C2RustXW: Program-Structure-Aware C-to-Rust Translation via Program Analysis and LLM

TL;DR

C2RustXW is a novel program-structure-aware C-to-Rust translation method that combines program analysis with LLMs to produce syntactically correct, safe, and maintainable Rust code, significantly improving over existing rule-based tools.

Contribution

It introduces a multi-level program structure extraction and a multi-stage repair pipeline that integrates rule-based and LLM-based techniques for high-quality C-to-Rust translation.

Findings

Achieves 100% syntactic correctness on CodeNet and 97.78% on GitHub.

Reduces code size by up to 43.70% and unsafe usage to 5.75%.

Attains an average semantic correctness of 78.87% at the project level.

Abstract

The growing adoption of Rust for its memory safety and performance has increased the demand for effective migration of legacy C codebases. However, existing rule-based translators (e.g., \ctorust) often generate verbose, non-idiomatic code that preserves unsafe C semantics, limiting readability, maintainability, and practical adoption. Moreover, manual post-processing of such outputs is labor-intensive and rarely yields high-quality Rust code, posing a significant barrier to large-scale migration. To address these limitations, we present \tool, a program-structure-aware C-to-Rust translation approach that integrates program analysis with Large Language Models (LLMs). \tool extracts the multi-level program structure, including global symbols, function dependencies, and control- and data-flow information, and encodes these as structured textual representations injected into LLM prompts to guide translation and repair. Based on this design, \tool performs dependency-aware translation and adopts a multi-stage repair pipeline that combines rule-based and structure-guided LLM-based techniques to ensure syntactic correctness. For semantic correctness, \tool further integrates execution-based validation with structure-guided reasoning to localize and repair behavioral inconsistencies. Experimental results show that \tool achieves 100\% syntactic correctness on CodeNet and 97.78\% on GitHub, while significantly reducing code size (up to 43.70\%) and unsafe usage (to 5.75\%). At the project level, \tool achieves perfect syntactic correctness and an average semantic correctness of 78.87\%, demonstrating its effectiveness for practical and scalable C-to-Rust migration.