TopGit: problem with patch series generation

[martin f krafft]

Hi folks,

I am playing around with TopGit and encountered a (conceptual)
problem. I'd love to hear some input.

I want to use TopGit for distro packaging. Any of my packages have
one or more feature branches, some intended for upstream, some
distro-specific. As I am packaging TopGit for Debian, I encountered
the situation that two branches conflict with each other (they
change the same line), but there is no dependency between the
branches. Thus, when I squash the branches into a series, the
resulting patches will not apply (they both change the same original
line to something else).

Obviously, I can introduce a "fake" dependency to force TopGit to
create one patch based on another. However, this then prevents me
from testing and developing the depending branch in isolation,
meaning that I always have to have the dependent branch applied when
I want to work on the second feature. Furthermore, it's not
trivially possible in this situation to cherry-pick only the second
patch.

I see that this is a hard problem with no obvious solution. The only
thing that comes to my mind is maintaining multiple patches for each
branch. In the above, if B "fake-depends" on A, which depends on
master, then I would have A and B depend on master only, but have
TopGit also manage B2 for me, which is a diff against A.

Doing this for all branches is polynomial, but then again, the
number of independent branches, or rather branch trees, is likely to
be pretty low in most cases.

As an alternative, it may be possible, however, to let TopGit know
about a "fake dependency" from B on A. When serialised, TopGit would
notice that there are multiple paths from master to B (master->B and
master->A->B) and use the longer one.

Do you see any other ways in which the situation could be handled?

Is the above something that TopGit could learn, Petr?

Cheers,

-- 
 .''`.   martin f. krafft <madduck at debian.org>
: :'  :  proud Debian developer, author, administrator, and user
`. `'`   http://people.debian.org/~madduck - http://debiansystem.info
  `-  Debian - when you have better things to do than fixing systems
 
"with sufficient thrust, pigs fly just fine. however, this is not
 necessarily a good idea. it is hard to be sure where they are going
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                                                           -- rfc 1925
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