AttributeError: 'bool' object has no attribute 'split' when arg is False in sphinx.ext.autodoc:members_option() in graphql-core

[hroncok]

Describe the bug
When I attempt to build the documentation of graphql-python/graphql-core (commit 9d9b465, which is the most recent one in master today) I get the following error ith Sphinx 3.2.1:

Exception occurred:
  File ".../graphql-core/.tox/docs/lib/python3.8/site-packages/sphinx/ext/autodoc/__init__.py", line 98, in members_option
    return [x.strip() for x in arg.split(',') if x.strip()]
AttributeError: 'bool' object has no attribute 'split'

To Reproduce
Steps to reproduce the behavior:

$ git clone https://github.com/graphql-python/graphql-core
$ cd graphql-core
$ git switch -d 9d9b465
$ sed -i 's/sphinx>=2.4,<3/sphinx>=3.2/' tox.ini
$ tox -e docs
...
Running Sphinx v3.2.1
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 23 source files that are out of date
updating environment: [new config] 23 added, 0 changed, 0 removed
reading sources... [  4%] diffs
reading sources... [  8%] index
reading sources... [ 13%] intro
reading sources... [ 17%] modules/error

Exception occurred:
  File ".../graphql-core/.tox/docs/lib/python3.8/site-packages/sphinx/ext/autodoc/__init__.py", line 97, in members_option
    return [x.strip() for x in arg.split(',') if x.strip()]
AttributeError: 'bool' object has no attribute 'split'
The full traceback has been saved in /tmp/sphinx-err-wxxmynxh.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!

Expected behavior
This used to work before (with Sphinx 3.1) and now it no longer works. I don't know where is the False value coming from.
I expect the documentation to be generated.

Your project
https://github.com/graphql-python/graphql-core

Environment info

• OS: Linux (Fedora)
• Python version: 3.8.5, 3.9.0rc1
• Sphinx version: 3.2.1
• Sphinx extensions: sphinx.ext.autodoc

Additional context
We've updated Sphinx in Fedora from 3.1.2 to 3.2.1 and this is the only package that fails to build with the new version.

Full traceback attached: log.txt

[tk0miya]

I confirmed the error with this setting:

autodoc_default_options = {
    'private-members': False,
}

Why did you set False value to this?

[hroncok]

Why did you set False value to this?

I haven't. I don't know where it is coming from. The conf has:

autodoc_default_options = {
    'members': True,
    'inherited-members': True,
    'private-members': False,
    'special-members': '__init__',
    'undoc-members': True,
    'show-inheritance': True
}

[hroncok]

Oh. Sorry, I've read it wrong. So it is private-members.

[tk0miya]

I posted #8144 to ignore private-members: False entry. I don't know how this is worthy. But it will help you.

[hroncok]

I don't know how this is worthy

I think it is. It helps, yes, thank you.