Apply changes that have been merged and then reverted

Question

The problem is: we want to merge topic into master, but topic is an ancestor of master, so the merge is a no-op. A commit between topic and master had reverted the previous merge of topic into master. It did that using reset not revert. Now, a diff between master..topic shows all the changes that we want to apply. How do we apply those changes?

       C      B      A      D
master * ---- * ---- * ---- * ---- * 
                       \ 
                        \
                   topic * ---- * ---- * ---- *

A was a merge.
B reverted both A and D but without using revert.
C added additional commits

Edit:

B reverted more than A, but we want to re-apply only the changes that A introduced. Therefore, reverting B will not accomplish our goal, because it will restore D.

@OliverCharlesworth Unfortunately, I failed to mention that `B` backed out more than the merge of `topic`. Apologies. — Shaun Luttin, Jun 19 '17 at 23:49
Hmm, so that means the `master..topic` diff you mentioned is actually a *superset* of the changes you wish to make? — Oliver Charlesworth, Jun 19 '17 at 23:51
@OliverCharlesworth No. `master..topic` is the exact set of changes we wish to make. — Shaun Luttin, Jun 19 '17 at 23:52
@JeffWang We did a `reset --hard D~1`, then a `reset --soft A`, and finally a `commit -m "Reverted a few commits"`. — Shaun Luttin, Jun 20 '17 at 00:05
Are there commits between A, B and C? I'm assuming there were some commits between D and A? — Jeff Wang, Jun 20 '17 at 00:15
@JeffWang This is a simplified diagram and there were other commits between A, B, C, and D. — Shaun Luttin, Jun 20 '17 at 04:09

score 3 · Accepted Answer · answered Jun 20 '17 at 03:56

3

There are some options:

You can revert B and revert D. Reverting B will restore D, so you revert D again.
If the diff is showing just what you want to apply, you can create a patch file from the diff and apply that patch file in the master branch.

Create the patch:

git diff master..topic > file.patch

Go to master and apply the patch:

git apply file.patch

answered Jun 20 '17 at 03:56

Fede

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Creating and applying a patch fit the requirements. – Shaun Luttin Jun 20 '17 at 04:09

score 0 · Answer 2 · answered Jun 19 '17 at 23:47

0

Look at:

Re-doing a reverted merge in Git

Short answer: revert the revert. but there are gotchas you should look at in the git documentation

answered Jun 19 '17 at 23:47

Jeff Wang

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yes, use git log to find the ref that you did the reset, revert that ref, and it's the same thing. – Jeff Wang Jun 19 '17 at 23:51
My apologies. I've updated my answer because I left out an important detail. – Shaun Luttin Jun 19 '17 at 23:53

Apply changes that have been merged and then reverted

2 Answers2