Resolve Conflicts

When collaborating with others on a big project, sometimes it occurs that someone's change conflicts with another change introduced in the meantime (e.g by another person).

First of all: Do not panic! You should be able to resolve merge conflicts with a little time and patience.

While it is a good idea to rebase your branch before creating a pull request, as described in the article on Pull requests and Git flow, sometimes merge conflicts are unavoidable.

This article will explain what to do in case of a merge conflict, and how to resolve it using the command line.

Unfortunately, Forgejo currently does not provide a GUI to resolve conflicts.

An issue in the Gitea upstream repository of Forgejo, #9014, requests this feature.

If you want to skip the setup of the examples, you can skip to the sections explaining the resolutions:

• Resolving the conflict (in files)
• Resolving the conflict (of deleted files)

Example of a conflict, and its resolution

To understand the steps to be taken during the resolution of a conflict, let's actually create an example of such a conflict:

Clone example repository

This example uses Knut's example repository. Let us create a clone of Knut's examples repository for this example:

git clone git@codeberg.org:knut/examples.git
cd examples

We will not change anything on the main branch just now.

Create a branch with a change

Here, we're creating another branch with our first commit:

git switch -c add-link-to-readme

In the README.md file, we change the line

An example repository for Codeberg Docs.

to

An example repository for [Codeberg Docs](https://docs.codeberg.org).

Now, we'll add the change to our branch:

git add README.md
git commit -m "Added link to Codeberg docs in README"

We will leave the branch. We won't merge it into main just yet.

Create another branch with a different change

Now, we'll create another branch based on main, and edit the README.md file in a different way:

git switch main
git switch -c update-last-sentence-in-readme

Again, we'll change the last line, but this time, we'll adjust the text differently, from

An example repository for Codeberg Docs.

to

An example repository to use with the Codeberg Documentation.

git add README.md
git commit -m "Adjusted last sentence in README"

We now have two branches with conflicting changes to the same line:

git switch main
git branch
  add-link-to-readme
* main
  update-last-sentence-in-readme

Merging the first branch

Now, we want to merge both of the branches into the main branch.

First, we merge the branch named add-link-to-readme. As this is a simple change to a yet unchanged main-branch, there is no conflict.

git switch main
git merge add-link-to-readme

Attempting to merge the second branch

Let's try to merge the second branch.

git merge update-last-sentence-in-readme

As expected there is a conflict:

$ git merge update-last-sentence-in-readme
Auto-merging README.md
CONFLICT (content): Merge conflict in README.md
Automatic merge failed; fix conflicts and then commit the result.

Issuing git status shows us that there are unmerged paths.

$ git status
On branch main
You have unmerged paths.
  (fix conflicts and run "git commit")
  (use "git merge --abort" to abort the merge)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
  both modified:   README.md

no changes added to commit (use "git add" and/or "git commit -a")

Issuing git diff shows the conflict:

diff --cc README.md
index 616dc84,088249f..0000000
--- a/README.md
+++ b/README.md
@@@ -1,3 -1,3 +1,7 @@@
  ![](https://docs.codeberg.org/images/getting-started/knut.svg)

++<<<<<<< HEAD
  +An example repository for [Codeberg Docs](https://docs.codeberg.org).
++=======
+ An example repository to use with the Codeberg Documentation.
++>>>>>>> update-last-sentence-in-readme

You have to resolve this conflict manually, as Git doesn't know how the resulting line should be.

Resolving the conflict

Use your favorite text editor to open the file. The editor will show you the conflict. Git actually added the conflict description into the README.md file.

The end of the file now looks like this:

<<<<<<< HEAD
An example repository for [Codeberg Docs](https://docs.codeberg.org).
=======
An example repository to use with the Codeberg Documentation.
>>>>>>> update-last-sentence-in-readme

The conflict description starts with <<<<<<< HEAD. The next line shows you that the current HEAD (the last commit on the main branch before we ran git merge update-last-sentence-in-readme) was:

An example repository for [Codeberg Docs](https://docs.codeberg.org).

The next line, ======= separates the current line from the line proposed in the branch that is to be merged.

An example repository to use with the Codeberg Documentation.

The last line >>>>>>> update-last-sentence-in-readme concludes the conflict description and tells you that the line(s) before are taken from the branch update-last-sentence-in-readme.

Use your editor of choice, and change the line to reflect the changes you wish to commit to the repository after the resolution of the conflict.

Remove all other lines, then the file should be in the form that you want to commit to the main branch.

A possible resolution of this conflict could be:

An example repository to use with the [Codeberg Documentation](https://docs.codeberg.org).

Calling git diff README.md shows the new line was added, and the two conflicting lines were removed:

diff --cc README.md
index 616dc84,088249f..0000000
--- a/README.md
+++ b/README.md
@@@ -1,3 -1,3 +1,3 @@@
  ![](https://docs.codeberg.org/images/getting-started/knut.svg)

- An example repository for [Codeberg Docs](https://docs.codeberg.org).
- An example repository to use with the Codeberg Documentation.
++An example repository to use with the [Codeberg Documentation](https://docs.codeberg.org).

You can now mark the conflict as resolved, by calling git add README.md.

If you have more than one conflict in one or more files, repeat the resolution process until all conflicts are resolved.

Make sure not to leave any lines starting with <<<<<<<, =======, and >>>>>>>, as Git no longer knows that these are special and will treat them as normal text.

Issuing git commit without any comment will open the default editor, and lets you edit a commit message for the merge commit. Closing the editor will complete the resolution of the merge conflict.

git log shows you both the original commit that lead to the conflict and the merge commit.

For example:

commit c10f2c3338979149d7c6fcb815a2072743b5bde6 (HEAD -> main)
Merge: 5e2cebd 7b5bf4f
Author: Knut <knut@...>
Date:   Sat May 21 19:44:43 2022 +0200

    Merge branch 'update-last-sentence-in-readme' into main

commit 7b5bf4f0fe2213ded938bc9de313f4cd3d9043db (update-last-sentence-in-readme)
Author: Knut <knut@...>
Date:   Sat May 21 18:38:16 2022 +0200

    Adjusted last sentence in README

commit 5e2cebd523754b655d1990fb48dbb7b973f07dfa (add-link-to-readme)
Author: Knut <knut@...>
Date:   Sat May 21 18:29:15 2022 +0200

    Added link to Codeberg docs to README

Note the line starting with Merge; it includes the commit IDs of the two merged commits.

Removed files

Let's create another conflict.

We'll start again at the main branch. If you didn't work through the example above, you can jumpstart the environment for this example with these commands:

git clone git@codeberg.org:knut/examples.git
cd examples

If you're still on another branch from the last example, make sure that you start this example on the main branch, by running git switch main.

Removing a file

Again, we'll create a new branch.

git switch -c remove-README-file

This time, we'll remove the README.md file.

git rm README.md
git commit -m "removed README.md"

We won't merge this branch yet.

Editing the file

First switch back to the main branch.

git switch main

On second branch we add a line to the end of the README.md file.

git switch -c adapt-README-file
echo "You can find this repository in the Forgejo Web GUI at https://codeberg.org/knut/examples" >> README.md
git add README.md
git commit -m "added repository url to README.md"

Merging the first branch

Again, switch back to the main branch.

git switch main

Merging the first branch does not lead to a conflict, because the main branch didn't change since the branch remove-README-file was created.

git merge remove-README-file

Conflict and resolution

When we try to merge the second branch adapt-README-file, we get a conflict because the file we are trying to change, README.md was removed by our previous merge.

$ git merge adapt-README-file
CONFLICT (modify/delete): README.md deleted in HEAD and modified in adapt-README-file.  Version adapt-README-file of README.md left in tree.
Automatic merge failed; fix conflicts and then commit the result.

git status also shows the conflict:

$ git status
On branch main
You have unmerged paths.
  (fix conflicts and run "git commit")
  (use "git merge --abort" to abort the merge)

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
  deleted by us:   README.md

no changes added to commit (use "git add" and/or "git commit -a")

You now have two choices:

• Keep the current status and remove the README.md file
• Re-introduce the README.md file into the main branch.

To keep the current status and remove the README.md file, you must tell Git once more to remove it:

git rm README.md

To re-introduce the README.md file, simply add it again:

git add README.md

Use git commit if you've resolved all conflicts (in this case it was only one).

As with before, issuing git commit without any comment will open your default editor, and ask you to provide a commit message for the merge commit.

Tips

• Try to avoid using git push -f on the target branch.
• Ensure that all branches are pushed to a remote repository before trying to resolve a conflict, as it makes it easier to start over in case you run into a problem.
• Search for <<<<<<<, ======= and >>>>>>> in the resolved files, in order to not leave a conflict description in your files.