Re[2]: rewrite history

[Ilya Basin <basinilya@gmail.com>]

JK> On Thu, Jun 16, 2011 at 12:43:00PM -0700, Junio C Hamano wrote:

>> >> Hi list. There were 2 branches. One's HEAD was modified to match a
>> >> specific commit at another branch. Now, how to merge them according to
>> >> this scheme?
>> >> 
>> >> A---B---X---E---F
>> >>                      =>  C---D---X---E---F
>> >> C---D---X'
>> >> 
>> >> X and X' have no difference. I tried to write a script to cherry-pick
>> >> E and F, but some of commits are merges and cherry-pick fails.
>> >
>> > I think you just want to rebase using the "-p" option to preserve
>> > merges. Something like:
>> >
>> >   $ git checkout -b rebased-branch F
>> >   $ git rebase -p --onto D B
>> >
>> > that will pick X, E, and F, and replay them on top of D, resulting in
>> > the graph you showed above.
>> 
>> Eh, careful. Nobody said the change between B and X is any similar to the
>> change between D and X'. Replaying the changes E and F introduce on top of
>> X' to arrive at C--D--X'-E--F is the best you could do, i.e.

JK> I thought that was exactly what Ilya said with "X and X' have no
JK> difference". I assumed that meant "they are semantically similar commits
JK> on different bases" (i.e., a cherry-pick) and not "they have the exact
JK> same tree state" (i.e., "git diff X X'" is empty).

>> But wouldn't filter-branch a better tool for this?  Graft to pretend that
>> the parent of X is D instead of B, and filter the branch with F at its
>> tip, that is.

JK> If my assumption on the meanings is reversed (i.e., X and X' really are
JK> the same tree state, not introducing equivalent commits), then yeah,
JK> that would be better.

JK> -Peff

sorry,
git diff X X' is empty


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