Generic Models cannot be typed with BaseModel subclasses

[hblunck]

Initial Checks

• I confirm that I'm using Pydantic V2

Description

I have created a generic class. Now I want to create a concrete subclass passing pydantic's BaseModel (or any class derived from it) as "placeholder". Upon creating the class (no instantiation required), pydantic throws an error.

Last entry in the call stack is:

File ~\<OMITTED>\pydantic\_internal\_model_construction.py:205, in ModelMetaclass.__getattr__(self, item)
    202         if rebuilt_validator is not None:
    203             # In this case, a validator was built, and so `__pydantic_core_schema__` should now be set
    204             return getattr(self, '__pydantic_core_schema__')
--> 205 raise AttributeError(item)

Raising

AttributeError: pydantic_generic_metadata

Example Code

from typing import TypeVar, Generic
from pydantic import BaseModel

T = TypeVar("T")

class SimpleGenericModel(
    BaseModel, Generic[T]
):
    pass

class Concrete(
    SimpleGenericModel[BaseModel]
):
    pass

Python, Pydantic & OS Version

pydantic version: 2.1.1
        pydantic-core version: 2.4.0
          pydantic-core build: profile=release pgo=false mimalloc=true
                 install path: <OMITTED>
               python version: 3.8.13 | packaged by conda-forge | (default, Mar 25 2022, 05:59:00) [MSC v.1929 64 bit (AMD64)]
                     platform: Windows-10-10.0.19045-SP0
     optional deps. installed: ['typing-extensions']

Selected Assignee: @lig

[dmontagu]

Thanks for reporting! Should be fixed by #6933.