Class with attribute function thinks first argument is self

[spagh-eddie]

Bug Report

I find this very similar to issue #5485.

I found myself using this flavor of idiom so as to not repeat myself when implementing comparison operations, etc.

To Reproduce

from operator import itemgetter

class A:
    id_getter = itemgetter('this', 'that', 'other')
    def __init__(self, d):
        self.d = d
    def __hash__(self) -> int:
        return hash(self.id_getter(self.d))

a = A({'this': 1, 'that': 2, 'other': 'a', 'extra': 'b'})
hash(a)

Expected Behavior

No error

Actual Behavior

$ mypy example.py
example.py:8: error: Too many arguments
Found 1 error in 1 file (checked 1 source file)

I tried to annotate id_getter: ClassVar[Callable[[Dict], Tuple[int, int, str]]] but just got back an additional error

examply.py:8: error: Invalid self argument "A" to attribute function "id_getter" with type "Callable[[Dict[Any, Any]], Tuple[Any, ...]]"

Your Environment

$ mypy --version
mypy 0.812

No flags or ini file.

[hauntsaninja]

Fixed by #10548