help() breaks on Python 3.15 after help("modules")

[treyhunner]

Bug report

Bug description:

On Python 3.15 alpha 7, after running help("modules"), the help() function breaks.

Run:

>>> help("modules")

Then pass an object to the help function and see a traceback:

>>> help(list)
Traceback (most recent call last):
  File "<python-input-1>", line 1, in <module>
    help(list)
    ~~~~^^^^^^
  File "<frozen _sitebuiltins>", line 91, in __call__
  File "/home/trey/.local/share/uv/python/cpython-3.15.0a7-linux-x86_64-gnu/lib/python3.15/pydoc.py", line 1989, in __call__
    self.help(request)
    ~~~~~~~~~^^^^^^^^^
  File "/home/trey/.local/share/uv/python/cpython-3.15.0a7-linux-x86_64-gnu/lib/python3.15/pydoc.py", line 2051, in help
    else: doc(request, 'Help on %s:', output=self._output, is_cli=is_cli)
          ~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/trey/.local/share/uv/python/cpython-3.15.0a7-linux-x86_64-gnu/lib/python3.15/pydoc.py", line 1731, in doc
    pager(render_doc(thing, title, forceload), f'Help on {what!s}')
          ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/trey/.local/share/uv/python/cpython-3.15.0a7-linux-x86_64-gnu/lib/python3.15/pydoc.py", line 1716, in render_doc
    return title % desc + '\n\n' + renderer.document(object, name)
                                   ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
  File "/home/trey/.local/share/uv/python/cpython-3.15.0a7-linux-x86_64-gnu/lib/python3.15/pydoc.py", line 464, in document
    if inspect.isclass(object): return self.docclass(*args)
                                       ~~~~~~~~~~~~~^^^^^^^
  File "/home/trey/.local/share/uv/python/cpython-3.15.0a7-linux-x86_64-gnu/lib/python3.15/pydoc.py", line 1370, in docclass
    doc = getdoc(object)
  File "/home/trey/.local/share/uv/python/cpython-3.15.0a7-linux-x86_64-gnu/lib/python3.15/pydoc.py", line 118, in getdoc
    result = _getdoc(object) or inspect.getcomments(object)
             ~~~~~~~^^^^^^^^
  File "/home/trey/.local/share/uv/python/cpython-3.15.0a7-linux-x86_64-gnu/lib/python3.15/pydoc.py", line 112, in _getdoc
    return inspect.getdoc(object,
           ~~~~~~~~~~~~~~^^^^^^^^
                          fallback_to_class_doc=False,
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                          inherit_class_doc=False)
                          ^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: _getdoc() got an unexpected keyword argument 'fallback_to_class_doc'

This is an issue I've been hitting pretty consistently when the Python 3.15 while teaching recently.

CPython versions tested on:

3.15

Operating systems tested on:

Linux

[treyhunner]

This seems to be a problem as far back as Python 3.15.0 alpha 2. It seems like this was not a problem on Python 3.15.0 alpha 1.

[zware]

I can't reproduce this with a fresh build. Note that help('modules') does pretty much import everything under the sun; are you running this from an environment with anything exotic?

[zware]

It seems this is probably related to gh-132686, but is actually a bug in some package that is monkey-patching inspect. Tellingly, _getdoc does not appear in the history of Lib/inspect.py at all.

Can you try the following in a fresh REPL?

>>> import inspect
>>> orig_getdoc = inspect.getdoc
>>> help('modules')
...
>>> inspect.getdoc is orig_getdoc  # should be True, but I expect False in your environment
...
>>> print(inspect.getdoc.__module__)  # should be 'inspect'

[vstinner]

but is actually a bug in some package that is monkey-patching inspect.

A code search on PyPI top 15,000 found one project which overrides inspect.getdoc:

PYPI-2026-01-07/ovld-0.5.13.tar.gz: ovld-0.5.13/src/ovld/core.py: inspect.getdoc = _getdoc

@treyhunner: Do you have the ovld project installed on Python 3.15?

[breuleux]

@treyhunner Yeah it seems to be ovld's fault, try version 0.5.15, it includes a fix from @zware (thanks!)

[zware]

@treyhunner please confirm, but I'm going to go ahead and close this as a third-party issue.

[treyhunner]

I thought I was working from a clean environment but I was not.

I had ovld installed (due to a dependency of a dependency of jurigged).

Thanks all!

[vstinner]

I had ovld installed (due to a dependency of a dependency of jurigged).

Aha, that explains the bug :-)

help("modules") is causing various issues (I recall that it already caused crashes in the past) and I'm not sure that it's useful. We should maybe deprecate this dangerous function.