Merge commit creation in Git - Step-by-Step Execution

Process Flow - Merge commit creation

Start on branch A

↓

Make commits on branch A

↓

Switch to branch B

↓

Make commits on branch B

↓

Run git merge A on branch B

↓

Git compares changes

↓

If no conflicts

↓

Create merge commit

↓

Merge complete

↓

End with merged history

This flow shows how Git creates a merge commit by combining changes from two branches, handling conflicts if any.

Execution Sample

Git

git checkout main
# On main branch

git checkout -b feature
# Create and switch to feature branch

git add .
git commit -m "Add feature"
# Commit on feature

git checkout main
# Switch back to main

git merge feature
# Merge feature into main

This sequence creates a feature branch, commits changes, then merges it back into main, producing a merge commit.

Process Table

Step	Command/Action	State Before	Git Action	State After
1	git checkout main	On any branch	Switch to main branch	HEAD points to main
2	git checkout -b feature	On main branch	Create and switch to feature branch	HEAD points to feature, feature branch created
3	git commit -m "Add feature"	On feature branch with changes staged	Create commit on feature	New commit added to feature branch
4	git checkout main	On feature branch	Switch back to main branch	HEAD points to main
5	git merge feature	main and feature branches diverged	Git compares commits, creates merge commit	main branch updated with merge commit combining feature
6	Merge complete	Merge commit created	History now includes commits from both branches	Branches merged, working directory updated

💡 Merge commit created successfully, combining changes from feature into main

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	After Step 5	Final
HEAD	points to original branch	points to feature	points to feature	points to main	points to main	points to main
main branch	original commit	unchanged	unchanged	unchanged	updated with merge commit	updated with merge commit
feature branch	does not exist	created at main commit	advanced by new commit	unchanged	unchanged	unchanged

Key Moments - 3 Insights

Why does Git create a new merge commit instead of just moving the branch pointer?

Because the branches have diverged with different commits, Git needs a merge commit to combine histories, as shown in step 5 of the execution_table.

What happens if there are conflicts during the merge?

Git pauses the merge and asks you to resolve conflicts manually before creating the merge commit, which is not shown here but would interrupt step 5.

Does the merge commit change the feature branch?

No, the merge commit is created on the main branch; the feature branch remains unchanged, as seen in the variable_tracker after step 5.

Visual Quiz - 3 Questions

Look at the execution_table at step 3, what is the state of the feature branch?

A Feature branch is deleted

B Feature branch has a new commit

C Feature branch points to main

D Feature branch has no commits

💡 Hint

Check the 'State After' column for step 3 in the execution_table

At which step does HEAD switch back to the main branch?

A Step 4

B Step 3

C Step 2

D Step 5

💡 Hint

Look at the 'Command/Action' and 'State After' columns in the execution_table

If there were conflicts during the merge, what would change in the execution flow?

A Git would delete the feature branch

B Git would create the merge commit immediately

C Git would pause and require manual conflict resolution before committing

D Git would switch back to the feature branch automatically

💡 Hint

Refer to the key_moments section about conflict handling

Concept Snapshot

git merge <branch>
- Combines changes from <branch> into current branch
- If branches diverged, creates a merge commit
- If conflicts, manual resolution needed before commit
- Keeps history of both branches intact
- Merge commit has two parents

Full Transcript

This visual execution shows how Git creates a merge commit. First, you start on the main branch, then create and switch to a feature branch. You make a commit on feature, then switch back to main. When you run git merge feature, Git compares the histories. If no conflicts, it creates a merge commit on main combining both branches. The feature branch remains unchanged. If conflicts occur, Git pauses for manual resolution before completing the merge. The merge commit links both histories, preserving all changes.