So what is the problematic data here? Is 'glyph' a NULL pointer or
something? Or is 'it' a garbled pointer? What do these commands
show:
(gdb) p glyph
(gdb) p glyph->charpos
(gdb) p it->position
This is what I got:
Thread 1 "emacs" received signal SIGSEGV, Segmentation fault.
0x000000000043d101 in append_glyph (it=0x7fffffff2370) at xdisp.c:25880
25880 xdisp.c: No such file or directory.
(gdb) bt
#0 0x000000000043d101 in append_glyph (it=0x7fffffff2370) at xdisp.c:25880
#1 x_produce_glyphs (it=0x7fffffff2370) at xdisp.c:27175
#2 0x0000000000452032 in display_line (it=0x7fffffff2370) at xdisp.c:20676
#3 0x0000000000457868 in try_window (window=18793157, pos=..., flags=1) at xdisp.c:17251
#4 0x0000000000460e41 in redisplay_window (window=18793157, just_this_one_p=false)
at xdisp.c:16700
#5 0x0000000000463b36 in redisplay_window_0 (window=<optimized out>) at xdisp.c:14491
#6 0x000000000055e7c6 in internal_condition_case_1 (bfun=0x463b10 <redisplay_window_0>,
arg=18793157, handlers=<optimized out>, hfun=0x429b40 <redisplay_window_error>)
at eval.c:1339
#7 0x000000000044612e in redisplay_windows (window=<optimized out>) at xdisp.c:14471
#8 0x000000000045cfd5 in redisplay_internal () at xdisp.c:14031
#9 0x00000000004f5299 in read_char (commandflag=1, map=102809939, prev_event=0,
used_mouse_menu=0x7fffffffb0ff, end_time=0x0) at keyboard.c:2482
#10 0x00000000004f90c0 in read_key_sequence (keybuf=0x7fffffffb170, prompt=0,
dont_downcase_last=false, can_return_switch_frame=true, fix_current_buffer=true,
prevent_redisplay=false, bufsize=30) at keyboard.c:9068
#11 0x00000000004fa3ba in command_loop_1 () at keyboard.c:1370
#12 0x000000000055e82a in internal_condition_case (bfun=0x4fa1f0 <command_loop_1>,
handlers=<optimized out>, hfun=0x4f8200 <cmd_error>) at eval.c:1315
#13 0x00000000004f81ec in command_loop_2 (ignore=<optimized out>) at keyboard.c:1112
#14 0x000000000055e8b8 in internal_catch (tag=<optimized out>,
func=0x4f81d0 <command_loop_2>, arg=0) at eval.c:1080
#15 0x00000000004f7f67 in command_loop () at keyboard.c:1091
#16 0x00000000004f7ff5 in recursive_edit_1 () at keyboard.c:697
#17 0x00000000004f8135 in Frecursive_edit () at keyboard.c:768
#18 0x00000000004e997e in main (argc=<optimized out>, argv=<optimized out>) at emacs.c:1629
(gdb) p glyph
$1 = (struct glyph *) 0x8f
(gdb) p glyph->charpos
Cannot access memory at address 0x8f
(gdb) p it->position
$2 = {charpos = 1, bytepos = 1}
(gdb)
Basically, I need you to run this under a debugger and answer several
questions. Bonus points for reproducing this in an unoptimized build
configured with --enable-checking='yes,glyphs', and then showing the
backtrace from the segfault.
IOW, this problem needs to be debugged, and for that we need data that
explains the crash. Could you please help in collecting that data?
Sure.
Another data point: I can prevent the crash if I add nlinum-enabling hooks in window-setup-hook instead of after-init-hook. When using emacsclient (daemon), I do that nlinum enabling in after-make-frame-functions. So I see this crash only when running emacs (not emacsclient), on 25.3.
Let me try to build emacs-25 branch with your suggested options.. hopefully I can recreate the crash on that.