Detecting extra `overload` entries after `*`

[jamesbraza]

Feature

mypy==1.18.2 is not detecting the b as extra here after the *:

from typing import overload


@overload
def some_method(a: int, **kwargs) -> None: ...
@overload
def some_method(a: str, *, b: None = None, **kwargs) -> None: ...


def some_method(a: int | str, **kwargs) -> None:
    pass

It may also be that due to **kwargs, that a type checker can't do anything here.

Pitch

Detecting extra overload parameters to keep code clean.

[A5rocks]

Sorry, I don't quite follow. What would it mean for mypy to detect something as extra? (I don't know the terminology you're using...)

[jamesbraza]

Note that the second overload has an extra b: None = None. Perhaps it can be detected as extra and removed

[A5rocks]

Sorry I still don't follow. What makes b extra? If you remove it, some_method("5", b=4) becomes valid?

[jamesbraza]

The reason it's extra is b is not in the core signature of some_method at the bottom, it's just accidentally present in an overload

[A5rocks]

But this is intentional! For instance you can do this:

@overload
def f(x: int) -> str: ...

@overload
def f(y: str) -> int: ...

def f(*args, **kwargs) -> object: ...

And if your overloads use a parameter not allowed by the actual signature, mypy already warns.