bug#34686: 26.1; unload-feature doesn't remove functions locally from hooks

[Robert Pluim]

Eli Zaretskii <eliz@gnu.org> writes:

>> Expectation: Emacs starts up with no error.
>> (`unload-feature' should remove `test-function' from `test-hook' as
>> documented, so `(run-hooks 'test-hook)' should be a no-op.)
>
> Where do you see it documented that the hook should be removed?  All I
> see is this:
>
>   Standard unloading activities include restoring old autoloads for
>   functions defined by the library, undoing any additions that the
>   library has made to hook variables or to ‘auto-mode-alist’[...]
>
> This says that hooks are removed if they were added by the library
> being unloaded.  But in your example, the hook was not added by
> test-unload.el, it was added by test.el, a different library.

In "(elisp) Unloading" it says:

     Before restoring the previous definitions, ‘unload-feature’ runs
     ‘remove-hook’ to remove functions in the library from certain
     hooks.  These hooks include variables whose names end in ‘-hook’
     (or the deprecated suffix ‘-hooks’), plus those listed in
     ‘unload-feature-special-hooks’, as well as ‘auto-mode-alist’.  This
     is to prevent Emacs from ceasing to function because important
     hooks refer to functions that are no longer defined.

and a quick look at the code confirms that it at least *tries* to do
that.

Robert