Subject: Re: [BUG] redundant error message

From: Junio C Hamano <[email-masked]>
Date: Thu, 05 Dec 2013 12:15:07 -0800

Jeff King <[email-masked]> writes:

> On Thu, Dec 05, 2013 at 12:00:16PM -0800, Junio C Hamano wrote:
>
>> Jeff King <[email-masked]> writes:
>> 
>> >   $ >foobar
>> >   $ git rev-parse foobar --
>> >   foobar
>> >   --
>> >   fatal: bad flag '--' used after filename
>> >
>> > That's not right.
>> 
>> Hmph, it looks like it is following the usual "zero-or-more dashed
>> options, zero-or-more revs and then zero-or-one double-dash and then
>> zero-or-more paths" rule to parse the thing.  "foobar" is a file and
>> not a rev, so "--" should not be there, no?
>> 
>> Confused why you think it is not right...
>
> Because once you say "--", then all ambiguity goes away, no?

But it is tricky (not from implementation but from semantics point
of view) to make rev-parse follow that "-- separates revs and paths"
rule literally.  The primary use of rev-parse is to convert revs in
extended SHA-1 expressions into concrete object names, so that
scripts do not have to worry about having to deal with object names
in a format that is not 40-hexdecimal.  "git rev-parse foobar --"
that gives

	foobar
        --

without any error, because 'foobar' cannot be made into an object
name, would be behaving in a way unexpected by the calling script,
no?