Re: char-displayable-p returns t for undisplayable characters

[Stefan Monnier]

> Using 'cat'.  When I start xterm using
>     % LANG=en_US.iso88591 xterm
> the terminal actually uses ISO-8859-1, but environment variable "LANG" is 
> still set to en_US.utf8 for some reason.

Probably it's set by the config files read by the shell started
inside xterm.

> Changing LANG to match xterm's actual locale makes Emacs behave properly.

The LANG setting is the only way for Emacs to guess at what encoding the
xterm expects.  If it's wrongly set, you need to call
set-terminal-coding-system explicitly.

KH> Currently Emacs can't detect if an iso10646-1 fonts surely
KH> contains specific glyph or not.

> So this is basically the same problem as with xterm?  If the display system 
> claims it supports iso10646-1, we have to take them at their word?

It seems that the `...' char is supported by almost all unicode fonts:
the only problem you've seen was when you had the encoding wrongly set
(which was a local misonfiguration problem).  I.e. the imperfect information
returned by char-displayable-p is actually not a problem in this case.

I.e. the default value of the config var could be `...' is
char-displayable-p says it's available.


        Stefan