bug#54017: add regexp translation option to read-regexp

[Eli Zaretskii]

> Date: Sun, 20 Feb 2022 19:06:53 +0000
> From: emacsq <laszlomail@protonmail.com>
> Cc: Eli Zaretskii <eliz@gnu.org>, 54017@debbugs.gnu.org
> 
> > Then need to wait when someone will step forward to write these
> > BRE/ERE/PCRE translation functions.
> 
> This is a bigger job and is there a current need for it?
> 
> People just want to make their life easier and change the way
> how the syntax of some of the symbols often used by them works
> in interactive input (e.g. grouping).

Like I said: I don't think we should support arbitrary
transformations of regular expressions' syntax.  It makes no sense to
me.


And we don't need to support _all_ of the above syntaxes, we could
support just the BRE or just the ERE.