From: Junio C Hamano <gitster@pobox.com>
Date: Fri, 22 Jan 2021 18:21:53 GMT
Subject: Re: [PATCH 3/3] range-diff(docs): explain how to specify commit ranges
Message-ID: <xmqq1recal32.fsf@gitster.c.googlers.com>
In-Reply-To: <nycvar.QRO.7.76.6.2101221720200.52@tvgsbejvaqbjf.bet>

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

>> > +- `<rev1>...<rev2>`. This resembles the symmetric ranges mentioned in
>> > +  the `SPECIFYING RANGES` section of linkgit:gitrevisions[7], and is
>> > +  equivalent to `<base>..<rev1> <base>..<rev2>` where `<base>` is the
>> > +  merge base as obtained via `git merge-base <rev1> <rev2>`.

The above paragraph says A...B is turned into $(git merge-base A
B)..A and $(git merge-base A B)..B, but I wonder if we should be
rewriting it into A..B and B..A instead; that would make it
unnecessary to explain what should happen when there are more than
one merge bases.

>> Does this merely resemble?  Isn't it exactly what a symmetric range is?
>
> No, it is not exactly what a symmetric range is because `range-diff`
> treats both arms of the symmetric range independently, as two distinct
> non-symmetric ranges.

This however is an end-user documentation, isn't it?

The fact that range-diff internally translates A...B into something
else is an implementation detail of achieving something, and from
the end-users' point of view, isn't it "take A...B from the
end-user, and show the difference between the left and right
branches of the symmetric range" that range-diff achieves to do?

So it processes exactly the same two sets of commits as what is
given by "--left-right A...B", no?