bug#24633: highlight-region func using (window-hscroll) in :align-to spec can cause inf loop

[npostavs]

tags 24633 fixed
close 24633 26
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Eli Zaretskii <eliz@gnu.org> writes:

>> From: npostavs@users.sourceforge.net
>> Cc: 24633@debbugs.gnu.org
>> Date: Sat, 22 Oct 2016 15:27:42 -0400
>> 
>> I tried adding a counter in redisplay_internal, it prevents having a
>> tight loop in C.  Actually, the behaviour becomes like the split window
>> case: there is additional hscrolling each time the cursor blinks, but it
>> can be interrupted with C-g.  That seems adequate behaviour to me, what
>> do you think?
>
> Did you see what happens when blink-cursor-mode is turned off?  (If
> that's what you meant by "each time the cursor blinks; if not, what
> caused it to blink?)

If I turn blink-cursor-mode off, then it stops scrolling after what
seems like immediately (though I can see from the message calls that the
highlight-region function was called several times).  So the counter is
limiting redisplay looping as expected.

>
> The patch looks OK to me, so if it gives better results than locking
> up Emacs with the current code, let's push it to master.

Okay, pushed as 241ae7a1 "Avoid infinite hscrolling in redisplay", and
closing the bug as fixed.