A Static Evaluation of Code Completion by Large Language Models
Authors: name: Hantian Ding, name: Varun Kumar, name: Yuchen Tian, name: Zijian Wang, name: Rob Kwiatkowski, name: Xiaopeng Li, name: Murali Krishna Ramanathan, name: Baishakhi Ray, name: Parminder Bhatia, name: Sudipta Sengupta, name: Dan Roth, name: Bing Xiang

Large language models trained on code have shown great potential to increase
productivity of software developers. Several execution-based benchmarks have
been proposed to evaluate functional correctness of model-generated code on
simple programming problems. Nevertheless, it is expensive to perform the same
evaluation on complex real-world projects considering the execution cost. On
the contrary, static analysis tools such as linters, which can detect errors
without running the program, haven't been well explored for evaluating code
generation models. In this work, we propose a static evaluation framework to
quantify static errors in Python code completions, by leveraging Abstract
Syntax Trees. Compared with execution-based evaluation, our method is not only
more efficient, but also applicable to code in the wild. For experiments, we
collect code context from open source repos to generate one million function
bodies using public models. Our static analysis reveals that Undefined Name and
Unused Variable are the most common errors among others made by language
models. Through extensive studies, we also show the impact of sampling
temperature, model size, and context on static errors in code completions.