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Incompatible override with **kwargs TypedDict and Any #13491
Description
Bug Report
Came across this override error while testing **kwargs unpack from #13471.
/CC: @ilevkivskyi
To Reproduce
from typing import Any, TypedDict
from typing_extensions import Unpack
class Details(TypedDict, total=False):
arg: str
value: int
class Parent:
def turn_on(self, **kwargs: Any) -> None: ...
class Child(Parent):
def turn_on(self, **kwargs: Unpack[Details]) -> None: ... # <-- errorExpected Behavior
The parent methods uses Any as annotation for **kwargs. Any override with Upack[_TypedDict_] should be compatible.
Actual Behavior
test.py:13: error: Signature of "turn_on" incompatible with supertype "Parent" [override]
test.py:13: note: Superclass:
test.py:13: note: def turn_on(self, **kwargs: Any) -> None
test.py:13: note: Subclass:
test.py:13: note: def turn_on(*, arg: str = ..., value: int = ...) -> None
Your Environment
- Mypy version used: mypy
0.980+dev.0c0f071ef5d41c24182a5a94a5db882f9e917802 (compiled: no) - Mypy command-line flags:
--enable-incomplete-features - Python version used:
3.10
Activity
ilevkivskyi commentedon Aug 23, 2022
This is not a bug. This actually violates Liskov. The suppertype can accept arbitrary keywords, while subtype only some.
If you really want to express "I don't care about arguments", use
*args: Any, **kwargs: Any. Mypy special-cases this as "whatever works".cdce8p commentedon Aug 23, 2022
Doesn't that depend on the definition of completeness? I.e. the TypedDict defines the keyword arguments which
mustbe present, but just technically you can still pass any other arguments to it, as well. The code wouldn't break.I also checked pyright, which does not emit an error, at the moment.
Adding
*argsisn't an option in this case, unfortunately.ilevkivskyi commentedon Aug 23, 2022
Allowing arbitrary keywords will significantly reduce safety. Imagine:
Well, use pyright then.