWriteable, deferred: defer.Deferred, max_size: int | None

synapse/http/federation/matrix_federation_agent.py

@@ -19,7 +19,7 @@
 #
 import logging
 import urllib.parse
-from typing import Any, Generator
+from typing import Any, Generator, Optional
 from urllib.request import (  # type: ignore[attr-defined]
     proxy_bypass_environment,
 )
@@ -173,7 +173,7 @@ class MatrixFederationAgent:
         method: bytes,
         uri: bytes,
         headers: Headers | None = None,
-        bodyProducer: IBodyProducer | None = None,
+        bodyProducer: Optional[IBodyProducer] = None,
     ) -> Generator[defer.Deferred, Any, IResponse]:
         """
         Args:

synapse/http/matrixfederationclient.py

@@ -33,6 +33,7 @@ from typing import (
     Callable,
     Generic,
     Literal,
+    Optional,
     TextIO,
     TypeVar,
     cast,
@@ -691,7 +692,7 @@ class MatrixFederationHttpClient:
                             destination_bytes, method_bytes, url_to_sign_bytes, json
                         )
                         data = encode_canonical_json(json)
-                        producer: IBodyProducer | None = QuieterFileBodyProducer(
+                        producer: Optional[IBodyProducer] = QuieterFileBodyProducer(
                             BytesIO(data), cooperator=self._cooperator
                         )
                     else:

synapse/http/proxy.py

@@ -22,7 +22,7 @@
 import json
 import logging
 import urllib.parse
-from typing import TYPE_CHECKING, Any, cast
+from typing import TYPE_CHECKING, Any, Optional, cast
 
 from twisted.internet import protocol
 from twisted.internet.interfaces import ITCPTransport
@@ -237,7 +237,7 @@ class _ProxyResponseBody(protocol.Protocol):
     request.
     """
 
-    transport: ITCPTransport | None = None
+    transport: Optional[ITCPTransport] = None
 
     def __init__(self, request: "SynapseRequest") -> None:
         self._request = request

synapse/http/proxyagent.py

@@ -21,7 +21,7 @@
 import logging
 import random
 import re
-from typing import Any, Collection, Sequence, cast
+from typing import Any, Collection, Optional, Sequence, cast
 from urllib.parse import urlparse
 from urllib.request import (  # type: ignore[attr-defined]
     proxy_bypass_environment,
@@ -119,8 +119,8 @@ class ProxyAgent(_AgentBase):
         self,
         *,
         reactor: IReactorCore,
-        proxy_reactor: IReactorCore | None = None,
+        proxy_reactor: Optional[IReactorCore] = None,
-        contextFactory: IPolicyForHTTPS | None = None,
+        contextFactory: Optional[IPolicyForHTTPS] = None,
         connectTimeout: float | None = None,
         bindAddress: bytes | None = None,
         pool: HTTPConnectionPool | None = None,
@@ -175,7 +175,7 @@ class ProxyAgent(_AgentBase):
         self._policy_for_https = contextFactory
         self._reactor = cast(IReactorTime, reactor)
 
-        self._federation_proxy_endpoint: IStreamClientEndpoint | None = None
+        self._federation_proxy_endpoint: Optional[IStreamClientEndpoint] = None
         self._federation_proxy_credentials: ProxyCredentials | None = None
         if federation_proxy_locations:
             assert federation_proxy_credentials is not None, (
@@ -221,7 +221,7 @@ class ProxyAgent(_AgentBase):
         method: bytes,
         uri: bytes,
         headers: Headers | None = None,
-        bodyProducer: IBodyProducer | None = None,
+        bodyProducer: Optional[IBodyProducer] = None,
     ) -> "defer.Deferred[IResponse]":
         """
         Issue a request to the server indicated by the given uri.
@@ -365,11 +365,11 @@ class ProxyAgent(_AgentBase):
 def http_proxy_endpoint(
     proxy: bytes | None,
     reactor: IReactorCore,
-    tls_options_factory: IPolicyForHTTPS | None,
+    tls_options_factory: Optional[IPolicyForHTTPS],
     timeout: float = 30,
     bindAddress: bytes | str | tuple[bytes | str, int] | None = None,
     attemptDelay: float | None = None,
-) -> tuple[IStreamClientEndpoint | None, ProxyCredentials | None]:
+) -> tuple[Optional[IStreamClientEndpoint], ProxyCredentials | None]:
     """Parses an http proxy setting and returns an endpoint for the proxy
 
     Args:

synapse/http/replicationagent.py

@@ -20,6 +20,7 @@
 #
 
 import logging
+from typing import Optional
 
 from zope.interface import implementer
 
@@ -149,7 +150,7 @@ class ReplicationAgent(_AgentBase):
         method: bytes,
         uri: bytes,
         headers: Headers | None = None,
-        bodyProducer: IBodyProducer | None = None,
+        bodyProducer: Optional[IBodyProducer] = None,
     ) -> "defer.Deferred[IResponse]":
         """
         Issue a request to the server indicated by the given uri.

synapse/logging/_remote.py

@@ -25,7 +25,7 @@ import traceback
 from collections import deque
 from ipaddress import IPv4Address, IPv6Address, ip_address
 from math import floor
-from typing import Callable
+from typing import Callable, Optional
 
 import attr
 from zope.interface import implementer
@@ -113,7 +113,7 @@ class RemoteHandler(logging.Handler):
         port: int,
         maximum_buffer: int = 1000,
         level: int = logging.NOTSET,
-        _reactor: IReactorTime | None = None,
+        _reactor: Optional[IReactorTime] = None,
     ):
         super().__init__(level=level)
         self.host = host

synapse/logging/handlers.py

@@ -3,7 +3,7 @@ import time
 from logging import Handler, LogRecord
 from logging.handlers import MemoryHandler
 from threading import Thread
-from typing import cast
+from typing import Optional, cast
 
 from twisted.internet.interfaces import IReactorCore
 
@@ -26,7 +26,7 @@ class PeriodicallyFlushingMemoryHandler(MemoryHandler):
         target: Handler | None = None,
         flushOnClose: bool = True,
         period: float = 5.0,
-        reactor: IReactorCore | None = None,
+        reactor: Optional[IReactorCore] = None,
     ) -> None:
         """
         period: the period between automatic flushes

synapse/media/_base.py

@@ -30,6 +30,7 @@ from typing import (
     Awaitable,
     BinaryIO,
     Generator,
+    Optional,
 )
 
 import attr
@@ -705,7 +706,7 @@ class ThreadedFileSender:
 
         self.file: BinaryIO | None = None
         self.deferred: "Deferred[None]" = Deferred()
-        self.consumer: interfaces.IConsumer | None = None
+        self.consumer: Optional[IConsumer] = None
 
         # Signals if the thread should keep reading/sending data. Set means
         # continue, clear means pause.

synapse/push/emailpusher.py

@@ -20,7 +20,7 @@
 #
 
 import logging
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 
 from twisted.internet.error import AlreadyCalled, AlreadyCancelled
 from twisted.internet.interfaces import IDelayedCall
@@ -71,7 +71,7 @@ class EmailPusher(Pusher):
         self.server_name = hs.hostname
         self.store = self.hs.get_datastores().main
         self.email = pusher_config.pushkey
-        self.timed_call: IDelayedCall | None = None
+        self.timed_call: Optional[IDelayedCall] = None
         self.throttle_params: dict[str, ThrottleParams] = {}
         self._inited = False
 

synapse/push/httppusher.py

@@ -21,7 +21,7 @@
 import logging
 import random
 import urllib.parse
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Optional
 
 from prometheus_client import Counter
 
@@ -120,7 +120,7 @@ class HttpPusher(Pusher):
         self.data = pusher_config.data
         self.backoff_delay = HttpPusher.INITIAL_BACKOFF_SEC
         self.failing_since = pusher_config.failing_since
-        self.timed_call: IDelayedCall | None = None
+        self.timed_call: Optional[IDelayedCall] = None
         self._is_processing = False
         self._group_unread_count_by_room = (
             hs.config.push.push_group_unread_count_by_room

synapse/server.py

@@ -34,6 +34,7 @@ from typing import (
     Any,
     Awaitable,
     Callable,
+    Optional,
     TypeVar,
     cast,
 )
@@ -320,7 +321,7 @@ class HomeServer(metaclass=abc.ABCMeta):
         self,
         hostname: str,
         config: HomeServerConfig,
-        reactor: ISynapseReactor | None = None,
+        reactor: Optional[ISynapseReactor] = None,
     ):
         """
         Args:
@@ -353,7 +354,7 @@ class HomeServer(metaclass=abc.ABCMeta):
         self._module_web_resources_consumed = False
 
         # This attribute is set by the free function `refresh_certificate`.
-        self.tls_server_context_factory: IOpenSSLContextFactory | None = None
+        self.tls_server_context_factory: Optional[IOpenSSLContextFactory] = None
 
         self._is_shutdown = False
         self._async_shutdown_handlers: list[ShutdownInfo] = []

synapse/util/file_consumer.py

@@ -19,7 +19,7 @@
 #
 
 import queue
-from typing import Any, BinaryIO, cast
+from typing import Any, BinaryIO, Optional, Union, cast
 
 from twisted.internet import threads
 from twisted.internet.defer import Deferred
@@ -50,7 +50,7 @@ class BackgroundFileConsumer:
         self._reactor: ISynapseReactor = reactor
 
         # Producer we're registered with
-        self._producer: IPushProducer | IPullProducer | None = None
+        self._producer: Optional[Union[IPushProducer, IPullProducer]] = None
 
         # True if PushProducer, false if PullProducer
         self.streaming = False
@@ -72,7 +72,7 @@ class BackgroundFileConsumer:
         self._write_exception: Exception | None = None
 
     def registerProducer(
-        self, producer: IPushProducer | IPullProducer, streaming: bool
+        self, producer: Union[IPushProducer, IPullProducer], streaming: bool
     ) -> None:
         """Part of IConsumer interface
 

tests/server.py

@@ -147,7 +147,7 @@ class FakeChannel:
     _reactor: MemoryReactorClock
     result: dict = attr.Factory(dict)
     _ip: str = "127.0.0.1"
-    _producer: IPullProducer | IPushProducer | None = None
+    _producer: Optional[Union[IPullProducer, IPushProducer]] = None
     resource_usage: ContextResourceUsage | None = None
     _request: Request | None = None
 
@@ -248,7 +248,7 @@ class FakeChannel:
         # TODO This should ensure that the IProducer is an IPushProducer or
         # IPullProducer, unfortunately twisted.protocols.basic.FileSender does
         # implement those, but doesn't declare it.
-        self._producer = cast(IPushProducer | IPullProducer, producer)
+        self._producer = cast(Union[IPushProducer, IPullProducer], producer)
         self.producerStreaming = streaming
 
         def _produce() -> None:
@@ -852,7 +852,7 @@ class FakeTransport:
     """Test reactor
     """
 
-    _protocol: IProtocol | None = None
+    _protocol: Optional[IProtocol] = None
     """The Protocol which is producing data for this transport. Optional, but if set
     will get called back for connectionLost() notifications etc.
     """
@@ -871,7 +871,7 @@ class FakeTransport:
     disconnected = False
     connected = True
     buffer: bytes = b""
-    producer: IPushProducer | None = None
+    producer: Optional[IPushProducer] = None
     autoflush: bool = True
 
     def getPeer(self) -> IPv4Address | IPv6Address:
@@ -1073,7 +1073,7 @@ def setup_test_homeserver(
     cleanup_func: Callable[[Callable[[], Optional["Deferred[None]"]]], None],
     server_name: str = "test",
     config: HomeServerConfig | None = None,
-    reactor: ISynapseReactor | None = None,
+    reactor: Optional[ISynapseReactor] = None,
     homeserver_to_use: type[HomeServer] = TestHomeServer,
     db_txn_limit: int | None = None,
     **extra_homeserver_attributes: Any,

tests/unittest.py

@@ -37,6 +37,7 @@ from typing import (
     Iterable,
     Mapping,
     NoReturn,
+    Optional,
     Protocol,
     TypeVar,
 )
@@ -636,7 +637,7 @@ class HomeserverTestCase(TestCase):
         self,
         server_name: str | None = None,
         config: JsonDict | None = None,
-        reactor: ISynapseReactor | None = None,
+        reactor: Optional[ISynapseReactor] = None,
         clock: Clock | None = None,
         **extra_homeserver_attributes: Any,
     ) -> HomeServer: