Re: Counter-intuitive result from diff -C --stat

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 1, 2017, 01:15 UTC
Message-ID: <xmqqd1g760n4.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20161228080916.72id4hzqxfbygtth@glandium.org>

Mike Hommey <mh@glandium.org> writes:

Show 14 quoted lines

> Hi,
>
> So I was checking out differences between two branches, accounting for
> file moves with -C, and was surprised by the number of insertions and
> deletions that it indicated, because it was telling me I had removed
> more than I added, which I really don't think is true.
>
> I took a closer look, and what happens is that I had a lot of stuff in
> a __init__.py file that I moved to another file, while keeping a now
> new, empty, __init__.py file.
>
> Which means while diff counts the deletions from __init__.py, it doesn't
> count the additions from the move because it is a move, leading to a
> counter-intuitive result.

Intuition is in the eyes of observer.

A pairing of the original and the result you saw might be not very useful (which I have no opinion on), but in the context of the chosen pairing of the original and the result, in order to produce the final result, you started from a copy of the original and removed quite a lot while adding just a bit, so what you saw was an outcome that was deliberately designed.