[darcs-users] rebase feedback and amend-record flexibility

[Miles Gould]

On 10/04/12 16:15, Michael Hendricks wrote:
>     Does that actually happen with rebase? I thought you end up with two
>     copies of the changes, or does it also rewind the source branch?
>
> Git rebase rewinds the source branch.

It does both :-) The original commits are still in there, and can be 
found again using the reflog, but the branch now points to the new commits.

In more detail: recall that git branches are just autoincrementing 
pointers to nodes in the history DAG. Suppose that we have branches 
branch_a and branch_b, pointing to commits A and B, with common ancestor 
C. For simplicity, let's suppose that A is a direct child of C. If we 
rebase branch_a onto branch_b, then we create a new commit A' which is 
the result of applying diff(C, A) to B. We then move branch_a to point 
at A'. The commit A is still in there, accessible as HEAD@{1}, but not 
reachable from any named branch. If it remains unreachable, it will 
eventually be garbage-collected.

HTH,
Miles