bug#29031: 25.3; Segmentation fault when starting emacs with my config

[Kaushal Modi]

Hello all,

I cannot understand why, but reverting nlinum to version 1.7 fixed this.

stable nlinum version for me: http://git.savannah.gnu.org/cgit/emacs/elpa.git/commit/?id=e885224c70f5fc03b23590304dd0fd21524d27e1

Also I couldn't figure out how to reproduce this issue on emacs -Q. But here are some observations (on emacs 25.3):

- I started this bug saying that I can reproduce this crash only on the company CAD built emacs 25.3. But turns out that the crash happens on my build of emacs-25 branch that I had done a long time back, only when running emacs, not emacsclient.

- Crash happened only when I loaded nlinum (not linum) AND had my config call the below modi/blend-linum function in wrapper function in window-setup-hook.

- Couldn't recreate crash if I commented out the lines calling that function, *or* the lines loading nlinum in my config.

- Even if I commented out the call to modi/blend-linum, emacs 25.3 does not crash, but the line numbers look BAD (see this gifv to see what I mean: https://i.imgur.com/8npahiz.gifv). That is with current line number highlight enabled in nlinum.

- The crash AND visual artifact issue went away on reverted to nlinum 1.7 without having to comment out the call to modi/blend-linum, on emacs 25.3.

=====

(defun modi/blend-linum ()

  "Set the linum foreground face to that of

`font-lock-comment-face' and background color to that of the

theme."

  (interactive)

  (set-face-attribute

   'linum nil

   :height 0.9

   :foreground (if (string= (face-foreground 'font-lock-comment-face) "unspecified-fg")

                   "#8f8f8f"

                 (face-foreground 'font-lock-comment-face))

   :background (if (string= (face-background 'default) "unspecified-bg")

                   "#282828"

                 (face-background 'default))))

=====

**I couldn't reproduce the visual artifact issues or crash on emacs 26.x+.**

Appendix: I generate my theme-loading function 'load-theme/smyx' (that loads my custom theme smyx). That is the wrapper fn I referred above, that's called in window-setup-hook. That wrapper fn calls modi/blend-linum. Relevant part from my config[1].

[1]: https://github.com/kaushalmodi/.emacs.d/blob/1e37e3502ed1337420d7fb0db7f940c52694bdca/setup-files/setup-visual.el#L157-L221

On Mon, Oct 30, 2017 at 10:17 AM Kaushal Modi <kaushal.modi@gmail.com> wrote:

The CAD department built 25.3 again, this time, with libotf. But I still get the segmentation fault. See the backtrace below. The backtrace looks different this time though.. "xdisp.c: No such file or directory"!?

Emacs version: GNU Emacs 25.3.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.24.23)

 of 2017-10-30, built using commit .

./configure options:

  --prefix=/cad/adi/apps/gnu/linux/x86_64/6/local/emacs/25.3 --with-modules

Features:

  XPM JPEG TIFF GIF PNG RSVG SOUND DBUS GCONF NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK2 X11 MODULES

=====

Starting program: /cad/adi/apps/gnu/linux/x86_64/6/local/emacs/25.3/bin/emacs

[Thread debugging using libthread_db enabled]

Using host libthread_db library "/lib64/libthread_db.so.1".

[New Thread 0x7fffef071700 (LWP 10664)]

Thread 1 "emacs" received signal SIGSEGV, Segmentation fault.

0x000000000043d101 in append_glyph (it=0x7fffffff2390) at xdisp.c:25880

25880   xdisp.c: No such file or directory.

(gdb) bt

#0  0x000000000043d101 in append_glyph (it=0x7fffffff2390) at xdisp.c:25880

#1  x_produce_glyphs (it=0x7fffffff2390) at xdisp.c:27175

#2  0x0000000000452032 in display_line (it=0x7fffffff2390) 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=109811619, prev_event=0,

    used_mouse_menu=0x7fffffffb11f, end_time=0x0) at keyboard.c:2482

#10 0x00000000004f90c0 in read_key_sequence (keybuf=0x7fffffffb190, 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

--

Kaushal Modi

--

Kaushal Modi