$ lldb nextstep/Emacs.app/Contents/MacOS/Emacs
Current executable set to 'nextstep/Emacs.app/Contents/MacOS/Emacs' (x86_64).
(lldb) run
Process 12942 launched: '/Volumes/disk/Sources/emacs/nextstep/Emacs.app/Contents/MacOS/Emacs' (x86_64)
2013-03-12 18:26:35.533 Emacs[12942:f0b] *** WARNING: Method userSpaceScaleFactor in class NSWindow is deprecated on 10.7 and later. It should not be used in new applications. Use convertRectToBacking: instead.
Process 12942 stopped
* thread #1: tid = 0x1c03, 0x00007fff8ed75650 libsystem_c.dylib`strlen + 16, stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
frame #0: 0x00007fff8ed75650 libsystem_c.dylib`strlen + 16
libsystem_c.dylib`strlen + 16:
-> 0x7fff8ed75650: pcmpeqb(%rdi), %xmm0
0x7fff8ed75654: andl $15, %ecx
0x7fff8ed75657: shll %cl, %eax
0x7fff8ed75659: pmovmskb%xmm0, %ecx
(lldb) bt
* thread #1: tid = 0x1c03, 0x00007fff8ed75650 libsystem_c.dylib`strlen + 16, stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
frame #0: 0x00007fff8ed75650 libsystem_c.dylib`strlen + 16
frame #1: 0x000000010018ed47 Emacs`Fns_read_file_name [inlined] build_string(str=0x0000000000000000) + 8 at lisp.h:3066
frame #2: 0x000000010018ed3f Emacs`Fns_read_file_name(, dir=4310933248, mustmatch=140734799802432, init=4320145466, dir_only_p=0) + 783 at nsfns.m:1539
frame #3: 0x0000000100114207 Emacs`Ffuncall(, args=0x000000010011436c) + 1047 at eval.c:2691
frame #4: 0x000000010014b518 Emacs`exec_byte_code(, vector=140734799802800, maxdepth=0, args_template=0, nargs=4300775328, args=0x000000010050eba0) + 1992 at bytecode.c:902
frame #5: 0x0000000100114297 Emacs`Ffuncall(, args=0x000000010432dfea) + 1191 at eval.c:2724
frame #6: 0x0000000100116316 Emacs`apply1(fn=4365410282) + 38 at eval.c:2436
frame #7: 0x000000010011018a Emacs`Fcall_interactively(function=140734799803216, record_flag=140734799803216, keys=140734799803216) + 1418 at callint.c:377
frame #8: 0x00000001001141d3 Emacs`Ffuncall(, args=0x000000010011436c) + 995 at eval.c:2682
frame #9: 0x000000010014b518 Emacs`exec_byte_code(, vector=140734799803584, maxdepth=0, args_template=4299906395, nargs=4300775328, args=0x000000010050eba0) + 1992 at bytecode.c:902
frame #10: 0x0000000100114297 Emacs`Ffuncall(, args=0x00000001018115ba) + 1191 at eval.c:2724
frame #11: 0x00000001001175ee Emacs`call1() + 30 at eval.c:2469
frame #12: 0x00000001000aef95 Emacs`command_loop_1 + 1557 at keyboard.c:1586
frame #13: 0x0000000100115c19 Emacs`internal_condition_case(bfun=0x00000001000ae980, handlers=4320211610, hfun=0x00000001000afe10) + 297 at eval.c:1193
frame #14: 0x00000001000ae95e Emacs`command_loop_2() + 62 at keyboard.c:1173
frame #15: 0x0000000100115d15 Emacs`internal_catch(, func=0x00000001000ae920) + 213 at eval.c:964
frame #16: 0x00000001000b0390 Emacs`recursive_edit_1 [inlined] command_loop + 96 at keyboard.c:1152
frame #17: 0x00000001000b0330 Emacs`recursive_edit_1 + 144 at keyboard.c:785
frame #18: 0x00000001000a197d Emacs`Frecursive_edit + 237 at keyboard.c:849
frame #19: 0x000000010009e865 Emacs`main(argc=5808032, argv=0x00007fff5fbffb70) + 5973 at emacs.c:1530
frame #20: 0x00007fff8cca47e1 libdyld.dylib`start + 1
(lldb) f 2
frame #2: 0x000000010018ed3f Emacs`Fns_read_file_name(, dir=4310933248, mustmatch=140734799802432, init=4320145466, dir_only_p=0) + 783 at nsfns.m:1539
1536 ret = (ret == NSOKButton) || panelOK;
1537
1538 if (ret)
-> 1539 fname = build_string ([[panel filename] UTF8String]);
1540
1541 [[FRAME_NS_VIEW (SELECTED_FRAME ()) window] makeKeyWindow];
1542 unblock_input ();
(lldb)