Overriding callable attribute with method not caught by [mutable-override] #18052
Description
Bug Report
Mypy has an optional error code mutable-override that checks for unsafe overrides of mutable attributes:
class Parent:
x: float
class Child(Parent):
x: int # E: Covariant override of a mutable attribute (base class "Parent" defined the type as "float", expression has type "int") [mutable-override]However, this error isn't emitted when overriding a callable attribute with a method:
from typing import Callable
class Parent:
func: Callable[[str], None]
class Child(Parent):
def func(self, x: object) -> None: pass # no errorThis allows dubious code like the following to pass type checking:
def foo(x: str) -> None:
assert isinstance(x, str)
def modify_parent(x: Parent) -> None:
x.func = foo
c = Child()
modify_parent(c)
c.func(1) # boom!Your Environment
- Mypy version used: master (1.14.0+dev.2b033cbd7)
- Mypy command-line flags:
--strict --enable-error-code=mutable-override - Mypy configuration options from
mypy.ini(and other config files): N/A (empty) - Python version used: 3.12.7