bug#60399: 30.0.50; Usage of `isearch-open-invisible-temporary' is not documented

[Ihor Radchenko <yantar92@posteo.net>]

Eli Zaretskii <eliz@gnu.org> writes:

> Thanks, this background was indeed missing.  However, even after
> reading it, I still don't understand how come you need or want to
> delete these overlays -- aren't they needed to hide the text to begin
> with?
>
> Or IOW, if you are deleting and recreating the overlays, why do you
> need to use this isearch feature at all? just delete them when you
> want to show the text, and reapply them later when you want the text
> hidden again.

This is pretty much what is being done: I try to hook into isearch code
to (1) when isearch is about to display the match, I save the old
overlays and re-arrange them to display the match as needed; (2) when
isearch moves to the next match, I restore the old overlays.

However, because isearch expects the overlays to exist even upon
revealing the isearch match, I cannot achieve what I want. Even though
my code would work fine, isearch itself errs in
`isearch-close-unnecessary-overlays'/`isearch-open-necessary-overlays'
where it does additional checks involving `overlay-start' and
`overlay-end' that must be non-nil.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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