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From:   Junio C Hamano <gitster@pobox.com>
To:     Robert Dailey <rcdailey.lists@gmail.com>
Cc:     Git <git@vger.kernel.org>
Subject: Re: diff <commit> using 3-dot behavior
References: <CAHd499DL2WiTgnk5A--qihUh-jF9m7aXDzHAQuW=bLRVW4Bniw@mail.gmail.com>
Date:   Wed, 24 Aug 2016 09:22:40 -0700
In-Reply-To: <CAHd499DL2WiTgnk5A--qihUh-jF9m7aXDzHAQuW=bLRVW4Bniw@mail.gmail.com>
        (Robert Dailey's message of "Wed, 24 Aug 2016 09:28:24 -0500")
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Robert Dailey <rcdailey.lists@gmail.com> writes:

> $ git diff master...topic

... which is defined roughly as

	git diff $(git merge-base master topic) topic

The merge-base is to compute the point you forked your topic from
the mainline.  So if you want to compare your current state in the
index with the fork point, you'd do

	git diff --cached $(git merge-base master topic)

and comparing your working tree state would be

	git diff --cached $(git merge-base master topic)