bug#81550: 30.2; add project-specific hooks to unload-feature-special-hooks

Eli Zaretskii <[email protected]> writes:

>> Cc: [email protected]
>> Date: Tue, 04 Aug 2026 15:28:33 +0800
>> From: Lin Jian via "Bug reports for GNU Emacs,
>>  the Swiss army knife of text editors" <[email protected]>
>> 
>> 
>> When supporting `unload-feature' for my project backend, I have to write
>> a FEATURE-unload-function to clean `project-find-functions' and
>> `project-list-exclude'.
>> 
>> That FEATURE-unload-function can be omitted if `project-find-functions'
>> and `project-list-exclude' are added to `unload-feature-special-hooks'.
>> I suggest adding them.
>
> Does it really happen frequently that unloading a feature affects
> which files project.el will consider, or is that a rare corner case?

If by "a feature" you mean a random feature, then probably that random
feature does not need to clean project-specific hooks.

However, note that I do not mean a random feature.  I mean specific
features: project backends.  See C-h P project RET for definition of
project backend.  These specific features always have to clean
project-specific hooks if they decide to support `unload-feature'.