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mypy fails to recognise dunder init method override #15213
Description
Bug Report
In an inheritance scenario with pydantic.BaseModel and generics, mypy 1.2.0 fails to recognise an overridden __init__(),
and wrongly reports an error (see "actual behavior").
To Reproduce
from __future__ import annotations
from typing import Generic, List, Type, TypeVar
from pydantic import BaseModel, PrivateAttr
B_co = TypeVar("B_co", bound=BaseModel, covariant=True)
class Container(Generic[B_co], BaseModel):
"""Container is the base class for any item-type specific containers,
to allow bundling and processing of aggregates
"""
_item_class: Type[B_co] = PrivateAttr()
__root__: List[B_co]
def __init__(self, *args: B_co) -> None:
super().__init__(__root__=list(args))
def __len__(self) -> int:
return len(self.__root__)
def __getitem__(self, index: int) -> B_co:
return self.__root__[index]
class Item(BaseModel):
name: str
class Items(Container[Item]):
_item_class = Item
items = Items(Item(name="one"), Item(name="two"))
print(items)Expected Behavior
The overridden __init__ method in the Container class has the correct signature, and mypy should not flag any issues.
Actual Behavior
ttt/ttt.py:33: error: Too many arguments for "Items" [call-arg]
ttt/ttt.py:33: error: Too many positional arguments for "Items" [misc]
ttt/ttt.py:33: error: Argument 1 to "Items" has incompatible type "Item"; expected "List[B_co]" [arg-type]
Found 3 errors in 1 file (checked 1 source file)
Your Environment
- Mypy version used: 1.2.0
- Mypy command-line flags: none
- Mypy configuration options from
mypy.ini(and other config files):
[tool.mypy]
python_version = "3.10"
strict = true
namespace_packages = false
explicit_package_bases = false
plugins = [
"pydantic.mypy"
]
follow_imports = "silent"
warn_redundant_casts = true
warn_unused_ignores = true
disallow_any_generics = true
check_untyped_defs = true
no_implicit_reexport = true
disallow_untyped_defs = true
[[tool.mypy.overrides]]
module = [
"html_text.*"
]
ignore_missing_imports = true
ignore_errors = true
[tool.pydantic-mypy]
init_forbid_extra = true
init_typed = true
warn_required_dynamic_aliases = true
warn_untyped_fields = true
- Python version used: 3.10.10
- Other versions: pydantic=1.10.7, typing-extensions=4.5.0
Activity
wesleywright commentedon May 9, 2023
Are you using the Pydantic MyPy plugin? Some functionality works better with the plugin, particularly since MyPy started adding support for
dataclass_transformin 1.1.1. (dataclass_transformstandardizes a subset of the functionality that Pydantic offers; with vanilla MyPy, only that subset can be typechecked. The plugin adds additional functionality that's not in thedataclass_transformstandard.)marekro commentedon May 9, 2023
Yes, I pasted the poetry config, listing the mypy pydantic plugin. The error message however appears, at least in my setup, with and without the plugin enabled. This error did not appear with mypy 1.0.
It seems that pydantic support wrongly takes precedence over the specific __init__ method.