Re: case-insensitive string comparison

[Robert Pluim]

>>>>> On Tue, 26 Jul 2022 16:05:50 +0300, Eli Zaretskii <eliz@gnu.org> said:

    >> From: Sam Steingold <sds@gnu.org>
    >> Date: Mon, 25 Jul 2022 15:39:34 -0400
    >> 
    >> > * Eli Zaretskii <ryvm@tah.bet> [2022-07-25 18:58:19 +0300]:
    >> >
    >> >> > (string-collate-equalp "a" "A" current-locale-environment t)
    >> >> > ==> nil
    >> >> > current-locale-environment
    >> >> > ==> "en_US.UTF-8"
    >> >
    >> > I cannot reproduce this:
    >> >
    >> >   (string-collate-equalp "a" "A" current-locale-environment t)
    >> >     => t
    >> >   current-locale-environment
    >> >     => "en_US.UTF-8"
    >> >
    >> > What OS is this, and which Emacs version?
    >> 
    >> GNU Emacs 29.0.50 (build 5, x86_64-apple-darwin21.5.0, NS appkit-2113.50 
Version 12.4 (Build 21F79))
    >> of 2022-07-25
    >> Repository revision: ffe12ff2503917e47c0356195b31430996c148f9
    >> Repository branch: master
    >> Windowing system distributor 'Apple', version 10.3.2113
    >> System Description:  macOS 12.4

    Eli> Could be something macOS-specific.  Maybe your system doesn't define
    Eli> the __STDC_ISO_10646__ feature?  In that case, string-collate-equalp
    Eli> (see the doc string) behaves like string-equal, and that one doesn't
    Eli> have a case-insensitive variant.

Neither Appleʼs clang nor llvm 13 clang define it. Looks like thereʼs
some plan to add it, but it hasnʼt happened yet. see
<https://reviews.llvm.org/D106577>

Robert
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