bug#34387: 26.1; Gnus: handle empty message parts

[Christophe Troestler]

Hi,

Some messages only contain an attachment (no body) and 
(gnus-article-prepare-display) choke on the empty part.  More specifically, 
`gnus-mime-display-single' does (narrow-to-region beg (point)) which fails if 
the part is empty.  An easy fix is to write

      (when (< beg (point))
        (narrow-to-region beg (point))
        (if (eq handle gnus-article-mime-handles)
          ...))



In GNU Emacs 26.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.2)
 of 2018-12-26, modified by Debian built on x86-ubc-01
Windowing system distributor 'The X.Org Foundation', version 11.0.12003000
System Description:     Debian GNU/Linux buster/sid

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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/26.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.1/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/26.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.1/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-3ThesY/emacs-26.1+1=. -fstack-protector-strong
 -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
 -D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'

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

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

Major mode: mu4e:view

Minor modes in effect:
  visual-fill-column-mode: t
  TeX-PDF-mode: t
  global-magit-file-mode: t
  diff-auto-refine-mode: t
  magit-auto-revert-mode: t
  global-git-commit-mode: t
  async-bytecomp-package-mode: t
  shell-dirtrack-mode: t
  desktop-save-mode: t
  show-paren-mode: t
  global-edit-server-edit-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  column-number-mode: t
  line-number-mode: t
  visual-line-mode: t
  transient-mark-mode: t

Load-path shadows:
~/software/OCaml/dune/editor-integration/emacs/dune-flymake hides 
/home/trch/.opam/4.06.1/share/emacs/site-lisp/dune-flymake
~/software/OCaml/dune/editor-integration/emacs/dune hides 
/home/trch/.opam/4.06.1/share/emacs/site-lisp/dune
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/deb-view hides 
/usr/share/emacs/site-lisp/elpa/debian-el-37/deb-view
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/debian-bug hides 
/usr/share/emacs/site-lisp/elpa/debian-el-37/debian-bug
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/apt-utils hides 
/usr/share/emacs/site-lisp/elpa/debian-el-37/apt-utils
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/preseed hides 
/usr/share/emacs/site-lisp/elpa/debian-el-37/preseed
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/apt-sources hides 
/usr/share/emacs/site-lisp/elpa/debian-el-37/apt-sources
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/debian-autoloads hides 
/usr/share/emacs/site-lisp/elpa/debian-el-37/debian-autoloads
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/debian-el hides 
/usr/share/emacs/site-lisp/elpa/debian-el-37/debian-el
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/debian-el-autoloads hides 
/usr/share/emacs/site-lisp/elpa/debian-el-37/debian-el-autoloads
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/gnus-BTS hides 
/usr/share/emacs/site-lisp/elpa/debian-el-37/gnus-BTS
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/debian-el-pkg hides 
/usr/share/emacs/site-lisp/elpa/debian-el-37/debian-el-pkg
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/deb-view hides 
/usr/share/emacs/site-lisp/elpa-src/debian-el-37/deb-view
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/apt-utils hides 
/usr/share/emacs/site-lisp/elpa-src/debian-el-37/apt-utils
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/preseed hides 
/usr/share/emacs/site-lisp/elpa-src/debian-el-37/preseed
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/debian-bug hides 
/usr/share/emacs/site-lisp/elpa-src/debian-el-37/debian-bug
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/apt-sources hides 
/usr/share/emacs/site-lisp/elpa-src/debian-el-37/apt-sources
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/debian-autoloads hides 
/usr/share/emacs/site-lisp/elpa-src/debian-el-37/debian-autoloads
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/debian-el hides 
/usr/share/emacs/site-lisp/elpa-src/debian-el-37/debian-el
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/debian-el-autoloads hides 
/usr/share/emacs/site-lisp/elpa-src/debian-el-37/debian-el-autoloads
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/gnus-BTS hides 
/usr/share/emacs/site-lisp/elpa-src/debian-el-37/gnus-BTS
/home/trch/.emacs.d/elpa/debian-el-20181020.1513/debian-el-pkg hides 
/usr/share/emacs/site-lisp/elpa-src/debian-el-37/debian-el-pkg

Features:
(shadow emacsbug network-stream starttls mailalias face-remap timezone
cl-print debug cus-start cus-load view cal-china lunar solar cal-dst
cal-islam holidays hol-loaddefs cal-move reftex-parse misearch
multi-isearch sh-script executable texmathp qp visual-fill-column sort
gnus-cite smiley shr-color color shr svg dom mm-archive mail-extr
make-mode org-rmail org-mhe org-irc org-info org-gnus nnir org-docview
org-bibtex org-bbdb org-w3m latexenc tuareg caml caml-help reftex-auc
preview prv-emacs tex-buf reftex-dcr reftex reftex-loaddefs reftex-vars
flyspell ispell latex latex-flymake tex-ispell tex-style tex-mode vc-git
elec-pair font-latex tex dbus xml bibtex dune-flymake flymake-proc
flymake compile warnings dune skeleton smie utop utop-minor-mode pcase
merlin-cap merlin caml-types caml-emacs magit-gh-pulls subr-x s gh
gh-users gh-issues gh-pulls gh-repos gh-comments gh-gist gh-oauth gh-api
logito gh-cache pcache eieio-base gh-auth gh-url url-http url url-proxy
url-privacy url-expand url-methods url-history url-auth url-cookie
url-domsuf url-util url-gw nsm gh-profile json map magit-submodule
magit-obsolete magit-blame magit-stash magit-bisect magit-push
magit-pull magit-fetch magit-clone magit-remote magit-commit
magit-sequence magit-notes magit-worktree magit-tag magit-merge
magit-branch magit-reset magit-files magit-refs magit-status magit
magit-repos magit-apply magit-wip magit-log which-func imenu magit-diff
smerge-mode diff-mode magit-core magit-autorevert magit-process
magit-margin magit-mode git-commit magit-git magit-section magit-utils
magit-popup crm log-edit pcvs-util add-log with-editor cl-extra
async-bytecomp async shell dash erc-goodies erc erc-backend erc-compat
pp org-mu4e gnus-icalendar org-capture mu4e-contrib mu4e desktop
frameset mu4e-speedbar speedbar sb-image ezimage dframe mu4e-main
mu4e-view thingatpt browse-url gnus-art mm-uu mml2015 mm-view mml-smime
smime dig mailcap gnus-sum gnus-group gnus-undo gnus-start gnus-cloud
nnimap nnmail mail-source tls gnutls utf7 netrc nnoo parse-time
gnus-spec gnus-int gnus-range gnus-win gnus nnheader wid-edit
mu4e-headers mu4e-compose mu4e-context mu4e-draft mu4e-actions ido
rfc2368 smtpmail sendmail mu4e-mark mu4e-message flow-fill mu4e-proc
mu4e-utils doc-view jka-compr image-mode mu4e-lists mu4e-vars message
rmc puny dired dired-loaddefs rfc822 mml mml-sec gnus-util rmail
rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231 rfc2047
rfc2045 ietf-drums mailabbrev mail-utils gmm-utils mailheader hl-line
mu4e-meta adoc-mode tempo markup-faces org-element avl-tree generator
org org-macro org-footnote org-pcomplete pcomplete org-list org-faces
org-entities noutline outline easy-mmode org-version ob-emacs-lisp ob
ob-tangle org-src ob-ref ob-lob ob-table ob-keys ob-exp ob-comint comint
ansi-color ring ob-core ob-eval org-compat org-macs org-loaddefs
format-spec find-func epa-file epa derived epg cl quail help-mode
mm-util mail-prsvr autorevert filenotify edmacro kmacro paren icalendar
diary-lib diary-loaddefs cal-menu calendar cal-loaddefs edit-server
advice server finder-inf rx tex-site debian-el gh-common marshal
eieio-compat info package easymenu epg-config url-handlers url-parse
auth-source cl-seq eieio eieio-core cl-macs eieio-loaddefs
password-cache url-vars seq byte-opt gv bytecomp byte-compile cconv
cl-loaddefs cl-lib 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 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 699181 113871)
 (symbols 48 59955 1)
 (miscs 40 3906 2143)
 (strings 32 212031 19012)
 (string-bytes 1 6376648)
 (vectors 16 80239)
 (vector-slots 8 2307806 160564)
 (floats 8 1465 2911)
 (intervals 56 9982 2963)
 (buffers 992 403))