Tare: Type-Aware Neural Program Repair.

Automated program repair (APR) aims to reduce the effort of software development. With the development of deep learning, lots of DL-based APR approaches have been proposed using an encoder-decoder architecture. Despite the promising performance, these models share the same limitation: generating lots of untypable patches. The main reason for this phenomenon is that the existing models do not consider the constraints of code captured by a set of typing rules. In this paper, we propose, Tare, a type-aware model for neural program repair to learn the typing rules. To encode an individual typing rule, we introduce three novel components: (1) a novel type of grammars, T-Grammar, that integrates the type information into a standard grammar, (2) a novel representation of code, T-Graph, that integrates the key information needed for type checking an AST, and (3) a novel type-aware neural program repair approach, Tare, that encodes the T-Graph and generates the patches guided by T-Grammar. The experiment was conducted on three benchmarks, 393 bugs from Defects4J v1.2, 444 additional bugs from Defects4J v2.0, and 40 bugs from QuixBugs. Our results show that Tare repairs 62, 32, and 27 bugs on these benchmarks respectively, and outperforms the existing APR approaches on all benchmarks. Further analysis also shows that Tare tends to generate more compilable patches than the existing DL-based APR approaches with the typing rule information.