Re: git-svn: Finding the svn-URL of the current branch in git

[Peter Baumann <waste.manager@gmx.de>]

On Wed, Aug 08, 2007 at 09:25:37PM +0200, Peter Baumann wrote:
> On Wed, Aug 08, 2007 at 08:51:55PM +0200, Matthias Kleine wrote:
> > Junio C Hamano wrote:
> >> Parents' order and which branch you are on may not have anything
> >> to do with each other.  Somebody else may have pulled a while on
> >> b, and you might have pulled from him the merge he created by
> >> doing so while you are on branch a.
> >
> > You're right, I didn't think of that. While pondering this I came up with
> > another problem: git-svn currently remembers which svn-branch a commit
> > belongs to by including this information in the git commit log message.
> 
> Thats true.
> 
> > This way it is not possible to have one git-commit appear in more than one
> > svn branch.
> 
> But there is no way that a git commit could appear on several branches
> in SVN, because SVN doesn't have the concept of multiple parents. So you
> can't have a commit which describes a merge of two branches, because SVN
> can't store the 2 parents. But you could have 2 commits which describe
> the same state (e.g. same root tree), but are on seperate branches.
> 
> t:= commits on trunk
> b:= commits on branch 'b'
> 
> repo1:
> 	t    <-trunk
> 	|
> 	t
> 	| \
> 	t  b <- branch
> 	| /
> 	t
> 
> But this graph is only local to the committers repo. Another person
> using git-svn to track the SVN repo sees this
> 
> repo2/SVN repo:
> 
> 	t     <-trunk
> 	|
> 	t
> 	|
> 	t  b  <- branch
> 	| /
> 	t
> 
> So if you do a 'git merge trunk' in repo1 on branch 'branch', git-svn
> should produce something like this:
> 
> repo2/SVN repo:
> 
> trunk->	t  t' <- branch
> 	|  |
> 	t  t'
> 	|  |
> 	t  b
> 	| /
> 	t
> 
> The interesting case is what it will produce in *YOUR* repo. There are 2
                                  ^- should, because both cases aren't
				  implemented yet.
> possibilities:
> 
> repo1 (I):				repo1 (II)
> 	tb   <-trunk <-branch		trunk->	t  b <- branch
> 	|					|  |
> 	tb					t  b
> 	| \					| \|
> 	t  b <- branch				t  b
> 	| /					| /
> 	t					t
> 
> (I)  would be nicer, but propably more difficult the way git-svn works now.
> 
> (II) would also be possible and more in line what other people importing
>      from SVN see.
> 
> These are the possible ways to describe the merge of 2 SVN branches.
> 
-Peter