bug#68958: [PATCH] Support bookmarking Xref results buffers

[Juri Linkov <juri@linkov.net>]

>>>> I once tried to use 'revert-buffer-function' to restore
>>>> xref buffers from the desktop, but abandoned the idea.
>>>> Not because xref.el doesn't set 'revert-buffer-function'.
>>>> But because it would take too much time to restore
>>>> the desktop while it will rerun all saved xref buffers.
>>>> OTOH, saving an xref bookmark makes more sense.
>>>> And probably your patch will help to implement
>>>> 'revert-buffer-function' for xref as well.
>>> I don't think bookmark would save the whole buffer contents. Would it?
>>> Otherwise, re-running the search(es) seems inevitable.
>> Indeed, saving the buffer contents of transient buffers
>> either to the bookmark or to the desktop makes no sense.
>> So re-running the command is inevitable.
>> But then I can't imagine how would it be possible
>> to move point to its saved location when initially
>> a restored buffer is empty before re-running the command.
>
> As long as the search is performed synchronously, first you "revert" the
> buffer and then move point. Right?

Sorry, I forgot that xref is not asynchronous as rgrep.
But this is not a problem: most of the time xref delay
is negligible.  Still would not want to run it while
restoring the desktop.  But from a bookmark is fine.