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From: Jonathan Nieder <jrnieder@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org, Stefan Monnier <monnier@iro.umontreal.ca>
Subject: Re: git-core: conflictstyle=diff3 doesn't actually use diff3 compatible format
Date: Sun, 7 Mar 2010 22:54:54 -0600	[thread overview]
Message-ID: <20100308045454.GA22672@progeny.tock> (raw)
In-Reply-To: <7vpr3itn89.fsf@alter.siamese.dyndns.org>

Junio C Hamano wrote:
> Jonathan Nieder <jrnieder@gmail.com> writes:

>> I’d be interested to hear from xdiff people
>> whether it should be easy to add the ancestor name to the output.
>
> I don't think there was any xdiff people involved in this area.
> 
> I suspect that our tools actually rely on the common ancestor markers not
> having any extra cruft after them, so it would be introducing a bug if you
> change this output without changing the places that read them (I know
> about "rerere", but there may be others).

I guess the relevant xdiff person was you. ;-)

Thank you for the quick response.  On the xdiff level, it looks like
all that is needed is to pass the ancestor label as a member of struct
s_xmparam, and then fill_conflict_hunk() could respect that.  Not
complicated at all.

For merge_trees() users, the ancestor label could be passed with
branch1 and branch2 in struct merge_options.

That leaves the question of merge_recursive().  With merge_recursive(),
there is more than one ancestor, so it is not completely clear what the
diff3 merge should do.  Currently it writes something like this:

 <<<<<<< HEAD
 Conflict resolution is hard;
 let's go shopping.
 |||||||
 <<<<<<< Temporary merge branch 1
 Who knows whose this is?
 |||||||
 Ancient history.
 =======
 Another intermediate result.
 >>>>>>> Temporary merge branch 2
 =======
 Git makes conflict resolution easy.
 >>>>>>> topic

which is hard to read [1].  Probably it would be better to use a consolidated
common ancestor, by cocatenating the internal common ancestors; in this
simple case, that would look like this:

 <<<<<<< HEAD
 Conflict resolution is hard;
 let's go shopping.
 ||||||||
 Ancient history.
 ========
 Git makes conflict resolution easy.
 >>>>>>>> topic

What should be the label of this possibly fictional merge base?

Jonathan

[1] For people and for rerere.  See http://bugs.debian.org/569645

  parent reply	other threads:[~2010-03-08  4:55 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20100305215253.364.63583.reportbug@localhost>
2010-03-05 22:19 ` git-core: conflictstyle=diff3 doesn't actually use diff3 compatible format Jonathan Nieder
2010-03-05 22:31   ` Junio C Hamano
2010-03-06 12:57     ` Bert Wesarg
2010-03-06 19:03       ` Junio C Hamano
2010-03-08  4:54     ` Jonathan Nieder [this message]
2010-03-15  7:47   ` [PATCH/RFC 0/10] Add label for common ancestor to conflictstyle=diff3 Jonathan Nieder
2010-03-15  7:49     ` [PATCH 01/10] xdl_merge(): add optional ancestor label to diff3-style output Jonathan Nieder
2010-03-15  8:10       ` Junio C Hamano
2010-03-15  8:35         ` Jonathan Nieder
2010-03-15  8:37           ` Junio C Hamano
2010-03-15  7:51     ` [PATCH 02/10] merge-file --diff3: add a label for ancestor Jonathan Nieder
2010-03-15  7:52     ` [PATCH 03/10] ll_merge(): add ancestor label parameter for diff3-style output Jonathan Nieder
2010-03-15  7:55     ` [PATCH 04/10] checkout --conflict=diff3: add a label for ancestor Jonathan Nieder
2010-03-15  8:20       ` Junio C Hamano
2010-03-15  8:32         ` Jonathan Nieder
2010-03-15  7:56     ` [PATCH 05/10] merge_file(): add comment explaining behavior wrt conflict style Jonathan Nieder
2010-03-15  8:00     ` [PATCH 06/10] merge_trees(): add ancestor label parameter for diff3-style output Jonathan Nieder
2010-03-15  8:00     ` [PATCH 07/10] tests: document format of conflicts from checkout -m Jonathan Nieder
2010-03-15  8:01     ` [PATCH 08/10] checkout -m --conflict=diff3: add a label for ancestor Jonathan Nieder
2010-03-15  8:05     ` [PATCH 09/10] cherry-pick: " Jonathan Nieder
2010-03-15  8:07     ` [PATCH 10/10] merge-recursive: " Jonathan Nieder
2010-03-15  8:29       ` Junio C Hamano
2010-03-15 13:18       ` Stefan Monnier

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