bug#65734: [BUG] kill-whole-line on folded subtrees [9.6.8 (release_9.6.8-3-g21171d @ /home/w/usr/emacs/0/29/0/lisp/org/)]

[Sebastian Miele]

> From: Ihor Radchenko <yantar92@posteo.net>
> Date: Wed, 2023-09-06 08:30 +0000
>
> Eli Zaretskii <eliz@gnu.org> writes:
>
>>> It would also make sense to group the two edits together via
>>> `combine-after-change-calls', although a more universal way to know that
>>> certain edits are a part of the same known command (even when called
>>> non-interactively) would be useful.
>>
>> The command kills in two parts for a good reason, which is explained
>> in the comments to the code.  So making a single group will not work,
>> I think, at least not in all situations.
>
> I think there is misunderstanding. `combine-after-change-calls' will not
> affect the two-step modification of the kill ring, if we put it around
> `kill-whole-line'. Or do I miss something?

I tried to wrap the problematic portion of `kill-whole-line' into
`combine-after-change-calls'.  It seems to have no effect.  The
after-change function `org-fold-core--fix-folded-region' still gets
called twice, not fixing the bug.  I did not dig deeper, because the
stuff that makes `combine-after-change-calls' work at least partially
goes in C and seems to be scattered over several places.

The Emacs Lisp manual states that `combine-after-change-calls' "arranges
to call the after-change functions just once for a series of several
changes—if that seems safe."  So this case does not seem safe.  Apart
from that, there is no stated guarantee for when it would seem it safe.

I conclude that, although this path looked possibly elegant at first,
and I wanted to give it a try, this cannot work out.