bug#16731: 24.3.50; Latin small letter sharp s is not considered lower-case

[Andreas Röhler]

Am 12.02.2014 21:16, schrieb Eli Zaretskii:
> > Date: Wed, 12 Feb 2014 21:10:57 +0100
> > From: Andreas Röhler <andreas.roehler@easy-emacs.de>
> > CC: 16731@debbugs.gnu.org
> >
> > While upcase1 can't succeed, downcase should - if "ß" is a member of 
> > downcase_table.
>
> But which character do you want to downcase in this case?
>
> This whole logic works only for _pairs_ of characters (and the
> char-table used here is populated by calls to set-case-syntax-pair).

So populate it differently, resp. allow empty slots.

> Such machinery cannot possibly work when there's no pair.
>
> The only way I can see out of this conundrum is to consult the
> Lowercase Unicode property of the character as fallback, assuming that
> won't slow down regex search too much.

You can do (downcase "d") for example, which results in "d".

Instead of

upcase1 (c) != c

what about

downcase (c) == c

?