Attributes that may contribute to the occurrence of merge conflicts

Collaborative software development typically involves the use of branches. The changes made in different branches are usually merged, and direct and indirect conflicts may arise. Some studies are concerned with investigating ways to deal with merge conflicts and measuring the effort that this activity may require. However, the investigation of factors that may reduce the occurrence of conflicts needs more and deeper attention. This paper aims at identifying and analyzing attributes of past merges with and without conflicts to understand what may induce direct conflicts. We analyzed 182,273 merge scenarios from 80 projects written in eight different programming languages to find characteristics that increase the chances of a merge to have a conflict. We found that attributes such as the number of changed files, the number of commits, the number of changed lines, and the number of committers demonstrated to have the strongest influence in the occurrence of merge conflicts. Moreover, attributes in the branch that is being integrated seem to be more influential than the same attributes in the receiving branch. Additionally, we discovered positive correlations between the occurrence of conflicts and both the duration of the branch and the intersection of developers in both branches. Finally, we observed that PHP, JavaScript, and Java are more prone to conflicts.