bug#45941: 28.0.50; rmail doesn't set modified flag when changing 'unseen' flag

[Andrea G. Monaco]

Hello,


when I read a message for the first time in rmail, the unseen flag gets
cleared, but this does not set the modified flag of the buffer:
therefore the buffer can't be saved, nor Emacs offers to save it when I
close the program, and information about read messages gets usually
lost.

These are the relevant lines in rmail.el, inside rmail-show-message-1:

  ;; Mark the message as seen, but preserve buffer modified flag.
  (let ((modiff (buffer-modified-p)))
    (rmail-set-attribute rmail-unseen-attr-index nil)
    (unless modiff
      (restore-buffer-modified-p modiff)))


I'd prefer no special treatment of 'unseen' flag modification, so that
it set the modified flag.

I think that some users might prefer the current behavior, so we could
add a variable, maybe named rmail-unseen-change-set-modified, to
customize this.


Warmly,
Andrea Monaco



In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.5, cairo 
version 1.16.0)
 of 2020-12-01 built on agm
Repository revision: 90a543e630012cc58c175d5bf3ffd42bb156c6b6
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description: Debian GNU/Linux 10 (buster)

Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND DBUS GSETTINGS GLIB NOTIFY
INOTIFY LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS LIBSYSTEMD JSON
PDUMPER LCMS2

Important settings:
  value of $LC_MONETARY: it_IT.UTF-8
  value of $LC_NUMERIC: it_IT.UTF-8
  value of $LC_TIME: it_IT.UTF-8
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: RMAIL Summary

Minor modes in effect:
  display-time-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-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
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug sendmail shr-color color eieio-opt
cl-extra speedbar ezimage dframe find-func shortdoc help-fns radix-tree
help-mode misearch multi-isearch rmailsum shr kinsoku svg xml dom
browse-url url url-proxy url-privacy url-expand url-methods url-history
url-cookie url-domsuf url-util url-parse url-vars mailcap qp rmailmm
message rmc puny dired dired-loaddefs rfc822 mml easymenu mml-sec epa
derived epg epg-config gnus-util text-property-search time-date
mm-decode mm-bodies mm-encode mailabbrev gmm-utils mailheader mail-parse
rfc2231 rmail rmail-loaddefs auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs cl-loaddefs cl-lib password-cache json subr-x map seq
byte-opt gv bytecomp byte-compile cconv rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils time 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 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 button
loaddefs faces cus-face macroexp files window 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 cairo
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 191396 51037)
 (symbols 48 8932 2)
 (strings 32 128911 15394)
 (string-bytes 1 12255982)
 (vectors 16 118062)
 (vector-slots 8 1212654 84005)
 (floats 8 190 282)
 (intervals 56 5799 1278)
 (buffers 984 16))