Program Repair without Regret

Abstract

We present a new and flexible approach to repair reactive programs with respect to a specification. The specification is given in linear-temporal logic. Like in previous approaches, we aim for a repaired program that satisfies the specification and is syntactically close to the faulty program. The novelty of our approach is that it produces a program that is also semantically close to the original program by enforcing that a subset of the original traces is preserved. Intuitively, the faulty program is considered to be a part of the specification, which enables us to synthesize meaningful repairs, even for incomplete specifications. Our approach is based on synthesizing a program with a set of behaviors that stay within a lower and an upper bound. We provide an algorithm to decide if a program is repairable with respect to our new notion, and synthesize a repair if one exists. We analyze several ways to choose the set of traces to leave intact and show the boundaries they impose on repairability. We also discuss alternative notions based on reward models to obtain repair systems that behave similar to the original system. We have evaluated the approach on several examples.

Deductive Program Repair

“…Repair has also been studied in the context of reactive and pushdown systems with otherwise finite control [8,10,11,19,20,26]. In [26], the authors generate repairs that preserve explicitly subsets of traces of the original program, in a way strengthening the specification automatically. We deal with the case of functions from inputs to outputs equipped with contracts.…”

“…The task of repair consists of automatically generating an alternative implementation that meets the specification. The repair problem has been studied in the past for reactive and pushdown systems [8,10,11,19,20,26]. We view repair as generalizing, for example, the choose construct of complete functional synthesis [15], sketching [21,22], and program templates [23], because the exact location and nature of expressions to be synthesized is left to the algorithm.…”

Must Fault Localization for Program Repair

“…In the literature there is also a wide range of techniques for automated program repair using formal methods [ 4 , 10 , 19 , 22 , 29 , 32 , 33 , 42 ]. Both [ 11 ] and [ 37 ] also use fault localization followed by applying mutations for repair.…”

Program repair without regret

“…This article is based on [44]. It adds further analysis with respect to optimal repair, suggests alternative approaches to define "close" repairs, provides more details about the experimental evaluation, and some new insides to improve the implementation.…”