Automatic Detection and Resolution of Software Merge Conflicts: Are We There Yet? (2102.11307v2)

Abstract: Developers create software branches for tentative feature addition and bug fixing, and periodically merge branches to release software with new features or repairing patches. When the program edits from different branches textually overlap (i.e., textual conflicts), or the co-application of those edits lead to compilation or runtime errors (i.e., compiling or dynamic conflicts), it is challenging and time-consuming for developers to eliminate merge conflicts. Prior studies examined %the popularity of merge conflicts and how conflicts were related to code smells or software development process; tools were built to find and solve conflicts. However, some fundamental research questions are still not comprehensively explored, including (1) how conflicts were introduced, (2) how developers manually resolved conflicts, and (3) what conflicts cannot be handled by current tools. For this paper, we took a hybrid approach that combines automatic detection with manual inspection to reveal 204 merge conflicts and their resolutions in 15 open-source repositories. %in the version history of 15 open-source projects. Our data analysis reveals three phenomena. First, compiling and dynamic conflicts are harder to detect, although current tools mainly focus on textual conflicts. Second, in the same merging context, developers usually resolved similar textual conflicts with similar strategies. Third, developers manually fixed most of the inspected compiling and dynamic conflicts by similarly editing the merged version as what they did for one of the branches. Our research reveals the challenges and opportunities for automatic detection and resolution of merge conflicts; it also sheds light on related areas like systematic program editing and change recommendation.

Overview of "Automatic Detection and Resolution of Software Merge Conflicts: Are We There Yet?"

The paper presents a comprehensive paper on the nature of software merge conflicts and the effectiveness of existing tools in detecting and resolving these conflicts. It aims to address gaps in understanding how different types of software merge conflicts are introduced and resolved by developers, focusing specifically on the resolution strategies and the insufficiencies of current automated tools.

Key Findings

1. Conflict Types and Introduction: The paper categorizes merge conflicts into textual, compiling, and dynamic types. It reveals that:
   • Textual Conflicts: Majority (66%) involve conflicting updates or insertions between branches.
   • Compiling Conflicts: Predominantly arise from broken def-use relationships, with 93% of conflicts involving classes, methods, or fields.
   • Dynamic Conflicts: Often result from inconsistencies between code implementation and test oracles or misalignments in class hierarchies.
2. Developer Resolution Strategies:
   • Textual Conflicts: Resolved by preferring one branch’s edits over the other or integrating changes from both branches, sometimes with corrections.
   • Compiling and Dynamic Conflicts: Predominantly addressed by developers through additional manual edits that often reflect similar changes made in one of the branches.
3. Tool Capabilities:
   • Existing tools like JDime and Crystal-like approaches can detect all textual conflicts but are insufficient for compiling and dynamic conflicts.
   • Only 21% of compiling and 25% of dynamic conflicts were revealed by such tools, leaving a gap for automatic detection and resolution.

Implications and Future Directions

The paper highlights the need for enhanced tools that can handle higher-order conflicts without requiring compilation and test execution. It identifies the potential for tools that perform static analysis to detect a comprehensive range of conflicts and suggests integrating change recommendation systems for conflict resolution. The authors recommend leveraging systematic editing tools, like SYDIT and LASE, to automate repetitive editing tasks typically performed by developers during conflict resolution.

Conclusions

The paper provides a detailed empirical analysis of merge conflicts, emphasizing the limitations of current tool support. It suggests that by understanding the typical developer strategies in conflict resolution, future tools can be designed to more effectively assist in the automatic detection and resolution of both textual and higher-order conflicts. This work lays a foundation for future research in improving merge tools, thereby enhancing developer productivity and reducing integration challenges in software development.