bug#24088: emacs 25.0.95; display problems in terminal emulator after unicode wheelcair symbol

[Eli Zaretskii]

> Date: Wed, 27 Jul 2016 20:34:23 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 24088@debbugs.gnu.org
> 
> > Date: Wed, 27 Jul 2016 18:32:11 +0200
> > From: Gregor Zattler <telegraph@gmx.net>
> > 
> > with this (see below) recently build emacs -Q -nw in an xterm /
> > urxvt (this does not happen in a graphical frame) enter this
> > Text:
> > 
> > 
> > Zwangsräumung von HG♿M99
> > 
> > 
> > The symbol between "HG" and "M99" is the unicode wheelchair symbol.
> > 
> > With point at the wheelchair symbol hit C-f: The cursor moves not to the
> > "M" but to the left "9".  This gives problems in the rest of the line
> > when one for instance swaps characters with C-t.  When doing so a few
> > times it's hard to tell if it's a display problem or if the letters are
> > swapped around.
> > 
> > The problem is also visible at the line between windows (see attached
> > screen shot).  This happens when hitting C-l.
> > 
> > 
> > Is this an emacs bug, a terminal emulators bug or a bug of the font used?
> 
> This character is marked as "wide" in the Unicode database, so Emacs
> thinks it takes up 2 columns.

Perhaps Handa-san (CC'ed) could look into this issue.  AFAICT, Emacs
correctly marks the character as wide, but then I'm not sure how this
indication should be taken into account while writing the text to the
TTY.

Thanks.