Interactive Rebase from the Merge-Base

Interactive Rebase from the Merge-Base

Thesis

git rebase -i main rebases onto main’s tip. Sometimes you only want to edit commits unique to your branch since it forked — that set is merge-base(HEAD, main)..HEAD. Starting the todo from the merge-base keeps upstream commits out of your squash/reword list.

Mental model

  o----o----o  main
   \
    a----b----c  feature
  merge-base = o
  rebase -i $(git merge-base HEAD main)  → todo: a, b, c

Worked examples

Lab output:

main=40c708e feature=3541637
merge-base=6a07c0a
--- log feature ---
3541637 f3
bb6b435 f2
261afe9 f1
--- after: git rebase -i $(git merge-base HEAD main) would open todo for: ---
261afe9 f1
bb6b435 f2
3541637 f3

Trap

Confusing this with git rebase --onto. See 07-rebase-onto.qmd for --onto.

Boring rule

When cleaning a feature branch before review, open the interactive todo from the merge-base so you only see your commits.

Try this

1. Add a conflicting upstream commit and finish the rebase.
2. Compare git rebase -i main todo vs merge-base todo after main moves.
3. Use git rebase -i --update-refs when stacked branches exist.

Sources

• git-merge-base(1), git-rebase(1)