Re: [RFC/PATCH v2] merge-base: teach "git merge-base" to accept more than 2 arguments

From: Junio C Hamano <gitster@pobox.com>
Date: Jul 28, 2008, 06:18 UTC
Message-ID: <7vej5ev8dw.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <200807280810.20922.chriscool@tuxfamily.org>

Christian Couder <chriscool@tuxfamily.org> writes:

> Yeah, but what is quite confusing I think is that a merge base seems to be 
> defined as "an as good as possible _common_ ancestor" but in this case, the 
> result of "git merge-base A B C" is not an ancestor of C (even with --all 
> option). So perhaps we need a better definition.

See my other message. "git merge-base A B C" is not the best common ancestors across A B and C. It is the best common ancestors between A and a commit that is a merge between B and C.

By defining/explaining it that way, you can avoid the "Huh, are you talking about OR or AND" question you would inevitably get when you say "Common ancestor of A and B or A and C". Also in "git merge-base A B C", A is fundamentally different from any other commit; a commit being (or not being) common between A and B (or A and C) is what we care about a lot, but a commit being (or not being) common between B and C does not matter in this computation.