bug#5275: Malayalam file names not rendered correctly (conjuncts are not formed) in message window and buffer title

[Kenichi Handa]

In article <wlpr5culg8.wl%mituharu@math.s.chiba-u.ac.jp>, YAMAMOTO Mitsuharu 
<mituharu@math.s.chiba-u.ac.jp> writes:

> Unfortunately, I couldn't reproduce it on GNU/Linux.  But the
> following examples spontaneously fail with the X11 build on Mac OS X
> 10.5.

>   (switch-to-buffer-other-window (string ?e 769))
>   (switch-to-buffer-other-window (string ?e 769 ?e 769))
>   (switch-to-buffer-other-window (string ?e 769 ?e 769 ?e 769))
>   (switch-to-buffer-other-window (string ?e 769 ?e 769 ?e 769 ?e 769))
>   (switch-to-buffer-other-window (string ?e 769 ?e 769 ?e 769 ?e 769 ?e 769))

Thank you for them.  I now find what is wrong and committed
a temporary fix.

> I suspect the problematic case is that `charpos + field_width' in
> reseat_to_string exceeds the length of the given string.  The value of
> `field_width' is 12 by default when displaying buffer names.

Actually, the bug was that I ignored it->string_nchars in
composition handling.

By the way, in the current code, field_width and precision
are not handled correctly.  The comments in xdisp.c say that
they are "number of characters" and the current code treats
them as such, but the original intention is "number of
columns occupied by characters".  It seems that fixing it is
not a trivial work.

---
Kenichi Handa
handa@m17n.org