IntFlag Enum - broken after py3.11

Reproduce la prueba proporcionada con Python 3.11–3.13 y, después, inspecciona cloudpickle/cloudpickle.py en _class_setstate alrededor de la línea 1177 y el comportamiento de Enum mostrado en el traceback. Se considera terminado cuando el valor de IntFlag hace round-trip a través de cloudpickle sin el error de reasignación del miembro, mientras el comportamiento existente de Enum sigue siendo satisfactorio.

Hi!
cloudpickling for IntFlag Enum seems to be broken after python 3.11

cloudpickle version : 3.1.1

Test Code

import enum
import cloudpickle
import pickle
import sys
print(sys.version)

class EnumClass(enum.Enum):
    RANK_0 = 11
    RANK_1 = 37
    RANK_2 = 389


class IntFlagClass(enum.IntFlag):
    RANK_0 = 11
    RANK_1 = 37
    RANK_2 = 389

    
def test(pickler, value):
    print(f"testing {pickler} for {value} ... ", end="")
    
    pickled = pickler.dumps(value)
    unpickled = pickler.loads(pickled)
    assert(unpickled == value)
    
    print(f" success.")

for mod in [pickle, cloudpickle]:
    for val in [EnumClass.RANK_1, IntFlagClass.RANK_1]:
        test(mod, val)

Results for python 3.8 to 3.10, which is fine

3.8.20 (default, Oct  3 2024, 10:22:23)
[Clang 14.0.6 ]
testing <module 'pickle' from '~/test/py3.8/lib/python3.8/pickle.py'> for EnumClass.RANK_1 ...  success.
testing <module 'pickle' from '~/test/py3.8/lib/python3.8/pickle.py'> for 37 ...  success.
testing <module 'cloudpickle' from '~/test/py3.8/lib/python3.8/site-packages/cloudpickle/__init__.py'> for EnumClass.RANK_1 ...  success.
testing <module 'cloudpickle' from '~/test/py3.8/lib/python3.8/site-packages/cloudpickle/__init__.py'> for 37 ...  success.

3.9.21 (main, Dec 11 2024, 10:21:40)
[Clang 14.0.6 ]
testing <module 'pickle' from '~/test/py3.9/lib/python3.9/pickle.py'> for EnumClass.RANK_1 ...  success.
testing <module 'pickle' from '~/test/py3.9/lib/python3.9/pickle.py'> for 37 ...  success.
testing <module 'cloudpickle' from '~/test/py3.9/lib/python3.9/site-packages/cloudpickle/__init__.py'> for EnumClass.RANK_1 ...  success.
testing <module 'cloudpickle' from '~/test/py3.9/lib/python3.9/site-packages/cloudpickle/__init__.py'> for 37 ...  success.

3.10.16 (main, Dec 11 2024, 10:22:29) [Clang 14.0.6 ]
testing <module 'pickle' from '~/test/py3.10/lib/python3.10/pickle.py'> for EnumClass.RANK_1 ...  success.
testing <module 'pickle' from '~/test/py3.10/lib/python3.10/pickle.py'> for 37 ...  success.
testing <module 'cloudpickle' from '~/test/py3.10/lib/python3.10/site-packages/cloudpickle/__init__.py'> for EnumClass.RANK_1 ...  success.
testing <module 'cloudpickle' from '~/test/py3.10/lib/python3.10/site-packages/cloudpickle/__init__.py'> for 37 ...  success.

We get same error for python 3.11 to 3.13

3.11.11 (main, Dec 11 2024, 10:25:04) [Clang 14.0.6 ]
testing <module 'pickle' from '~/test/py3.11/lib/python3.11/pickle.py'> for EnumClass.RANK_1 ...  success.
testing <module 'pickle' from '~/test/py3.11/lib/python3.11/pickle.py'> for 37 ...  success.
testing <module 'cloudpickle' from '~/test/py3.11/lib/python3.11/site-packages/cloudpickle/__init__.py'> for EnumClass.RANK_1 ...  success.
testing <module 'cloudpickle' from '~/test/py3.11/lib/python3.11/site-packages/cloudpickle/__init__.py'> for 37 ... Traceback (most recent call last):
  File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 30, in <module>
    test(mod, val)
  File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 23, in test
    unpickled = pickler.loads(pickled)
                ^^^^^^^^^^^^^^^^^^^^^^
  File "~/test/py3.11/lib/python3.11/site-packages/cloudpickle/cloudpickle.py", line 1177, in _class_setstate
    setattr(obj, attrname, attr)
  File "~/test/py3.11/lib/python3.11/enum.py", line 838, in __setattr__
    raise AttributeError('cannot reassign member %r' % (name, ))
AttributeError: cannot reassign member 'RANK_0'



3.12.9 | packaged by Anaconda, Inc. | (main, Feb  6 2025, 12:55:12) [Clang 14.0.6 ]
testing <module 'pickle' from '~/test/py3.12/lib/python3.12/pickle.py'> for EnumClass.RANK_1 ...  success.
testing <module 'pickle' from '~/test/py3.12/lib/python3.12/pickle.py'> for 37 ...  success.
testing <module 'cloudpickle' from '~/test/py3.12/lib/python3.12/site-packages/cloudpickle/__init__.py'> for EnumClass.RANK_1 ...  success.
testing <module 'cloudpickle' from '~/test/py3.12/lib/python3.12/site-packages/cloudpickle/__init__.py'> for 37 ... Traceback (most recent call last):
  File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 30, in <module>
    test(mod, val)
  File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 23, in test
    unpickled = pickler.loads(pickled)
                ^^^^^^^^^^^^^^^^^^^^^^
  File "~/test/py3.12/lib/python3.12/site-packages/cloudpickle/cloudpickle.py", line 1177, in _class_setstate
    setattr(obj, attrname, attr)
  File "~/test/py3.12/lib/python3.12/enum.py", line 854, in __setattr__
    raise AttributeError('cannot reassign member %r' % (name, ))
AttributeError: cannot reassign member 'RANK_0'



3.13.2 | packaged by Anaconda, Inc. | (main, Feb  6 2025, 12:55:35) [Clang 14.0.6 ]
testing <module 'pickle' from '~/test/py3.13/lib/python3.13/pickle.py'> for EnumClass.RANK_1 ...  success.
testing <module 'pickle' from '~/test/py3.13/lib/python3.13/pickle.py'> for 37 ...  success.
testing <module 'cloudpickle' from '~/test/py3.13/lib/python3.13/site-packages/cloudpickle/__init__.py'> for EnumClass.RANK_1 ...  success.
testing <module 'cloudpickle' from '~/test/py3.13/lib/python3.13/site-packages/cloudpickle/__init__.py'> for 37 ... Traceback (most recent call last):
  File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 30, in <module>
    test(mod, val)
    ~~~~^^^^^^^^^^
  File "/Users/ekrem/Desktop/work/test/pickle_test.py", line 23, in test
    unpickled = pickler.loads(pickled)
  File "~/test/py3.13/lib/python3.13/site-packages/cloudpickle/cloudpickle.py", line 1177, in _class_setstate
    setattr(obj, attrname, attr)
    ~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File "~/test/py3.13/lib/python3.13/enum.py", line 835, in __setattr__
    raise AttributeError('cannot reassign member %r' % (name, ))
AttributeError: cannot reassign member 'RANK_0'