On Thu, Jan 18, 2018 at 7:35 AM, Johannes Schindelin
[off-list ref] wrote:

Once upon a time, I dreamt of an interactive rebase that would not
flatten branch structure, but instead recreate the commit topology
faithfully.

My original attempt was --preserve-merges, but that design was so
limited that I did not even enable it in interactive mode.

Subsequently, it *was* enabled in interactive mode, with the predictable
consequences: as the --preserve-merges design does not allow for
specifying the parents of merge commits explicitly, all the new commits'
parents are defined *implicitly* by the previous commit history, and
hence it is *not possible to even reorder commits*.

This design flaw cannot be fixed. Not without a complete re-design, at
least. This patch series offers such a re-design.

Think of --recreate-merges as "--preserve-merges done right". It
introduces new verbs for the todo list, `label`, `reset` and `merge`.
For a commit topology like this:

            A - B - C
              \   /
                D

the generated todo list would look like this:

            # branch D
            pick 0123 A
            label branch-point
            pick 1234 D
            label D

            reset branch-point
            pick 2345 B
            merge 3456 D C

There are more patches in the pipeline, based on this patch series, but
left for later in the interest of reviewable patch series: one mini
series to use the sequencer even for `git rebase -i --root`, and another
one to add support for octopus merges to --recreate-merges.

I've been looking forward to seeing this hit the list! Overall I don't
think I have any major complaints, except to make sure the special
label "onto" is documented.

I think it's possible to "reword" or "edit" the merge commit by
inserting "x false" after the merge commnd to halt the rebase and let
the user perform commands to edit, so that should work well.

Thanks for taking the time to make this a reality!

Thanks,
Jake

Johannes Schindelin (8):
  sequencer: introduce new commands to reset the revision
  sequencer: introduce the `merge` command
  sequencer: fast-forward merge commits, if possible
  rebase-helper --make-script: introduce a flag to recreate merges
  rebase: introduce the --recreate-merges option
  sequencer: handle autosquash and post-rewrite for merge commands
  pull: accept --rebase=recreate to recreate the branch topology
  rebase -i: introduce --recreate-merges=no-rebase-cousins

 Documentation/config.txt               |   8 +
 Documentation/git-pull.txt             |   5 +-
 Documentation/git-rebase.txt           |  13 +-
 builtin/pull.c                         |  14 +-
 builtin/rebase--helper.c               |  13 +-
 builtin/remote.c                       |   2 +
 contrib/completion/git-completion.bash |   4 +-
 git-rebase--interactive.sh             |   6 +
 git-rebase.sh                          |  16 +
 refs.c                                 |   3 +-
 sequencer.c                            | 697 ++++++++++++++++++++++++++++++++-
 sequencer.h                            |   9 +
 t/t3430-rebase-recreate-merges.sh      | 208 ++++++++++
 13 files changed, 977 insertions(+), 21 deletions(-)
 create mode 100755 t/t3430-rebase-recreate-merges.sh


base-commit: 2512f15446149235156528dafbe75930c712b29e
Published-As: https://github.com/dscho/git/releases/tag/recreate-merges-v1
Fetch-It-Via: git fetch https://github.com/dscho/git recreate-merges-v1
--
2.15.1.windows.2.1430.ga56c4f9e2a9