balance-windows causes core dump

[Stefan Monnier]

On my GNU/Linux system here, I can crash Emacs as follows:

   emacs -Q
   C-x 2
   M-x balance-windows RET

   Emacs fatal error: window.c:4292: assertion failed: GC_WINDOWP(parent)
   Fatal error (6)zsh: abort (core dumped)  ../../trunk/src/emacs -Q

I don't have time to look into it right now, but the problem is in
adjust-window-trailing-edge.  And it's only correctly caught if you compile
with ENABLE_CHECKING.


        Stefan


#0  0xb7c1dbf1 in kill () from /lib/tls/libc.so.6
#1  0x081306bc in abort () at emacs.c:464
#2  0x0819ce06 in die (msg=0x0, file=0x0, line=0) at alloc.c:6199
#3  0x080beed3 in Fadjust_window_trailing_edge (window=138362889, delta=-8, 
    horizontal=138362889) at window.c:4290
#4  0x081bd903 in Feval (form=137729213) at eval.c:2247
#5  0x081c0aab in internal_lisp_condition_case (var=138707377, 
    bodyform=137729213, handlers=137729245) at eval.c:1418
#6  0x081f6440 in Fbyte_code (bytestr=137729139, vector=137729188, maxdepth=3)
    at bytecode.c:884
#7  0x081be16f in funcall_lambda (fun=<value optimized out>, nargs=3, 
    arg_vector=0xbf8d77c4) at eval.c:3088
#8  0x081be739 in Ffuncall (nargs=4, args=0xbf8d77c0) at eval.c:2956
#9  0x081f7259 in Fbyte_code (bytestr=137729451, vector=137729772, maxdepth=6)
    at bytecode.c:694
#10 0x081be16f in funcall_lambda (fun=<value optimized out>, nargs=3, 
    arg_vector=0xbf8d78f4) at eval.c:3088
#11 0x081be739 in Ffuncall (nargs=4, args=0xbf8d78f0) at eval.c:2956
#12 0x081f7259 in Fbyte_code (bytestr=137729451, vector=137729772, maxdepth=6)
    at bytecode.c:694
#13 0x081be16f in funcall_lambda (fun=<value optimized out>, nargs=3, 
    arg_vector=0xbf8d7a24) at eval.c:3088
#14 0x081be739 in Ffuncall (nargs=4, args=0xbf8d7a20) at eval.c:2956
#15 0x081f7259 in Fbyte_code (bytestr=137728699, vector=137728916, maxdepth=9)
    at bytecode.c:694
#16 0x081be16f in funcall_lambda (fun=<value optimized out>, nargs=0, 
    arg_vector=0xbf8d7b64) at eval.c:3088
#17 0x081be739 in Ffuncall (nargs=1, args=0xbf8d7b60) at eval.c:2956
#18 0x081c0758 in apply1 (fn=140510433, arg=138362889) at eval.c:2646
#19 0x081ba1c0 in Fcall_interactively (function=140510433, 
    record_flag=138362937, keys=138419788) at callint.c:412
#20 0x0813ce3d in Fcommand_execute (cmd=140510433, record_flag=138362937, 
    keys=0, special=138362889) at keyboard.c:9768
#21 0x0813d241 in Fexecute_extended_command (prefixarg=138362889)
    at keyboard.c:9878
#22 0x081be9c5 in Ffuncall (nargs=2, args=0xbf8d7e90) at eval.c:2901
#23 0x081b9fe2 in Fcall_interactively (function=138420281, 
    record_flag=138362889, keys=138419788) at callint.c:884
#24 0x0813ce3d in Fcommand_execute (cmd=138420281, record_flag=138362889, 
    keys=0, special=138362889) at keyboard.c:9768
#25 0x08149248 in command_loop_1 () at keyboard.c:1791
#26 0x081bc0b2 in internal_condition_case (bfun=0x8148c70 <command_loop_1>, 
    handlers=138423929, hfun=0x813e010 <cmd_error>) at eval.c:1473
#27 0x081337be in command_loop_2 () at keyboard.c:1328
#28 0x081bbcfc in internal_catch (tag=0, func=0x8133790 <command_loop_2>, 
    arg=138362889) at eval.c:1211
#29 0x0813336e in command_loop () at keyboard.c:1307
#30 0x08133414 in recursive_edit_1 () at keyboard.c:1000
#31 0x08133596 in Frecursive_edit () at keyboard.c:1061
#32 0x0813218f in main (argc=2, argv=0xbf8d8754) at emacs.c:1789