Bugzilla Bug 75028

I get this error message:

/bin/sh: line 1: 13095 Segmentation fault      ./xemacs -nd -batch -l /gentoo/build/portage/xemacs-21.4.15-r2/work/xemacs-21.4.15/src/../lisp/make-docfile.el -- -o ../lib-src/DOC -d /gentoo/build/portage/xemacs-21.4.15-r2/work/xemacs-21.4.15/src-i ../lib-src/../site-packages abbrev.c alloc.c blocktype.c buffer.c bytecode.c callint.c callproc.c casefiddle.c casetab.c chartab.c cmdloop.c cmds.c console.c console-stream.c data.c device.c dired.c doc.c doprnt.c dynarr.c editfns.c elhash.c emacs.c eval.c events.c filelock.c dumper.c balloon_help.c balloon-x.c postgresql.c menubar.c scrollbar.c dialog.c toolbar.c menubar-x.c scrollbar-x.c dialog-x.c toolbar-x.c gui-x.c mule.c mule-ccl.c mule-charset.c file-coding.c input-method-motif.c realpath.c inline.c linuxplay.c miscplay.c console-tty.c device-tty.c event-tty.c frame-tty.c objects-tty.c redisplay-tty.c cm.c terminfo.c gpmevent.c event-unixoid.c database.c sysdll.c emodules.c process-unix.c event-stream.c extents.c faces.c fileio.c filemode.c floatfns.c fns.c font-lock.c frame.c general.c glyphs.c glyphs-eimage.c glyphs-widget.c gui.c gutter.c hash.c imgproc.c indent.c insdel.c intl.c keymap.c line-number.c lread.c lstream.c macros.c marker.c md5.c minibuf.c objects.c opaque.c print.c process.c profile.c rangetab.c redisplay.c redisplay-output.c regex.c search.c select.c signal.c sound.c specifier.c strftime.c symbols.c syntax.c sysdep.c undo.c console-x.c device-x.c event-Xt.c frame-x.c glyphs-x.c objects-x.c redisplay-x.c select-x.c xgccache.c widget.c window.c
make[1]: *** [../lib-src/DOC] Error 139
make[1]: Leaving directory `/gentoo/build/portage/xemacs-21.4.15-r2/work/xemacs-21.4.15/src'
make: *** [src] Error 2


Reproducible: Always
Steps to Reproduce:
emerge xemacs

Actual Results:  
emerge stops 
 

Expected Results:  
xemacs should be compiled and installed. 
 

Portage 2.0.51-r8 (!/linux26-x86-2004.2.profile, gcc-3.4.3, 
glibc-2.3.4.20041102-r0, 2.6.9 i686) 
================================================================= 
System uname: 2.6.9 i686 Intel(R) Pentium(R) M processor 1500MHz 
Gentoo Base System version 1.6.8 
Python:              dev-lang/python-2.3.4 [2.3.4 (#1, Oct 21 2004, 14:22:16)] 
distcc 2.18.3 i686-pc-linux-gnu (protocols 1 and 2) (default port 3632) 
[disabled] 
ccache version 2.3 [enabled] 
dev-lang/python:     2.3.4 
sys-devel/autoconf:  2.59-r6, 2.13 
sys-devel/automake:  1.8.5-r2, 1.5, 1.4_p6, 1.6.3, 1.7.9, 1.9.3 
sys-devel/binutils:  2.15.92.0.2-r2 
sys-devel/libtool:   1.5.10-r2 
virtual/os-headers:  2.6.8.1-r1 
ACCEPT_KEYWORDS="x86 ~x86" 
AUTOCLEAN="yes" 
CFLAGS="-O3 -march=pentium4 -fomit-frame-pointer -pipe" 
CHOST="i686-pc-linux-gnu" 
CONFIG_PROTECT="/etc /usr/X11R6/lib/X11/xkb /usr/kde/2/share/config /usr/kde/3.3/env /usr/kde/3.3/share/config /usr/kde/3.3/shutdown /usr/kde/3/share/config /usr/share/config /usr/share/texmf/dvipdfm/config/ /usr/share/texmf/dvips/config/ /usr/share/texmf/tex/generic/config/ /usr/share/texmf/tex/platex/config/ /usr/share/texmf/xdvi/ /var/qmail/control" 
CONFIG_PROTECT_MASK="/etc/gconf /etc/terminfo /etc/env.d" 
CXXFLAGS="-O3 -march=pentium4 -fomit-frame-pointer -pipe" 
DISTDIR="/gentoo/distfiles" 
FEATURES="autoaddcvs ccache distlocks sandbox" 
GENTOO_MIRRORS="ftp://ftp-stud.fht-esslingen.de/pub/Mirrors/gentoo/ 
ftp://mirrors.sec.informatik.tu-darmstadt.de/gentoo/ 
http://ftp.easynet.nl/mirror/gentoo/ 
http://ftp.snt.utwente.nl/pub/os/linux/gentoo 
http://ftp.uni-erlangen.de/pub/mirrors/gentoo" 
MAKEOPTS="-j2" 
PKGDIR="/usr/portage/packages" 
PORTAGE_TMPDIR="/gentoo/build" 
PORTDIR="/usr/portage" 
PORTDIR_OVERLAY="/usr/local/portage" 
SYNC="rsync://rsync.gentoo.org/gentoo-portage" 
USE="X Xaw3d aalib acl alsa apm arts avi berkdb bitmap-fonts bluetooth cddb 
cdparanoia cdr crypt cups doc dvd emacs encodefoomaticdb ftp gdbm gif gnokii 
gphoto2 gpm gstreamer gtk2 guile hardened hbci icq imap imlib irda jpeg kde 
koffice-plugin lcms libg++ libwww mad maildir mbox mime motif mpeg mule 
ncurses nls no-old-linux noamazon noantlr nobcel nobeanutils 
nobshnocommonslogging nocommonsnet nojdepend nojsch nojython nolog4j nooro 
noregexp norhino noxalan noxerces nptl nptlonly objcofx oggvorbis opengl oss 
pam pcre pdflib perl perlsuid pic pie png postgres ppds pwdb python qt 
quicktime readline savedconfig sdl slang sms speex spell sse ssl tcltk tcpd 
tetex theora threads tiff truetype unicode wifi wxwindows x86 xine xml2 xmms 
xosd xprint xscreensaver xv zlib linguas_de"

xemacs started segfaulting on startup some time ago on my laptop. As I don't
use it too often, I have only a vague idea of when :-(

Trying to reemerge glibc,gcc,xemacs didin't help as now on `emerge xemacs -av`
I get the following:
===============
...
[ebuild   R   ] app-editors/xemacs-21.4.15-r2  +X -Xaw3d -athena +berkdb -canna
-dnd -freewnn -gpm -jpeg -ldap -motif +mule -nas -neXt -png -postgres -tiff
-xface 0 kB 

....
Loading loadhist.el...
Loading loaddefs.el...
Loading site-load.el...

Bootstrapping from temacs...
Fatal error (11).

Your files have been auto-saved.
Use `M-x recover-session' to recover them.
[snip useless comments]
in case of future recurrance of the crash.

Lisp backtrace follows:

make[1]: *** [update-elc.stamp] Segmentation fault
make[1]: Leaving directory
`/var/tmp/portage/xemacs-21.4.15-r2/work/xemacs-21.4.15/src'
make: *** [src] Error 2

!!! ERROR: app-editors/xemacs-21.4.15-r2 failed.
!!! Function src_compile, Line 168, Exitcode 2
!!! (no error message)
!!! If you need support, post the topmost build error, NOT this status message.
===========

I produces core after `ulimit -c unlimited` and here is what gdb says:
#0  0x402b3d61 in kill () from /lib/libc.so.6
(gdb) where
#0  0x402b3d61 in kill () from /lib/libc.so.6
#1  0x080b317f in fatal_error_signal ()
#2  0x0000000b in ?? ()
#3  0x00000001 in ?? ()
#4  0x402b5784 in bsearch () from /lib/libc.so.6
#5  0x080adae0 in init_editfns ()
#6  0x00000004 in ?? ()
#7  0x08ac884c in ?? ()
#8  0xffffffff in ?? ()
#9  0x080b3895 in xemacs_21_4_15_i686_pc_linux ()
#10 0x080b4b7e in main ()

Well, not too usefull. So I tried to emerge with -g ang here it goes:
(gdb) where
#0  0x402b3d61 in kill () from /lib/libc.so.6
#1  0x080b11a5 in fatal_error_signal (sig=11) at emacs.c:642
#2  <signal handler called>
#3  0x402f0c23 in strlen () from /lib/libc.so.6
#4  0x081b172e in init_system_name () at sysdep.c:2349
#5  0x080aa799 in init_editfns () at editfns.c:87
#6  0x080b23e0 in xemacs_21_4_15_i686_pc_linux (argc=10, argv=0x8aba8e0,
envp=0xbfffe06c, restart=1) at emacs.c:2363
#7  0x080b30d1 in main (argc=5, argv=0xbfffe054, envp=0xbfffe06c) at
emacs.c:2892
#8  0x402a0297 in __libc_start_main () from /lib/libc.so.6
#9  0x0807ffa1 in _start ()

No idea at all what to look after...# gcc -v
Reading specs from /usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.5/specs
Configured with: /var/tmp/portage/gcc-3.3.5-r1/work/gcc-3.3.5/configure
--enable-version-specific-runtime-libs --prefix=/usr
--bindir=/usr/i686-pc-linux-gnu/gcc-bin/3.3.5
--includedir=/usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.5/include
--datadir=/usr/share/gcc-data/i686-pc-linux-gnu/3.3.5
--mandir=/usr/share/gcc-data/i686-pc-linux-gnu/3.3.5/man
--infodir=/usr/share/gcc-data/i686-pc-linux-gnu/3.3.5/info
--with-gxx-include-dir=/usr/lib/gcc-lib/i686-pc-linux-gnu/3.3.5/include/g++-v3
--host=i686-pc-linux-gnu --disable-altivec --enable-nls
--without-included-gettext --enable-__cxa_atexit --enable-clocale=gnu
--with-system-zlib --disable-checking --disable-werror
--disable-libunwind-exceptions --enable-shared --enable-threads=posix
--disable-multilib --disable-libgcj --enable-languages=c,c++
Thread model: posix
gcc version 3.3.5  (Gentoo Linux 3.3.5-r1, ssp-3.3.2-3, pie-8.7.7.1)

Well, well, well...

After some unknown magic (a few unsuccesfull emerges and a few reboots) my already installed xemacs works again.

I tried to emerge xemacs again and this time I did it right.

Spooky at best.

I see this error also:

gcc -c -O2 -fPIC  -Demacs -I. -DHAVE_CONFIG_H -I/usr/X11R6/include EmacsManager.c
../lib-src/make-dump-id
gcc -c -O2 -fPIC  -Demacs -I. -DHAVE_CONFIG_H -I/usr/X11R6/include dump-id.c
gcc -O2 -fPIC   -L/usr/X11R6/lib -Wl,-export-dynamic -o xemacs  abbrev.o alloc.o
blocktype.o buffer.o bytecode.o callint.o callproc.o casefiddle.o casetab.o
chartab.o cmdloop.o cmds.o console.o console-stream.o data.o device.o dired.o
doc.o doprnt.o dynarr.o editfns.o elhash.o emacs.o eval.o events.o filelock.o
dumper.o balloon_help.o balloon-x.o eldap.o postgresql.o menubar.o scrollbar.o
dialog.o toolbar.o menubar-x.o scrollbar-x.o dialog-x.o toolbar-x.o gui-x.o
realpath.o inline.o linuxplay.o nas.o miscplay.o console-tty.o device-tty.o
event-tty.o frame-tty.o objects-tty.o redisplay-tty.o cm.o terminfo.o gpmevent.o
event-unixoid.o database.o sysdll.o emodules.o process-unix.o event-stream.o
extents.o faces.o fileio.o  filemode.o floatfns.o fns.o font-lock.o frame.o
general.o glyphs.o glyphs-eimage.o glyphs-widget.o gui.o gutter.o  hash.o
imgproc.o indent.o insdel.o intl.o keymap.o  line-number.o lread.o lstream.o
macros.o marker.o md5.o minibuf.o objects.o opaque.o print.o process.o profile.o
rangetab.o redisplay.o redisplay-output.o regex.o search.o select.o  signal.o
sound.o specifier.o strftime.o symbols.o syntax.o sysdep.o undo.o console-x.o
device-x.o event-Xt.o frame-x.o glyphs-x.o objects-x.o redisplay-x.o select-x.o
xgccache.o widget.o window.o  lastfile.o vm-limit.o  EmacsFrame.o EmacsShell.o
TopLevelEmacsShell.o TransientEmacsShell.o EmacsManager.o   dump-id.o
../lwlib/liblw.a  -laudio -lXm -ltiff -lpng -ljpeg -lz -lXpm -lXmu -lXt -lXext
-lX11 -lSM -lICE -lgdbm -lgdbm_compat -lgpm -lncurses -lpq -lldap -lm -lutil
./xemacs -nd -batch -l
/var/tmp/portage/xemacs-21.4.15-r3/work/xemacs-21.4.15/src/../lisp/update-elc.el
make[1]: *** [update-elc.stamp] Segmentation fault
make[1]: Leaving directory
`/var/tmp/portage/xemacs-21.4.15-r3/work/xemacs-21.4.15/src'


The command:

SANDBOX_DISABLED="1" emerge xemacs

Portage 2.0.51.19 (default-linux/amd64/2004.3, gcc-3.4.3,
glibc-2.3.4.20041102-r1, 2.6.9-gentoo-r1 x86_64)
=================================================================
System uname: 2.6.9-gentoo-r1 x86_64 AMD Opteron(tm) Processor 246
Gentoo Base System version 1.4.16
Python:              dev-lang/python-2.3.5 [2.3.5 (#1, May 14 2005, 12:28:21)]
ccache version 2.3 [enabled]
dev-lang/python:     2.3.5
sys-apps/sandbox:    [Not Present]
sys-devel/autoconf:  2.13, 2.59-r6
sys-devel/automake:  1.5, 1.8.5-r3, 1.6.3, 1.9.5, 1.7.9-r1, 1.4_p6
sys-devel/binutils:  2.15.92.0.2-r10
sys-devel/libtool:   1.5.16
virtual/os-headers:  2.6.8.1-r4
ACCEPT_KEYWORDS="amd64"
AUTOCLEAN="yes"
CFLAGS="-O2 -fPIC"
CHOST="x86_64-pc-linux-gnu"
CONFIG_PROTECT="/etc /opt/resin/conf /usr/kde/2/share/config /usr/kde/3.3/env
/usr/kde/3.3/share/config /usr/kde/3.3/shutdown /usr/kde/3/share/config
/usr/lib/X11/xkb /usr/lib/mozilla/defaults/pref /usr/share/config
/usr/share/texmf/dvipdfm/config/ /usr/share/texmf/dvips/config/
/usr/share/texmf/tex/generic/config/ /usr/share/texmf/tex/platex/config/
/usr/share/texmf/xdvi/ /var/qmail/control"
CONFIG_PROTECT_MASK="/etc/gconf /etc/terminfo /etc/env.d"
CXXFLAGS="-O2 -fPIC"
DISTDIR="/opt/no_archive/portage/distfiles"
FEATURES="autoaddcvs autoconfig buildpkg ccache distlocks sandbox sfperms strict"
GENTOO_MIRRORS="http://128.213.5.34/gentoo/"
MAKEOPTS="-j2"
PKGDIR="/opt/no_archive/portage/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY="/usr/local/portage"
SYNC="rsync://rsync.gentoo.org/gentoo-portage"
USE="amd64 X acpi alsa arts berkdb bitmap-fonts cdr crypt cups curl doc esd fam
flac font-server fortran gd gdbm gif gphoto2 gpm gtk imagemagick imlib ipv6 java
jp2 jpeg junit kde ldap libg++ libwww log4cpp lzw lzw-tiff mikmod motif mozilla
mp3 multilib mysql nas ncurses nls ogg opengl oss pam pdflib perl plotutils png
postgres python qt readline ruby sdl slang spell ssl svg tcltk tcpd tetex tiff
truetype truetype-fonts type1-fonts usb userlocales vorbis wxwindows xine
xinerama xml2 xmms xpm xrandr xv zlib userland_GNU kernel_linux elibc_glibc"
Unset:  ASFLAGS, CBUILD, CTARGET, LANG, LC_ALL, LDFLAGS, LINGUAS

same problem with xemacs-21.4.15-r3 on AMD64

USE="mule" emerge -vuD xemacs


gcc -c -march=athlon64 -O3 -pipe -fomit-frame-pointer  -Demacs -I.
-DHAVE_CONFIG_H -I/usr/X11R6/include dump-id.c
gcc -march=athlon64 -O3 -pipe -fomit-frame-pointer   -L/usr/X11R6/lib
-Wl,-export-dynamic -o xemacs  abbrev.o alloc.o blocktype.o buffer.o bytecode.o
callint.o callproc.o casefiddle.o casetab.o chartab.o cmdloop.o cmds.o console.o
console-stream.o data.o device.o dired.o doc.o doprnt.o dynarr.o editfns.o
elhash.o emacs.o eval.o events.o filelock.o dumper.o balloon_help.o balloon-x.o
menubar.o scrollbar.o dialog.o toolbar.o menubar-x.o scrollbar-x.o dialog-x.o
toolbar-x.o gui-x.o mule.o mule-ccl.o mule-charset.o file-coding.o
input-method-xlib.o realpath.o inline.o linuxplay.o miscplay.o console-tty.o
device-tty.o event-tty.o frame-tty.o objects-tty.o redisplay-tty.o cm.o
terminfo.o gpmevent.o event-unixoid.o database.o sysdll.o emodules.o
process-unix.o event-stream.o extents.o faces.o fileio.o  filemode.o floatfns.o
fns.o font-lock.o frame.o general.o glyphs.o glyphs-eimage.o glyphs-widget.o
gui.o gutter.o  hash.o imgproc.o indent.o insdel.o intl.o keymap.o 
line-number.o lread.o lstream.o macros.o marker.o md5.o minibuf.o objects.o
opaque.o print.o process.o profile.o rangetab.o redisplay.o redisplay-output.o
regex.o search.o select.o  signal.o sound.o specifier.o strftime.o symbols.o
syntax.o sysdep.o undo.o console-x.o device-x.o event-Xt.o frame-x.o glyphs-x.o
objects-x.o redisplay-x.o select-x.o xgccache.o widget.o window.o  lastfile.o
vm-limit.o  EmacsFrame.o EmacsShell.o TopLevelEmacsShell.o TransientEmacsShell.o
EmacsManager.o   dump-id.o ../lwlib/liblw.a  -lXaw -ltiff -lpng -ljpeg -lz -lXpm
-lXmu -lXt -lXext -lX11 -lSM -lICE -lgdbm -lgdbm_compat -lgpm -lncurses -lm -lutil
./xemacs -nd -batch -l
/var/tmp/portage/xemacs-21.4.15-r3/work/xemacs-21.4.15/src/../lisp/update-elc.el
make[1]: *** [update-elc.stamp] Segmentation fault


Portage 2.0.51.19 (default-linux/amd64/2005.0, gcc-3.4.3,
glibc-2.3.4.20041102-r1, 2.6.11-gentoo-r7 x86_64)
=================================================================
System uname: 2.6.11-gentoo-r7 x86_64 AMD Athlon(tm) 64 Processor 3000+
Gentoo Base System version 1.6.12
Python:              dev-lang/python-2.3.5 [2.3.5 (#1, May 30 2005, 19:34:17)]
dev-lang/python:     2.3.5
sys-apps/sandbox:    [Not Present]
sys-devel/autoconf:  2.13, 2.59-r6
sys-devel/automake:  1.8.5-r3, 1.6.3, 1.5, 1.7.9-r1, 1.4_p6, 1.9.5
sys-devel/binutils:  2.15.92.0.2-r10
sys-devel/libtool:   1.5.16
virtual/os-headers:  2.6.8.1-r4
ACCEPT_KEYWORDS="amd64"
AUTOCLEAN="yes"
CFLAGS="-march=athlon64 -O3 -pipe -fomit-frame-pointer"
CHOST="x86_64-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/kde/2/share/config /usr/kde/3/share/config
/usr/lib/X11/xkb /usr/share/config /usr/share/texmf/dvipdfm/config/
/usr/share/texmf/dvips/config/ /usr/share/texmf/tex/generic/config/
/usr/share/texmf/tex/platex/config/ /usr/share/texmf/xdvi/ /var/qmail/control"
CONFIG_PROTECT_MASK="/etc/gconf /etc/terminfo /usr/X11R6/bin/startx /etc/env.d"
CXXFLAGS="-march=athlon64 -O3 -pipe -fomit-frame-pointer"
DISTDIR="/usr/portage/distfiles"
FEATURES="autoaddcvs autoconfig candy ccache distlocks sandbox severe sfperms
strict test"
GENTOO_MIRRORS="http://pandemonium.tiscali.de/pub/gentoo/
ftp://ftp.tu-clausthal.de/pub/linux/gentoo/
ftp://ftp.gentoo.mesh-solutions.com/gentoo/
http://ftp-stud.fht-esslingen.de/pub/Mirrors/gentoo/"
LANG="de_DE@euro"
LC_ALL="de_DE@euro"
LINGUAS="de_DE@euro"
MAKEOPTS="-j2"
PKGDIR="/usr/portage/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
SYNC="rsync://rsync.de.gentoo.org/gentoo-portage"
USE="X aac acpi alsa amd64 avi berkdb bitmap-fonts bzlib cdr crypt cups curl dga
directfb dlloader dts dvd dvdr dvdread eds emacs encode esd exif fam fbcon
ffmpeg font-server foomaticdb fortran gdbm gif gimpprint gnome gpm gstreamer gtk
gtk2 hal hardened howl imagemagick imlib ipv6 ithreads javascript jp2 jpeg lcms
libwww lzo lzw lzw-tiff mad matroska memlimit mikmod mmap mng mozdevelop mozsvg
mp3 mpeg ncurses nls nptl nvidia ogg oggvorbis on-the-fly-crypt openal opengl
oss pam pda pdflib perl png ppds python quicktime readline real sdl slang ssl
svg tcltk tcpd test tetex tga threads tidy tiff truetype truetype-fonts
type1-fonts unicode usb userlocales videos vorbis wmf xine xml2 xmms xpm xprint
xrandr xtermtoolbar xv xvid xvmc zlib linguas_de_DE@euro userland_GNU
kernel_linux elibc_glibc"
Unset:  ASFLAGS, CBUILD, CTARGET, LDFLAGS, PORTDIR_OVERLAY

Problem is still there in xemacs-21.4.15-r3. 

I gave it another try, after switching from hardened gcc to vanilla (3.4.4). 
Now xemacs compiles just fine. So it seems to be a hardened toolchain issue. 

affirmed

hardened@gentoo.org added to CC list

Looks like something doesn't like PIE.  Try:

CFLAGS="-nopie" emerge xemacs

with the hardened compiler and report back, please.

Okay, the "-nopie" did it :) ==>

CFLAGS="-nopie -march=athlon64 -O3 -ffast-math -funroll-all-loops -fpeel-loops
-ftracer -funswitch-loops -funit-at-a-time -pipe -fomit-frame-pointer"
CXXFLAGS="-nopie -march=athlon64 -O3 -ffast-math -funroll-all-loops -fpeel-loops
-ftracer -funswitch-loops -funit-at-a-time -pipe -fomit-frame-pointer" emerge
-vD xemacs

Can the ebuild file / source code altered that way that giving "-nopie" as CFLAG
is not needed?

Adding -nopie to CFLAGS works for me too. 

Thanks everyone for the feedback, it's good to know that this issue is solved
with the -nopie flag in CFLAGS. This is not something that can be put in the
ebuild automatically, though, because it would silently subvert the purpose of
being on a hardened profile. I will put a note about this issue in the ebuild,
though.

I'm leaving this bug open for now as the real problem should still be solved.
It would be great if someone on a hardened profile could do a bit more
investigating to see if the actual cause of this crash be be found and fixed.

Ah; this one had dropped into the mists of time for us.  The '-nopie' confirms
it's an incompatibility with the hardened toolchain.  If that incompatibility
turns out to be too much trouble to solve, adding:

filter-flags -fPIE

to the ebuild will disable it.  However before that happens I wanted to
determine what is causing the problem and whether it can be easily fixed.

ok; what's happening is that src/vm-limits.c:check_memory_limits is issuing a
warning via (*warn_function)(), and the data used by the warning function has
not been initialised (Vpending_warnings in eval.c) because
src/eval.c:vars_of_eval hasn't yet been called.  This means it dereferences a
null object which causes a segfault.

This is all because xemacs is doing it's own thing to work out memory limits. 
In particular, it's using 'environ' to find the base of the heap
(src/sysdep.c), which not a particularly good way of doing it - there's nothing
to say that environ is at the bottom of the heap, which is what xemacs is
assuming, and it's simply false for PIEs.

This was fixed for emacs itself, which (at least when built PIE) uses the
'data_start' symbol.

Of course really there are two problems:
(1) the use of 'environ' is relying on undefined behaviour
(2) the warning function is using un-initialised data.

I suggest chatting to upstream about it - perhaps if they're planning to import
more recent code from the emacs base (src/sysdep.c is (c) 1995 in xemacs, (c)
2001 in emacs) this issue can be resolved in xemacs the same way it was in
emacs.

*** Bug 63358 has been marked as a duplicate of this bug. ***

I've (finally...) posted a note about this to the XEmacs development list.

still on xemacs-21.4.21-r1 ... updating title...

any response from upstream?

No response. XEmacs development is very slow at the moment, so I don't really
expect this to get fixed any time soon.