bug#27743: 26.0.50; Native Line Numbers seem to reset Tab Width

[Frank Terbeck]

At work we're using a tab-width of 4 (yeah, I know). I tried the new
native line number code with that and saw that the tab-width reverted to
eight characters. As soon as you disable line number display, tab-width
is back to whatever it is actually configured to.

This can in fact be reproduced from "emacs -Q". Just open a file that
uses tabs for indentation. Then set tabulator width:

  (setq tab-width 4)

The display of the tabulator width should now visibly be four
characters. Now enable line number display:

  (setq display-line-numbers 'relative)

Now the tabulator display returns to eight characters. This is the bug
that I'm reporting. Disabling line number display:

  (setq display-line-numbers nil)

...returns the tabulator width to four characters.


Regards, Frank


In GNU Emacs 26.0.50 (build 3, x86_64-pc-linux-gnu, GTK+ Version 3.22.16)
 of 2017-07-15 built on spock
Repository revision: 89c5d59280edaf89b959597a39d848b54c36975a
Windowing system distributor 'The X.Org Foundation', version 11.0.11903000
System Description:     Debian GNU/Linux unstable (sid)

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
irtt.c has auto save data; consider M-x recover-this-file
Making completion list... [3 times]
4 (#o4, #x4, ?\C-d)
Making completion list...
relative
user-error: Beginning of history; no preceding item

Configured using:
 'configure --prefix=/opt/emacs --with-modules'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GCONF GSETTINGS
NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 MODULES LIBSYSTEMD

Important settings:
  value of $LANG: en_GB.UTF-8
  locale-coding-system: utf-8-unix

Major mode: C/*l

Minor modes in effect:
  diff-auto-refine-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t
  abbrev-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message subr-x puny seq byte-opt gv
bytecomp byte-compile cconv dired dired-loaddefs format-spec rfc822 mml
mml-sec password-cache epa derived epg epg-config gnus-util rmail
rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils vc-git diff-mode easy-mmode cc-mode
cc-fonts easymenu cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine
cc-vars cc-defs cl-loaddefs cl-lib time-date mule-util tooltip eldoc
electric uniquify ediff-hook vc-hooks lisp-float-type mwheel term/x-win
x-win term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow isearch timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote dbusbind inotify dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 120767 9161)
 (symbols 48 22938 1)
 (miscs 40 55 190)
 (strings 32 35982 939)
 (string-bytes 1 1080868)
 (vectors 16 17064)
 (vector-slots 8 522375 8842)
 (floats 8 53 383)
 (intervals 56 958 9)
 (buffers 976 13))