in libXft, xftdpy.c, around line 547:

    if (FcPatternGet (pattern, XFT_MAX_GLYPH_MEMORY, 0, &v) == FcResultNoMatch)
    {
	FcPatternAddInteger (pattern, XFT_MAX_GLYPH_MEMORY,
			     XftDefaultGetInteger (dpy, XFT_MAX_GLYPH_MEMORY,
						   screen,
						   XFT_FONT_MAX_GLYPH_MEMORY));
    }

libXft adds a custom fontconfig object which has not been registered
with fontconfig, i.e. FcNameRegisterObjectTypes has not been called
for this object.

This leads to a crash in rxvt-unicode when starting rxvt-unicode like
this:

    urxvt -fn "fixed,xft:courier"

and then displaying Japanese:

    LC_ALL=ja_JP.UTF-8 date

Created attachment 61879 [details]
p_xft_bugzilla_141216.diff

Patch to fix the problem.

patch by Dirk Müller <dmueller@suse.de> and me.

After fixing the problem with the bitmap fonts mentioned in bug
#137145, urxvt still crashed often, but this fix for libXft finally
seems to avoid all remaining fontconfig related crashes of urxvt.

Added Jan Blunck <jblunck@suse.de> to CC: because he suffered from
the urxvt crashes. Jan, you can try the xorg-x11 packages from the following
mbuild jobs (for STABLE):

magellan-mfabian-23 xorg-x11: finished - succeeded: 1
magellan-mfabian-24 xorg-x11: finished - succeeded: 1

They should fix the problem for you.

Reassigning to sndirsch@suse.de to add the patch to our xorg-x11
package.

Created attachment 61886 [details]
fontconfig-test.c

Test program to demonstrate the problem.

Compiling and running the test program:

mfabian@magellan:~/c$ make fontconfig-test
gcc -g -O0 -Wall -o fontconfig-test fontconfig-test.c -I/usr/X11R6/include -I/usr/include/freetype2 -I/usr/include/freetype2/config -I/usr/X11R6/include -L/usr/X11R6/lib64 -lXft -lX11 -lfreetype -lfontconfig -L/usr/X11R6/lib64 -lXrender -lX11
fontconfig-test.c: In function ‘main’:
fontconfig-test.c:41: warning: pointer targets in passing argument 1 of ‘FcNameParse’ differ in signedness
fontconfig-test.c:42: warning: pointer targets in assignment differ in signedness
fontconfig-test.c:46: warning: pointer targets in assignment differ in signedness
fontconfig-test.c:38: warning: unused variable ‘p’
mfabian@magellan:~/c$ ./fontconfig-test courier
1: courier
1: courier:maxglyphmemory=1048576:\_\_DUMMY\_\_=1048576
mfabian@magellan:~/c$


Note the weird __DUMMY__ which has been added to the pattern after

    FcPatternAddInteger (pattern, XFT_MAX_GLYPH_MEMORY, 1048576);

Created attachment 61887 [details]
fontconfig-test.c

"fixed" test program which adds

    { XFT_MAX_GLYPH_MEMORY,	FcTypeInteger, }, 

to _XftObjectTypes[].

Compiling and running the "fixed" test-program:

mfabian@magellan:~/c$ make fontconfig-test
gcc -g -O0 -Wall -o fontconfig-test fontconfig-test.c -I/usr/X11R6/include -I/usr/include/freetype2 -I/usr/include/freetype2/config -I/usr/X11R6/include -L/usr/X11R6/lib64 -lXft -lX11 -lfreetype -lfontconfig -L/usr/X11R6/lib64 -lXrender -lX11
fontconfig-test.c: In function ‘main’:
fontconfig-test.c:41: warning: pointer targets in passing argument 1 of ‘FcNameParse’ differ in signedness
fontconfig-test.c:42: warning: pointer targets in assignment differ in signedness
fontconfig-test.c:46: warning: pointer targets in assignment differ in signedness
fontconfig-test.c:38: warning: unused variable ‘p’
mfabian@magellan:~/c$ ./fontconfig-test courier
1: courier
1: courier:maxglyphmemory=1048576
mfabian@magellan:~/c$

The fixed test-program shows that after properly registering the new
fontconfig object the weird __DUMMY__ element is not added
to the pattern anymore.

probably this should be committed upstream as an obvious bugfix. 

fixed for STABLE, i.e. 10.1 Beta1.

Reported upstream:

  https://bugs.freedesktop.org/show_bug.cgi?id=5491