GNU bug report logs - #45016
26.3; when in ediff-current-file, 'D' (view diff) shows empty diff

Please note: This is a static page, with minimal formatting, updated once a day.
Click here to see this page with the latest information and nicer formatting.

Package: emacs; Reported by: Guilhem Bichot <guilhem.bichot@HIDDEN>; dated Wed, 2 Dec 2020 21:05:01 UTC; Maintainer for emacs is bug-gnu-emacs@HIDDEN.

Message received at 45016 <at> debbugs.gnu.org:


Received: (at 45016) by debbugs.gnu.org; 23 Jan 2021 23:27:34 +0000
From debbugs-submit-bounces <at> debbugs.gnu.org Sat Jan 23 18:27:34 2021
Received: from localhost ([127.0.0.1]:35608 helo=debbugs.gnu.org)
	by debbugs.gnu.org with esmtp (Exim 4.84_2)
	(envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>)
	id 1l3SJa-0006pf-8E
	for submit <at> debbugs.gnu.org; Sat, 23 Jan 2021 18:27:34 -0500
Received: from quimby.gnus.org ([95.216.78.240]:57160)
 by debbugs.gnu.org with esmtp (Exim 4.84_2)
 (envelope-from <larsi@HIDDEN>) id 1l3SJY-0006pP-C5
 for 45016 <at> debbugs.gnu.org; Sat, 23 Jan 2021 18:27:32 -0500
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnus.org;
 s=20200322; h=Content-Type:MIME-Version:Message-ID:In-Reply-To:Date:
 References:Subject:Cc:To:From:Sender:Reply-To:Content-Transfer-Encoding:
 Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender:
 Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:
 List-Subscribe:List-Post:List-Owner:List-Archive;
 bh=SU0Au7lWlysUFWg6sK3frq5zer2jrtuyhxwf8r7reco=; b=WlsiUjdYxnkPYdmB+yvEqhZgwd
 /p8NycZNB/eWT7O60BYp2VyyEQofHYMTzSc/sC/OHYN7lCf1XEePg9XjaowHAqNWORwB+ih0+KbwN
 LKP0MePdkSB0/nTtSobeichNh5Gh94yLsdyAd+yRebDlUHH4npMzgP1F5TEds40Y5uWc=;
Received: from cm-84.212.202.86.getinternet.no ([84.212.202.86] helo=xo)
 by quimby.gnus.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256)
 (Exim 4.92) (envelope-from <larsi@HIDDEN>)
 id 1l3SJM-0006iJ-VC; Sun, 24 Jan 2021 00:27:26 +0100
From: Lars Ingebrigtsen <larsi@HIDDEN>
To: Guilhem Bichot <guilhem.bichot@HIDDEN>
Subject: Re: bug#45016: 26.3; when in ediff-current-file, 'D' (view diff)
 shows empty diff
References: <d8511480-4240-b124-6b00-5cc32380d1d8@HIDDEN>
X-Now-Playing: Mourning A BLKstar's _The Cycle_: "Sense Of An Ending"
Date: Sun, 24 Jan 2021 00:27:19 +0100
In-Reply-To: <d8511480-4240-b124-6b00-5cc32380d1d8@HIDDEN> (Guilhem
 Bichot's message of "Wed, 2 Dec 2020 21:52:56 +0100")
Message-ID: <87im7nqlns.fsf@HIDDEN>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain
X-Spam-Report: Spam detection software, running on the system "quimby.gnus.org",
 has NOT identified this incoming email as spam.  The original
 message has been attached to this so you can view it or label
 similar future email.  If you have any questions, see
 @@CONTACT_ADDRESS@@ for details.
 Content preview: Guilhem Bichot <guilhem.bichot@HIDDEN> writes: > * start
 emacs -Q > * create a file named, for example, /tmp/a > * put a line of text
 in it, save it > * add some characters to this line, don't save > * launch
 M-x ediff-current-file > * press D to [...] 
 Content analysis details:   (-2.9 points, 5.0 required)
 pts rule name              description
 ---- ---------------------- --------------------------------------------------
 -1.0 ALL_TRUSTED            Passed through trusted hosts only via SMTP
 -1.9 BAYES_00               BODY: Bayes spam probability is 0 to 1%
 [score: 0.0000]
X-Spam-Score: 0.0 (/)
X-Debbugs-Envelope-To: 45016
Cc: 45016 <at> debbugs.gnu.org
X-BeenThere: debbugs-submit <at> debbugs.gnu.org
X-Mailman-Version: 2.1.18
Precedence: list
List-Id: <debbugs-submit.debbugs.gnu.org>
List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, 
 <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe>
List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/>
List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org>
List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help>
List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, 
 <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe>
Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org
Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org>
X-Spam-Score: -1.0 (-)

Guilhem Bichot <guilhem.bichot@HIDDEN> writes:

> * start emacs -Q
> * create a file named, for example, /tmp/a
> * put a line of text in it, save it
> * add some characters to this line, don't save
> * launch M-x ediff-current-file
> * press D to view the diff
> * a buffer opens to show the diff but it is empty. I expected to see a
> non-empty diff (a context diff, as ediff-custom-diff-options is at its
> default "-c").
> * if instead of D I press C-u D then I do get a non-empty plain diff
> (non-context, non-unified).

This bug is still present in Emacs 28.

This is how the `D' command starts:

(defun ediff-show-diff-output (arg)
  (interactive "P")
[...]
  (let ((buf (cond ((and arg (ediff-buffer-live-p ediff-diff-buffer))
		    ediff-diff-buffer)
		   ((ediff-buffer-live-p ediff-custom-diff-buffer)
		    ediff-custom-diff-buffer)

There's helpfully no doc string here (or comments) about what `arg' is
meant to express, but if we have `arg', we work on `ediff-diff-buffer'
(and this works), and if we don't have `arg', then
`ediff-custom-diff-buffer' is used (and this doesn't work).

I'm pretty unfamiliar with ediff -- does anybody know what the intention
here is for the prefix arg?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no




Information forwarded to bug-gnu-emacs@HIDDEN:
bug#45016; Package emacs. Full text available.

Message received at 45016 <at> debbugs.gnu.org:


Received: (at 45016) by debbugs.gnu.org; 3 Dec 2020 11:19:36 +0000
From debbugs-submit-bounces <at> debbugs.gnu.org Thu Dec 03 06:19:36 2020
Received: from localhost ([127.0.0.1]:38658 helo=debbugs.gnu.org)
	by debbugs.gnu.org with esmtp (Exim 4.84_2)
	(envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>)
	id 1kkme8-00089i-Dy
	for submit <at> debbugs.gnu.org; Thu, 03 Dec 2020 06:19:36 -0500
Received: from smtp03.smtpout.orange.fr ([80.12.242.125]:17173
 helo=smtp.smtpout.orange.fr)
 by debbugs.gnu.org with esmtp (Exim 4.84_2)
 (envelope-from <guilhem.bichot@HIDDEN>) id 1kkme6-00089R-54
 for 45016 <at> debbugs.gnu.org; Thu, 03 Dec 2020 06:19:34 -0500
Received: from [192.168.1.10] ([90.38.22.79]) by mwinf5d26 with ME
 id znKN2300B1iNpua03nKRZk; Thu, 03 Dec 2020 12:19:25 +0100
X-ME-Helo: [192.168.1.10]
X-ME-Auth: Z3VpbGhlbS5iaWNob3RAd2FuYWRvby5mcg==
X-ME-Date: Thu, 03 Dec 2020 12:19:25 +0100
X-ME-IP: 90.38.22.79
To: 45016 <at> debbugs.gnu.org
From: Guilhem Bichot <guilhem.bichot@HIDDEN>
Subject: additional information
Message-ID: <74325a41-96e4-84f3-41fa-a1dcff4dacde@HIDDEN>
Date: Thu, 3 Dec 2020 12:19:23 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
X-Spam-Score: 0.0 (/)
X-Debbugs-Envelope-To: 45016
X-BeenThere: debbugs-submit <at> debbugs.gnu.org
X-Mailman-Version: 2.1.18
Precedence: list
List-Id: <debbugs-submit.debbugs.gnu.org>
List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, 
 <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe>
List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/>
List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org>
List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help>
List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, 
 <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe>
Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org
Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org>
X-Spam-Score: -1.0 (-)

Apparently a person hit this issue in 2016 too:
https://emacs.stackexchange.com/questions/22090/emacs-show-diff-output-produces-empty-buffer




Information forwarded to bug-gnu-emacs@HIDDEN:
bug#45016; Package emacs. Full text available.

Message received at submit <at> debbugs.gnu.org:


Received: (at submit) by debbugs.gnu.org; 2 Dec 2020 21:04:41 +0000
From debbugs-submit-bounces <at> debbugs.gnu.org Wed Dec 02 16:04:41 2020
Received: from localhost ([127.0.0.1]:37553 helo=debbugs.gnu.org)
	by debbugs.gnu.org with esmtp (Exim 4.84_2)
	(envelope-from <debbugs-submit-bounces <at> debbugs.gnu.org>)
	id 1kkZIn-00040Y-4J
	for submit <at> debbugs.gnu.org; Wed, 02 Dec 2020 16:04:41 -0500
Received: from lists.gnu.org ([209.51.188.17]:40428)
 by debbugs.gnu.org with esmtp (Exim 4.84_2)
 (envelope-from <guilhem.bichot@HIDDEN>) id 1kkZ8D-0001Zc-C1
 for submit <at> debbugs.gnu.org; Wed, 02 Dec 2020 15:53:45 -0500
Received: from eggs.gnu.org ([2001:470:142:3::10]:52976)
 by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256)
 (Exim 4.90_1) (envelope-from <guilhem.bichot@HIDDEN>)
 id 1kkZ8D-000524-3h
 for bug-gnu-emacs@HIDDEN; Wed, 02 Dec 2020 15:53:45 -0500
Received: from smtp01.smtpout.orange.fr ([80.12.242.123]:25899
 helo=smtp.smtpout.orange.fr)
 by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:128)
 (Exim 4.90_1) (envelope-from <guilhem.bichot@HIDDEN>)
 id 1kkZ88-0001oB-0f
 for bug-gnu-emacs@HIDDEN; Wed, 02 Dec 2020 15:53:43 -0500
Received: from [192.168.1.10] ([90.38.22.79]) by mwinf5d53 with ME
 id zYsu230041iNpua03Yt9NK; Wed, 02 Dec 2020 21:53:09 +0100
X-ME-Helo: [192.168.1.10]
X-ME-Auth: Z3VpbGhlbS5iaWNob3RAd2FuYWRvby5mcg==
X-ME-Date: Wed, 02 Dec 2020 21:53:09 +0100
X-ME-IP: 90.38.22.79
To: bug-gnu-emacs@HIDDEN
From: Guilhem Bichot <guilhem.bichot@HIDDEN>
Subject: 26.3; when in ediff-current-file, 'D' (view diff) shows empty diff
Message-ID: <d8511480-4240-b124-6b00-5cc32380d1d8@HIDDEN>
Date: Wed, 2 Dec 2020 21:52:56 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Received-SPF: none client-ip=80.12.242.123;
 envelope-from=guilhem.bichot@HIDDEN; helo=smtp.smtpout.orange.fr
X-Spam_score_int: -18
X-Spam_score: -1.9
X-Spam_bar: -
X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001,
 RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001,
 SPF_NONE=0.001 autolearn=ham autolearn_force=no
X-Spam_action: no action
X-Spam-Score: -2.3 (--)
X-Debbugs-Envelope-To: submit
X-Mailman-Approved-At: Wed, 02 Dec 2020 16:04:39 -0500
X-BeenThere: debbugs-submit <at> debbugs.gnu.org
X-Mailman-Version: 2.1.18
Precedence: list
List-Id: <debbugs-submit.debbugs.gnu.org>
List-Unsubscribe: <https://debbugs.gnu.org/cgi-bin/mailman/options/debbugs-submit>, 
 <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=unsubscribe>
List-Archive: <https://debbugs.gnu.org/cgi-bin/mailman/private/debbugs-submit/>
List-Post: <mailto:debbugs-submit <at> debbugs.gnu.org>
List-Help: <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=help>
List-Subscribe: <https://debbugs.gnu.org/cgi-bin/mailman/listinfo/debbugs-submit>, 
 <mailto:debbugs-submit-request <at> debbugs.gnu.org?subject=subscribe>
Errors-To: debbugs-submit-bounces <at> debbugs.gnu.org
Sender: "Debbugs-submit" <debbugs-submit-bounces <at> debbugs.gnu.org>
X-Spam-Score: -3.3 (---)

Hello!

* start emacs -Q
* create a file named, for example, /tmp/a
* put a line of text in it, save it
* add some characters to this line, don't save
* launch M-x ediff-current-file
* press D to view the diff
* a buffer opens to show the diff but it is empty. I expected to see a
non-empty diff (a context diff, as ediff-custom-diff-options is at its
default "-c").
* if instead of D I press C-u D then I do get a non-empty plain diff
(non-context, non-unified).

I'm using Emacs 26.3 from Ubuntu 20.04. I reproduced it on another Emacs
installation on another computer (CentOS 7) where I built Emacs 27.1 
from source.

Thank you for bringing Emacs to developers.

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 20.04.1 LTS

Recent messages:
Saving file /tmp/a...
Wrote /tmp/a
Making completion list...
Computing differences between ediffZdQdH1 and aEcIRJR ...
Buffer A: Processing difference region 0 of 1
Buffer B: Processing difference region 0 of 1
Processing difference regions ... done
Refining difference region 1 ...
Quit this Ediff session? (y or n) y
Making completion list...

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: fr_FR.UTF-8
   value of $XMODIFIERS: @im=ibus
   locale-coding-system: utf-8-unix

Major mode: Fundamental

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

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc 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 diff-mode easymenu easy-mmode ediff-merg
ediff-wind ediff-diff ediff-mult ediff-help ediff-init cl-loaddefs
cl-lib ediff-util ediff 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 105677 13166)
  (symbols 48 21758 1)
  (miscs 40 67 140)
  (strings 32 31945 1163)
  (string-bytes 1 877549)
  (vectors 16 15315)
  (vector-slots 8 519098 11532)
  (floats 8 68 143)
  (intervals 56 282 0)
  (buffers 992 16))




Acknowledgement sent to Guilhem Bichot <guilhem.bichot@HIDDEN>:
New bug report received and forwarded. Copy sent to bug-gnu-emacs@HIDDEN. Full text available.
Report forwarded to bug-gnu-emacs@HIDDEN:
bug#45016; Package emacs. Full text available.
Please note: This is a static page, with minimal formatting, updated once a day.
Click here to see this page with the latest information and nicer formatting.
Last modified: Sat, 23 Jan 2021 23:30:02 UTC

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997 nCipher Corporation Ltd, 1994-97 Ian Jackson.