Translating Large-Scale C Repositories to Idiomatic Rust (arxiv.org)

Researchers introduce Rustine, a fully automated pipeline for translating large-scale C repositories into idiomatic, safe Rust that balances quality and scalability where prior methods fall short. Unlike transpilers that scale but yield unreadable, unsafe Rust and LLM-based approaches that are costly and rely on frontier models, Rustine produces compilable Rust for all 23 evaluated C programs (27–13,200 LOC) and achieves 87% functional equivalence — passing 1,063,099 of 1,221,192 test assertions — with average function and line coverage of 74.7% and 72.2%. Translations are measurably safer (fewer raw pointers, pointer arithmetic, and unsafe blocks), more idiomatic (fewer linter violations), and easier to read than outputs from six prior repository-level techniques. Technically, Rustine operates at repository scale and emphasizes idiomatic Rust patterns and safety while remaining fully automated, enabling a practical migration path for legacy C code. Where full test parity wasn’t achieved, Rustine served as an effective debugging aid: human developers completed remaining fixes in about 4.5 hours on average. For the AI/ML and software-engineering community, Rustine demonstrates a viable middle ground between brittle, low-quality transpilation and expensive LLM-heavy solutions — accelerating safe modernization of critical C codebases and reducing manual rewriting effort.