bug#64939: 30.0.50; The default auto-mode-interpreter-regexp does not match env with flags

[Eli Zaretskii <eliz@gnu.org>]

> From: Wilhelm Kirschbaum <wkirschbaum@gmail.com>
> Cc: 64939@debbugs.gnu.org
> Date: Sun, 30 Jul 2023 10:28:14 +0200
> 
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > That line _is_ matched by auto-mode-interpreter-regexp:
> >
> >   (string-match-p auto-mode-interpreter-regexp "#!/usr/bin/env 
> >   -S ruby -e 'puts 123'") => 0
> >
> > The problem is how to find the name of the interpreter if the text
> > after "/usr/bin/env" includes more than one word?  Once we start
> > using command-line switches and their arguments, and take into
> > consideration that many GNU/Linux programs can freely intersperse
> > options and non-option arguments on the command line in any order,
> > where does this end?
> 
> I am hoping there is some way of effectively matching command-line
> switches for '/usr/bin/env', but sounds like it is perhaps too 
> complex?

How can we do that without incurring non-trivial maintenance costs?
'env' is being actively developed; e.g., the old version I have where
I'm typing this doesn't even have the -S option.  Are we supposed to
track every new command-line option added to 'env', and update our
code accordingly?  That is even impractical, because someone could use
2-year old Emacs with Coreutils released just yesterday.