building psf/requests documentation fails with AttributeError: 'LookupDict' object has no attribute '__name__'

[eriol]

Describe the bug

Since sphinx 3.4.1 building psf/requests documentation fails with the following:

sphinx-build -b html -d _build/doctrees   . _build/html
Running Sphinx v3.4.1
loading intersphinx inventory from https://docs.python.org/3/objects.inv...
loading intersphinx inventory from https://urllib3.readthedocs.io/en/latest/objects.inv...
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 15 source files that are out of date
updating environment: [new config] 15 added, 0 changed, 0 removed
reading sources... [  6%] api                                                                                                                                                                
Exception occurred:
  File "/usr/lib/python3/dist-packages/sphinx/util/typing.py", line 160, in _restify_py37
    return ':obj:`%s.%s`' % (cls.__module__, cls.__name__)
AttributeError: 'LookupDict' object has no attribute '__name__'
The full traceback has been saved in /tmp/sphinx-err-yt45bplo.log, if you want to report the issue to the developers.

Attached the full log: sphinx-err-yt45bplo.log

The issue is not reproducible using sphinx 3.3.1.

To Reproduce
In addiction to build requests' documentation I managed to reproduce the issue in the interactive python console using the following:

Python 3.9.1 (default, Dec  8 2020, 07:51:42) 
[GCC 10.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import requests
>>> import sphinx
>>> requests.__version__
'2.25.0'
>>> sphinx.__version__
'3.4.1'
>>> from requests import codes
>>> from sphinx.util.typing import restify
>>> restify(codes)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3/dist-packages/sphinx/util/typing.py", line 103, in restify
    return _restify_py37(cls)
  File "/usr/lib/python3/dist-packages/sphinx/util/typing.py", line 160, in _restify_py37
    return ':obj:`%s.%s`' % (cls.__module__, cls.__name__)
AttributeError: 'LookupDict' object has no attribute '__name__'

I'm able to reproduce the issue in a clean virtualenv with only requests and sphinx installed.

Thanks!

[ConstantinoSchillebeeckx]

I'm seeing the same building docs with Airflow

File "/somewhere/lib/python3.7/site-packages/sphinx/util/typing.py", line 158, in _restify_py37
    return ':obj:`%s.%s`' % (cls.__module__, cls.__name__)
AttributeError: 'PythonOperator' object has no attribute '__name__'

Downgrading to 3.3.1 avoids the issue.

[tk0miya]

It seems requests' document is using autoclass for requests.codes.
https://github.com/psf/requests/blob/4f6c0187150af09d085c03096504934eb91c7a9e/docs/api.rst

But it is not a class. Is this mark-up intended?
https://github.com/psf/requests/blob/4f6c0187150af09d085c03096504934eb91c7a9e/requests/status_codes.py#L105

I don't know autoclass directive should support non-class items. But it is not intended to make a breaking change. So I'll try to fix it if possible.

[tk0miya]

@ConstantinoSchillebeeckx Is your case the same as requests' case? Please check your document. If not, please file another issue to investigate your case in detail.

[eriol]

@tk0miya many thanks for the analysis and the fix! That line was not touched in 5 years, so I think that since just worked it was used and never touched again.

[tk0miya]

@eriol :-) I recommend you to use autodata directive for variables instead of autoclass. At present, Sphinx renders it as an attribute. But the behavior might be changed because the author considers it is a "class".