Examination of Coding Violations Focusing on Their Change Patterns over Releases

Code review is an essential activity to ensure the quality of code being developed, and there have been static code checkers for aiding an effective code review. However, such tools have not been actively utilized in the world of programmers due to a lot of coding violations (warning) produced by tools and their false-positiveness. In order to analyze the automatically pointed violations and the actual attentions which programmers paid to those violations, this paper proposes a novel metric— the Index of Programmers' Attention (IPA)—and conducts an empirical study focusing on the change patterns of violations over the releases of popular seven open source software products, under two research questions (RQs): (RQ1) What kind of coding violations are related to the parts that many programmers tend to improve? and what kind of coding violations are likely to be disregarded?; (RQ2) How can we reduce the meaningless violations for programmers by omitting disregarded coding violations?The empirical results showed the following findings: (1) important violations (having high IPA values) may vary from project to project; (2) there are some unimportant violations common to different projects, but they are a minority of automatically detected violations (about 12%). Therefore, while many violations may be made by a code checker, most of them are likely to be worthy in improving the code quality, and it is ineffective to reduce the violations by eliminating such unimportant violations.