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rustccodegenc

rustic compiler compiles full-set Rust code into C

The rustccodegenc crate implements an experimental codegen backend that transpiles Rust's MIR into C source code, then compiles the C code with a system C compiler (e.g., gcc or clang) to produce object files.

This enables Rust compilation for targets where an LLVM backend is unavailable but a C compiler exists.

A Rust compiler built with rustccodegenc passes 99.2% of the rustc UI test suite (./x test --stage=2 ui), confirming that the backend preserves Rust semantics at the MIR level with high fidelity.

Related projects:

Quick start

Download the compiler

# Donwload and link
curl -L "https://github.com/rustic-compiler/rustccodegenc/releases/latest/download/rustic-toolchain-$(rustc --print=host-tuple)-gcc.tar.gz" | tar xz -C rustic-sysroot
rustup toolchain link rustic rustic-sysroot
Run
cargo new hello && cd hello
rustup run rustic cargo run --release

Build `rustc` from pre-built C files

curl -L "https://github.com/rustic-compiler/rustccodegenc/releases/latest/download/rustic-rustc-csources-$(rustc --print=host-tuple)-gcc.tar.gz" | tar xz -C rustic-rustc-csources
cd rustic-rustc-csources
make build

Build your Rust program from C sources

To transpile a Rust program into C and then build it from the generated C sources:

RUSTC_BOOTSTRAP=1 rustup run rustic cargo build --release -Z build-std
cd target/release
make build

Known problems

Some crates (e.g., ring) rely on CPU-specific extended instructions (such as Neon) and may fail to compile with the C backend. You may be able to work around this by changing the compilation target to one without those features.

Build the compiler

# Clone repos
git clone https://github.com/rustic-compiler/rustccodegenc.git
git clone https://github.com/rustic-compiler/rust.git
Make sym link
cd rust/compiler
ln -s ../../rustccodegenc ./rustccodegenc
Setup Rust build config
cd ../
cat << EOF > bootstrap.toml
profile = "dist"
[llvm]
download-ci-llvm = true
[rust]
codegen-backends = ["c"]
EOF
Build rustc and std
./compiler/rustccodegenc/y build --stage=2 compiler library
Run
rustup toolchain link rustic build/host/stage2
cargo new hello && cd hello
rustup run rustic cargo run --release

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