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Re: [Monotone-devel] Re: 3-way merge considered harmful
From: |
Florian Weimer |
Subject: |
Re: [Monotone-devel] Re: 3-way merge considered harmful |
Date: |
Tue, 03 May 2005 01:21:31 +0200 |
* Richard Levitte:
> In message <address@hidden> on Sun, 1 May 2005 00:29:48 -0700, Nathaniel
> Smith <address@hidden> said:
>
> njs> Here's another pathological case for 3-way merge:
> njs> A
> njs> |
> njs> B
> njs> / \
> njs> C D
> njs> Suppose that a file was added on the A->B edge, and then removed again
> njs> in B->C, while it was left alone on the B->D edge. We want to merge
> njs> C and D. Let's assume that for some reason we decide to use A as a
> njs> common ancestor. What will happen? Our file does not exist in either
> njs> A or C, so when comparing A and C 3-way merge will think that nothing
> njs> has happened. Our file _does_ exist in D, though, so when comparing A
> njs> and D, 3-way merge will decide that a file has been added. Therefore,
> njs> says 3-way merge, this file should exist in the new merged node.
> njs> But, this is obviously wrong; the file was deleted between B and C,
> njs> and this delete should have caused a delete of D's copy as well.
>
> I disagree with that conclusion. It's quite possible the removal of
> the file in the B->C edge is a mistake, and that the person leaving it
> along in the B->D edge had it right. Especially in a fairly loose
> network of cooperating programmers, disagreements of that kind are
> bound to happen (and have happened). Others might call them "oopses"
> rather than disagreements...
I think Nathaniel wanted to say that there is an implied conflict
which 3-way merge cannot detect, not that one choice is better than
the other. The argument that there is a hidden conflict which should
be flagged as such is quite convincing (and, as a result, the "zombie
changeset" term is misleading).
- Re: [Monotone-devel] Re: 3-way merge considered harmful, (continued)
- Re: [Monotone-devel] Re: 3-way merge considered harmful, Nathaniel Smith, 2005/05/02
- Re: [Monotone-devel] Re: 3-way merge considered harmful, K. Richard Pixley, 2005/05/02
- Re: [Monotone-devel] Re: 3-way merge considered harmful, Nathaniel Smith, 2005/05/02
- Re: [Monotone-devel] Re: 3-way merge considered harmful, K. Richard Pixley, 2005/05/03
- Re: [Monotone-devel] Re: 3-way merge considered harmful, Nathaniel Smith, 2005/05/03
- Re: [Monotone-devel] Re: 3-way merge considered harmful, K. Richard Pixley, 2005/05/04
- Re: [Monotone-devel] Re: 3-way merge considered harmful, Nathaniel Smith, 2005/05/04
- Re: [Monotone-devel] Re: 3-way merge considered harmful, K. Richard Pixley, 2005/05/05
Re: [Monotone-devel] Re: 3-way merge considered harmful, K. Richard Pixley, 2005/05/02
Re: [Monotone-devel] Re: 3-way merge considered harmful, Joel Crisp, 2005/05/02
Re: [Monotone-devel] Re: 3-way merge considered harmful,
Florian Weimer <=
Re: [Monotone-devel] Re: 3-way merge considered harmful, Brian Campbell, 2005/05/03
Re: [Monotone-devel] Re: 3-way merge considered harmful, Sergio . Garcia, 2005/05/04
Re: [Monotone-devel] Re: 3-way merge considered harmful, Oren Ben-Kiki, 2005/05/07
Re: [Monotone-devel] Re: 3-way merge considered harmful, Nathaniel Smith, 2005/05/13
Re: [Monotone-devel] Re: 3-way merge considered harmful, Oren Ben-Kiki, 2005/05/16
Re: [Monotone-devel] Re: 3-way merge considered harmful, Oren Ben-Kiki, 2005/05/07
Re: 3-way merge considered harmful (was Re: [Monotone-devel] merge weirdness...), K. Richard Pixley, 2005/05/02