Warn when using deprecated functions (warnings.warn)

[KotlinIsland]

Feature

import warnings
from typing import NoReturn

def foo() -> NoReturn:
    warnings.warn("this is deprecated", DeprecationWarning)
    raise NotImplementedError

foo()  # I would expect a warning here

Pitch

I think it would be based to report against deprecated methods, PyCharm supports this:

Another use case for this is warning of "unsupported operations":

class A:
    def foo(self) -> None:
        print()

class B(A):
    def foo(self) -> NoReturn:
        warnings.warn("this is an unsupported operation", DeprecationWarning)
        raise NotImplementedError()


B().foo()  # I would like a warning that this is unsupported

[hauntsaninja]

Thanks for the suggestion! PEP 702 is the way mypy would do this.

[bluenote10]

@hauntsaninja What is the status of supporting PEP 702 in mypy? I tried to find some information or a tracking issue, but on first glance I couldn't find anything.

[hauntsaninja]

Feel free to open a tracking issue, or even better, a PR that implements it. Note that PEP 702 hasn't yet been officially accepted, so support would be provisional.