Re: strip accents and sorting [was: BibTeX issues]

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 30 Aug 2019 11:27:33 -0500
> From: "Roland Winkler" <winkler@gnu.org>
> Cc: Eli Zaretskii <eliz@gnu.org>,
>     emacs-devel@gnu.org
> 
> > But (string-collate-lessp "ä-umlaut" "ö-combine") gives t
> 
> ...not for me, which is likely due to my locale LC_COLLATE=C
> 
> I could use instead, say, LC_COLLATE=en_US.utf8.  Then the above
> call of string-collate-lessp yields t.  But this also implies case
> folding and ignoring dots in directory listings, which is not what I
> want.  In other words, these locales have too many features bundled
> together.

You could set LC_COLLATE=en_US.utf8 inside Emacs, or even bind it
around the call to string-collate-lessp.  I think we support that on
GNU/Linux.

> > The Unicode Standard mandates that they be handled identically,
> > including in searching and sorting.  We don't yet implement that
> > 100%, but see char-fold.el for a partial (and not very efficient)
> > implementation during search.
> 
> So I would assume that the locale should not matter at all in the
> context of unicode combining characters.

Not entirely true, as some aspects of this equivalence can be
locale-dependent.  See UAX#10 (http://www.unicode.org/reports/tr10/)
for more about that.