Re: Trimming strings, /emacs/lisp/emacs-lisp/subr-x.el modification

[Eli Zaretskii <eliz@gnu.org>]

> From: Michael Heerdegen <michael_heerdegen@web.de>
> Cc: Johan Bockgård <bojohan@gnu.org>,  mvoteiza@udel.edu,
>   Eli Zaretskii <eliz@gnu.org>,  tino.calancha@gmail.com,
>   emacs-devel@gnu.org
> Date: Tue, 09 May 2017 14:05:13 +0200
> 
> Jean-Christophe Helary <jean.christophe.helary@gmail.com> writes:
> 
> > >    (split-string "abc, ;def g,hi" nil nil ",\\|;")
> > >    =>
> > >      ("abc" "def" "g")  ; BUG
> >
> > Ok, and the way to get your result is:
> >
> > (split-string "abc, ;def g,hi" nil nil "\\(,\\|;\\)")
> >
> > which means that Emacs thinks it is the caller's duty to provide the
> > grouping construct, which also happens to be ugly, and non-intuitive
> > since ",\\|;" is an otherwise valid regexp...
> >
> > So, how do we go about that? Do we report a bug? Or do we find a good
> > reason for that to happen and modify the documentation for
> > split-string ?
> 
> I'm curious what could be reasons not to fix this (in the code).
> Allowing only a subset of possible regexps would be quite strange.
> Would there be any advantages?

How about if we proceed with the change in string-trim, and file a
separate bug against both it and split-string, for such regexps?
These seem to be largely unrelated issues, and it's a pity to block
Jean-Christophe's changes due to that.