erroneous complaint that overloaded function implementation does not accept all possible arguments of signature

Bug Report

Erroneous complaint that overloaded function implementation does not accept all possible arguments of signature.

To Reproduce

from datetime import datetime
from typing import overload

class Sample:

    @overload
    @classmethod
    def set(cls, year: int) -> None:
        ...

    @overload
    @classmethod
    def set(cls, instance: datetime, / ) -> None:
        ...

    @classmethod
    def set(cls, *args: datetime | int, **kw: int) -> None:
        pass

Expected Behavior

The above should pass type checking.

Pyright's happy enough:

$ pyright typing_bug.py 
0 errors, 0 warnings, 0 informations 

Actual Behavior

$ mypy typing_bug.py 
typing_bug.py:16: error: Overloaded function implementation does not accept all possible arguments of signature 1  [misc]
Found 1 error in 1 file (checked 1 source file)

Your Environment

• Mypy version used: 1.14.1 (compiled: yes)
• Mypy command-line flags: None, see above
• Mypy configuration options from mypy.ini (and other config files): None.
• Python version used: Python 3.12.1

typing_bug.py の報告を mypy 1.14.1 で再現し、結果を pyright と比較します。classmethod の例に対する overload 実装の互換性チェックを追跡します。完了の条件は、mypy が誤った指摘なしに示されたコードを受け入れ、互換性のない実装に対する妥当な診断を維持することです。