gh-126881: store debug flag for event loops as a boolean

Lib/asyncio/base_events.py

@@ -2052,7 +2052,9 @@ def get_debug(self):
         return self._debug
 
     def set_debug(self, enabled):
-        self._debug = enabled
+        # Storing a non-boolean 'debug' flag causes a crash upon finalization.
+        # See: https://github.com/python/cpython/issues/126881.
+        self._debug = enabled = bool(enabled)
 
         if self.is_running():
             self.call_soon_threadsafe(self._set_coroutine_origin_tracking, enabled)

Lib/test/test_asyncio/test_base_events.py

@@ -6,6 +6,7 @@
 import platform
 import socket
 import sys
+import textwrap
 import threading
 import time
 import unittest
@@ -393,6 +394,37 @@ def test_set_debug(self):
         self.loop.set_debug(False)
         self.assertFalse(self.loop.get_debug())
 
+    def test_set_debug_non_boolean(self):
+        # Assert that set_debug with a non-boolean value does not crash.
+        #
+        # In order to check that the crash does not happen anymore, we
+        # deliberately leave the loop unclosed. Note that the loop will
+        # be closed automatically when calling __del__() but a warning
+        # will be emitted.
+        #
+        # See: https://github.com/python/cpython/issues/126881.
+        code = textwrap.dedent("""
+            from asyncio.base_events import BaseEventLoop
+            loop = BaseEventLoop()
+            loop.set_debug(0.0005)
+            loop._run_forever_setup()
+            loop.__del__()
+        """)
+        _, stdout, stderr = assert_python_ok('-c', code)
+        self.assertEqual(stdout, b'')
+        self.assertIn(b'ResourceWarning: unclosed event loop', stderr)
+
+        code = textwrap.dedent("""
+            from asyncio.base_events import BaseEventLoop
+            loop = BaseEventLoop()
+            loop.set_debug([])
+            loop._run_forever_setup()
+            loop.__del__()
+        """)
+        _, stdout, stderr = assert_python_ok('-c', code)
+        self.assertEqual(stdout, b'')
+        self.assertIn(b'ResourceWarning: unclosed event loop', stderr)
+
     def test__run_once_schedule_handle(self):
         handle = None
         processed = False

Misc/NEWS.d/next/Library/2024-11-16-10-44-58.gh-issue-126881.W4TXxX.rst

@@ -0,0 +1,2 @@
+Fix a crash upon finalization when passing a non-boolean value to
+:meth:`loop.set_debug <asyncio.loop.set_debug>`. Patch by Bénédikt Tran.