Sphinx version 4.2.0 fails on Python 3.10

[Nelson-Gon]

Describe the bug

Sphinx 4.2.0 fails to build docs with Python 3.1.0.

How to Reproduce

$ git clone https://github.com/Nelson-Gon/pyfdc.git
$ cd pyfdc
# Here one should instead use the latest Sphinx not the one in requirements.txt
$ pip install -r requirements.txt
$ ./scripts/mkdocs.sh

Expected behavior

I expected to have Sphinx build docs without any error.

Your project

https://github.com/Nelson-Gon/pyfdc

Screenshots

No response

OS

Windows 10

Python version

3.10

Sphinx version

4.2.0

Sphinx extensions

No response

Extra tools

No response

Additional context

The error message is ImportError: cannot import name 'Union' from 'types'
This is marked as resolved in #9562 but the solutions there do not work for me.

[tk0miya]

Could you paste or attach a stacktrace file here?

[Nelson-Gon]

This is the stack trace

Traceback (most recent call last):
  File "C:\Users\Nelg\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\Nelg\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "C:\Users\Nelg\AppData\Local\Programs\Python\Python310\Scripts\sphinx-build.exe\__main__.py", line 4, in <module>
  File "C:\Users\Nelg\AppData\Local\Programs\Python\Python310\lib\site-packages\sphinx\cmd\build.py", line 25, in <module>
    from sphinx.application import Sphinx
  File "C:\Users\Nelg\AppData\Local\Programs\Python\Python310\lib\site-packages\sphinx\application.py", line 31, in <module>
    from sphinx.config import Config
  File "C:\Users\Nelg\AppData\Local\Programs\Python\Python310\lib\site-packages\sphinx\config.py", line 21, in <module>
    from sphinx.util import logging
  File "C:\Users\Nelg\AppData\Local\Programs\Python\Python310\lib\site-packages\sphinx\util\__init__.py", line 41, in <module>
    from sphinx.util.typing import PathMatcher
  File "C:\Users\Nelg\AppData\Local\Programs\Python\Python310\lib\site-packages\sphinx\util\typing.py", line 37, in <module>
    from types import Union as types_Union
ImportError: cannot import name 'Union' from 'types' (C:\Users\Nelg\AppData\Local\Programs\Python\Python310\lib\types.py)

[tk0miya]

  File "C:\Users\Nelg\AppData\Local\Programs\Python\Python310\lib\site-packages\sphinx\util\typing.py", line 37, in <module>
    from types import Union as types_Union

Strange. Sphinx-4.2.0 does not contain this line.

sphinx/sphinx/util/typing.py

Lines 36 to 39 in 21db4b1

	try:
	from types import UnionType # type: ignore # python 3.10 or above
	except ImportError:
	UnionType = None

Please check the version of Sphinx.

[Nelson-Gon]

@tk0miya Thank you for your response. Here is the output from pip freeze on my system.

Sphinx==4.2.0
sphinxcontrib-applehelp==1.0.2
sphinxcontrib-devhelp==1.0.2
sphinxcontrib-htmlhelp==2.0.0
sphinxcontrib-jsmath==1.0.1
sphinxcontrib-qthelp==1.0.3
sphinxcontrib-serializinghtml==1.1.5

I am not sure, I installed the stable version from PyPI directly. Maybe this is the issue?

[tk0miya]

Sorry, I'm not sure what is happened on your environment. Only I can say is that the stacktrace let us know you're using incorrect version of Sphinx. So you need to find a way to upgrade it.

[Nelson-Gon]

I decided to upgrade to the dev version and instead got this message during the docs build:

Running Sphinx v4.4.0+
loading pickled environment... failed
failed: ObjectEntry.__new__() missing 1 required positional argument: 'aliased'

It seems this is not an error and instead some message?

[tk0miya]

It seems Sphinx failed to load the environment data for the incremental build. I'm not sure why it happened. But it can be recovered automatically by full-build. So you don't need to worry.