underscore_attrs_are_private breaks generics #2138
Description
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- I added a descriptive title to this issue
- I have searched (google, github) for similar issues and couldn't find anything
- I have read and followed the docs and still think this is a bug
Bug
Output of python -c "import pydantic.utils; print(pydantic.utils.version_info())":
pydantic version: 1.7.2
pydantic compiled: False
install path: /nix/store/4snc9a6ywd1m75z7k5v863h9kl3s38dy-python3.7-pydantic-1.7.2/lib/python3.7/site-packages/pydantic
python version: 3.7.7 (default, Mar 10 2020, 06:34:06) [GCC 9.3.0]
platform: Linux-4.15.0-123-generic-x86_64-with-debian-buster-sid
optional deps. installed: ['typing-extensions', 'email-validator']
The underscore_attrs_are_private config option seems to break generics. In particular, it seems to be messing up with the model's __orig_bases__, which ends up causing a TypeError in typing.Generic. Unfortunately, I'm not familiar enough with Pydantic's code to pinpoint the exact root of the issue.
To reproduce:
from pydantic.generics import GenericModel
from typing import TypeVar, Generic
T = TypeVar('T')
class Model(GenericModel, Generic[T]):
class Config:
underscore_attrs_are_private = True
value: TOutput:
TypeError Traceback (most recent call last)
<ipython-input-17-86d3af5f0365> in <module>
----> 1 class Model(GenericModel, Generic[T]):
2 class Config:
3 underscore_attrs_are_private = True
4 id: T
5
/nix/store/5mlyrz5jm75dbjd92wsq89b9lsd0bhww-python3-3.7.7-env/lib/python3.7/site-packages/pydantic/main.py in __new__(mcs, name, bases, namespace, **kwargs)
322 }
323
--> 324 cls = super().__new__(mcs, name, bases, new_namespace, **kwargs)
325 # set __signature__ attr only for model class, but not for its instances
326 cls.__signature__ = ClassAttribute('__signature__', generate_model_signature(cls.__init__, fields, config))
/nix/store/k2w1idz2vdag50xl88113845mr74z823-python3-3.7.7/lib/python3.7/abc.py in __new__(mcls, name, bases, namespace, **kwargs)
124 """
125 def __new__(mcls, name, bases, namespace, **kwargs):
--> 126 cls = super().__new__(mcls, name, bases, namespace, **kwargs)
127 _abc_init(cls)
128 return cls
/nix/store/k2w1idz2vdag50xl88113845mr74z823-python3-3.7.7/lib/python3.7/typing.py in __init_subclass__(cls, *args, **kwargs)
848 tvars = []
849 if '__orig_bases__' in cls.__dict__:
--> 850 error = Generic in cls.__orig_bases__
851 else:
852 error = Generic in cls.__bases__ and cls.__name__ != '_Protocol'
TypeError: argument of type 'member_descriptor' is not iterableRemoving underscore_attrs_are_private or setting it to False makes it work as expected. Using PrivateAttr instead of the config option works well too.