fedora-csb-system-manager

Merge Workflow

Merge branches with proper strategies and conflict resolution.

When to Use

  • “merge git branch”
  • “merge conflicts”
  • “resolve conflicts”
  • “merge strategies”

Quick Commands

Basic Merge

# Merge feature branch into current branch
git merge feature/user-auth

# Merge with commit message
git merge feature/user-auth -m "Merge user authentication feature"

# No fast-forward (always create merge commit)
git merge --no-ff feature/user-auth

# Abort merge
git merge --abort

Merge Strategies

# Fast-forward only (fail if not possible)
git merge --ff-only feature/user-auth

# Squash merge (combine all commits)
git merge --squash feature/user-auth
git commit -m "feat: add user authentication"

# No commit (stage changes only)
git merge --no-commit feature/user-auth

Merge vs Fast-Forward

Fast-Forward Merge

# When feature is ahead of main, no divergence
git checkout main
git merge feature/simple-fix

# Result: main pointer moves forward, no merge commit
# main:    A---B
# feature:     C---D
# After:   A---B---C---D (main)

Three-Way Merge

# When both branches have diverged
git checkout main
git merge feature/complex-feature

# Result: creates merge commit
# main:    A---B-------E (merge commit)
#               \     /
# feature:       C---D

Resolving Conflicts

Conflict Resolution Process

# 1. Attempt merge
git merge feature/user-auth
# Auto-merging file.txt
# CONFLICT (content): Merge conflict in file.txt

# 2. See conflicting files
git status
# Unmerged paths:
#   both modified:   file.txt

# 3. View conflicts
git diff

# 4. Edit file to resolve
# Remove conflict markers and choose resolution

# 5. Stage resolved files
git add file.txt

# 6. Complete merge
git commit

# Or abort
git merge --abort

Conflict Markers

<<<<<<< HEAD (current branch)
const API_URL = "https://api.example.com/v1";
=======
const API_URL = "https://api.example.com/v2";
>>>>>>> feature/api-update

Resolution Options

// Option 1: Keep current
const API_URL = "https://api.example.com/v1";

// Option 2: Take incoming
const API_URL = "https://api.example.com/v2";

// Option 3: Combine both
const API_URL = process.env.API_VERSION === "2"
    ? "https://api.example.com/v2"
    : "https://api.example.com/v1";

Merge Tools

Using Merge Tool

# Configure merge tool
git config --global merge.tool vimdiff

# Run merge tool for conflicts
git mergetool

# Common merge tools:
# - vimdiff
# - meld
# - kdiff3
# - p4merge
# - code (VS Code)

VS Code as Merge Tool

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

Merge Strategies

Recursive (Default)

# Default for two branches
git merge -s recursive feature/branch

Ours/Theirs

# Keep our version on conflict
git merge -X ours feature/branch

# Keep their version on conflict
git merge -X theirs feature/branch

Octopus

# Merge multiple branches at once
git merge feature/auth feature/api feature/ui

Squash Merge

When to Use

  • Feature branch with many small commits
  • Want clean main branch history
  • Don’t need to preserve individual commits

How to Squash Merge

# 1. Squash merge
git checkout main
git merge --squash feature/many-commits

# 2. All changes staged, no commit created
git status

# 3. Create single commit
git commit -m "feat: complete user authentication

- Add login/logout functionality
- Implement JWT token management
- Add password hashing
- Create user session handling"

Cherry-Pick During Merge

# If you want specific commits instead of full merge
git cherry-pick abc1234 def5678

Undoing Merges

Before Committing

# Abort in-progress merge
git merge --abort

# Reset staged changes
git reset --hard HEAD

After Committing

# Undo merge commit (keep changes)
git reset --soft HEAD~1

# Undo merge commit (discard changes)
git reset --hard HEAD~1

# Revert merge (safe for public branches)
git revert -m 1 HEAD
# -m 1 means keep main branch side

Best Practices

  1. Always pull before merge: Ensure you have latest changes
  2. Merge into correct branch: Double-check current branch
  3. Test before merging: Run tests on feature branch first
  4. Use –no-ff for features: Preserve branch history
  5. Squash for cleanup: Use squash merge for messy branches
  6. Communicate conflicts: Discuss non-trivial resolutions
  7. Never merge broken code: Ensure tests pass first

Common Workflows

Feature Branch Merge

# 1. Update main
git checkout main
git pull

# 2. Merge feature
git merge --no-ff feature/user-auth

# 3. Push
git push

Hotfix Merge

# 1. Create hotfix from main
git checkout -b hotfix/security-patch main

# 2. Fix and commit
git commit -m "fix: security vulnerability"

# 3. Merge to main
git checkout main
git merge --no-ff hotfix/security-patch

# 4. Tag release
git tag -a v1.0.1 -m "Security patch"

# 5. Merge to develop if exists
git checkout develop
git merge --no-ff hotfix/security-patch

Configuration

# Always create merge commit (no fast-forward)
git config --global merge.ff false

# For pull specifically
git config --global pull.ff only

# Show conflict style
git config --global merge.conflictstyle diff3

Resources