GNU bug report logs - #34179
27.0.50; message hangs when buffer with process visible

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From: martin rudalics <rudalics <at> gmx.at>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: michael_heerdegen <at> web.de, 34179 <at> debbugs.gnu.org
Subject: bug#34179: 27.0.50; message hangs when buffer with process visible
Date: Fri, 25 Jan 2019 17:51:53 +0100

> You are right, but window-font-width called by
> window-max-chars-per-line also calls select-window.
>
> Btw, I don't think replacing with-selected-window with
> with-current-buffer will necessarily yield the same results.

Right.  I attach a more correct patch now that does not select a
window in these cases.  Michael, please check whether it fixes your
use case.

> And we
> cannot in general forbid calls to with-selected-window in hooks called
> from run_window_change_functions anyway, can we?

Certainly not.

>> I can't get the hang with a single frame.  Can you?
>
> OK, but does that change anything?  Why is having a separate frame a
> problem?

That's what I would have liked to find out.

>> It's an infloop triggered in ‘window-configuration-change-hook’ and it
>> was always easy to trigger an infloop there.
>
> Not sure I understand what you mean.  The loop is in
> redisplay_internal, not in window-configuration-change-hook.  How was
> it easy to trigger that in the past?  And even if it was, shouldn't we
> avoid such a loop?

Agreed.

> In any case, it is way too easy to do in functions called from
> run_window_change_functions something that sets
> windows_or_buffers_changed, so automatically retrying redisplay based
> on that variable after run_window_change_functions returns is IMO
> dangerous.

But what would be the alternatives?  Having clients ask for redisplay
explicitly every time they are in a hook?  Or maybe just suppress
redisplay_other_windows when running from the hook.

Thanks, martin

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