Git Squash by author - All author commits into a single commit

Question

I am trying squash many commits into a single one, the problem is that I need do that by author (name or email).

The case:

Lets say I have a branch called feature-a, in this branch I have many commits for many authors. How can I squash all commits by author (email for example) into a single commit. I want do that to be able to merge all author commits into master.

Any help here?

Thanks in advance

Answer 1

Be careful rewriting history

The end result you want might be possible if you create branches for each author, cherry-pick the commits from each author into the right branch, then squash those changes. However, I don't think that will work if these commits meaningfully depend on each other.

If you have a series of commits:

            Author1                Author2                Author1
version1 ---commit---> version2 ---commit---> version3 ---commit--->...

If you were to try to extract the changes from Author2, and apply them to version1, there's a good chance it won't make sense (For example, if Author2 modifies code that Author1 created).

Answer 2

With Kenkron's caveats in mind, you could do a:

SORTED_GIT_LOGS=$(git log --pretty="format:%an %H" master..feature_a | sort -g | cut -d' ' -f2); \
IFS=$(echo -en "\n\b"); for LOG in $SORTED_GIT_LOGS; do \
    git cherry-pick $LOG; \
done | less

The git log --pretty="format:%an %H" master..feature_a | sort -g would sort the logs of the feature_a commits (not the ones from master because of the master..feature_a syntax)

You would still need to do an interactive rebase to squash the (now ordered by author) commits on master.