Re: [PATCH 7/7] xdiff: make diff3 the default conflictStyle

From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: "Johannes Sixt" <j6t@kdbg.org>,
	"Felipe Contreras" <felipe.contreras@gmail.com>,
	"David Aguilar" <davvid@gmail.com>,
	"Sergey Organov" <sorganov@gmail.com>,
	"Bagas Sanjaya" <bagasdotme@gmail.com>,
	"Elijah Newren" <newren@gmail.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Denton Liu" <liu.denton@gmail.com>,
	git@vger.kernel.org
Subject: Re: [PATCH 7/7] xdiff: make diff3 the default conflictStyle
Date: Fri, 11 Jun 2021 10:20:22 +0900	[thread overview]
Message-ID: <xmqqh7i5ci3t.fsf@gitster.g> (raw)
In-Reply-To: <YMIYUgo71aKJ1Nnx@coredump.intra.peff.net> (Jeff King's message of "Thu, 10 Jun 2021 09:49:06 -0400")

Jeff King <peff@peff.net> writes:

> I didn't look too deeply at your example, but I suspect it may be
> related to the fact that diff3 does not try to minimize the conflicts as
> much (and then the recursive merge on top of that piles on extra layers
> of confusion).
>
> There's a lot more discussion in this old thread:
>
>   https://lore.kernel.org/git/20130306150548.GC15375@pengutronix.de/

Yes, it does not help that the given sample involves conflicts in
the inner merge, which is unfortunately almost unreadable.  For less
confusing merges, diff3 style is often a lifesaver necessary for
avoiding mismerges by showing what the common ancestor looked like,
so that the reader/merger/integrator can tell what each side wanted
to do to the conflicted section.

Rejecting diff3 style output because of the way a conflicted part in
the inner merge appears as a common ancestor version may be throwing
the baby out with the bathwater.  A different way to say it is that
until we improve the way the conflicted inner merge is shown, diff3
style is not something we can recommend to new users as a default, I
would think.