bug#5131: Subject: 23.1; interaction of transpose-regions with markers and multibyte chars

[Andrew Hyatt <ahyatt@gmail.com>]

Sorry for the late reply.  I can reproduce the problem of unexpected
characters when transposing using markers in Emacs 25.

schochet@post.tau.ac.il writes:

> From: schochet@post.tau.ac.il
> To: bug-gnu-emacs@gnu.org, 5131@debbugs.gnu.org
> Subject: 23.1; interaction of transpose-regions with markers and  multibyte
> chars
> --text follows this line--
>
> Repeated use of the function transpose-regions on regions defined by
> markers sometimes yields unexpected results when those regions contain
> multibyte characters. In some cases the text obtained after running
> transpose-regions even includes characters that were not present before.
>
> The function reverse-all given below is designed to reverse the order
> of the characters in a specified region. However, I obtain the following
> results:
>
> input region: abcd    output region: dcba               as expected
> input region: ÷bcd    output region: d÷bc               expected: dcb÷
> input region: ÷ab"äé  output region has CJK ideograph   expected: éä"ba÷
>
> To reproduce this bug, simply copy to a file the text below,
> beginning with the line starting with a semicolon,
> visit it in emacs, and evaluate the indicated lisp expressions
> by entering \C-j at the end of the indicated lines.
> Note that the lisp expressions set markers to specific locations,
> so the file should begin precisely where indicated.
> The first character after the space after the word "case1:" should be at
> position 64 in the file. If for some reason it
> is not, the values given to the variable start should be adjusted.
>
> The file below also contains an alternative function reverse-all2,
> which differs from reverse-all only in using variables instead of markers.
> The function reverse-all2 yields the expected results in all the above cases.
>
> This bug does not depend on my .emacs file, since I have reproduced it with
> a blank .emacs file.
>
> Please let me know if you need any more information.
>
> Steve Schochet
>
> ;-*- mode: lisp-interaction; coding: utf-8-unix -*-
>
> ; case 1: abcd      was: abcd
> ; case 2: ÷bcd      was: ÷bcd
> ; case 3: ÷ab"äé    was: ÷ab"äé
>
> (progn (defvar start nil) (defvar len nil)) ;do \C-j here
>
> ; Using markers to move multi-byte characters may cause problems
>
> (progn (setq begm (make-marker)) (setq endm (make-marker))) ;do \C-j here
>
> (defun reverse-all ()
> (set-marker begm start)
> (set-marker endm (+ start (1- len)))
>  (while (> endm begm)
> (progn (transpose-regions begm (1+ begm) endm (1+ endm) t)
>  (set-marker begm (1+ begm))
>  (set-marker endm (1- endm))))) ;do \C-j here
>
> ;case1
> (progn (setq start 64) (setq len 4) (reverse-all)) ;do \C-j here
>
> ;case2
> (progn (setq start 94) (setq len 4) (reverse-all)) ;do \C-j here
>
> ;case3
> (progn (setq start 124) (setq len 6) (reverse-all)) ;do \C-j here
>
>
> ; Using variables instead of markers works
>
> (progn (defvar begv nil) (defvar endv nil))
>
> (defun reverse-all2 ()
>  (setq begv start)
>  (setq endv (+ start (1- len)))
>  (while (> endv begv)
> (progn (transpose-regions  begv (1+ begv) endv (1+ endv) t)
>  (setq begv (1+ begv))
>  (setq endv (1- endv)))))
>
> ;case1
> (progn (setq start 64) (setq len 4) (reverse-all2))
>
> ;case2
> (progn (setq start 94) (setq len 4) (reverse-all2))
>
> ;case3
> (progn (setq start 124) (setq len 6) (reverse-all2))
>
> ; end of attached file
>
>
>
>
> In GNU Emacs 23.1.1 (i586-suse-linux-gnu, GTK+ Version 2.18.1)
>  of 2009-10-24 on build16
> Windowing system distributor `The X.Org Foundation', version 11.0.10605000
> configured using `configure  '--with-pop' '--without-hesiod'  '--with-kerberos'
> '--with-kerberos5' '--with-xim' '--prefix=/usr'  '--mandir=/usr/share/man'
> '--infodir=/usr/share/info'  '--datadir=/usr/share' '--localstatedir=/var'
> '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' '--with-x'  '--with-sound'
> '--with-sync-input' '--with-xpm' '--with-jpeg'  '--with-tiff' '--with-gif'
> '--with-png' '--with-rsvg' '--with-dbus'  '--without-gpm' '--with-x-toolkit=gtk'
> '--x-includes=/usr/include'  '--x-libraries=/usr/lib:/usr/share/X11'
> '--with-xft' '--with-libotf'  '--with-m17n-flt' '--build=i586-suse-linux'
> 'build_alias=i586-suse-linux' 'CC=gcc' 'CFLAGS=-fomit-frame-pointer
> -fmessage-length=0 -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector
> -funwind-tables -fasynchronous-unwind-tables -g -D_GNU_SOURCE  -std=gnu89 -pipe
> -Wno-pointer-sign -Wno-unused-variable  -Wno-unused-label
> -Wno-unprototyped-calls  -DSYSTEM_PURESIZE_EXTRA=55000
> -DSITELOAD_PURESIZE_EXTRA=10000 '  'LDFLAGS=-Wl,-O2 -Wl,--hash-size=65521''
>
> Important settings:
>   value of $LC_ALL: nil
>   value of $LC_COLLATE: nil
>   value of $LC_CTYPE: nil
>   value of $LC_MESSAGES: nil
>   value of $LC_MONETARY: nil
>   value of $LC_NUMERIC: nil
>   value of $LC_TIME: nil
>   value of $LANG: en_US.UTF-8
>   value of $XMODIFIERS: @im=local
>   locale-coding-system: utf-8-unix
>   default-enable-multibyte-characters: t
>
> Major mode: Lisp Interaction
>
> Minor modes in effect:
>   show-paren-mode: t
>   tooltip-mode: t
>   tool-bar-mode: t
>   mouse-wheel-mode: t
>   menu-bar-mode: t
>   file-name-shadow-mode: t
>   global-font-lock-mode: t
>   font-lock-mode: t
>   blink-cursor-mode: t
>   global-auto-composition-mode: t
>   auto-composition-mode: t
>   auto-encryption-mode: t
>   auto-compression-mode: t
>   line-number-mode: t
>   transient-mark-mode: t
>
> Recent input:
> C-x 1 <down-mouse-1> <mouse-1> C-j <down-mouse-1> <mouse-1>
> C-j <down-mouse-1> <mouse-1> C-j <down-mouse-1> <mouse-1>
> C-j <down-mouse-1> <mouse-1> C-j <down> <down> <down>
> <down> <down> <down-mouse-1> <mouse-1> C-j C-x C-s
> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up>
> <help-echo> <help-echo> <help-echo> <help-echo> <help-echo>
> <help-echo> <help-echo> <menu-bar> <help-menu> <se
> nd-emacs-bug-report>
>
> Recent messages:
> Loading /usr/share/emacs/site-lisp/nxml-mode/rng-auto.el (source)...done
> For information about GNU Emacs and the GNU system, type C-h C-a.
> Invalid image size (see `max-image-size') [9 times]
> Saving file /home/schochet/try/files/reverse-out.el...
> Wrote /home/schochet/try/files/reverse-out.el