Bug report

Bug description:

PEP 702 – Marking deprecations using the type system introduces a new API warnings.deprecated for deprecation.

While decorating a class object, it will update the __new__ method:

and the __init_subclass__ method:

For a class (cls) that does not implement the __new__ and __init_subclass__ methods, the warnings.deprecated decorator will generate these two methods (based on object.__new__ and type.__init_subclass__ ) and assign them to cls.__dict__.

However, if users want to inspect the methods in cls.__dict__, the inspect module fails to get the correct definition of cls.__new__. It is defined in warnings.py rather than object.__new__.

# test.py

from warnings import deprecated  # or from typing_extensions import deprecated


class Foo:
    def __new__(cls):
        return super().__new__(cls)


@deprecated("test")
class Bar:
    pass

In [1]: import inspect

In [2]: from test import Foo, Bar

In [3]: inspect.getsourcelines(Foo.__new__)
Out[3]: (['    def __new__(cls):\n', '        return super().__new__(cls)\n'], 7)

In [4]: inspect.getsourcelines(Bar.__new__) 
TypeError: module, class, method, function, traceback, frame, or code object was expected, got builtin_function_or_method

Expected to have inspect.getsourcelines(Bar.__new__) to be source code in /.../lib/python3.13/warnings.py.

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Linked PRs

• gh-119605: Respect follow_wrapped for __init__ and __new__ when getting class signature with inspect.signature #132055
• [3.13] gh-119605: Respect follow_wrapped for __init__ and __new__ when getting class signature with inspect.signature (GH-132055) #133277