Safely evolving configurable systems

Developers use configuration options to tailor systems to different platforms. This configurability leads to exponential configuration spaces and traditional tools (e.g., gcc) check only one configuration at a time. As a result, developers introduce configuration-related issues (i.e., bad smells and faults) that appear only when we select certain configuration options. By interviewing 40 developers and performing a survey with 202 developers, we found that configuration- related issues are harder to detect and more critical than is- sues that appear in all configurations. We propose a strategy to detect configuration-related issues and a catalogue of refactorings to remove bad smells in preprocessor directives. We found 131 faults and 500 bad smells in 40 real-world configurable systems, including Apache and Libssh.