使用Git，我如何只合并属于不同分支中较大提交的一部分的文件删除

Question

I spent a few hours and exhausted my google-foo skills with nothing to show for, so here is a question to more experiences git users coming from a git newbie...

Scenario:

I have two branches - B1 and B2

B2 branched from B1 and has had the following commits - C5, C6, C7

Commit C5 has the following changes:

• Many files changed
• Many files deleted

Now, if possible, I'd like to merge only a part of C5 to B1, namely, the "many files deleted" change.

Should I just delete these same files in B1 directly and commit, or is there a better way?

The intention is to eventually merge B1 and B2 back together, so I'm not sure if there will be issues if the same files are deleted in both branches in separate commits.

I appreciate any input on this.

Answer 1

Summary

It is not possible to merge only a part of a commit.

You can, however, reset (soft or mixed) to the commit before C5 , commit the changes and the removals in two separate commits and apply your other commits on top of that. This will, however, change your branches history, so you should not do that if you pushed the branch to a remote and/or anyone else is working on top of your commits.

Details

The first advisable step, as always when you want to mess with your branches' history, is to create a backup branch in case everything goes south. git branch backup_branch shoud do this. If you mess everything up, you can just git checkout backup_branch and be on your old stage.

Then, you can do a git reset --hard HEAD~2 . This sets all your files back to the state right after you commited C5 . We lost the changes of commits C6 and C7 now, but can cherry-pick them later on top of our new commits.

The magic step now is a git reset HEAD~1 . This performs a mixed reset, resetting your branch to the commit before C5 , but keeping all the changes you did in C5 as unstaged changes in your working directory. Now, you can just stage all deletions, do a commit, and then stage all changes and do another commit. Voilà, two seperate commits, one with deletions and one with changes.

To obtain the other commits C6 and C7 , you can just git checkout backup_branch , git log -n2 to show you info about those two commits, along with their SHA ids. Back on your original branch, you can just git cherry-pick either one commit after another or both at the same time.

Your data will be in the old state, but your C5 commit was replaced by two separate commits. Cherry pick one of them to your B1 branch, and that's it.

Answer 2

Say C5 changes foo.c and deletes bar.c.

git checkout B1
git cherry-pick C5 -n
git reset HEAD -- foo.c
git commit

This is the simplest scenario. But in your case a lot more files are changed, so you need to reset the changed files all. This may not be more convenient than deleting the bar.c files directly from B1.