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Leak test of test_descr fails Base2 != Base #133122
Description
Bug report
Bug description:
This seems to be caused by GH-133114.
Command to re-produce:
./python -m test -R 3:3 -j12 test_descr
The failure output:
FAIL: test_type_lookup_mro_reference (test.test_descr.MiscTests.test_type_lookup_mro_reference)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/buildbot/buildarea/3.13.cstratak-RHEL8-x86_64.refleak/build/Lib/test/test_descr.py", line 5181, in test_type_lookup_mro_reference
self.assertEqual(X.mykey, 'from Base')
~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 'from Base2' != 'from Base'
- from Base2
? -
+ from Base
----------------------------------------------------------------------
Ran 156 tests in 0.829s
FAILED (failures=1, skipped=1, expected failures=2)
test test_descr failed
This appears to be another bug in the type lookup (MRO) cache.
CPython versions tested on:
3.13
Operating systems tested on:
Linux
Activity
nascheme commentedon Apr 29, 2025
Some progress on debugging this. It seems to be an issue with the specialize. In specialize.c, we have
analyze_descriptor()calling_PyType_Lookup()and that's causing the tricky__eq__to be executed before the real lookup happens. So the__bases__gets replaced before the unit test expects. At least, that's my theory.I'm not sure if we consider the bytecode specializer buggy for doing this or the unit test buggy for expecting it to work exactly as is being test. Perhaps you can not expect deterministic results when changing
__bases__while doing a type lookup.[3.13] gh-133122: Fix for test_type_lookup_mro_reference. (gh-133127)