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

From: Vincent Lefevre <[email-masked]>
Date: Fri, 4 Nov 2022 16:02:33 +0100

On 2022-11-04 15:35:28 +0100, Andreas Schwab wrote:
> On Nov 04 2022, Vincent Lefevre wrote:
> 
> > On 2022-11-04 14:25:20 +0100, Andreas Schwab wrote:
> >> On Nov 04 2022, Vincent Lefevre wrote:
> >> 
> >> > 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?
> >> 
> >> Yes, I did.
> >
> > No, you didn't.
> >
> >> ‘[:space:]’
> >>      This matches any character that has whitespace syntax (*note Syntax
> >>      Class Table::).
> >
> > This is NOT a POSIX feature!!!
> 
> Yes, it is.  POSIX has introduced that syntax, and Emacs copied it.

Since the meaning in Emacs is different, Emacs didn't copy it.
It was merely inspired by POSIX.

-- 
Vincent Lefèvre <[email-masked]> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)