Report protocol problems in no_variant_matches_arguments if possible

Feature

Report protocol problems in no_variant_matches_arguments if possible.

Pitch

Given following example:

from typing import Protocol, overload


class Foo(Protocol):
    def some_method(self, value: int = 0) -> None: ...


class Bar:
    def some_method(self, value: int) -> None:
        pass


@overload
def accept_foo(value: Foo, v: int) -> None:
    pass


@overload
def accept_foo(value: Foo, v: float) -> None:
    pass


def accept_foo(value: Foo, v: int | float) -> None:
    pass


accept_foo(Bar(), 1)

The Bar has conflict with the Protocol Foo, but currently Mypy won't report the protocol problems. This is the current error report:

protocol_example.py:27: error: No overload variant of "accept_foo" matches argument types "Bar", "int"  [call-overload]
protocol_example.py:27: note: Possible overload variants:
protocol_example.py:27: note:     def accept_foo(value: Foo, v: int) -> None
protocol_example.py:27: note:     def accept_foo(value: Foo, v: float) -> None
Found 1 error in 1 file (checked 1 source file)

If we can report the protocol problems in this case, it may save developers time to figure out what' wrong.

I did a proof-of-concept implementation here: https://github.com/python/mypy/commit/a2040d3680320afbac6e13b3b04593a7965242bc. This is the updated error report:

protocol_example.py:27: error: No overload variant of "accept_foo" matches argument types "Bar", "int"  [call-overload]
protocol_example.py:27: note: Following member(s) of "Bar" have conflicts:
protocol_example.py:27: note:     Expected:
protocol_example.py:27: note:         def some_method(self, value: int = ...) -> None
protocol_example.py:27: note:     Got:
protocol_example.py:27: note:         def some_method(self, value: int) -> None
protocol_example.py:27: note:     Expected:
protocol_example.py:27: note:         def some_method(self, value: int = ...) -> None
protocol_example.py:27: note:     Got:
protocol_example.py:27: note:         def some_method(self, value: int) -> None
protocol_example.py:27: note: Possible overload variants:
protocol_example.py:27: note:     def accept_foo(value: Foo, v: int) -> None
protocol_example.py:27: note:     def accept_foo(value: Foo, v: float) -> None
Found 1 error in 1 file (checked 1 source file)

If this is OK, I'd happy to refine the implementation and submit a PR.

Thanks.

no_variant_matches_arguments のエントリポイントから始め、issue にリンクされた proof-of-concept commit を確認してください。提供された Protocol と overload の例を再現し、診断が競合するメンバーを重複した、または誤解を招く出力なしに正確に報告することを確認してください。