problem with commit message after conflicts been resolved when merge

Question

I am new in Git. Currently, I am experiencing this scenario:

Step 0. I am working on a sub-branch

Step 1. I have added & commited file1, file2, file3 on my sub-branch with commit message msg1, msg2, msg3 respectively.

Step 2. I checkout master to switch to master branch

Step 3. I pull origin master to update master branch with latest origin version code

Step 4. I merge sub-branch to merge my working code to the current master branch code

Then, I got conflict in file2,

Then, I manually resolved the conflicts. Now, file2 needs to be added because there is changes on this file.

Step 5. I add file2 in master branch, because I have resolved the conflicts on this file

Step 6. What commit message should I write now? the msg2 only? or msg1, msg2, msg3 all needs to be rewritten now? (I don't want to loose the commit messages msg1,msg2,msg3 for the files I worked)

Answer 1

You're not writing a new commit message for those merged commits; you're writing a commit message for the merge commit itself. Your history is going to look like this:

- x - o - o - o (origin/master) - X (master)
   \                             /
    1 - 2 - 3 (sub-branch) ------

The commit message you're writing is for X. Commits 1, 2, and 3 are ancestors, still in the history, and they still have their commit messages. There's no way to change those with a merge.

The commit message for X, if you don't have conflicts, will default to something like Merge branch 'sub-branch'. If you do have conflicts, it'll still have that as the first line, but also a list of files which had conflicts:

 Merge branch 'sub-branch'

 Conflicts:
     file2

This is a gentle hint that you've done something more significant than just a simple merge - you had to do some manual work to resolve conflicts in file2. If you like, you can add a quick note about what caused those conflicts and how they were resolved. Otherwise, just use that message as-is! Remember, this is only a description of the merge (and conflict resolution). The commits you merged have their own commit messages.