Trouble merging upstream changes back into my branch

Question

I'm running into conflicts while trying to merge upstream changes back into my branch and I'm not sure how to resolve them.

I created my own fork. I cloned it. I made changes to the branch on my fork, committed, and pushed. But then the main fork updated, and I tried to update my own fork by merging upstream in like so:

$ cd repo-name $ git remote add upstream git://github.com/username/repo-name.git $ git fetch upstream $ git merge upstream/master 

The merge says that there's some problem with a file and auto-merging doesn't work. It tells me to fix it myself and re-merge. So I actually went to the (upstream) repository on GitHub of the main fork and copied all the code of the new file into the file on my fork, and tried to merge again. Then, git gives me this error:

fatal: 'merge' is not possible because you have unmerged files. Please, fix them up in the work tree, and then use 'git add/rm ' as appropriate to mark resolution and make a commit, or use 'git commit -a'.

Is there some argument I'm leaving out? Am I doing something stupid? What does it mean by "unmerged files?" Isn't the whole point of merging to merge files? Do I have to commit my changes before I merge?

Answer 1

What you are seeing means that automatic merge could not resolve the conflicts in the files. You need to resolve these conflicts manually. Run git mergetool or git gui.

Answer 2

The "git merge" command tries to incorporate changes from another branch onto the present branch. If the merge is clean, meaning no conflicts, it will commit. Since your merge did have conflicts, it didn't commit. You need to resolve the conflict.

Pulling the copy from the upstream repo is one way to do that - by accepting the upstream repo's version. You can do that within git using "git checkout --theirs conflicting_file.txt"

Editing the file to get it into the shape you want is another way.

Once it's fixed, you need to add using "git add conflicting_file.txt" then commit. Then your working copy is clean and ready for more hacking. Good luck.