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From: Philip Martin <philip.martin@wandisco.com>
To: "Bert Huijben" <bert@qqmail.nl>
Cc: "'Daniel Shahaf'" <d.s@daniel.shahaf.name>,
  "'Michal Matyl'" <Michal.Matyl@zf.com>,  <dev@subversion.apache.org>,
  <jcorvel@apache.org>,  <philip@apache.org>
Subject: merging adjacent changes
References: 
 <BLUPR0601MB738480182C1642DE3B2EAA385A80@BLUPR0601MB738.namprd06.prod.outlook.com>
	<20160214143442.GA5664@tarsus.local2>
	<3f4901d16d6b$7c9a72c0$75cf5840$@qqmail.nl>
	<3f9301d16d8c$036f2640$0a4d72c0$@qqmail.nl>
Date: Mon, 22 Feb 2016 17:23:56 +0000
In-Reply-To: <3f9301d16d8c$036f2640$0a4d72c0$@qqmail.nl> (Bert Huijben's
	message of "Mon, 22 Feb 2016 17:13:45 +0100")
Message-ID: <87wppw3bgz.fsf_-_@wandisco.com>
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"Bert Huijben" <bert@qqmail.nl> writes:

> Personally I agree that I would like to see a text-conflict raised in
> this specific case where the change regions touch each other. But then
> there is that old discussion, ....

I added the test because we had already, perhaps inadvertently,
implemented the behaviour.

Back in 2003 we didn't have 'svn resolve' so resolving a text conflict
required the user to edit the file.  Now we have 'svn resolved' which
may make resolving text conflicts easier.  Perhaps that allows us to
change Subversion to create more conflicts?

We know merge is essentially imperfect or fuzzy, the question is where
to draw the line.  Which, if any, of these cases should merge without
conflict and what should the merged result be?

1.  common           first              second
    ancestor         branch             branch

    A                A                  A
    B                Bbr1               B
    C                C                  Cbr2
    D                D                  D


2.  common           first              second
    ancestor         branch             branch

    A                A                  A
    B                Bbr1               B
    C                new                new
    D                C                  C
                     D                  D

3.  common           first              second
    ancestor         branch             branch

    A                A                  A
    B                Bbr1               B
    C                new                new
    D                C                  Cbr2
                     D                  D

4.  common           first              second
    ancestor         branch             branch

    A                A                  A
    B                Bbr1               B
    C                newbr1             newbr2
    D                C                  Cbr2
                     D                  D

There are probably more cases.

-- 
Philip Martin
WANdisco