Case mapping of sharp s

[Ulrich Mueller <ulm@gentoo.org>]

In Unicode since version 5.1.0 the U+1E9E code point is assigned to
"LATIN CAPITAL LETTER SHARP S". Would it be possible to add a mapping
from this to the lower case ß, as in the patch below?

However, I've noticed that similar mappings for Turkish ı (dotless i)
and İ (I with dot) were commented out [1]. Is it still so that such a
change would "make searches slow", as stated in the comment?

Ulrich

[1] <http://cvs.savannah.gnu.org/viewvc/emacs/lisp/international/characters.el?root=emacs&r1=1.56&r2=1.57>


--- emacs/lisp/international/characters.el
+++ emacs/lisp/international/characters.el
@@ -589,6 +589,11 @@
 	 (or (<= c #x1e94) (>= c #x1ea0))
 	 (set-case-syntax-pair c (1+ c) tbl))
     (setq c (1+ c)))
+  ;; U+1E9E LATIN CAPITAL LETTER SHARP S
+  ;; Note: In regular German orthography the sharp s has no upper case
+  ;; form, but is written as double S instead. Therefore the inverse
+  ;; mapping from lower to upper case shouldn't be done by default.
+  (set-downcase-syntax ?ẞ ?ß tbl)
 
   ;; Greek
   (modify-category-entry '(#x0370 . #x03ff) ?g)