From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 01 Dec 2014 17:49:25 GMT
Subject: Re: [BUG] Documentation: git log: --exit-code undocumented?
Message-ID: <xmqqwq6bp8ey.fsf@gitster.dls.corp.google.com>
In-Reply-To: <874mtfl1hx.fsf@fencepost.gnu.org>

David Kastrup <dak@gnu.org> writes:

> I disagree that --exit-code does nothing: it indicates whether the
> listed log is empty.  So for example
>
> git log -1 --exit-code a..b > /dev/null
>
> can be used to figure out whether "a" is a proper ancestor of "b" or
> not.

Hmph.

    $ git log --exit-code master..maint >/dev/null; echo $?
    0
    $ git log --exit-code maint..master >/dev/null; echo $?
    1

That is a strange way to use --exit-code.  I suspect that if you did
this, you will get 0 from the log between HEAD~..HEAD

    $ git checkout master^0
    $ git commit --allow-empty -m empty
    $ git log --exit-code HEAD~..HEAD

even though HEAD~ is a proper ancestor of HEAD, so it is not giving
us anything useful.  Isn't it a mere artifact that "log" happens to
share the underlying machinery with "diff" that --exit-code shows a
non-zero exit when there is any single commit in the range that has
any change?