arXiv AI By Xiaobo Chen, Genliang Zhu, Ziyuan Wang, Chu Wang

Accepted but Wrong: Silent Failures of LLM Code Repairs after API Migrations

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The study examines how large language models (LLMs) repair code after runtime or API migrations, revealing that many repaired procedures run without errors yet produce incorrect results. Across 73 tasks and 60 documented changes in CPython, Node.js, and SQLite, the authors found that typical test inputs allowed 41% of wrong repairs to pass, while targeted edge inputs reduced this to 6–7%. Even with additional hard distractors and blind model writers, a significant fraction of incorrect repairs still passed the preregistered tests.

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