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

[Eli Zaretskii]

> Date: Thu, 3 Nov 2022 19:28:09 +0100
> From: Vincent Lefevre <vincent@vinc17.net>
> Cc: Eli Zaretskii <eliz@gnu.org>, 58992@debbugs.gnu.org
> 
> This is still buggy in Emacs 28.2 if I change the value:

It isn't a bug.

> search-whitespace-regexp is a variable defined in ‘isearch.el’.
> 
> Its value is "\\s-+"
> Original value was "[         ]+"
> 
> This works in Fundamental mode, but not in Lisp mode.

Because the meaning of \\s is different.  That's why we changed the
default value not to use \\s.

> BTW, I don't understand what "\\s-+" means. I thought it was a
> whitespace followed by a minus character repeated at least once.

No, it means a sequence of 1 or more characters whose syntax is '-'.
See the documentation of regular expressions in the manual.