Sphinx 4.3 raises an 'autodoc-before-process-signature' error with functools.partial

[bhrutledge]

Describe the bug

When using autodoc_preserve_defaults and a module that defines a partial, I get the following warning from sphinx-build:

WARNING: error while formatting arguments for example_package.example_partial: Handler <function update_defvalue at 0x102f24310> for event 'autodoc-before-process-signature' threw an exception (exception: module, class, method, function, traceback, frame, or code object was expected, got partial).

I don't get this warning in Sphinx 4.2.0.

How to Reproduce

I re-used an example repo from an earlier issue: https://github.com/bhrutledge/sphinx-requests-typehints, which includes setup instructions. The rendered docs show the current behavior with Sphinx 4.2.0.

On that repo, I created a PR with Sphinx 4.3.0, where the rendered docs show the missing partial signature.

I also opened PR with Sphinx 4.3.0 but not autodoc_preserve_defaults. The rendered docs show the restored partial signature, but the default arguments are less useful.

Expected behavior

I expect Sphinx 4.3.0 to generate the same documentation as 4.2.0 without errors.

Your project

https://github.com/bhrutledge/sphinx-requests-typehints

Screenshots

No response

OS

Mac

Python version

3.9.7

Sphinx version

4.3.0

Sphinx extensions

sphinx.ext.autodoc

Extra tools

No response

Additional context

No response