Understanding and Resolving Conflicts

Conflicts happen when Git can't automatically merge changes. Learning to resolve them confidently is essential for team collaboration.

When Conflicts Occur

Conflicts happen when:

• Two branches modify the same line differently
• One branch deletes a file another branch modified
• Both branches add files with the same name

Git handles many situations automatically, but when it can't determine the correct result, it asks you to decide.

Anatomy of a Conflict

When a conflict occurs, Git marks the file:

1<<<<<<< HEAD
2This is the content from your current branch
3=======
4This is the content from the branch being merged
5>>>>>>> feature-branch

Marker Meanings

Three-Way Conflicts (During Rebase)

Sometimes you see three sections:

1<<<<<<< HEAD
2Your changes
3||||||| parent of abc123
4Original content (common ancestor)
5=======
6Their changes
7>>>>>>> abc123

The middle section shows the original, helping you understand what each side changed.

Resolution Strategies

Keep One Version

Sometimes you want to accept one side completely:

bash
1# Keep your version
2$ git checkout --ours file.txt
3
4# Keep their version
5$ git checkout --theirs file.txt

Manual Merge

Edit the file to combine both changes:

Before:

1<<<<<<< HEAD
2function greet() {
3  return "Hello!";
4}
5=======
6function greet(name) {
7  return `Hi ${name}!`;
8}
9>>>>>>> feature

After (manual resolution):

1function greet(name = "World") {
2  return `Hello, ${name}!`;
3}

Remove conflict markers and create the desired result.

Use a Merge Tool

Visual merge tools can help:

bash
1$ git mergetool

Configure your preferred tool:

bash
1$ git config --global merge.tool vscode
2$ git config --global mergetool.vscode.cmd 'code --wait $MERGED'

Popular merge tools:

• VS Code (built-in)
• Sublime Merge
• Beyond Compare
• Meld (Linux)
• Kaleidoscope (macOS)

Conflict During Merge

bash
1$ git merge feature-branch
2Auto-merging app.js
3CONFLICT (content): Merge conflict in app.js
4Automatic merge failed; fix conflicts and then commit the result.

Resolution Steps

1. Identify conflicts:

   bash
   1$ git status
   2Unmerged paths:
   3  both modified:   app.js

2. Edit conflicted files:

   bash
   1$ vim app.js
   2# Remove markers, create correct content

3. Stage resolutions:

   bash
   1$ git add app.js

4. Complete merge:

   bash
   1$ git commit
   2# Editor opens with merge commit message

Abort Merge

If you want to start over:

bash
1$ git merge --abort

Conflict During Rebase

bash
1$ git rebase main
2CONFLICT (content): Merge conflict in app.js
3error: could not apply abc123... Add feature

Resolution Steps

1. Fix conflicts in files

2. Stage resolutions:

   bash
   1$ git add app.js

3. Continue rebase:

   bash
   1$ git rebase --continue

4. Repeat for each conflicting commit

Skip or Abort

bash
1# Skip this commit (dangerous: loses changes)
2$ git rebase --skip
3
4# Cancel rebase entirely
5$ git rebase --abort

Rerere: Remember Resolutions

Enable rerere to remember how you resolved conflicts:

bash
1$ git config --global rerere.enabled true

Next time Git sees the same conflict, it auto-resolves:

bash
1$ git rebase main
2Resolved 'app.js' using previous resolution.

Review what rerere recorded:

bash
1$ git rerere diff

Conflict Prevention

Stay Updated

Regularly sync with main to minimize divergence:

bash
1$ git fetch origin
2$ git rebase origin/main

Small, Focused Changes

Large changes = more conflict potential. Small PRs merge easier.

Communicate with Team

If you know you'll modify heavily-used files, coordinate with teammates.

Common Conflict Scenarios

Binary Files

Git can't merge binary files. Choose one:

bash
1$ git checkout --ours image.png
2# or
3$ git checkout --theirs image.png
4$ git add image.png

Deleted vs Modified

One branch deleted a file, another modified it:

bash
1$ git status
2deleted by them: config.json
3
4# Keep the file
5$ git add config.json
6
7# Accept deletion
8$ git rm config.json

Renamed Files

If detection fails, Git sees it as delete + create:

bash
1# Check rename detection
2$ git diff --name-status main
3R100    old-name.js    new-name.js

Key Takeaway

Conflicts are normal in collaborative development. Read the markers carefully, understand what each side changed, and create a resolution that preserves the intent of both changes. Enable rerere to avoid resolving the same conflicts repeatedly.