bug#6576: documentation `string-to-char' is incorrect

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 07 Jul 2010 17:23:40 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: monkey@sandpframing.com, 6576@debbugs.gnu.org
> 
> > >> >   Note: eight-bit characters are returned as single-byte values in the
> > >> >   range 160 to 255, inclusive."
> > >> 
> > >> That depends on the multibyteness of the string.
> > >
> > > Eight-bit characters are defined as such only in multibyte strings.
> > 
> > That makes it even more incorrect.  For multibyte strings you'll get the
> > internal encoding, which is not in the range 160 to 255.
> 
> Sounds like a bug, assuming it's true.

Actually, there's no way we could return the eight-bit characters in
the 160 to 255 range, since that range is already taken by Unicode
codepoints of Latin characters.  So how about

  "Return the codepoint of the first character of STRING.

  Value is the Unicode codepoint, if it is below #x110000 (in hex).
  Codepoints beyond that are Emacs extensions of Unicode.  In
  particular, eight-bit characters are returned as codepoints in
  the range #x3FFF80 through #x3FFFFF, inclusive."