Re: On language-dependent defaults for character-folding

[Eli Zaretskii <eliz@gnu.org>]

> From: Richard Stallman <rms@gnu.org>
> CC: lokedhs@gmail.com, larsi@gnus.org, emacs-devel@gnu.org
> Date: Mon, 22 Feb 2016 12:59:03 -0500
> 
> Users seem to disagree on whether to fold diacritics that make
> different letters (ñ, ç, polish l with slash) or only those that
> modify a single letter (as á, à, â in French).
> 
> I think that we should have a user option which controls this and only
> this.
> 
> That means we should have two levels of folding group definitions: the
> smaller groups which hold variants of the same letter, and the bigger
> groups which hold similar letters.
> 
> These groups need to depend on the language setting.  In English (and
> in French), ö is a modified o.  In Swedish (and German, I think), ö
> and o are different letters.

This can be done if it will help.  But no one responded to these ideas
until now, so I'm not sure we are not in for another round of
rejections.

> I think that each folding group should specify one character that is
> the base.

I'm not sure what that means.  What is a "folding group"?

> This is because users also seem to disagree on what it
> should mean to specify a non-base letter in the search string.
> 
> Some plausible meanings are
> 
> * Find that one and only that one.
> * Treat it the same as specifying the base letter.
> 
> There should be a user option to choose between those two (and maybe
> some other behaviors for a non-base letter in the search string).

We already have both options, and in particular, if a non-base letter
appears explicitly in the search string, it will be searched
literally, similarly to what we do with case-insensitive search.
E.g., searching for ö doesn't find o or any other of its variants.