[logging] Fix Formatter.converter assignment in subclasses

Signed-off-by: Emmanuel Ferdman <emmanuelferdman@gmail.com>

Author: emmanuel-ferdman

stdlib/@tests/test_cases/check_logging.py

@@ -4,6 +4,7 @@
 import logging.handlers
 import multiprocessing
 import queue
+import time
 from typing import Any
 
 # This pattern comes from the logging docs, and should therefore pass a type checker
@@ -28,3 +29,8 @@ def record_factory(*args: Any, **kwargs: Any) -> logging.LogRecord:
 logging.handlers.QueueListener(queue.Queue())
 logging.handlers.QueueListener(queue.SimpleQueue())
 logging.handlers.QueueListener(multiprocessing.Queue())
+
+
+# Formatter.converter can be overridden with time.gmtime or time.localtime (regression test for #14880)
+class UTCFormatter(logging.Formatter):
+    converter = time.gmtime

stdlib/logging/__init__.pyi

@@ -267,7 +267,7 @@ if sys.version_info >= (3, 12):
     def getHandlerNames() -> frozenset[str]: ...
 
 class Formatter:
-    converter: Callable[[float | None], struct_time]
+    converter: ClassVar[Callable[[float | None], struct_time]]
     _fmt: str | None  # undocumented
     datefmt: str | None  # undocumented
     _style: PercentStyle  # undocumented