Migrating Client Code without Change Examples

Abstract

API developers evolve software libraries to fix bugs, add new features, or refactor code. To benefit from such library evolution, the programmers of client projects have to repetitively upgrade their library usages and adapt their codebases to any library API breaking changes (e.g., API renaming). Such adaptive changes can be tedious and error-prone. Existing tools provide limited support to help programmers migrate client projects from old library versions to new ones. For instance, some tools extract API mappings between library versions and only suggest simple adaptive changes (i.e., statement updates); other tools suggest or automate more complicated edits (e.g., statement insertions) based on user-provided exemplar code migrations. However, when new library versions are available, it is usually cumbersome and time-consuming for users to provide sufficient human-crafted samples in order to guide automatic migration.In this paper, we propose a novel approach-AUTOUPDATEto further improve the state of the art. Instead of learning from change examples, we designed AUTOUPDATE to automate migration in a compiler-directed way. Namely, given a compilation error triggered by upgrading libraries, AUTOUPDATE exploits 13 migration operators to generate candidate edits, and tentatively applies each edit until the error is resolved or all edits are explored. We conducted two evaluations. The first evaluation involves migrating 371 tutorial examples between versions of 5 popular libraries. AUTOUPDATE reduced migrationrelated compilation errors for 92.7% of tasks. It eliminated such errors for 32.4% of tasks, and 33.9% of the tasks have identical edits to manual migrations. In the second evaluation, we applied AUTOUPDATE to migrate two real client projects of lucene. AUTOUPDATE successfully migrated both projects, and the migrated code passed all tests.