Refactoring references for library migration

Abstract

Automated refactoring is a key feature of modern IDEs. Existing refactorings rely on the transformation of source code declarations, in which references may also be transformed as a side effect. However, there exist situations in which a declaration is not available for refactoring or would be inappropriate to transform, for example, in the presence of dangling references or where a set of references should be retargeted to a different declaration. We investigate the problem of dangling references through a detailed study of three open source libraries. We find that the introduction of dangling references during library migration is a significant real problem, and characterize the specific issues that arise. Based on these findings we provide and test a prototype tool, called Trident, that allows programmers to refactor references. Our results suggest that supporting the direct refactoring of references is a significant improvement over the state-of-the-art.