A comparative study on the bug-proneness of different types of code clones

• Published in: ICSME : 2015 IEEE International Conference on Software Maintenance and Evolution : September 29, 2015-October 1, 2015 pp. 91 - 100
• Main Authors: Mondal, Manishankar, Roy, Chanchal K., Schneider, Kevin A.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.09.2015
• Subjects: Cloning; Computer bugs; Java; Maintenance engineering; Software systems; Terminology
• DOI: 10.1109/ICSM.2015.7332455

Code clones are defined to be the exactly or nearly similar code fragments in a software system's code-base. The existing clone related studies reveal that code clones are likely to introduce bugs and inconsistencies in the code-base. However, although there are different types of clones, it is still unknown which types of clones have a higher likeliness of introducing bugs to the software systems and so, should be considered more important for managing with techniques such as refactoring or tracking. With this focus, we performed a study that compared the bug-proneness of the major clone-types: Type 1, Type 2, and Type 3. According to our experimental results on thousands of revisions of seven diverse subject systems, Type 3 clones exhibit the highest bug-proneness among the three clone-types. The bug-proneness of Type 1 clones is the lowest. Also, Type 3 clones have the highest likeliness of being co-changed consistently while experiencing bug-fixing changes. Moreover, the Type 3 clones that experience bug-fixes have a higher possibility of evolving following a Similarity Preserving Change Pattern (SPCP) compared to the bug-fix clones of the other two clone-types. From the experimental results it is clear that Type 3 clones should be given a higher priority than the other two clone-types when making clone management decisions. We believe that our study provides useful implications for ranking clones for refactoring and tracking.