Re: quotearg.c's shell_quoting_style and MinGW

> From: Bruno Haible <[email protected]>
> Cc: [email protected], [email protected], [email protected]
> Bcc: [email protected]
> Date: Sun, 06 May 2012 19:41:39 +0200
> 
> Eli Zaretskii wrote:
> > The rare situation where it doesn't (described by "cmd /?")
> 
> Rare or not - the text that you refer to mentions that the following
> characters need to be quoted as well when passing through cmd.exe:
>   &()[]{}^=;!'+,`~

Aren't these all handled by quotearg, after the changes that I sent?
If not, which ones did I miss?

> And they forgot to mention at least % which also has an interpretation.

The % character only needs quoting if you have %FOO%, _and_ FOO
happens to be defined as an environment variable.  Otherwise, it will
be preserved.

When % does need to be quoted, it cannot be in the way on which
quotearg's design is based, because "%FOO%" will still expand the
variable.

> That's why I'm saying that when passing through cmd.exe you need a
> more complex quoting.

With the exception of %, you don't.

> > A command line such as
> > 
> >   diff -r -x foo\ bar foo gaz
> > 
> > is impossible on MS-Windows
> 
> I was assuming a Cygwin or MSYS shell with diff.exe being a native Windows
> program.

I don't see a need to support such a mix; life is too short and too
hard.  These Posix-like environments have their own versions of diff
and diff3, which use the original Posix code.  People who mix them are
asking for trouble.

> But you are splitting hairs.

Are you sure it's me who's splitting hair? ;-)

>   1) We don't want to change the default output of 'diff' on Unix.

Of course.  The change I suggested fits this requirement.

>   2) We don't want 'diff' to produce different output on Windows than on
>      Unix (modulo end-of-line convention),

I think this is fundamentally wrong: the required compatibility will;
certainly break some uses of 'diff's output.  That is a wrong way of
handling the kind of conflict between two requirements that we have
here.  Correct functionality should come before identical form, since
the latter is nothing more than convenience.