Git: Open merge tool without conflict

Question

I have problems with a merge, but git doesn't mark the file as conflicted. When I try to open the file with git mergetool, git just says: No files need merging.

How can I open a file without merge conflict in a three way compare?

Answer 1

You can do the following:

git merge --no-commit topic
git checkout --merge that_file
git mergetool that_file
git commit

That is, you avoid that the successful merge creates a commit, then you pretend that there was a conflict in that_file, then you can treat the file with git mergetool. Finally, you commit the result.