From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH] Improve errors from 'git diff --no-index'.
Date: Sun, 22 May 2011 20:18:09 -0700
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Cc: Junio C Hamano <gitster@pobox.com>, git@vger.kernel.org
To: Anthony Foiani <anthony.foiani@gmail.com>
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In-Reply-To: <BANLkTinKpSP5oEms914TWD7Tsjab1B87QQ@mail.gmail.com> (Anthony
 Foiani's message of "Sun, 22 May 2011 20:35:40 -0600")
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Anthony Foiani <anthony.foiani@gmail.com> writes:

> On Sun, May 22, 2011 at 8:14 PM, Junio C Hamano <gitster@pobox.com> wrote:
>> Anthony Foiani <anthony.foiani@gmail.com> writes:
>>
>>> I accidentally tried to use "git diff" when I wasn't within a git
>>> repository, only to be confused by getting a usage message with no
>>> particular error output.
>>
>> I do not understand this at all.
>>
>>    $ cd /
>>    $ git diff
>>    usage: git diff [--no-index] <path> <path>
>>
>> What's unclear about it?
>
> It's hard for me to explain right now,...

No, it was only your 'I tried to use "git diff"' that was confusing to me.

With pathspecs or any other options, it is understandable that you were
confused, for example from an output like this:

> $ git diff -b main.c
> usage: git diff [--no-index] <path> <path>

At that point we are committed to no-index codepath, so probably a good
thing to do is to update that confusing usage message a bit better.

It already does change the behaviour when --no-index is not given by the
end user, so perhaps it would be sufficient to change this part:

	if (argc != i + 2)
        	usagef("git diff %s <path> <path>",
                	no_index ? "--no-index" : "[--no-index]");

to something like (caution: I am not typing this in my MUA):

	if (argc != i + 2) {
        	if (no_index)
			warning("Assuming '--no-index'; you are in no repository");
        	usagef("git diff %s <path> <path>",
                	no_index ? "--no-index" : "[--no-index]");
	}

without changing anything else.

That would be just a patch with 1 line removed, 4 lines added, no?