bug#17130: 24.4.50; Deficient Unicode case folding

[Nathan Trapuzzano]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Nathan Trapuzzano <nbtrap@nbtrap.com>
>> Cc: 17130@debbugs.gnu.org
>> Date: Sat, 29 Mar 2014 14:36:42 -0400
>> 
>> Er, let me rephrase.  Case _conversion_ (such as in case-preserving
>> replace) and case _folding_ (such as ought be used in case-insensitive
>> searching) are orthogonal.
>
> But they can very well use the same database.

It's not clear what you mean.

We already have a place to store upper- and lower- case variants.  What
I'm proposing is to use the CANONICALIZE slot as a place to store the
case-folding mapping.  If this would mess up Emacs' case-preserving
replace, then I think that would just mean that case-preserving replace
is broken.  There is no such case as "canonicalize"--you can't say, "Oh,
this string is in the canonical case, so when I want to replace it with
this other string in canonical case".  A case-preserving replace should
only consult the upper- and lower-case slots (and perhaps the title-case
slot if it existed).