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

[Eli Zaretskii]

> Date: Thu, 3 Nov 2022 19:52:07 +0100
> From: Vincent Lefevre <vincent@vinc17.net>
> Cc: 58992@debbugs.gnu.org
> 
> > Yes.  But in programming modes the newline didn't match.
> 
> Any reason why (perhaps except for shell modes)?

Because the newline's syntax is not "whitespace" in those modes.

> In C, except for the preprocessor, a newline is similar to a space
> character.

The syntax we give to each character in a major mode depends on what
the mode needs to do with that character.  For example, a mode might
have a good reason to give the newline the '>' syntax, because the
newline ends a comment in those modes.

> BTW, it actually doesn't match either for the Texinfo mode, and
> I don't see any reason why.

In which version of Emacs, and with what value of
search-whitespace-regexp?