GNU bug report logs - #58992
28.2; "lax space matching" no longer works

Previous Next

Full log

Message #85 received at 58992 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Vincent Lefevre <vincent <at> vinc17.net>
Cc: 58992 <at> debbugs.gnu.org
Subject: Re: bug#58992: 28.2; "lax space matching" no longer works
Date: Fri, 04 Nov 2022 09:14:57 +0200

> Date: Fri, 4 Nov 2022 03:29:50 +0100
> From: Vincent Lefevre <vincent <at> vinc17.net>
> Cc: 58992 <at> debbugs.gnu.org
> 
> > Because the newline's syntax is not "whitespace" in those modes.
> 
> OK, but then, the question is why the newline's syntax is not
> "whitespace" in those modes...

Because the mode sets up its syntax tables for various needs, none of
which is Isearch.

> > > 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.
> 
> In C, the conventional comment is /* ... */ and the newline does not
> end a comment. In any case, /* ... */ is more practical to write
> multi-line comments in C (no need to repeat comment starters at the
> beginning of every line), and if one wants to search in comments,
> the newline should be regarded as a whitespace.

This is not really relevant.  Major modes set up their syntax tables
as they consider relevant, and we won't change that for the benefit of
search-whitespace-regexp.  The lesson to learn here is not to base
Isearch-related regexps on character syntax, because that changes its
meaning with the major mode, something many users will not expect.

> > > 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?
> 
> Both 27.1 and 28.2 (Debian for both), with search-whitespace-regexp
> set to "\\s-+".

Then don't use "\\s-+".  The manual suggests a different regexp for
your preference, and it does so for a good reason.  Why are you using
a regexp that we already concluded to be problematic and stopped
using?  You will get yourself in the same problems we decided to
avoid.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.