for non ABC base class, abstract method with NotImplementedError be infer as Never then in an inconsistent manner

[asukaminato0721]

Describe the Bug

I wonder is this by design?

from abc import ABC, abstractmethod
class A:
    @abstractmethod
    def foo(self):
        raise NotImplementedError()

class B(A):
    def foo(self):
        x = 1
        print(x)

Sandbox Link

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeSIAxAAQDqMUAxrgLYzUAuunAFuwAqkATjDBRS1AMoYcBADS8IcakuqpqxVAHMYAHXQ0A7nxHVSuAK7VGGaoaEQOMBXB6pTM6rHfo1eCxycpMQQ6FoqvoIcPLjohPqUCdQAEjAeHtaWxLDUYDCoHBYiyrhgispoWHj4iEkAtNQA4jCBIqhQdRwQbEHE7Ix8jADWoeF5MDiow-XUAKpw7CIAbvlQAPocwTAAFACUnNyhcH2MgaF5QiKYvfAzMPh9DmzogYaOPLzsAJIAIgCiuXyhWKvAKdnYcAsxGIuCEgW2MEIWkIagCuGYLGyLWc1C0uE6%2BMwolCjggsQUMRWQgULUYuxmtAcTjUWGoQgskVI0VimSJ1EwEBEp3EETMliE1GwQlwhgWQn0%2BjA0pYfkYKkxsMCAEEAEIAYQUqGwcA4QimHDY3Mw%2BkYUFQcGUWtqvmoroAAkaTWbTpaYtaXa6iWUwLhcNsFlAwLtna7Y7GzUp2AA5XAcL6Y2DPJyYP6XWF7BXoW325Q67Za6P6ONB3Kh8MMKMxuOx-DUAC81AAjFXm67iA4Xtt8PT0CA5CAAtA4CRyIgqHMulBHBIwBzTmT0HBCzWQ0IWAU1ugLCxsGkh4gIhx9nUAHzUL1N10iYG%2BMC6EBJ4%2BnoQX4D4AC%2B776GOIBkCIYikIQXAsFAFA0II4EipUsitsw6CQFoRQFBu8QGFIMDsDwHAcMQcCIAA9ORYGiOIhCwlo5EwOg5GYOicDkWhGFYV0sTkbWEqoEsqDQEaOScRAmFmjxvi4MQ0nTvoZDcugdRUnAG7ttQ74AMyEJ2ABMQGjv%2B47mhAKwAGLQDAFDIdUM4gP%2BQA

(Only applicable for extension issues) IDE Information

No response

[asukaminato0721]

seems like code bug...

https://stackoverflow.com/questions/49051638/python-abstract-method-in-normal-class

[yangdanny97]

I wonder if we should warn against this pattern

[grievejia]

Regardless of the ABC issue, It's probably undesirable to infer Never as the base class return type. Local experiments showed ~1000+ FPs in projects like this across prefect, sqlalchmy and django

[asukaminato0721]

I wonder if we should warn against this pattern

astral-sh/ruff#14688 not merged yet though.

[asukaminato0721]

Regardless of the ABC issue, It's probably undesirable to infer Never as the base class return type. Local experiments showed ~1000+ FPs in projects like this across prefect, sqlalchmy and django

I think for raise not Implemented, we can infer Any instead?

[yangdanny97]

astral-sh/ruff#14688 not merged yet though

Hmm, if the addition to Ruff isn't happening in the part we import (the parser) we might want to re-implement this (as a followup, fixing the inference takes first priority)

I think for raise not Implemented, we can infer Any instead?

Seems reasonable, worth trying and seeing what mypy primer says, at least.