How to rebase over already rebased branch

Question

My git branches look like this:

master-*-*-*-*-*-*-implement_x
 \                    \-*-further_foo_fixes_that_depend_on_x
  \                    \-*-*-further_bar_fixes_that_depend_on_x
   \
    \-implement_x_rebased

It ended this way, because I thought my branch implement_x would be merged upstream as it is, but I was asked to squash it to a single commit, thus implement_x_rebased. However, I already started several branches for further fixing and developing that depend on my work, while waiting for the implement_x to get merged.

Now I'd like to rebase the further work on implement_x_rebased. I thought this was a no-op, since implement_x and implement_x_rebased were in the exactly same state - there would be no merge conflicts, just applying the changes between implement_x and further_foo_fixes_that_depend_on_x etc. on top of implement_x_rebased. However, it seems that git isn't that smart, and it tries to rebase all the way from the base - introducing needless merge conflicts.

I thought that the easy way out is rebase&squash the further fixes on implement_x and then stash them, and apply the stashes to implement_x_rebased, but I'm curious whether there is any proper way to make git realise that implement_x and implement_x_rebased are actually in the same state?

Answer 1

This seems to be a task for the --onto option of git rebase.

git rebase --onto implement_x_rebased implement_x further_bar_fixes_that_depend_on_x

You may want to have look at the --onto example in the git rebase manual.