Subject: bug#40317: 27.0.90; Reverting a buffer that visits C file signals an error

From: Eli Zaretskii <[email-masked]>
Date: Sun, 29 Mar 2020 16:26:33 +0300

When I visit a C source file that already has a buffer that visits it,
and that file has been changed behind Emacs's back by "git pull",
Emacs frequently signals an error.  Here's an example:

  Debugger entered--Lisp error: (args-out-of-range #<buffer xfaces.c> 1 217135)
    parse-partial-sexp(1 217135 nil nil nil syntax-table)
    c-after-change-mark-abnormal-strings(214738 215088 0)
    #f(compiled-function (fn) #<bytecode -0x1ffffffff8fc4c10>)(c-after-change-mark-abnormal-strings)
    mapc(#f(compiled-function (fn) #<bytecode -0x1ffffffff8fc4c10>) (c-depropertize-new-text c-after-change-escape-NL-in-string c-parse-quotes-after-change c-after-change-mark-abnormal-strings c-extend-font-lock-region-for-macros c-neutralize-syntax-in-CPP c-change-expand-fl-region))
    c-after-change(214738 215088 0)
    insert-file-contents("branch/src/xfaces.c" t nil nil t)
    revert-buffer-insert-file-contents--default-function("branch/src/xfaces.c" nil)
    revert-buffer--default(t t)
    revert-buffer(t t)
    find-file-noselect("branch/src/xfaces.c" nil nil t)
    find-file("branch/src/xfaces.c" t)
    funcall-interactively(find-file "branch/src/xfaces.c" t)
    call-interactively(find-file nil nil)
    command-execute(find-file)

In this particular case, the buffer's point-max is 216784, which
explains the error, but I have no idea where did the 217135 value come
from, because AFAICT the latest change in Git (the emacs-27 branch)
made that file larger, not smaller.

I hope this can be fixed soon, as this happens quite a lot to me, and
is very annoying.

In GNU Emacs 27.0.90 (build 3, i686-pc-mingw32)
 of 2020-03-06 built on HOME-C4E4A596F7
Windowing system distributor 'Microsoft Corp.', version 5.1.2600
System Description: Microsoft Windows XP Service Pack 3 (v5.1.0.2600)

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure -C --prefix=/d/usr --with-wide-int --with-modules
 'CFLAGS=-Og -gdwarf-4 -g3''

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY W32NOTIFY ACL GNUTLS LIBXML2
HARFBUZZ ZLIB TOOLKIT_SCROLL_BARS MODULES THREADS JSON PDUMPER LCMS2 GMP

Important settings:
  value of $LANG: ENU
  locale-coding-system: cp1255

Major mode: Lisp Interaction

Minor modes in effect:
  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 dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg
epg-config gnus-util rmail rmail-loaddefs text-property-search time-date
subr-x seq byte-opt gv bytecomp byte-compile cconv mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs
cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel dos-w32 ls-lisp disp-table term/w32-win w32-win w32-vars
term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame minibuffer 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 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 w32notify w32 lcms2 multi-tty make-network-process
emacs)

Memory information:
((conses 16 50720 11407)
 (symbols 48 7171 1)
 (strings 16 18862 2117)
 (string-bytes 1 532860)
 (vectors 16 9508)
 (vector-slots 8 127133 8382)
 (floats 8 21 66)
 (intervals 40 252 93)
 (buffers 888 11))