Resolving Merge Conflicts Manually

# CHAPTER 5

Resolving Merge Conflicts Manually #

1. Introduction #

2. Learning Objectives #

• Manually edit a file to remove Git conflict markers.

• Choose between keeping Current changes, Incoming changes, or a synthesis of both.

• Use git add to mark a conflict as resolved.

• Conclude the merge process with a final commit.

• Abort a merge entirely using git merge --abort.

3. Beginner Explanation #

• The script has a conflict block. Writer A wrote: "The hero escapes in a car." Writer B wrote: "The hero escapes in a helicopter."

• The Fix: You open a word processor. You are the boss. You delete the ugly Git markers around the text. You delete the line about the car. You keep the line about the helicopter.

• You save the document.

• You tell the publisher, "The script is fixed and ready to print" (This is git add).

• You officially publish it (This is git commit).

4. The 4 Steps to Manual Resolution #

1. 1. Open & Edit: Open the file in a raw text editor. Manually delete the <<<<<<<, =======, and >>>>>>> lines. Keep only the code you want.

1. 2. Save: Save the file to your hard drive.

1. 3. Stage: Tell Git you have fixed the file by adding it to the staging area.

   git add filename.txt
   ```
4. **Commit:** Finalize the merge process.
   ```bash
   git commit -m "Resolve conflict in filename.txt"
   ```
   *Note: As soon as you hit enter on the commit, the `(MERGING)` state disappears from your terminal. The crisis is over!*

### 5. The Three Choices of Resolution
When you edit the file, you have three distinct choices:
- **Accept Current (HEAD):** You delete the incoming code and keep what was already on `main`. You are rejecting your coworker's work.
- **Accept Incoming:** You delete the `main` code and keep the code from the feature branch. You are replacing the old code.
- **Synthesize (Accept Both):** You realize *both* developers wrote valid code. You delete the markers and manually arrange both lines of code so they work together.

### 6. Mini Project: Resolve PHP Project Merge Conflict
Let's resolve a simulated PHP code conflict manually.

**Step-by-Step Walkthrough:**
1. Imagine you open `database.php` and see this:
   ```php
   <<<<<<< HEAD
   $db = new PDO(&#039;mysql:host=localhost;dbname=prod', 'root', 'old_password');
   =======
   $db = new PDO(&#039;mysql:host=localhost;dbname=prod', 'admin', 'new_secure_pass');
   >>>>>>> feature-security-update
   ```
2. You recognize that the `feature-security-update` branch contains the correct, updated credentials.
3. Place your cursor on the `<<<<<<< HEAD` line and delete the entire line.
4. Delete the "old_password" line entirely.
5. Delete the `=======` line.
6. Delete the `>>>>>>> feature-security-update` line.
7. Your file should now look like perfectly clean PHP:
   ```php
   $db = new PDO(&#039;mysql:host=localhost;dbname=prod', 'admin', 'new_secure_pass');
   ```
8. Save the file.
9. In the terminal, type:
   ```bash
   git add database.php
   git commit -m "Resolve database credential conflict"
   ```

### 7. The Panic Button (`git merge --abort`)
Sometimes, a merge goes horribly wrong. You open a file and see thousands of conflict markers. You try to fix them, but you get confused and accidentally delete critical code. Your file is ruined, and you haven&#039;t committed yet.
**Do not panic.** You can instantly time-travel back to safety.

bash git merge --abort `` This command instantly cancels the entire merge process, deletes all conflict markers, and restores your files exactly to how they looked 5 minutes ago before you ever typed git merge. It is the ultimate "undo" button.

• Test Before Committing: Just because you deleted the conflict markers does not mean the code actually works! If you merged two complex PHP functions together, you might have accidentally created a syntax error. Always run your application locally (or run your unit tests) to verify the code executes flawlessly *before* you type the final git commit.

• Forgetting to Add: Beginners will painstakingly edit the file, save it, and immediately type git commit. Git will throw an error saying "Umerged paths". You *must* run git add <file> first. Using git add is how you officially communicate to Git: "I have reviewed this file and the conflict is formally resolved."

13. Next Chapter Recommendation #