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_PyObject_StoreInstanceAttribute assertion fails in setattr after __dict__.clear() #117750

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_PyObject_StoreInstanceAttribute assertion fails in setattr after __dict__.clear()#117750
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markshannon
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interpreter-core(Objects, Python, Grammar, and Parser dirs)release-blockertype-bugAn unexpected behavior, bug, or error

Description

@encukou
encukou
opened on Apr 11, 2024

Bug report

Bug description:

On current main (edit: debug build),

class C:
    def __init__(self):
        self.__dict__.clear()


obj = C()
obj.foo = None

fails with:

python: Objects/dictobject.c:6704: _PyObject_StoreInstanceAttribute: Assertion 'dict->ma_values == values' failed.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Notes

Originally reported here: https://discuss.python.org/t/python-3-12-3-and-3-13-0a6-released/50601/2

Linked PRs

Activity

  1. encukou
    added
    type-bugAn unexpected behavior, bug, or error
    interpreter-core(Objects, Python, Grammar, and Parser dirs)
    release-blocker
    on Apr 11, 2024
  2. ezio-melotti
    added this to Release and Deferred blockers 🚫on Apr 11, 2024
  3. github-project-automation
    moved this to Todo in Release and Deferred blockers 🚫on Apr 11, 2024

  4. encukou commented on Apr 11, 2024

    @encukou
    encukou
    on Apr 11, 2024
    MemberAuthor

    Bisected to #116115

  5. gvanrossum
    assigned
    markshannon
    on Apr 12, 2024

  6. hroncok commented on Apr 12, 2024

    @hroncok
    hroncok
    on Apr 12, 2024
    Contributor

    In Fedora, we see a similar problem when trying to import django.conf.urls when building Django, but it's different. Commenting here, because @encukou asked us if the debug-build assertion is the same:

    Traceback (most recent call last):
  File "/usr/lib/rpm/redhat/import_all_modules.py", line 171, in <module>
    main()
    ~~~~^^
  File "/usr/lib/rpm/redhat/import_all_modules.py", line 167, in main
    import_modules(modules)
    ~~~~~~~~~~~~~~^^^^^^^^^
  File "/usr/lib/rpm/redhat/import_all_modules.py", line 100, in import_modules
    importlib.import_module(module)
    ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
  File "/usr/lib64/python3.13/importlib/__init__.py", line 88, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1387, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1360, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1331, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 935, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 1020, in exec_module
  File "<frozen importlib._bootstrap>", line 488, in _call_with_frames_removed
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/conf/urls/__init__.py", line 1, in <module>
    from django.urls import include
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/urls/__init__.py", line 1, in <module>
    from .base import (
    ...<11 lines>...
    )
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/urls/base.py", line 8, in <module>
    from .exceptions import NoReverseMatch, Resolver404
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/urls/exceptions.py", line 1, in <module>
    from django.http import Http404
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/http/__init__.py", line 9, in <module>
    from django.http.response import (
    ...<16 lines>...
    )
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/http/response.py", line 19, in <module>
    from django.core.serializers.json import DjangoJSONEncoder
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/core/serializers/__init__.py", line 23, in <module>
    from django.core.serializers.base import SerializerDoesNotExist
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/core/serializers/base.py", line 9, in <module>
    from django.db import models
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/db/__init__.py", line 50, in <module>
    signals.request_started.connect(reset_queries)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/dispatch/dispatcher.py", line 83, in connect
    if settings.configured and settings.DEBUG:
                               ^^^^^^^^^^^^^^
  File "/builddir/build/BUILDROOT/python-django-4.2.11-3.fc41.x86_64/usr/lib/python3.13/site-packages/django/conf/__init__.py", line 104, in __getattr__
    val = getattr(_wrapped, name)
          ~~~~~~~^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'DEBUG'
python3-debug: /builddir/build/BUILD/Python-3.13.0a6/Objects/dictobject.c:7119: _PyObject_InlineValuesConsistencyCheck: Assertion `0' failed.

  7. hroncok commented on Apr 12, 2024

    @hroncok
    hroncok
    on Apr 12, 2024
    Contributor

    The Django problem can be reproduced with:

    $ python3.13d -m venv venv3.13d
$ venv3.13d/bin/pip install django==5.0.4
$ venv3.13d/bin/python -c 'import django.conf.urls'
...
AttributeError: 'NoneType' object has no attribute 'DEBUG'
python: /builddir/build/BUILD/Python-3.13.0a6/Objects/dictobject.c:7119: _PyObject_InlineValuesConsistencyCheck: Assertion `0' failed.
  8. markshannon
    added a commit that references this issue on Apr 15, 2024

    GH-117750: When clearing object's dict, clear inline values but leave…

    784e076

  9. thmo commented on Apr 15, 2024

    @thmo
    thmo
    on Apr 15, 2024

    Here's a small reproducer for the AttributeError case:

    class A():
    pass

a = A()
vars(a).clear()
vars(a).update({'foo':'bar'})
print(vars(a))
print(a.foo)

    Works with 3.12, fails with 3.13a06.

  10. gvanrossum commented on Apr 16, 2024

    @gvanrossum
    gvanrossum
    on Apr 16, 2024
    Member

    Fixed in main, so this can be closed.

  11. gvanrossum
    closed this as completedon Apr 16, 2024
  12. github-project-automation
    moved this from Todo to Done in Release and Deferred blockers 🚫on Apr 16, 2024

  13. hroncok commented on Apr 16, 2024

    @hroncok
    hroncok
    on Apr 16, 2024
    Contributor

    The _PyObject_InlineValuesConsistencyCheck in Django is also fixed on main.

  14. diegorusso
    added a commit that references this issue on Apr 17, 2024

    pythonGH-117750: When clearing object's dict, clear inline values but…

    f667a76
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