Automated Program Repair Tools Research Articles

An Empirical Study on the Suitability of Test-based Patch Acceptance Criteria

In this article, we empirically study the suitability of tests as acceptance criteria for automated program fixes, by checking patches produced by automated repair tools using a bug-finding tool, as opposed to previous works that used tests or manual inspections. We develop a number of experiments in which faulty programs from IntroClass , a known benchmark for program repair techniques, are fed to the program repair tools GenProg, Angelix, AutoFix and Nopol, using test suites of varying quality, including those accompanying the benchmark. We then check the produced patches against formal specifications using a bug-finding tool. Our results show that, in the studied scenarios, automated program repair tools are significantly more likely to accept a spurious program fix than producing an actual one. Using bounded-exhaustive suites larger than the originally given ones (with about 100 and 1,000 tests) we verify that overfitting is reduced but a) few new correct repairs are generated and b) some tools see their performance reduced by the larger suites and fewer correct repairs are produced. Finally, by comparing with previous work, we show that overfitting is underestimated in semantics-based tools and that patches not discarded using held-out tests may be discarded using a bug-finding tool.

Patch Correctness Assessment: A Survey

Most automated program repair methods rely on test cases to determine the correctness of the generated patches. However, due to the incompleteness of available test suites, some patches that pass all the test cases may still be incorrect. This issue is known as the patch overfitting problem. Overfitting problem is a longstanding problem in automated program repair. Due to overfitting patches, the patches obtained by automated program repair tools require further validation to determine their correctness. Researchers have proposed many methods to automatically assess the correctness of patches, but no systematic review provides a detailed introduction to this problem, the existing solutions, and the challenges. To address this deficiency, we systematically review the existing approaches to patch correctness assessment. We first offer a few examples of overfitting patches to acquire a more detailed understanding of this problem. We then propose a comprehensive categorization of publicly available techniques and datasets, examine the commonly used evaluation metrics, and perform an in-depth analysis of the effectiveness of the existing models in addressing the challenge of overfitting. Based on our analysis, we provided the difficulties encountered by current methodologies, alongside the possible avenues for future research exploration.

Evolving Paradigms in Automated Program Repair: Taxonomy, Challenges, and Opportunities

With the rapid development and large-scale popularity of program software, modern society increasingly relies on software systems. However, the problems exposed by software have also come to the fore. The software bug has become an important factor troubling developers. In this context, Automated Program Repair (APR) techniques have emerged, aiming to automatically fix software bug problems and reduce manual debugging work. In particular, benefiting from the advances in deep learning, numerous learning-based APR techniques have emerged in recent years, which also bring new opportunities for APR research. To give researchers a quick overview of APR techniques’ complete development and future opportunities, we review the evolution of APR techniques and discuss in depth the latest advances in APR research. In this article, the development of APR techniques is introduced in terms of four different patch generation schemes: search-based, constraint-based, template-based, and learning-based. Moreover, we propose a uniform set of criteria to review and compare each APR tool and then discuss the current state of APR development. Finally, we analyze current challenges and future directions, especially highlighting the critical opportunities that large language models bring to APR research.

On the acceptance by code reviewers of candidate security patches suggested by Automated Program Repair tools

ObjectiveWe investigated whether (possibly wrong) security patches suggested by Automated Program Repairs (APR) for real world projects are recognized by human reviewers. We also investigated whether knowing that a patch was produced by an allegedly specialized tool does change the decision of human reviewers.MethodWe perform an experiment with n=72\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$n= 72$$\\end{document} Master students in Computer Science. In the first phase, using a balanced design, we propose to human reviewers a combination of patches proposed by APR tools for different vulnerabilities and ask reviewers to adopt or reject the proposed patches. In the second phase, we tell participants that some of the proposed patches were generated by security-specialized tools (even if the tool was actually a ‘normal’ APR tool) and measure whether the human reviewers would change their decision to adopt or reject a patch.ResultsIt is easier to identify wrong patches than correct patches, and correct patches are not confused with partially correct patches. Also patches from APR Security tools are adopted more often than patches suggested by generic APR tools but there is not enough evidence to verify if ‘bogus’ security claims are distinguishable from ‘true security’ claims. Finally, the number of switches to the patches suggested by security tool is significantly higher after the security information is revealed irrespective of correctness.LimitationsThe experiment was conducted in an academic setting, and focused on a limited sample of popular APR tools and popular vulnerability types.

Automated patch correctness predicting to fix software defect

Automated Program Repair (APR) is a technique that can automatically fix software defects without manual debugging, playing a crucial role in software development and maintenance. However, the patches generated by APR still suffer from the problem of overfitting, which poses a significant threat to practical applications. Previous studies have proposed various approaches to predict the correctness of the patch to address this issue, primarily including static-based methods, dynamic-based methods, and learning-based methods. However, these methods all have their own limitations, making it difficult to accurately extract code semantic features and achieve comprehensive prediction. To address the aforementioned challenges, we propose a learning-based unsupervised classification model, Automated Patch cOrrectness aSsessmenT based on muLtiple pErspectives (APOSTLE), for predicting the correctness of patches. Specifically, APOSTLE consists of three components: code vectorization component, where advanced pre-trained models are used to achieve efficient extraction of semantic features from the code; similarity and code change degree calculation component, where APOSTLE calculates the similarity and the degree of change to the code; comprehensive evaluation component, where APOSTLE conducts comprehensive evaluation, addressing the issue of prediction comprehensiveness. Experiments on a collection of 1278 patches (written by developers or generated by 32 APR tools) demonstrate that APOSTLE achieves an AUC value of 0.801, an MAP value of 0.855, and an MRR value of 0.944, outperforming the state-of-the-art approach BATS by 8.3%, 6.0%, and 9.0%, respectively. APOSTLE successfully achieves accurate extraction of code semantic features while achieving comprehensive patch correctness prediction.

Boosting fault localization of statements by combining topic modeling and Ochiai

Context:Reducing the cost of maintenance tasks by fixing bugs automatically is the cornerstone of Automated Program Repair (APR). To do this, automated Fault Localization (FL) is essential. Two families of FL techniques are Spectrum-based Fault Localization (SBFL) and Information Retrieval Fault Localization (IRFL). In SBFL, the coverage information and execution results of test cases are utilized. Ochiai is one of the most effective and used SBFL strategies. In IRFL, the bug report information is utilized as well as the identifier names and comments in source code files. Latent Dirichlet Allocation (LDA) is a generative statistical model and one of the most popular topic modeling methods. However, LDA has been used at the method level of granularity as IRFL technique, whereas most existing APR tools are focused on the statement level. Objective:This paper presents our approach that combines topic modeling and Ochiai to boost FL at the statement level. Method:We evaluate our approach considering five different projects in Defects4J benchmark. We report the performance of our approach in terms of hit@k and MRR. To study the impact on the results, we compare our approach against five baselines: two SBFL approaches (Ochiai and Dstar), two IRFL approaches (LDA and Blues), and one hybrid approach (SBIR). In addition, we compare the number of bugs that are found by our approach with the baselines. Results:Our approach significantly outperforms the baselines in all metrics. Especially, when hit@1, hit@3 and hit@5 are compared. Also, our approach locates more bugs than Ochiai and Blues. Conclusion:The results of our approach indicate that the integration of topic modeling with Ochiai boosts FL. This uncovers the potential of topic modeling for FL at statement level, which is valuable for the APR community.

Improving Automated Program Repair with Domain Adaptation

Automated Program Repair (APR) is defined as the process of fixing a bug/defect in the source code, by an automated tool. APR tools have recently experienced promising results by leveraging state-of-the-art Neural Language Processing (NLP) techniques. APR tools such as TFix and CodeXGLUE that combine text-to-text transformers with software-specific techniques are outperforming alternatives, these days. However, in most APR studies, the train and test sets are chosen from the same set of projects (i.e., when APR fixes a bug in the test set from project A, the model has already seen example fixed bugs from project A in the training set). In the real world, however, APR models are meant to be generalizable to new and different projects. Therefore, there is a potential threat that reported APR models with high effectiveness perform poorly when the characteristics of the new project or its bugs are different than the training set’s (“Domain Shift”). In this study, we first define the problem of domain shift in automated program repair. Next, we measure the potential damage of domain shift on two recent APR models (TFix and CodeXGLUE). Based on this observation, we then propose a domain adaptation framework that can adapt an APR model for a given target project. We conduct an empirical study with three domain adaptation methods FullFineTuning , TuningWithLightWeightAdapterLayers , and CurriculumLearning and two APR models on 2,672 bugs from 12 projects. The results show that our proposed framework on average can improve the effectiveness of TFix by 13.05% and CodeXGLUE by 48.78%, in terms of “Exact Match”. Through experiments, we also show that the framework provides high efficiency and reliability (in terms of “Exposure Bias”). Using synthetic data to domain adapt TFix and CodeXGLUE on the projects with no data (Zero-shot learning), also results in an average improvement of 5.76% and 17.62% for TFix and CodeXGLUE, respectively.

APR4Vul: an empirical study of automatic program repair techniques on real-world Java vulnerabilities

Security vulnerability fixes could be a promising research avenue for Automated Program Repair (APR) techniques. In recent years, APR tools have been thoroughly developed for fixing generic bugs. However, the area is still relatively unexplored when it comes to fixing security bugs or vulnerabilities. In this paper, we evaluate nine state-of-the-art APR tools and one vulnerability-specific repair tool. In particular, we investigate their ability to generate patches for 79 real-world Java vulnerabilities in the Vul4J dataset, as well as the level of trustworthiness of these patches. We evaluate the tools with respect to their ability to generate security patches that are (i) testable, (ii) having the positive effect of closing the vulnerability, and (iii) not having side effects from a functional point of view. Our results show that the evaluated APR tools were able to generate testable patches for around 20% of the considered vulnerabilities. On average, nearly 73% of the testable patches indeed eliminate the vulnerabilities, but only 44% of them could actually fix security bugs while maintaining the functionalities. To understand the root cause of this phenomenon, we conduct a detailed comparative study of the general bug fix patterns in Defect4J and the vulnerability fix patterns in ExtraVul (which we extend from Vul4J). Our investigation shows that, although security patches are short in terms of lines of code, they contain unique characteristics in their fix patterns compared to general bugs. For example, many security fixes require adding method calls. These method calls contain specific input validation-related keywords, such as encode, normalize, and trim. In this regard, our study suggests that additional repair patterns should be implemented for existing APR tools to fix more types of security vulnerabilities.

Reliable Fix Patterns Inferred from Static Checkers for Automated Program Repair

Fix pattern-based patch generation is a promising direction in automated program repair (APR). Notably, it has been demonstrated to produce more acceptable and correct patches than the patches obtained with mutation operators through genetic programming. The performance of pattern-based APR systems, however, depends on the fix ingredients mined from fix changes in development histories. Unfortunately, collecting a reliable set of bug fixes in repositories can be challenging. In this article, we propose investigating the possibility in an APR scenario of leveraging fix patterns inferred from code changes that address violations detected by static analysis tools. To that end, we build a fix pattern-based APR tool, Avatar , which exploits fix patterns of static analysis violations as ingredients for the patch generation of repairing semantic bugs. Evaluated on four benchmarks (i.e., Defects4J, Bugs.jar, BEARS, and QuixBugs), Avatar presents the potential feasibility of fixing semantic bugs with the fix patterns inferred from the patches for fixing static analysis violations and can correctly fix 26 semantic bugs when Avatar is implemented with the normal program repair pipeline. We also find that Avatar achieves performance metrics that are comparable to that of the closely related approaches in the literature. Compared with CoCoNut, Avatar can fix 18 new bugs in Defects4J and 3 new bugs in QuixBugs. When compared with HDRepair, JAID, and SketchFix, Avatar can newly fix 14 Defects4J bugs. In terms of the number of correctly fixed bugs, Avatar is also comparable to the program repair tools with the normal fault localization setting and presents better performance than most program repair tools. These results imply that Avatar is complementary to current program repair approaches. We further uncover that Avatar can present different bug-fixing performances when it is configured with different fault localization tools, and the stack trace information from the failed executions of test cases can be exploited to improve the bug-fixing performance of Avatar by fixing more bugs with fewer generated patch candidates. Overall, our study highlights the relevance of static bug-finding tools as indirect contributors of fix ingredients for addressing code defects identified with functional test cases (i.e., dynamic information).

How do Developers Really Feel About Bug Fixing? Directions for Automatic Program Repair

Automatic program repair (APR) is a rapidly advancing field of software engineering that aims to supplement or replace manual bug fixing with an automated tool. For APR to be successfully adopted in industry, it is vital that APR tools respond to developer needs and preferences. However, very little research has considered developers' general attitudes to APR or developers' current bug fixing practices (the activity APR aims to replace). This paper responds to this gap by reporting on a survey of 386 software developers about their bug finding and fixing practices and experiences, and their instinctive attitudes towards APR. We find that bug finding and fixing is not necessarily as onerous for developers as has often been suggested, being rated as more satisfying than developers' general work. The fact that developers derive satisfaction and benefit from bug fixing indicates that APR adoption is not as simple as APR replacing an unwanted activity. When it comes to potential APR approaches, we find a strong preference for developers being kept in the loop (for example, choosing between different fixes or validating fixes) as opposed to a fully automated process. This suggests that advances in APR should be careful to consider the agency of the developer, as well as what information is presented to developers alongside fixes. It also indicates that there are key barriers related to trust that would need to be overcome for full scale APR adoption, supported by the fact that even those developers who stated that they were positive about APR listed several caveats and concerns. We find very few statistically significant relationships between particular demographic variables (for example, developer experience, age, education) and key attitudinal variables, suggesting that developers' instinctive attitudes towards APR are little influenced by experience level but are held widely across the developer community.

Let’s Talk With Developers, Not About Developers: A Review of Automatic Program Repair Research

Automatic program repair (APR) offers significant potential for automating some coding tasks. Using APR could reduce the high costs historically associated with fixing code faults and deliver significant benefits to software engineering. Adopting APR could also have profound implications for software developers’ daily activities, transforming their work practices. To realise the benefits of APR it is vital that we consider how developers feel about APR and the impact APR may have on developers’ work. Developing APR tools without consideration of the developer is likely to undermine the success of APR deployment. In this paper, we critically review how developers are considered in APR research by analysing how human factors are treated in 260 studies from Monperrus’s Living Review of APR. Over half of the 260 studies in our review were motivated by a problem faced by developers (e.g., the difficulty associated with fixing faults). Despite these human-oriented motivations, fewer than 7% of the 260 studies included a human study. We looked in detail at these human studies and found their quality mixed (for example, one human study was based on input from only one developer). Our results suggest that software developers are often talked <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">about</i> in APR studies, but are rarely talked <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">with</i> . A more comprehensive and reliable understanding of developer human factors in relation to APR is needed. Without this understanding, it will be difficult to develop APR tools and techniques which integrate effectively into developers’ workflows. We recommend a future research agenda to advance the study of human factors in APR.

Predicting Patch Correctness Based on the Similarity of Failing Test Cases

How do we know a generated patch is correct? This is a key challenging question that automated program repair (APR) systems struggle to address given the incompleteness of available test suites. Our intuition is that we can triage correct patches by checking whether each generated patch implements code changes (i.e., behavior) that are relevant to the bug it addresses. Such a bug is commonly specified by a failing test case. Towards predicting patch correctness in APR, we propose a novel yet simple hypothesis on how the link between the patch behavior and failing test specifications can be drawn: similar failing test cases should require similar patches . We then propose BATS , an unsupervised learning-based approach to predict patch correctness by checking patch B ehavior A gainst failing T est S pecification. BATS exploits deep representation learning models for code and patches: For a given failing test case, the yielded embedding is used to compute similarity metrics in the search for historical similar test cases to identify the associated applied patches, which are then used as a proxy for assessing the correctness of the APR-generated patches. Experimentally, we first validate our hypothesis by assessing whether ground-truth developer patches cluster together in the same way that their associated failing test cases are clustered. Then, after collecting a large dataset of 1,278 plausible patches (written by developers or generated by 32 APR tools), we use BATS to predict correct patches: BATS achieves AUC between 0.557 to 0.718 and recall between 0.562 and 0.854 in identifying correct patches. Our approach outperforms state-of-the-art techniques for identifying correct patches without the need for large labeled patch datasets—as is the case with machine learning-based approaches. While BATS is constrained by the availability of similar test cases, we show that it can still be complementary to existing approaches: When combined with a recent approach that relies on supervised learning, BATS improves the overall recall in detecting correct patches. We finally show that BATS is complementary to the state-of-the-art PATCH-SIM dynamic approach for identifying correct patches generated by APR tools.

Identifying Incorrect Patches in Program Repair Based on Meaning of Source Code

Automatic Program Repair (APR) techniques have shown the potential of reducing debugging costs while improving software quality by generating patches for fixing bugs automatically. However, they often generate many overfitting patches which pass only a specific test-suite but do not fix the bugs correctly. This paper proposes MIPI, a novel approach to reducing the number of overfitting patches generated in the APR. We leverage recent advances in deep learning to exploit the similarity between the patched method&#x2019;s name (which often encloses the developer&#x2019;s intention about the code) and the semantic meaning of the method&#x2019;s body (which represents the actual implemented behavior) for identifying and removing overfitting patches generated by APR tools. Experiments with a large dataset of patches for QuixBugs and Defects4J programs show the promise of our approach. Specifically, in a total of 1,191 patches generated by 23 existing APR tools, MIPI successfully filters out 254 (32&#x0025;) of the total 797 overfitting patches with a precision of 90&#x0025; while preserving 93&#x0025; of the correct patches. MIPI is more precise and less damaging to the APR than existing heuristic patch assessment techniques, achieving a higher recall than automated testing-based techniques that do not have access to the test oracle. In addition, MIPI is highly complementary to existing automated patch assessment techniques.

Evaluating the usage of fault localization in automated program repair: an empirical study

Fault localization techniques are originally proposed to assist in manual debugging by generally producing a rank list of suspicious locations. With the increasing popularity of automated program repair, the fault localization techniques have been introduced to effectively reduce the search space of automated program repair. Unlike developers who mainly focus on the rank information, current automated program repair has two strategies to use the fault localization information: suspiciousness-first algorithm (SFA) based on the suspiciousness accuracy and rank-first algorithm (RFA) relying on the rank accuracy. However, despite the fact that the two different usages are widely adopted by current automated program repair and may result in different repair results, little is known about the impacts of the two strategies on automated program repair. In this paper we empirically compare the performance of SFA and RFA in the context of automated program repair. Specifically, we implement the two strategies and six well-studied fault localization techniques into four state-of-the-art automated program repair tools, and then use these tools to perform repair experiments on 60 real-world bugs from Defects4J. Our study presents a number of interesting findings: RFA outperforms SFA in 70.02% of cases when measured by the number of candidate patches generated before a valid patch is found (NCP), while SFA performs better in parallel repair and patch diversity; the performance of SFA can be improved by increasing the suspiciousness accuracy of fault localization techniques; finally, we use SimFix that deploys SFA to successfully repair four extra Defects4J bugs which cannot be repaired by SimFix originally using RFA. These observations provide a new perspective for future research on the usage and improvement of fault localization in automated program repair.

A critical review on the evaluation of automated program repair systems

Automated Program Repair (APR) has attracted significant attention from software engineering research and practice communities in the last decade. Several teams have recorded promising performance in fixing real bugs and there is a race in the literature to fix as many bugs as possible from established benchmarks. Gradually, repair performance of APR tools in the literature has gone from being evaluated with a metric on the number of generated plausible patches to the number of correct patches. This evolution is necessary after a study highlighting the overfitting issue in test suite-based automatic patch generation. Simultaneously, some researchers are also insisting on providing time cost in the repair scenario as a metric for comparing state-of-the-art systems.In this paper, we discuss how the latest evaluation metrics of APR systems could be biased. Since design decisions (both in approach and evaluation setup) are not always fully disclosed, the impact on repair performance is unknown and computed metrics are often misleading. To reduce notable biases of design decisions in program repair approaches, we conduct a critical review on the evaluation of patch generation systems and propose eight evaluation metrics for fairly assessing the performance of APR tools. Eventually, we show with experimental data on 11 baseline program repair systems that the proposed metrics allow to highlight some caveats in the literature. We expect wide adoption of these metrics in the community to contribute to boosting the development of practical, and reliably performable program repair tools.

Restore: Retrospective Fault Localization Enhancing Automated Program Repair

Fault localization is a crucial step of automated program repair, because accurately identifying program locations that are most closely implicated with a fault greatly affects the effectiveness of the patching process. An ideal fault localization technique would provide precise information while requiring moderate computational resources—to best support an efficient search for correct fixes. In contrast, most automated program repair tools use standard fault localization techniques—which are not tightly integrated with the overall program repair process, and hence deliver only subpar efficiency. In this paper, we present <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">retrospective fault localization</i> : a novel fault localization technique geared to the requirements of automated program repair. A key idea of retrospective fault localization is to reuse the outcome of failed patch validation to support mutation-based dynamic analysis—providing accurate fault localization information without incurring onerous computational costs. We implemented retrospective fault localization in a tool called <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Restore</small> —based on the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Jaid</small> Java program repair system. Experiments involving faults from the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Defects4J</small> standard benchmark indicate that retrospective fault localization can boost automated program repair: <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Restore</small> efficiently explores a large fix space, delivering state-of-the-art effectiveness (41 <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Defects4J</small> bugs correctly fixed, 8 of which no other automated repair tool for Java can fix) while simultaneously boosting performance (speedup over 3 compared to <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Jaid</small> ). Retrospective fault localization is applicable to any automated program repair techniques that rely on fault localization and dynamic validation of patches.

APRSuite: A suite of components and use cases based on categorical decomposition of automatic program repair techniques and tools

During the last decade, we are witnessing the advent of a proliferation of techniques and associated tools for automatic program repair (APR). The current techniques and tools provide rich sources of knowledge that should be taken into consideration for future research. An overview of the current APR techniques and tools can serve the research community as a knowledge accumulator. However, APR techniques and tools differ in many aspects making knowledge accumulation challenging. To overcome this challenge, in this paper, we propose to leverage common components that constitute the APR techniques and tools. To achieve this objective, we surveyed current APR techniques and tools to identify the APR Suite of common constituent components, namely as APRSuite. Repair source and defect class are examples of identified components. We grouped these components into several categories such as patch evaluation and target defects. We have also identified some of the possible use cases per component as well as different lessons learned in studies for each component and for each use case. In addition, we developed a principled way for application of the components. The APRSuite and the principled way to apply it comprise a framework for knowledge accumulation, evaluation, and comparison of APR techniques and tools. The novelty of our work lies in its original viewpoint to the process of literature review in the APR research field. To demonstrate the applicability of the framework, we mapped out several concrete APR techniques, as a first instantiation of the framework. We observed that the framework brings discipline into the evaluation and/or comparison of APR techniques and tools. The framework offers these benefits objectively and systematically. We concluded that knowledge accumulation and characterization through literature reviews can be therefore facilitated through the identified suite of components while at the same time the existing component suite can be modified, augmented, or improved.

Fault localization for automated program repair: effectiveness, performance, repair correctness

Automated program repair (APR) tools apply fault localization (FL) techniques to identify the locations of likely faults to be repaired. The effectiveness, performance, and repair correctness of APR depends in part on the FL method used. If FL does not identify the location of a fault, the application of an APR tool will not be effective--it will fail to repair the fault. If FL assigns the actual faulty statement a low priority for repair, APR performance will be reduced by increasing the time required to find a potential repair. In addition, the correctness of a generated repair will be decreased since APR will modify fault-free statements that are assigned a higher priority for repair than an actual faulty statement. We conducted a controlled experiment to evaluate the impact of ten FL techniques on APR effectiveness, performance, and repair correctness using a brute force APR tool applied to faulty versions of the Siemens Suite and two other large programs: space and sed. All FL techniques were effective in identifying all faults; however, Wong3 and Ample1 were the least effective FL techniques since they assigned the lowest priority for repair in more than 26 % of the trials. We obtained the worst APR performance significantly when Ample1 was used since it generated a large number of variants in 29.11 % of the trials, and took the longest time to produce potential repairs. Jaccard FL improved repair correctness by generating more validated repairs---potential repairs that pass a set of regression tests, and generating potential repairs that failed fewer regression tests. Also Jaccard's performance is noteworthy in that it never generated a large number of variants during the repair process compared to the alternatives.