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.

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.…”

Executing Specifications Using Synthesis and Constraint Solving

“…These techniques usually take specifications in a fragment of temporal logic [54] and have resulted in tools that can synthesize useful hardware components [33,34]. Recently such synthesis techniques have been extended to repair that preserves good behaviors [23], which is related to our notion of partial programs that have remaining choose statements.…”