Bug report

Bug description:

Steps to reproduce:

• Create a module (testmodule.py):

  from warnings import deprecated
  
  @deprecated("Test")
  class A: pass

• In the Python shell, run:

  import testmodule
  help(testmodule) 

This will raise a TypeError:

  File "/fakepath/uv/python/cpython-3.13.1-linux-x86_64-gnu/lib/python3.13/pydoc.py", line 245, in parentname
    return object.__module__ + '.' + name
           ~~~~~~~~~~~~~~~~~~^~~~~
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

warnings.deprecated is defining custom __new__ and __init_subclass__ methods:

and because these methods don't have a __module__ available (maybe they should?), we end up with the above exception.

Should we special case deprecated classes and other objects using the warnings.deprecated decorator in pydoc to display specific information? I don't think it's relevant to show the __new__ and __init_subclass__ overridden methods in the documentation output.

CPython versions tested on:

3.14

Operating systems tested on:

Linux

Linked PRs

• gh-128772: Fix - warnings.deprecated doesn't work well with pydoc #128781
• gh-128772: Fix pydoc for methods with __module__ is None #129177
• [3.13] gh-128772: Fix pydoc for methods with __module__ is None (GH-129177) #129653
• [3.12] gh-128772: Fix pydoc for methods with __module__ is None (GH-129177) #129654
• [3.13] gh-128772: Fix pydoc for methods with __module__ is None (GH-129177) #129655