Re: Emacs and UTF-8 locale

[Dave Love]

>>>>> Markus Kuhn writes:

 > There are UTF-8 locales in use (e.g., vi_VI), which do NOT have
 > UTF-8 in their name,

That looks like a bad example since, at least in glibc 2.2.4, the
locale is listed as `vi_VN.UTF-8'.  That's fortunate, since Emacs uses
VISCII for the unqualified Vietnamese language environment.
(Similarly for Devanagari.)  I documented other cases from glibc in
the code.  Apparently they aren't all consistent with the source that
eggert originally used.

 > therefore the direct test of the locale environment
 > variables is just a less reliable fallback option.

 > It is my understanding that elisp currently has no direct access to
 > the output of the API function nl_langinfo(CODESET), and I hope
 > this can be fixed.

I've implemented it, but it's not installed, partly _because_ people
may not end up with the coding they expect.  I haven't yet tried to
check compatibility properly.

 > Fortunately, there exists only one single standard string that
 > nl_langinfo(CODESET) returns in a UTF-8 locale, and that is
 > "UTF-8".  (For ISO 8859-1, both "ISO-8859-1" and "ISO8859-1" are
 > used by different manufacturers.)

Emacs already deals with that sort of issue and DTRT with the
environment variables, including matching something more general than
`UTF-8'.  Please see the code in mule-cmds.el.

 >     if (strstr(s, "UTF-8"))
 >       utf8_mode = 1;

Testing solely for utf-8 isn't useful.

-- 
$ locale -c charmap
LC_CTYPE
ISO-8859-1