Code comment generation aims at generating natural language descriptions for a code snippet to facilitate developers' program comprehension activities. Despite being studied for a long time, a bottleneck for existing approaches is that given a code snippet, they can only generate one comment while developers usually need to know information from diverse perspectives such as what is the functionality of this code snippet and how to use it. To tackle this limitation, this study empirically investigates the feasibility of utilizing large language models (LLMs) to generate comments that can fulfill developers' diverse intents. Our intuition is based on the facts that (1) the code and its pairwise comment are used during the pre-training process of LLMs to build the semantic connection between the natural language and programming language, and (2) comments in the real-world projects, which are collected for the pre-training, usually contain different developers' intents. We thus postulate that the LLMs can already understand the code from different perspectives after the pre-training. Indeed, experiments on two large-scale datasets demonstrate the rationale of our insights: by adopting the in-context learning paradigm and giving adequate prompts to the LLM (e.g., providing it with ten or more examples), the LLM can significantly outperform a state-of-the-art supervised learning approach on generating comments with multiple intents. Results also show that customized strategies for constructing the prompts and post-processing strategies for reranking the results can both boost the LLM's performances, which shed light on future research directions for using LLMs to achieve comment generation.

Despite the capability in successfully fixing more and more real-world bugs, existing Automated Program Repair (APR) techniques are still challenged by the long-standing overfitting problem (i.e., a generated patch that passes all tests is actually incorrect). Plenty of approaches have been proposed for automated patch correctness assessment (APCA ). Nonetheless, dynamic ones (i.e., those that needed to execute tests) are time-consuming while static ones (i.e., those built on top of static code features) are less precise. Therefore, embedding techniques have been proposed recently, which assess patch correctness via embedding token sequences extracted from the changed code of a generated patch. However, existing techniques rarely considered the context information and program structures of a generated patch, which are crucial for patch correctness assessment as revealed by existing studies. In this study, we explore the idea of context-aware code change embedding considering program structures for patch correctness assessment. Specifically, given a patch, we not only focus on the changed code but also take the correlated unchanged part into consideration, through which the context information can be extracted and leveraged. We then utilize the AST path technique for representation where the structure information from AST node can be captured. Finally, based on several pre-defined heuristics, we build a deep learning based classifier to predict the correctness of the patch. We implemented this idea as Cache and performed extensive experiments to assess its effectiveness. Our results demonstrate that Cache can (1) perform better than previous representation learning based techniques (e.g., Cache relatively outperforms existing techniques by \( \approx \) 6%, \( \approx \) 3%, and \( \approx \) 16%, respectively under three diverse experiment settings), and (2) achieve overall higher performance than existing APCA techniques while even being more precise than certain dynamic ones including PATCH-SIM (92.9% vs. 83.0%). Further results reveal that the context information and program structures leveraged by Cache contributed significantly to its outstanding performance.

Software is constantly changing, requiring developers to perform several derived tasks in a timely manner, such as writing a description for the intention of the code change, or identifying the defect-prone code changes. Considering that the cost of dealing with these tasks can account for a large proportion (typically around 70 percent) of the total development expenditure, automating such processes will significantly lighten the burdens of developers. To achieve such a target, existing approaches mainly rely on training deep learning models from scratch or fine-tuning existing pre-trained models on such tasks, both of which have weaknesses. Specifically, the former uses comparatively small-scale labelled data for training, making it difficult to learn and exploit the domain knowledge of programming language hidden in the large-amount unlabelled code in the wild; the latter is hard to fully leverage the learned knowledge of the pre-trained model, as existing pre-trained models are designed to encode a single code snippet rather than a code change (the difference between two code snippets). We propose to pre-train a model specially designed for code changes to better support developers in software maintenance. To this end, we first collect a large-scale dataset containing 1.5M+ pairwise data of code changes and commit messages. Based on these data, we curate five different tasks for pre-training, which equip the model with diverse domain knowledge about code changes. We fine-tune the pre-trained model, CCT5, on three widely-studied tasks incurred by code changes and two tasks specific to the code review process. Results show that CCT5 outperforms both conventional deep learning approaches and existing pre-trained models on these tasks.

Context: Tangled commits are changes to software that address multiple concerns at once. For researchers interested in bugs, tangled commits mean that they actually study not only bugs, but also other concerns irrelevant for the study of bugs. Objective: We want to improve our understanding of the prevalence of tangling and the types of changes that are tangled within bug fixing commits. Methods: We use a crowd sourcing approach for manual labeling to validate which changes contribute to bug fixes for each line in bug fixing commits. Each line is labeled by four participants. If at least three participants agree on the same label, we have consensus. Results: We estimate that between 17% and 32% of all changes in bug fixing commits modify the source code to fix the underlying problem. However, when we only consider changes to the production code files this ratio increases to 66% to 87%. We find that about 11% of lines are hard to label leading to active disagreements between participants. Due to confirmed tangling and the uncertainty in our data, we estimate that 3% to 47% of data is noisy without manual untangling, depending on the use case. Conclusion: Tangled commits have a high prevalence in bug fixes and can lead to a large amount of noise in the data. Prior research indicates that this noise may alter results. As researchers, we should be skeptics and assume that unvalidated data is likely very noisy, until proven otherwise.

Fault Localization (FL) is an essential step during the debugging process. With the strong capabilities of code comprehension, the recent Large Language Models (LLMs) have demonstrated promising performance in diagnosing bugs in the code. Nevertheless, due to LLMs’ limited performance in handling long contexts, existing LLM-based fault localization remains on localizing bugs within a small code scope (i.e., a method or a class), which struggles to diagnose bugs for a large code scope (i.e., an entire software system). To address the limitation, this paper presents SoapFL, which builds an LLM-driven standard operating procedure (SOP) to automatically localize buggy methods from the entire software. By simulating the behavior of a human developer, SoapFL models the FL task as a three-step process, which involves comprehension, navigation, and confirmation. Within specific steps, SoapFL provides useful test behavior or coverage information to LLM through program analysis. Particularly, we adopt a series of auxiliary strategies such as Test Behavior Tracking, Document-Guided Search, and Multi-Round Dialogue to overcome the challenges in each step. The evaluation on the widely used Defects4J-V1.2.0 benchmark shows that SoapFL can localize 175 out of 395 bugs within Top-1, which outperforms the other LLM-based approaches and exhibits complementarity to the state-of-the-art learning-based techniques. Additionally, we confirm the indispensability of the components in SoapFL with the ablation study and demonstrate the usability of SoapFL through a user study. Finally, the cost analysis shows that SoapFL spends an average of only 0.081 dollars and 92 seconds for a single bug.

The quality of method names is critical for the readability and maintainability of source code. However, it is often challenging to construct concise method names. To alleviate this problem, a number of approaches have been proposed to automatically recommend high-quality names for methods. Despite being effective, existing approaches meet their bottlenecks mainly in two aspects: (1) the leveraged information is restricted to the target method itself; and (2) lack of distinctions towards the contributions of tokens extracted from different program contexts. Through a large-scale empirical analysis on +12M methods from +14K real-world projects, we found that (1) the tokens composing a method’s name can be frequently observed in its callers/callees; and (2) tokens extracted from different specific contexts have diverse probabilities to compose the target method’s name. Motivated by our findings, we propose, in this paper, a context-guided method name recommender, which mainly embodies two key ideas: (1) apart from the local context, which is extracted from the target method itself, we also consider the global context, which is extracted from other methods in the project that have call relations with the target method, to include more useful information; and (2) we utilize our empirical results as the prior knowledge to guide the generation of method names and also to restrict the number of tokens extracted from the global contexts. We implemented the idea as Cognac and performed extensive experiments to assess its effectiveness. Results reveal that can (1) perform better than existing approaches on the method name recommendation task (e.g., it achieves an F-score of 63.2%, 60.8%, 66.3%, and 68.5%, respectively, on four widely-used datasets, which all outperform existing techniques); and (2) achieve higher performance than existing techniques on the method name consistency checking task (e.g., its overall accuracy reaches 76.6%, outperforming the state-of-the-art MNire by 11.2%). Further results reveal that the caller/callee information and the prior knowledge all contribute significantly to the overall performance of Cognac.