From: Daniel Barkalow <barkalow@iabervon.org>
Date: Tue, 19 Apr 2005 23:07:22 GMT
Subject: Re: Bug in merge-base
Message-ID: <Pine.LNX.4.21.0504191853310.30848-100000@iabervon.org>
In-Reply-To: <20050419223420.GF9305@pasky.ji.cz>

On Wed, 20 Apr 2005, Petr Baudis wrote:

> Dear diary, on Wed, Apr 20, 2005 at 12:17:12AM CEST, I got a letter
> where Daniel Barkalow <barkalow@iabervon.org> told me that...
> 
> > I can think of. Are you sure there isn't another path to 5b53d3?
> 
> I'm not. Actually there well might be.
> 
> I think merge-base should never take a path which is effectively
> "upside-down" when a straight "upside" one is available.
> 
> Hmm. So what I depended on for merge-base was that when doing it on A
> and B and A is predecessor of B, then it will always just return A.  I
> will perhaps need to abuse rev-tree somehow for this then, it looks.

It is currently optimizing for the shortest longer path, but I guess it
should optimize for the shortest shorter path (i.e., the 0-length path
from A to itself always wins).

On the other hand, the date-based comparison (which you'd get with the
version I sent yesterday with [2/4] and [4/4]) would give you the most
recent common ancestor, which would necessarily avoid this situation.

Do you want to go with the date-based approach, or should I work out a 
shortest shorter path algorithm?

	-Daniel
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