Git 100 · lesson 3

Divergence and Conflicts

What happens when you and a teammate both commit on top of the same history, and how a pull puts it back together.

What is divergence?

The same picture

origin/main has commits A then C; John's local main has A then C (Improve error handling); your local main has A then B (Add cute dog)

Both histories start at A, then split: they have diverged.

If you pull with divergence

git pull output: hint: You have divergent branches and need to specify how to reconcile them. Options: git config pull.rebase false (merge), git config pull.rebase true (rebase), git config pull.ff only (fast-forward only). fatal: Need to specify how to reconcile divergent branches.

Git will not guess: it stops with fatal: Need to specify how to reconcile divergent branches.
It offers three strategies. Set one once with git config (add --global for every repository), or per pull with --no-rebase, --rebase or --ff-only.

Three ways to reconcile

When it becomes a conflict

If B and C changed the same lines, Git cannot combine them by itself. The merge (or rebase) stops and marks the file:


        <<<<<<< HEAD
        print("Hello, dog!")
        =======
        print("Hello, world!")
        >>>>>>> origin/main

Edit the file to the version you want and delete the markers
git add the file
Finish with git commit (merge) or git rebase --continue (rebase)