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Description
Bug Report
When using a dataclass with slots=True or __slots__, if an argument to a function is annotated with Self (not necessarily the self argument), then assigning to an attribute not annotated in slots doesn't raise an error.
To Reproduce
Type check the below (playground).
from dataclasses import dataclass
from typing import Self
@dataclass(slots=True)
class Exp:
x: int
def foo(self) -> None:
self.y = 1
def bar(self, arg: Self) -> None:
self.y = 1
def baz(self: Self) -> None:
self.y = 1
class Exp2:
__slots__ = 'x',
x: int
def foo(self) -> None:
self.y = 1
def bar(self, arg: Self) -> None:
self.y = 1
def baz(self: Self) -> None:
self.y = 1Expected Behavior
All 3 invalid asignments to y would raise an error, dataclass or not.
Actual Behavior
Only the foo function raises an error for assigning to an attribute not in slots.
main.py:8: error: Trying to assign name "y" that is not in "__slots__" of type "__main__.Exp" [misc]
main.py:18: error: Trying to assign name "y" that is not in "__slots__" of type "__main__.Exp2" [misc]
Found 2 errors in 1 file (checked 1 source file)
Your Environment
- Mypy version used: 1.16.1
- Python version used: 3.12