Subject: bug#41805: 26.3; icomplete in buffer throws an error if there's an elisp special character after point

From: James Thomas <[email-masked]>
Date: Thu, 11 Jun 2020 19:37:15 +0530

1. emacs -Q
2. M-: (setq icomplete-in-buffer t)
3. M-x icomplete-mode
4. Type a single quote (')
5. C-b
6. C-M-i

Error in post-command-hook (icomplete-post-command-hook): (args-out-of-range #(";; This buffer is for text that is not saved, and for Lisp evaluation.
;; To create a file, visit it with C-x C-f and enter text in its buffer.

" 0 3 (fontified t face font-lock-comment-delimiter-face) 3 71 (fontified t face font-lock-comment-face) 71 74 (fontified t face font-lock-comment-delimiter-face) 74 144 (fontified t face font-lock-comment-face) 144 145 (fontified t)) 0 146)

Happens also in Emacs 28 development version; and with other special
characters: " \ ) ( etc in step 4.

In GNU Emacs 26.3 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.14)
 of 2020-03-26, modified by Debian built on lcy01-amd64-020
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description:	Ubuntu 20.04 LTS

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
t
Icomplete mode enabled
Error in post-command-hook (icomplete-post-command-hook): (args-out-of-range #(";; This buffer is for text that is not saved, and for Lisp evaluation.
;; To create a file, visit it with C-x C-f and enter text in its buffer.

" 0 3 (fontified t face font-lock-comment-delimiter-face) 3 71 (fontified t face font-lock-comment-face) 71 74 (fontified t face font-lock-comment-delimiter-face) 74 144 (fontified t face font-lock-comment-face) 144 145 (fontified t)) 0 146)

Configured using:
 'configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --enable-libsystemd --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/26.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.3/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils --build
 x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
 --libexecdir=/usr/lib --localstatedir=/var/lib
 --infodir=/usr/share/info --mandir=/usr/share/man --enable-libsystemd
 --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/26.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.3/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-mailutils --with-x=yes
 --with-x-toolkit=gtk3 --with-toolkit-scroll-bars 'CFLAGS=-g -O2
 -fdebug-prefix-map=/build/emacs-mEZBk7/emacs-26.3+1=. -fstack-protector-strong
 -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
 -D_FORTIFY_SOURCE=2' 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro''

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS GLIB
NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM THREADS LIBSYSTEMD LCMS2

Important settings:
  value of $LANG: en_IN
  locale-coding-system: iso-latin-1-unix

Major mode: Lisp Interaction

Minor modes in effect:
  icomplete-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  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

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny seq byte-opt gv
bytecomp byte-compile cconv cl-loaddefs cl-lib dired dired-loaddefs
format-spec rfc822 mml easymenu 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 cus-start cus-load
icomplete elec-pair 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 threads dbusbind inotify lcms2 dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 102444 5789)
 (symbols 48 21318 1)
 (miscs 40 49 104)
 (strings 32 29961 1070)
 (string-bytes 1 769922)
 (vectors 16 13939)
 (vector-slots 8 501270 9470)
 (floats 8 51 76)
 (intervals 56 339 277)
 (buffers 992 11))