bug#23833: 24.5; assoc-string with CASE-FOLD may fail

[Noam Postavsky]

On Thu, Jun 23, 2016 at 11:11 AM, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Noam Postavsky <npostavs@users.sourceforge.net>
>> Date: Thu, 23 Jun 2016 08:26:22 -0400
>> Cc: 23833@debbugs.gnu.org
>>
>> assoc-string uses compare-strings, which uses upcase to ignore case,
>> but upcase is not always the inverse of downcase:
>>
>> (upcase (downcase "DZ")) ;=> "Dz"
>> ;; Or to put it another way
>> (= (upcase (downcase ?\u01F1)) ?\u01F2) ;=> t
>>
>> Same behaviour seen in emacs-25 and master
>
> Thanks.
>
> This is a documentation issue: both 'assoc-string' and
> 'compare-strings' had inaccuracies in their doc strings.  I fixed this
> on the emacs-25 branch, and I'm marking this bug done.

Would it not make more sense if upcase converted dz into DZ? According
to https://en.wikipedia.org/wiki/Dz_(digraph)#Unicode Dz is the "title
case" form, not upper case form. Or is this something that depends on
locale?