分支后从master删除某些代码时，Git分支并合并

Question

I branched X from master, Deleted some code Y from master. When i merge code from X back to master how do I make it such that Y is added back to master(since it hasn't been deleted from X).

Answer 1

If you create a branch, change code in master and merge the (at least in this part) unchanged branch, that code won't come back.

Git is about the changes ("commit") made. If you merge a branch which has changed parts at the same place where the master has changed you get a notification and the merge is paused. Otherwise the changes are, well, merged .

Answer 2

When you eventually run git checkout master && git merge branch-X , Git will:

1. find the merge base of the current tip of master and the commit to which the name branch-X resolves;
2. run two git diff s to compare the base to each branch-tip; and
3. attempt to combine the resulting change-sets, applying this combination to the merge-base content, to come up with the merged content.

If the master -side change involves deleting some set of lines Y , that's one of the inputs to step 3. There is no way to avoid it being one of the inputs to step 3.

Unless you use a different merge strategy ¹ —merge strategies have total control, hence can modify any or all of the above three steps, or even eliminate some or all of those steps—the only things you can do right now to prepare for disaster during step 3 are:

• Leave yourself (or the person doing the merge) notes. For instance, replace the removed lines with a line that shouts: "PUT THINGS BACK HERE LATER WHEN MERGING."
• Attempt to arrange for a merge conflict , by making sure that whatever commit will be the tip of branch-X in the future will contain changes to the same set of lines.

Doing both is going to have the highest probability of success, since whoever does the merge (you or someone else) will see the shouty warning. But note that both of these preparation steps might be undone by someone else down the line, some time before the future git merge . There is nothing you can do to prevent that.

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¹ Whoever actually runs git merge , in the future, has this control, via git merge -s <strategy-name> . However, at the present and in what I consider the foreseeable future, there is no magical merge strategy that would do what you want anyway. So this is little help either.

Answer 3

Just run git merge , that's what this command is for.

It will try to combine the modifications from Y and X together.