Sphinx 7.3 raises a warning on needs_functions

[sigma67]

When specifying needs_functions in conf.py

Warning, treated as error:
cannot cache unpickable configuration value: 'needs_functions' (because it contains a function, class, or module object)

Sphinx also states in its documentation that configuration values must be pickleable:

https://www.sphinx-doc.org/en/master/usage/configuration.html

The contents of the config namespace are pickled (so that Sphinx can find out when configuration changes), so it may not contain unpickleable values – delete them from the namespace with del if appropriate. Modules are removed automatically, so you don’t need to del your imports after use.

[sigma67]

Current workaround: set

suppress_warnings = ["config.cache"]

[danwos]

Assigning functions to needs_functions is not the best way, as it also deactivates incremental build.

Have you taken a look at the related documentation?
https://sphinx-needs.readthedocs.io/en/latest/configuration.html#needs-functions
There is a note, that it is better to use the Sphinx-Needs API to assign functions.

[danwos]

So for me, the Sphinx warning is correct.
But maybe Sphinx-Needs itself should throw such a warning and give the hint to use the API instead.

[chrisjsewell]

So for me, the Sphinx warning is correct.

Well that's lucky, because I was the one that added this warning 😆 sphinx-doc/sphinx#12203

Note, if you are happy to live with the rebuild issues, then you can use suppress_warnings = ["config.cache"]

[sigma67]

Thanks for the quite useful suggestion and pointer to the docs.

May I suggest to remove the incorrect way from the documentation then to avoid leading users into this error?

Or at least switch the order, I guess.