git range-diff

Compare two commit ranges (e.g. two versions of a branch). More information: https://git-scm.com/docs/git-range-diff.

git range-diff commit_1^! commit_2^!

Diff the changes of ours and theirs from their common ancestor, e.g. after an interactive rebase:

git range-diff theirs...ours

Diff the changes of two commit ranges, e.g. to check whether conflicts have been resolved appropriately when rebasing commits from base1 to base2:

git range-diff base1..rev1 base2..rev2