bug#35429: 27.0.50; Arbitrary xdisp.c related crashes when working with overlay-using packages

[Kaushal Modi]

Hello,

In the past one-two weeks, I have been noticing arbitrary crashes when working in Org mode, with other packages like org-tree-slide and artist-mode. My guess is that this has to do with packages dealing with overlays.

I do not have a reproducible recipe, but this time, I got the full backtrace (attached as gdb.txt).

The log shows the the beacon package caused this. For reference, here is the source of beacon.el: http://git.savannah.gnu.org/cgit/emacs/elpa.git/tree/packages/beacon/beacon.el

---

In GNU Emacs 27.0.50 (build 22, x86_64-pc-linux-gnu, GTK+ Version 2.24.23)
 of 2019-04-24 built on
Repository revision: c5358e831f05cdd110f12a4260e6fb607c66c0b4
Repository branch: master
Windowing system distributor 'Open Text', version 11.0.11505
System Description: Red Hat Enterprise Linux Workstation release 6.8 (Santiago)

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
C-c C-c is undefined

Configured using:
 'configure --with-modules
 --prefix=/home/kmodi/usr_local/apps/6/emacs/master
 '--program-transform-name=s/^ctags$/ctags_emacs/'
 --enable-checking=yes,glyphs --enable-check-lisp-object-type
 'CPPFLAGS=-I/home/kmodi/stowed/include
 -I/home/kmodi/usr_local/6/include -I/usr/include/freetype2
 -I/usr/include' 'CFLAGS=-ggdb3 -Og' 'CXXFLAGS=-ggdb3 -Og'
 'LDFLAGS=-L/home/kmodi/stowed/lib -L/home/kmodi/stowed/lib64
 -L/home/kmodi/usr_local/6/lib -L/home/kmodi/usr_local/6/lib64 -ggdb3''

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS GLIB
NOTIFY INOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF
XFT ZLIB TOOLKIT_SCROLL_BARS GTK2 X11 XDBE XIM MODULES THREADS PDUMPER
GMP

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

--
Kaushal Modi

gdb.txt
Description: Text document