Re: search-default-mode char-fold-to-regexp and Greek Extended block characters

[Robert Pluim]

>>>>> On Thu, 25 Jul 2019 05:36:12 +0300, Eli Zaretskii <address@hidden> said:

    >> From: Juri Linkov <address@hidden>
    >> Date: Thu, 25 Jul 2019 02:12:01 +0300
    >> 
    >> This is an interesting case like (upcase "ß") => "SS" that required
    >> adding (?ß "ss") to pass the tests.

    Eli> Isn't there now an upper-case eszet that eliminates that problem?

There is, but the mapping is one-way.

UnicodeData.txt has:

00DF;LATIN SMALL LETTER SHARP S;Ll;0;L;;;;;N;;;;;
1E9E;LATIN CAPITAL LETTER SHARP S;Lu;0;L;;;;;N;;;;00DF;

and SpecialCasing.txt has

00DF; 00DF; 0053 0073; 0053 0053; # LATIN SMALL LETTER SHARP S

which gives us

(upcase "ß") => "SS" ; \udf => "SS"
(downcase "ẞ") => "ß" ; \u1e9e => \udf

Perhaps this is different in a later version of Unicode than what
weʼre using.

Robert