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

From: Vincent Lefevre <[email-masked]>
Date: Fri, 4 Nov 2022 13:47:55 +0100

On 2022-11-04 12:38:14 +0100, Andreas Schwab wrote:
> On Nov 04 2022, Vincent Lefevre wrote:
> 
> > Wow! This is really confusing! [:space:] is defined by POSIX,
> 
> Emacs regexps are _not_ defined by POSIX.
> 
> >     A character alternative can also specify named character classes
> >     (*note Char Classes::).  This is a POSIX feature.  [...]
                                 ^^^^^^^^^^^^^^^^^^^^^^^

> Did you read the referenced node?

Did you read what the manual says?

It is not up to the user to search for contradictory information.

Instead of saying that this is a POSIX feature, the manual should say
that even they look like POSIX character classes, the Emacs ones are
different. Moreover, since this is surprising[*], this section should
also say that the character classes depend on the major mode (the
referenced node is there to give details, but surprising behavior
should be emphasized).

[*] Regexps (in particular, character classes) conventionally depend
on locales, but on nothing else. Emacs is the exception to the general
rule.

-- 
Vincent Lefèvre <[email-masked]> - Web: <https://www.vinc17.net/>
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