Bug Report

If the base class / prototype has a method that accepts only *args: Any or / and **kwargs: Any, mypy doesn't show any errors, even if the child class accepts only limited set of parameters. If I add a: int to foo in the base class, nothing changes. If I add b: int to foo in the base class, mypy show an error "Signature of "foo" incompatible with supertype "HasFoo"", that is expected.

To Reproduce

from typing import Protocol, Any


class HasFoo:
    def foo(self, *arg: Any, **kwargs: Any) -> str: return 'foo'


class Foo(HasFoo):
    def foo(self, a: int) -> str:
        print(a)
        return 'foo'
        

f: HasFoo = Foo()
f.foo(3, 4, 5)

Gist URL: https://gist.github.com/mypy-play/1a858925c056f8b5391e09a247b29ece
Playground URL: https://mypy-play.net/?mypy=latest&python=3.13&gist=1a858925c056f8b5391e09a247b29ece

Expected Behavior

Mypy should raise an error "Signature of "foo" incompatible with supertype "HasFoo"".

Actual Behavior

Mypy doesn't raise any errors. The code above fails in runtime.

Your Environment

• Mypy version used: 1.15.0
• Mypy command-line flags: -
• Mypy configuration options from mypy.ini (and other config files):

[tool.mypy]
disallow_untyped_defs = true
disallow_any_unimported = true
no_implicit_optional = true
check_untyped_defs = true
warn_return_any = true
warn_unused_ignores = true
packages = ['src']

• Python version used: 3.13.3