AWS CodeCommit now supports two additional merge strategies for pull requests: squash merges and three-way merges, and a conflict resolution editor in the console that allows developers to manually resolve conflicts at the time of a merge. A pull request is the primary way developers review, comment on, and merge code changes. Collaboratively reviewing code changes in pull requests helps developers maintain high code quality and better understand each other’s code. 

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/06/aws-codecommit-supports-2-additional-merge-strategies-and-merge-conflict-resolution/