Re: [PATCH v2 04/13] Teach rebase interactive the mark command

[Junio C Hamano <gitster@pobox.com>]

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

> On Tue, 29 Apr 2008, Junio C Hamano wrote:
>
>> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
>> 
>> > It is a simple matter of the word "acyclic" in the term "DAG".  It means 
>> > that whenever you need to refer to a commit, it either comes before or 
>> > after the commit you need it for, not both directions.
>> 
>> I fell in the same "acyclic" fallacy before I realized it was a mistake, 
>> especially after thought about the "rewritten B needs to be used more 
>> than twice as a merge source" issue.  That's why I earlier said the 
>> beauty of your approach is attractive but it "unfortunately" breaks 
>> down.
>
> I do not understand.  The topological order assures that you have 
> rewritten every commit that needs to be rewritten before rewriting the 
> current commit.

Perhaps it would help to go back to the message J6t incompletely quoted,
and try the example with the parent order of Y swapped (i.e. B == Y^2, C
== Y^1)

Recreating X and Y both need to refer to the rewritten B as the parameter
to "merge" insn.  You create X first then you cannot refer to B anymore to
recreate Y.  The other way around you cannot name B to recreate X.