Debug: Git merge conflict resolution strategies

Git merge conflicts are confusing and risky to resolve, especially in complex files or with many conflicting changes.

Git merge conflict resolution:

# 1. Understanding conflict markers
<<<<<<< HEAD (or current branch)
Your changes
=======
Their changes
>>>>>>> feature-branch (or incoming branch)

# 2. See what changed on each side
git diff --merge  # Show only conflicting changes
git log --merge -p -- path/to/conflicted/file
# Shows commits from both sides that touch the file

# 3. Choose a resolution strategy BEFORE resolving

# Take ours (current branch wins)
git checkout --ours path/to/file
git add path/to/file

# Take theirs (incoming branch wins)
git checkout --theirs path/to/file
git add path/to/file

# For entire merge:
git merge feature -X ours    # Prefer current on conflicts
git merge feature -X theirs  # Prefer incoming on conflicts

# 4. Three-way merge in editor (recommended)
git mergetool  # Opens configured merge tool
# Shows: BASE (common ancestor), LOCAL (yours), REMOTE (theirs)

# 5. After resolving
git add resolved-file.txt
git merge --continue
# Or: git commit (if no more conflicts)

# 6. Abort if it gets messy
git merge --abort  # Undo the entire merge attempt

# 7. Prevent future conflicts
# - Merge main into feature branch frequently
# - Keep changes small and focused
# - Avoid reformatting files you're not otherwise changing
# - Use .editorconfig for consistent formatting

# 8. Check for remaining conflict markers
grep -rn '<<<<<<' .  # Should return nothing
grep -rn '======' .  # Double-check
grep -rn '>>>>>>' .  # Triple-check

For complex conflicts:

• Understand WHAT both sides intended, not just the diff
• Talk to the other developer if unsure
• Test thoroughly after resolution
• Consider cherry-picking specific changes instead

Merge conflicts happen when two branches modify the same lines. Understanding the three-way merge (base, ours, theirs) makes resolution much easier than guessing from conflict markers alone.

Git merge and collaboration