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

From: Andreas Röhler <[email-masked]>
Date: Wed, 12 Feb 2014 20:31:20 +0100

Am 12.02.2014 18:55, schrieb Glenn Morris:
> Jorgen Schaefer wrote:
>
>> Not sure why it would not be considered a lower-case letter. Umlauts
>> like ä, ö and ü are matched correctly.
>
> See http://debbugs.gnu.org/10576
>
> (I have no idea whether this is an Emacs bug or not.)
>
>
>
>

IMO the answer given at link is not valid. Indeed the implementation in buffer.h does check --&& upcase1 (c)-- and expects a result, i.e. ignores the fact, some characters 
might not have an upcase variant.

When seeing there is a downcase-table, the check probably should be done against this.