bug#58608: 29.0.50; Nasty bug with pasting primary selection in term buffers

[Phil Sainty]

This one has been causing me occasional pain for years, but
only rarely, and I didn't have a recipe to reproduce it until
now.  The following steps don't all need to be followed to
the letter, but hopefully demonstrate the issue well.

0. emacs -Q
1. M-x term (and run your shell; term must be in char-mode)
2. Run "ls" # or anything else to produce a decent amount of
   output.
3. Run "cat >/dev/null" # for safety
4. Using the mouse, select any small piece of text several
   lines above the bottom of the term buffer (e.g. double-
   click a word).
5. Move the mouse to the shell prompt at the end of the buffer
   and middle click to paste that selected text as input.
6. Without moving the mouse, middle click again at the same
   position.
7. Be thankful for step 3.

My impression is that the first middle-click unexpectedly
creates a new primary selection based on the current mouse
position, so the second middle-click then pastes that new
selection as input.

This has bitten me on many occasions when I wanted to repeat
the previously-pasted command as input again, and find that
I've instead asked the shell to execute a ton of unintended
commands! (which, thankfully, tend to only rarely be valid).

This bug exists in all the versions of Emacs I have installed
at present (back to 26.3), and I think this is severe enough
to fix in the emacs-28 branch as well as master.


-Phil




In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.15.10, Xaw scroll bars) of 2022-10-18 built on phil-lp
Repository revision: be3d9f717dd317eafc8f511072040a5ff8c1071c
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 
11.0.12008000
System Description: Ubuntu 18.04.6 LTS

Configured using:
 'configure --prefix=/home/phil/emacs/trunk/usr/local
 --with-x-toolkit=lucid --without-sound
 '--program-transform-name=s/^ctags$/ctags_emacs/''

Configured features:
CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG JSON
LCMS2 LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP THREADS
TIFF TOOLKIT_SCROLL_BARS WEBP X11 XDBE XIM XINPUT2 XPM LUCID ZLIB

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

Major mode: Term

Minor modes in effect:
  minibuffer-line-mode: t
  global-edit-server-edit-mode: t
  savehist-mode: t
  magit-wip-initial-backup-mode: t
  magit-wip-before-change-mode: t
  magit-wip-after-apply-mode: t
  magit-wip-after-save-mode: t
  magit-wip-mode: t
  global-git-commit-mode: t
  magit-auto-revert-mode: t
  shell-dirtrack-mode: t
  my-contextual-help-mode: t
  global-so-long-mode: t
  display-battery-mode: t
  my-visible-bell-mode: t
  global-display-fill-column-indicator-mode: t
  display-fill-column-indicator-mode: t
  minibuffer-depth-indicate-mode: t
  which-key-mode: t
  windmove-mode: t
  winner-mode: t
  global-subword-mode: t
  display-time-mode: t
  keep-buffers-mode: t
  my-keys-local-minor-mode: t
  auto-compile-on-load-mode: t
  auto-compile-on-save-mode: t
  url-handler-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-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
  buffer-read-only: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
/home/phil/.emacs.d.sandboxes/trunk/HOME/.emacs.d/el-get/scratch/el-get 
hides 
/home/phil/.emacs.d.sandboxes/trunk/HOME/.emacs.d/el-get/el-get/el-get
/home/phil/.emacs.d.sandboxes/trunk/HOME/.emacs.d/el-get/delight/delight 
hides 
/home/phil/.emacs.d.sandboxes/trunk/HOME/.emacs.d/elpa/delight-1.7/delight
/home/phil/.emacs.d.sandboxes/trunk/HOME/.emacs.d/el-get/transient/lisp/transient 
hides 
/home/phil/emacs/trunk/usr/local/share/emacs/29.0.50/lisp/transient
/home/phil/.emacs.d.sandboxes/trunk/HOME/.emacs.d/lisp/python hides 
/home/phil/emacs/trunk/usr/local/share/emacs/29.0.50/lisp/progmodes/python

Features:
(shadow sort project-local-variables ecomplete mail-extr emacsbug term
disp-table ehelp dired-aux elisp-slime-nav etags fileloop generator xref
project hl-sexp lexbind-mode idle-highlight-mode tramp-sh warnings
docker-tramp tramp-cache time-stamp tramp tramp-loaddefs trampver
tramp-integration cus-start files-x tramp-compat parse-time iso8601
ls-lisp tabify minibuffer-line edit-server my-org my-projects my-session
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my-libraries sudo my-version-control magit-wip magit-log which-func
imenu edebug debug backtrace find-func magit-diff smerge-mode diff
git-commit rx log-edit message sendmail yank-media puny rfc822 mml
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project-local-variables-autoloads advice wtf-autoloads package
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url-cookie generate-lisp-file url-domsuf url-util mailcap url-handlers
url-parse auth-source cl-seq eieio eieio-core cl-macs password-cache
json subr-x map byte-opt gv bytecomp byte-compile cconv url-vars
cl-loaddefs cl-lib rmc iso-transl tooltip eldoc paren electric uniquify
ediff-hook vc-hooks lisp-float-type elisp-mode mwheel term/x-win x-win
term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
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page tab-bar menu-bar rfn-eshadow isearch easymenu timer select
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frame minibuffer nadvice seq simple cl-generic indonesian philippine
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
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cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget keymap hashtable-print-readable backquote
threads dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting cairo x-toolkit xinput2 x multi-tty
make-network-process emacs)

Memory information:
((conses 16 257815 38654)
 (symbols 48 24320 0)
 (strings 32 74590 14132)
 (string-bytes 1 2492927)
 (vectors 16 39953)
 (vector-slots 8 456801 46856)
 (floats 8 202 110)
 (intervals 56 886 0)
 (buffers 1000 14))