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

[Wilhelm Kirschbaum]

Eli Zaretskii <eliz@gnu.org> writes:

> > From: Wilhelm Kirschbaum <wkirschbaum@gmail.com>
> > Date: Sat, 29 Jul 2023 23:38:07 +0200
> >
> > This is a very naive solution to the above, but I am probably
> > missing some knowledge here and will break for anyone setting 
> > the
> > var to something custom.
>
> Feel free to make this change locally, but I don't see how this 
> can be
> general enough for us to install it as the default value.

The problem is that even with a local change, the match group 2 is 
hard
coded. 

> For starters, 'env' can be invoked with several options, not 
> just with
> one.  Also, some 'env' options accept arguments, and how do we 
> know if
> the word that follows "env -OPTION" is the command to check 
> against
> interpreter-mode-alist or an argument of an option?

Understand, it is a bit complex perhaps. 

> IOW, I don't think this is a problem for a regexp-based 
> solution.  If
> we want to support such complex shebang lines (btw, does the 
> Posix or
> GNU/Linux shell support them?), we should analyze the text after 
> "env"
> to find the candidate interpreter.  Not sure whether even that 
> will
> provide a robust solution.

I can perhaps have a look if there is something concrete about how 
this
can be interpreted. 

> Btw, can't you satisfy your needs via file-local variables?

Not without convincing the project maintainers to add Emacs 
specific
lines to the code, which I don't really think is appropriate in 
some
cases.

It is not a common occurrence to run into this issue, but thought 
is
strange to not work as expected.  If I am the only one, then happy 
to
close this and just keep a local patch.