bug#29661: 27.0.50; emacs crashing on exchange-point-and-mark

[Robert Marshall <robert@capuchin.co.uk>]

On Fri, Dec 15 2017, Robert Marshall <robert.marshall@codethink.co.uk> wrote:

> Eli Zaretskii <eliz@gnu.org> writes:
>
>>> From: Robert Marshall <robert.marshall@codethink.co.uk>
>>> Cc: rudalics@gmx.at,  29661@debbugs.gnu.org
>>> Date: Fri, 15 Dec 2017 10:58:47 +0000
>>> 
>>> >> When running klipper from the command line and replicating the problem I
>>> >> see
>>> >> 
>>> >> QClipboardWatcher::empty: Internal error: Application owns the selection
>>> >
>>> > Ah, in that case we have an entry in PROBLEMS about klipper.  Does
>>> > upgrading to a newer version as indicated there solve the problem?  If
>>> > not, perhaps we should update that entry with some new information.
>>> >
>>> I have 4.14.2 of kde, Klipper: 0.9.7

With 4.14.34 of kde Klipper 5.10.5 (that's a huge version leap!) I also
see the crash. I also have the problem with clipit (v 1.4.2) which I use in
another desktop environment for clipboard management

>>> 
>>> Which would appear to be newer than the entry in PROBLEMS - update
>>> to say emacs may crash? And mention select-active-regions?

Reading bug#29889 I set select-active-regions to 'only and the problem no
longer happens.

>> Please propose the text to add there, and thanks.
>
> I'll take a look at my home machine tonight - which probably has a later
> version to see if the problem is still present and then suggest an
> amendment.
>

Here's a suggested change:
----------------------------------------------------------------
diff --git a/etc/PROBLEMS b/etc/PROBLEMS
index c9b11fbc56..36df5493f4 100644
--- a/etc/PROBLEMS
+++ b/etc/PROBLEMS
@@ -1034,18 +1034,17 @@ It is also reported that a bug in the gtk-engines-qt engine can cause this if
 Emacs is compiled with Gtk+.
 The bug is fixed in version 0.7 or newer of gtk-engines-qt.
 
-*** KDE: Emacs hangs on KDE when a large portion of text is killed.
+*** Clipboard: Emacs hangs or crashes when a large portion of text is selected or killed.
 
-This is caused by a bug in the KDE applet 'klipper' which periodically
-requests the X clipboard contents from applications.  Early versions
-of klipper don't implement the ICCCM protocol for large selections,
-which leads to Emacs being flooded with selection requests.  After a
-while, Emacs may print a message:
+This is caused by a bug in the clipboard management applets (it has
+been observer in 'klipper' and 'clipit') which periodically request
+the X clipboard contents from applications.  After a while, Emacs may
+print a message:
 
   Timed out waiting for property-notify event
 
-A workaround is to not use 'klipper'.  Upgrading 'klipper' to the one
-coming with KDE 3.3 or later also solves the problem.
+A workaround is to not use 'klipper'or 'clipit'. Alternatively setting
+select-active-regions to 'only also solves the problem.
 
 *** KDE / Plasma 5: Emacs exhausts memory and needs to be killed
----------------------------------------------------------------

Robert