crustc translates the Rust compiler to about 46 million lines of C

Category: Languages
Status: discussion
Sources: crustc repository, HN discussion
Summary: crustc is a demonstration that compiles rustc 1.98.0-nightly into roughly 46 million lines of C that build with GCC and make, without LLVM. It is produced by "cilly," a Rust-to-C backend that adapts output to a target C compiler using small witness programs and targets close to ANSI C. The stated motivation is Rust portability to old or obscure hardware without LLVM or a GCC Rust frontend. The author labels it a proof of concept: the full cilly toolchain is not released, optimization bugs remain, compilation is slow, and it crashes when run from the repository root.
Why it matters: Rust portability to niche targets is a recurring argument against choosing Rust over C, and a C-buildable rustc is a concrete, if early, response to that gap.
Follow-up: Track a cilly toolchain release and any move from proof of concept toward reproducible builds on real minority platforms.