bug#58992: 28.2; "lax space matching" no longer works

[Vincent Lefevre]

On 2022-11-04 09:21:04 +0200, Eli Zaretskii wrote:
> > Date: Fri, 4 Nov 2022 04:30:38 +0100
> > From: Vincent Lefevre <vincent@vinc17.net>
> > Cc: 58992@debbugs.gnu.org
> > 
> > The [[:space:]\n]+ in the doc is misleading. Since a newline character
> > is a whitespace, [[:space:]]+ is sufficient.
> 
> That is only true in major modes where the newline has the
> "whitespace" syntax, see the description of [:space:] in the ELisp
> manual.  I guess you tried this in Fundamental mode or somesuch?

Wow! This is really confusing! [:space:] is defined by POSIX, and the
manual even refers to it:

    A character alternative can also specify named character classes
    (*note Char Classes::).  This is a POSIX feature.  [...]

You must not change its behavior! Making it depend on the major mode
is even worse.

If the intent is to have a different meaning, a different name should
be chosen, such as [:whitespace:] (though I'm not sure whether some
names are reserved by POSIX).

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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