René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"list is not equivalent to typing.List under combination of generics and futures","articleBody":"### Initial Checks\n\n- [X] I have searched GitHub for a duplicate issue and I'm sure this is something new\n- [X] I have searched Google & StackOverflow for a solution and couldn't find anything\n- [X] I have read and followed [the docs](https://docs.pydantic.dev) and still think this is a bug\n- [X] I am confident that the issue is with pydantic (not my code, or another library in the ecosystem like [FastAPI](https://fastapi.tiangolo.com) or [mypy](https://mypy.readthedocs.io/en/stable))\n\n\n### Description\n\nThis is a strange one - under the below conditions, exchanging `typing.List` for the more modern `list` produces the below error. I can't reproduce in a simpler example than this - it looks to me like a bug in pydantic:\r\n\r\n```\r\nTraceback (most recent call last):\r\n  File \"pydantic/validators.py\", line 751, in pydantic.validators.find_validators\r\nTypeError: issubclass() arg 1 must be a class\r\n\r\nDuring handling of the above exception, another exception occurred:\r\n\r\nTraceback (most recent call last):\r\n  File \"{path_to_test}/test.py\", line 11, in \u003cmodule>\r\n    outer = Outer[\"Inner\"]\r\n  File \"{path_to_pydantic}/pydantic/generics.py\", line 163, in __class_getitem__\r\n    _prepare_model_fields(created_model, fields, instance_type_hints, typevars_map)\r\n  File \"{path_to_pydantic}/pydantic/generics.py\", line 389, in _prepare_model_fields\r\n    field.prepare()\r\n  File \"pydantic/fields.py\", line 552, in pydantic.fields.ModelField.prepare\r\n  File \"pydantic/fields.py\", line 758, in pydantic.fields.ModelField._type_analysis\r\n  File \"pydantic/fields.py\", line 808, in pydantic.fields.ModelField._create_sub_type\r\n  File \"pydantic/fields.py\", line 436, in pydantic.fields.ModelField.__init__\r\n  File \"pydantic/fields.py\", line 557, in pydantic.fields.ModelField.prepare\r\n  File \"pydantic/fields.py\", line 831, in pydantic.fields.ModelField.populate_validators\r\n  File \"pydantic/validators.py\", line 760, in find_validators\r\nRuntimeError: error checking inheritance of 'Inner' (type: str)\r\n```\r\n\r\nI've also displayed the minimal example below - thanks!\n\n### Example Code\n\n```Python\nfrom typing import Generic, List, TypeVar\r\n\r\nfrom pydantic import BaseModel\r\nfrom pydantic.generics import GenericModel\r\n\r\nChangingType = TypeVar(\"ChangingType\")\r\n\r\nclass Outer(GenericModel, Generic[ChangingType]):\r\n    fields_: list[ChangingType] # Swapping list -> List on this line fixes the bug\r\n\r\nouter = Outer[\"Inner\"]\r\nclass Inner(BaseModel):\r\n    new: list[outer]\r\n\r\nouter.update_forward_refs()\r\nInner.update_forward_refs()\r\n\r\nout = Inner.parse_obj({\"new\": [{\"fields_\": []}]})\r\n\r\nprint(out)\n```\n\n\n### Python, Pydantic & OS Version\n\n```Text\npydantic version: 1.10.9\r\npydantic compiled: True\r\ninstall path: /{package location}/.venv/lib64/python3.10/site-packages/pydantic\r\npython version: 3.10.10 (main, Feb  8 2023, 00:00:00) [GCC 12.2.1 20221121 (Red Hat 12.2.1-4)]\r\nplatform: Linux-5.10.16.3-microsoft-standard-WSL2-x86_64-with-glibc2.35\r\noptional deps. installed: ['typing-extensions']\n```\n\n\n### Affected Components\n\n- [ ] [Compatibility between releases](https://docs.pydantic.dev/changelog/)\n- [ ] [Data validation/parsing](https://docs.pydantic.dev/usage/models/#basic-model-usage)\n- [ ] [Data serialization](https://docs.pydantic.dev/usage/exporting_models/) - `.dict()` and `.json()`\n- [ ] [JSON Schema](https://docs.pydantic.dev/usage/schema/)\n- [ ] [Dataclasses](https://docs.pydantic.dev/usage/dataclasses/)\n- [ ] [Model Config](https://docs.pydantic.dev/usage/model_config/)\n- [x] [Field Types](https://docs.pydantic.dev/usage/types/) - adding or changing a particular data type\n- [ ] [Function validation decorator](https://docs.pydantic.dev/usage/validation_decorator/)\n- [X] [Generic Models](https://docs.pydantic.dev/usage/models/#generic-models)\n- [ ] [Other Model behaviour](https://docs.pydantic.dev/usage/models/) - `construct()`, pickling, private attributes, ORM mode\n- [ ] [Plugins](https://docs.pydantic.dev/) and integration with other tools - mypy, FastAPI, python-devtools, Hypothesis, VS Code, PyCharm, etc.","author":{"url":"https://github.com/mark-todd","@type":"Person","name":"mark-todd"},"datePublished":"2023-06-14T10:26:47Z","url":"https://github.com/pydantic/pydantic/issues/6130"}