GNU bug report logs - #40338
27.0.60; c-fill-paragraph and after-change-functions

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Yuan Fu <casouri <at> gmail.com>
To: Bug Report Emacs <bug-gnu-emacs <at> gnu.org>
Subject: 27.0.60; c-fill-paragraph and after-change-functions
Date: Mon, 30 Mar 2020 21:27:33 -0400

[Message part 1 (text/plain, inline)]

Background: I use eglot with c-mode and every time I use c-fill-paragraph, eglot breaks—it reports a syntax error when there isn’t. It seems that eglot’s image of the buffer’s content (or what it thinks is in the buffer) is corrupted. I can fix this by revert-buffer. I have a feeling that this has something to do with after-change-functions because that’s the only way eglot gets updated with buffer changes. So I setup an experiment. It goes like this:

Open track.el and eval-buffer; then go to test.c and M-: (mytrack); then open the tracking buffer “trackbuf” in another window. Now if you edit in test.c, the change should be reflected in trackbuf. Now try M-q. Both buffer ends up in a corrupted state. 

I tried to look at c-fill-paragraph but it’s too complicated. I hope someone with more expertise in c-mode could give some insight.

Yuan

[track.el (application/octet-stream, attachment)]

[test.c (application/octet-stream, attachment)]

[Message part 4 (text/plain, inline)]

In GNU Emacs 27.0.60 (build 1, x86_64-apple-darwin19.3.0, NS appkit-1894.30 Version 10.15.3 (Build 19D76))
of 2020-02-25 built on missSilver
Repository revision: f27187f963e9e36435b508e29256e048799e0ff2
Repository branch: emacs-27
Windowing system distributor 'Apple', version 10.3.1894
System Description:  Mac OS X 10.15.4

Recent messages:
Wrote /Users/yuan/Desktop/test.c
C-= is undefined
scroll-up-command: End of buffer
Mark set [3 times]
Saving file /Users/yuan/Desktop/track.el...
Wrote /Users/yuan/Desktop/track.el
mytrack-hook
(mytrack-hook)
save-current-buffer: Args out of range: #<buffer trackbuf>, 421, 422
Undo
(mytrack-hook)
Configured using:
'configure --with-modules --with-pdumper=yes
--oldincludedir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/libxml2/'

Configured features:
RSVG GLIB NOTIFY KQUEUE ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS XIM
NS MODULES THREADS PDUMPER LCMS2

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

Major mode: C/*l

Minor modes in effect:
  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 rmc puny dired dired-loaddefs
format-spec rfc822 mml mml-sec password-cache epa derived epg epg-config
gnus-util rmail rmail-loaddefs text-property-search seq byte-opt gv
bytecomp byte-compile cconv mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils time-date subr-x 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 tooltip eldoc electric uniquify
ediff-hook vc-hooks lisp-float-type mwheel term/ns-win ns-win
ucs-normalize mule-util 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 kqueue cocoa ns
lcms2 multi-tty make-network-process emacs)

Memory information:
((conses 16 70716 8607)
(symbols 48 8390 1)
(strings 32 21585 1417)
(string-bytes 1 808085)
(vectors 16 12103)
(vector-slots 8 152019 12686)
(floats 8 25 62)
(intervals 56 999 22)
(buffers 1000 16))

Message #8 received at 40338 <at> debbugs.gnu.org (full text, mbox):

From: Noam Postavsky <npostavs <at> gmail.com>
To: Yuan Fu <casouri <at> gmail.com>
Cc: 40338 <at> debbugs.gnu.org
Subject: Re: bug#40338: 27.0.60; c-fill-paragraph and after-change-functions
Date: Mon, 30 Mar 2020 21:56:56 -0400

Yuan Fu <casouri <at> gmail.com> writes:

> (defun mytrack-hook (beg end len)
>   (if (> len 0)
>       ;; delete
>       (with-current-buffer trackbuf
>         (delete-region beg (+ beg len)))
>     ;; insert
>     (let ((content (buffer-substring beg end)))
>       (with-current-buffer trackbuf
>         (goto-char beg)
>         (insert content)))))

I'm not very familiar with either eglot or cc-mode, but I can say the
problem in your example lies with mytrack-hook: there can be kinds of
changes other than just pure delete or insert (replace, for example).
It can be fixed like this:

(defun mytrack-hook (beg end len)
  (when (> len 0)
    ;; Delete old text.
    (with-current-buffer "trackbuf"
      (delete-region beg (+ beg len))))
  ;; Insert new text.
  (let ((content (buffer-substring beg end)))
    (with-current-buffer "trackbuf"
      (goto-char beg)
      (insert content))))

Message #11 received at 40338 <at> debbugs.gnu.org (full text, mbox):

From: Yuan Fu <casouri <at> gmail.com>
To: Noam Postavsky <npostavs <at> gmail.com>
Cc: 40338 <at> debbugs.gnu.org
Subject: Re: bug#40338: 27.0.60; c-fill-paragraph and after-change-functions
Date: Tue, 31 Mar 2020 11:27:23 -0400

> On Mar 30, 2020, at 9:56 PM, Noam Postavsky <npostavs <at> gmail.com> wrote:
> 
> Yuan Fu <casouri <at> gmail.com> writes:
> 
>> (defun mytrack-hook (beg end len)
>>  (if (> len 0)
>>      ;; delete
>>      (with-current-buffer trackbuf
>>        (delete-region beg (+ beg len)))
>>    ;; insert
>>    (let ((content (buffer-substring beg end)))
>>      (with-current-buffer trackbuf
>>        (goto-char beg)
>>        (insert content)))))
> 
> I'm not very familiar with either eglot or cc-mode, but I can say the
> problem in your example lies with mytrack-hook: there can be kinds of
> changes other than just pure delete or insert (replace, for example).
> It can be fixed like this:
> 
> (defun mytrack-hook (beg end len)
>  (when (> len 0)
>    ;; Delete old text.
>    (with-current-buffer "trackbuf"
>      (delete-region beg (+ beg len))))
>  ;; Insert new text.
>  (let ((content (buffer-substring beg end)))
>    (with-current-buffer "trackbuf"
>      (goto-char beg)
>      (insert content))))
> 

Thank you. Indeed this works. Maybe the problem is not in c-fill-paragraph. 

Yuan

Message #16 received at 40338-done <at> debbugs.gnu.org (full text, mbox):

From: Yuan Fu <casouri <at> gmail.com>
To: 40338-done <at> debbugs.gnu.org
Subject: Fwd: bug#40338: 27.0.60; c-fill-paragraph and after-change-functions
Date: Tue, 31 Mar 2020 13:09:18 -0400

[Message part 1 (text/plain, inline)]

> Begin forwarded message:
> 
> From: Yuan Fu <casouri <at> gmail.com>
> Subject: Re: bug#40338: 27.0.60; c-fill-paragraph and after-change-functions
> Date: March 31, 2020 at 11:27:23 AM GMT-4
> To: Noam Postavsky <npostavs <at> gmail.com>
> Cc: 40338 <at> debbugs.gnu.org
> 
> 
> 
>> On Mar 30, 2020, at 9:56 PM, Noam Postavsky <npostavs <at> gmail.com> wrote:
>> 
>> Yuan Fu <casouri <at> gmail.com> writes:
>> 
>>> (defun mytrack-hook (beg end len)
>>> (if (> len 0)
>>>     ;; delete
>>>     (with-current-buffer trackbuf
>>>       (delete-region beg (+ beg len)))
>>>   ;; insert
>>>   (let ((content (buffer-substring beg end)))
>>>     (with-current-buffer trackbuf
>>>       (goto-char beg)
>>>       (insert content)))))
>> 
>> I'm not very familiar with either eglot or cc-mode, but I can say the
>> problem in your example lies with mytrack-hook: there can be kinds of
>> changes other than just pure delete or insert (replace, for example).
>> It can be fixed like this:
>> 
>> (defun mytrack-hook (beg end len)
>> (when (> len 0)
>>   ;; Delete old text.
>>   (with-current-buffer "trackbuf"
>>     (delete-region beg (+ beg len))))
>> ;; Insert new text.
>> (let ((content (buffer-substring beg end)))
>>   (with-current-buffer "trackbuf"
>>     (goto-char beg)
>>     (insert content))))
>> 
> 
> Thank you. Indeed this works. Maybe the problem is not in c-fill-paragraph. 
> 
> Yuan

[Message part 2 (text/html, inline)]

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