bug#21320: diff-buffer-with-file fails on remote files

[Stefan Monnier]

Package: Emacs
Version: 25.0.50


If you visit a file via Tramp, then make some changes and do M-x
diff-buffer-with-file, you'll get an error in the diff buffer because
"diff" is executed locally with the Tramp file name.


        Stefan




In GNU Emacs 25.0.50.1 (x86_64-unknown-linux-gnu, X toolkit, Xaw scroll bars)
 of 2015-08-10 on pastel
Repository revision: 3fe0089e26b6b4d0da4126826c1f0df9be5624cf
Windowing system distributor `The X.Org Foundation', version 11.0.11604000
System Description:     Debian GNU/Linux 8.1 (jessie)

Configured using:
 `configure -C --enable-checking --enable-check-lisp-object-type
 'CFLAGS=-Wall -g3 -Og -Wno-pointer-sign'
 PKG_CONFIG_PATH=/home/monnier/lib/pkgconfig'

Configured features:
XPM JPEG TIFF GIF PNG SOUND NOTIFY GNUTLS LIBXML2 FREETYPE XFT ZLIB
TOOLKIT_SCROLL_BARS LUCID X11

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

Major mode: InactiveMinibuffer

Minor modes in effect:
  c-electric-flag: t
  shell-dirtrack-mode: t
  diff-auto-refine-mode: t
  electric-pair-mode: t
  url-handler-mode: t
  global-reveal-mode: t
  reveal-mode: t
  auto-insert-mode: t
  savehist-mode: t
  minibuffer-electric-default-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  global-prettify-symbols-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
Mark saved where search started
Mark set
Mark saved where search started [2 times]
Saving file /home/monnier/share/misc/todo...
Wrote /home/monnier/share/misc/todo
Entering debugger...
Quit
Entering debugger...
Quit
Back to top level
Quit

Load-path shadows:
/home/monnier/src/emacs/elpa/packages/ada-mode/ada-ref-man hides 
/home/monnier/src/emacs/elpa/packages/ada-ref-man/ada-ref-man
/home/monnier/src/emacs/elpa/packages/ada-mode/ada-prj hides 
/home/monnier/src/emacs/work/lisp/progmodes/ada-prj
/home/monnier/src/emacs/elpa/packages/ada-mode/ada-stmt hides 
/home/monnier/src/emacs/work/lisp/progmodes/ada-stmt
/home/monnier/src/emacs/elpa/packages/ada-mode/ada-mode hides 
/home/monnier/src/emacs/work/lisp/progmodes/ada-mode
/home/monnier/src/emacs/elpa/packages/ada-mode/ada-xref hides 
/home/monnier/src/emacs/work/lisp/progmodes/ada-xref
/home/monnier/src/emacs/elpa/packages/crisp/crisp hides 
/home/monnier/src/emacs/work/lisp/obsolete/crisp
/home/monnier/src/emacs/elpa/packages/landmark/landmark hides 
/home/monnier/src/emacs/work/lisp/obsolete/landmark
/home/monnier/src/emacs/work/lisp/emacs-lisp/cl-generic hides 
/home/monnier/src/emacs/elpa/packages/cl-generic/cl-generic

Features:
(mail-extr emacsbug dabbrev log-edit message sendmail rfc822 mml mml-sec
mm-decode mm-bodies mm-encode mail-parse rfc2231 rfc2047 rfc2045
ietf-drums mailabbrev mail-utils mailheader pcvs-util vc-bzr vc-src
vc-sccs vc-svn vc-cvs vc-rcs vc-dir css-mode bug-reference add-log
whitespace diff dts-mode smie tramp-cmds tramp-cache tramp-sh tramp
tramp-compat tramp-loaddefs trampver autorevert filenotify epa-file epa
derived epg semantic/bovine/c semantic/db-mode semantic/decorate/include
semantic/decorate/mode semantic/decorate pulse semantic/bovine/c-by
semantic/lex-spp semantic/idle semantic/bovine/gcc semantic/dep
semantic/bovine semantic/analyze/refs semantic/db-find semantic/db-ref
semantic/analyze semantic/sort semantic/scope semantic/analyze/fcn
semantic/db eieio-base semantic/ctxt semantic/format semantic/tag-ls
semantic/find semantic/util-modes semantic/util semantic semantic/tag
semantic/lex semantic/fw mode-local cedet hideif cpp cmacexp smerge-mode
ox-latex ox-icalendar ox-html ox-ascii ox-publish ox org-protocol
org-mouse org-mobile org-agenda org-indent org-feed org-crypt
org-capture org-attach org-id org-element org-rmail org-mhe org-irc
org-info org-gnus org-docview doc-view jka-compr image-mode dired
org-bibtex bibtex org-bbdb org-w3m org org-macro org-footnote
org-pcomplete org-list org-faces org-entities org-version ob-emacs-lisp
ob ob-tangle ob-ref ob-lob ob-table ob-exp org-src ob-keys ob-comint
ob-core ob-eval org-compat org-macs org-loaddefs format-spec cal-french
diary-lib diary-loaddefs cal-move cal-menu calendar cal-loaddefs cc-mode
cl-seq cc-fonts cc-guess cc-menus cc-cmds cc-styles cc-align cc-engine
cc-langs cc-vars cc-defs sort network-stream nsm starttls tls mpc
executable copyright shell pcomplete grep compile misearch multi-isearch
xscheme warnings unsafep trace testcover shadow scheme re-builder
profiler inf-lisp ielm pp gmm-utils ert ewoc debug elp edebug cl-indent
cus-edit cus-start cus-load wid-edit vc vc-dispatcher vc-git diff-mode
filecache eieio-opt speedbar sb-image ezimage dframe find-func
hippie-exp comint ansi-color ring server noutline outline easy-mmode
flyspell ispell checkdoc thingatpt load-dir elec-pair url-handlers
url-parse auth-source eieio byte-opt bytecomp byte-compile cl-extra seq
cconv eieio-core gnus-util time-date mm-util help-fns help-mode
mail-prsvr password-cache url-vars reveal autoinsert proof-site
proof-autoloads cl-macs cl gv pg-vars savehist minibuf-eldef disp-table
finder-inf edmacro kmacro cl-loaddefs pcase cl-lib advice info package
easymenu epg-config bbdb-autoloads vm-autoloads mule-util tooltip eldoc
electric uniquify ediff-hook vc-hooks lisp-float-type mwheel x-win
term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list newcomment elisp-mode lisp-mode prog-mode register page
menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock
syntax font-core 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 charscript case-table epa-hook jka-cmpr-hook help simple abbrev
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 inotify dynamic-setting
font-render-setting x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 491698 88311)
 (symbols 48 42770 0) (miscs 40 8617 1424) (strings 32 118525 12636)
 (string-bytes 1 3440704)
 (vectors 16 71129) (vector-slots 8 2300229 108056) (floats 8 748 1076)
 (intervals 56 34337 94)
 (buffers 976 66) (heap 1024 685811 1726))