Bug when type checking dynamic enum creation in a metaclass #18736
Description
Ran into this bug while type-checking a meta class which dynamically creates and stores an enum of all the target class' properties which are also decorated with a custom @ocr_series:
from pydantic import BaseModel
from pydantic._internal._model_construction import ModelMetaclass
from enum import Enum
class OCRContentMeta(ModelMetaclass):
def __new__(mcs, name, bases, namespace):
cls = super().__new__(mcs, name, bases, namespace)
# Collect all ocr_series cached_properties
series_names = [
name
for name, value in namespace.items()
if isinstance(value, cached_property)
and hasattr(value.func, "is_ocr_series")
]
# Create enum dynamically
cls.OCRValidationKind = Enum("OCRValidationKind", {name: name for name in series_names}) #! THIS IS src/my_project/core/document.py:94
return clsfrom functools import cached_property
class OCRSeries[T]:
...
class OCRContent(BaseModel, metaclass=OCRContentMeta):
text: str
@ocr_series # type: ignore[prop-decorator]
@cached_property
def numbers_float(self) -> OCRSeries[float]:
return OCRSeries[float]([float(x) for x in self.numbers.list])
...MyPy traceback:
~ uv run mypy --config-file pyproject.toml src/my_project --show-traceback
src/my_project/core/document.py:94: error: Enum type as attribute is not supported [misc]
src/my_project/core/document.py:94: error: Second argument of Enum() must be string, tuple, list or dict literal for mypy to determine Enum members [misc]
src/my_project/core/document.py:97: error: Type cannot be declared in assignment to non-self attribute [misc]
src/my_project/core/document.py:94: error: INTERNAL ERROR -- Please try using mypy master on GitHub:
https://mypy.readthedocs.io/en/stable/common_issues.html#using-a-development-mypy-build
Please report a bug at https://github.com/python/mypy/issues
version: 1.13.0
Traceback (most recent call last):
File "mypy/semanal.py", line 7113, in accept
File "mypy/nodes.py", line 1351, in accept
File "mypy/semanal.py", line 3141, in visit_assignment_stmt
File "mypy/semanal.py", line 3372, in record_special_form_lvalue
AssertionError:
src/my_project/core/document.py:94: : note: use --pdb to drop into pdb