Automatic Repair of Timestamp Comparisons

Abstract

Automated program repair has the potential to reduce the developers' effort to fix errors in their code. In particular, modern programming languages, such as Java, C, and C#, represent time as integer variables that suffer from integer overflow, introducing subtle errors that are hard to discover and repair. Recent researches on automated program repair rely on test cases to discover failures to correct, making them suitable only for regression errors. We propose a new strategy to automatically repair programs that suffer from timestamp overflows that are manifested in comparison expressions. It unifies the benefits of static analysis and automatic program repair avoiding to depend on testing to identify and correct defected code. Our approach performs an abstract analysis over the time domain of a program using a Time Type System to identify the problematic comparison expressions. The repairing strategy rewrites the timestamp comparisons exploiting the binary representation of machine numbers to correct the code. We have validated the applicability of our approach with 20 open source Java projects. The results show that it is able to correctly repair all 246 identified errors. Furthermore, several patches for three open source projects have been acknowledged and accepted by their developers.

Evaluating Automatic Program Repair Capabilities to Repair API Misuses

“…To be selected for inclusion in our study, a repair tool, from these listed in Table 1, must use the test suite of a project under examination for validation and meet the following inclusion criteria according to the guidelines of the recent related work [9], [10]. We exclude from the beginning CLOTHO [26], Exception repair [28], JAVACC [31], JIST [33], and Timestamps [37] since they are not typical test-suite-based repair tools.…”

“…Constraint-based ACS [25] if conditions DEFECTS4J CLOTHO [26] Invalid String inputs Custom DYNAMOTH [27] Method calls REPAIRTHEMALL Exception repair [28] Incorrect assignments Custom FOOTPATCH [29] Memory leaks Custom JAID [30] Generic DEFECTS4J JAVACC [31] Syntax errors Custom JFIX [32] Generic DEFECTS4J JIST [33] Branching-time logics Custom LOOPFIX [34] Loop conditions DEFECTS4J NOPOL [35] Conditional checks REPAIRTHEMALL NPEFIX [36] Null pointer checks REPAIRTHEMALL Timestamps [37] Timestamp overflows Custom VFIX [38] Null pointer checks Custom…”