Can Program Synthesis be Used to Learn Merge Conflict Resolutions?: An Empirical Analysis

• Main Authors: Pan, Rangeet, Le, Vu, Nagappan, Nachiappan, Gulwani, Sumit, Lahiri, Shuvendu, Kaufman, Mike
• Format: Conference Proceeding
• Language: English
• Subjects: automated fixing; C++ languages; Chromium; Collaboration; Domain specific languages; DSL; merge conflict; Open source software; program synthesis; Software and its engineering; Software and its engineering > Software creation and management; Software and its engineering > Software creation and management > Software post-development issues; Software and its engineering > Software creation and management > Software verification and validation; Software and its engineering > Software creation and management > Software verification and validation > Software defect analysis; Software and its engineering > Software notations and tools; Software and its engineering > Software notations and tools > General programming languages; Software and its engineering > Software notations and tools > Software configuration management and version control systems; Software and its engineering > Software notations and tools > Software maintenance tools; Software engineering
• ISSN: 1558-1225; 1558-1225
• DOI: 10.1109/ICSE43902.2021.00077

Forking structure is widespread in the open-source repositories and that causes a significant number of merge conflicts. In this paper, we study the problem of textual merge conflicts from the perspective of Microsoft Edge, a large, highly collaborative fork of the main Chromium branch with significant merge conflicts. Broadly, this study is divided into two sections. First, we empirically evaluate textual merge conflicts in Microsoft Edge and classify them based on the type of files, location of conflicts in a file, and the size of conflicts. We found that ~28% of the merge conflicts are 1-2 line changes, and many resolutions have frequent patterns. Second, driven by these findings, we explore Program Synthesis (for the first time) to learn patterns and resolve structural merge conflicts. We propose a novel domain-specific language (DSL) that captures many of the repetitive merge conflict resolution patterns and learn resolution strategies as programs in this DSL from example resolutions. We found that the learned strategies can resolve 11.4% of the conflicts (~41% of 1-2 line changes) that arise in the C++ files with 93.2% accuracy.