SpongeBugs: Automatically generating fix suggestions in response to static code analysis warnings

Static code analysis tools such as FindBugs and SonarQube are widely used on open-source and industrial projects to detect a variety of issues that may negatively affect the quality of software. Despite these tools’ popularity and high level of automation, several empirical studies report that developers normally fix only a small fraction (typically, less than 10% (Marcilio et al., 2019) of the reported issues—so-called “warnings”. If these analysis tools could also automatically provide suggestions on how to fix the issues that trigger some of the warnings, their feedback would become more actionable and more directly useful to developers. In this work, we investigate whether it is feasible to automatically generate fix suggestions for common warnings issued by static code analysis tools, and to what extent developers are willing to accept such suggestions into the codebases they are maintaining. To this end, we implemented SpongeBugs, a Java program transformation technique that fixes 11 distinct rules checked by two well-known static code analysis tools (SonarQube and SpotBugs). Fix suggestions are generated automatically based on templates, which are instantiated in a way that removes the source of the warnings; templates for some rules are even capable of producing multi-line patches. Based on the suggestions provided by SpongeBugs, we submitted 38 pull requests, including 946 fixes generated automatically by our technique for various open-source Java projects, including Eclipse UI – a core component of the Eclipse IDE – and both SonarQube and SpotBugs. Project maintainers accepted 87% of our fix suggestions (97% of them without any modifications). We further evaluated the applicability of our technique on software written by students and on a curated collection of bugs. All results indicate that our approach to generating fix suggestions is feasible, flexible, and can help increase the applicability of static code analysis tools.