Fix type hint errors from Twisted trunk (#16526)

1 files changed, 11 insertions, 5 deletions

diff --git a/synapse/util/file_consumer.py b/synapse/util/file_consumer.py
index 46771a401b..26b46be5e1 100644
--- a/synapse/util/file_consumer.py
+++ b/synapse/util/file_consumer.py
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import queue
-from typing import BinaryIO, Optional, Union, cast
+from typing import Any, BinaryIO, Optional, Union, cast
 
 from twisted.internet import threads
 from twisted.internet.defer import Deferred
@@ -58,7 +58,9 @@ class BackgroundFileConsumer:
         self._bytes_queue: queue.Queue[Optional[bytes]] = queue.Queue()
 
         # Deferred that is resolved when finished writing
-        self._finished_deferred: Optional[Deferred[None]] = None
+        #
+        # This is really Deferred[None], but mypy doesn't seem to like that.
+        self._finished_deferred: Optional[Deferred[Any]] = None
 
         # If the _writer thread throws an exception it gets stored here.
         self._write_exception: Optional[Exception] = None
@@ -80,9 +82,13 @@ class BackgroundFileConsumer:
         self.streaming = streaming
         self._finished_deferred = run_in_background(
             threads.deferToThreadPool,
-            self._reactor,
-            self._reactor.getThreadPool(),
-            self._writer,
+            # mypy seems to get confused with the chaining of ParamSpec from
+            # run_in_background to deferToThreadPool.
+            #
+            # For Twisted trunk, ignore arg-type; for Twisted release ignore unused-ignore.
+            self._reactor,  # type: ignore[arg-type,unused-ignore]
+            self._reactor.getThreadPool(),  # type: ignore[arg-type,unused-ignore]
+            self._writer,  # type: ignore[arg-type,unused-ignore]
         )
         if not streaming:
             self._producer.resumeProducing()