Building

This page is about calling Rust from C++ with cpp_api_from_rust. If you want to call C++ from Rust, see Rust bindings for C++ libraries instead.

cpp_api_from_rust is available in these build systems:

Build system	How	Example
Bazel	The cpp_api_from_rust rule from the rules_crubit module	examples/build_systems/bazel
CMake	corrosion_experimental_crubit() from Corrosion	examples/build_systems/cmake

Each build system page above walks through the setup. Other build systems can use the cargo cpp_api_from_rust subcommand, which writes a C++ header and a static library for a Cargo package; see Build System Integrations.

Quick start

The Crubit repository includes ready-to-run CMake and Bazel example projects where a C++ main binary calls into a Rust library through bindings generated by cpp_api_from_rust.

To run the examples on Linux x86_64, you need:

• CMake: CMake 3.22 or later, Ninja, Clang (which the example‘s CMakeLists.txt uses to compile the C++ binary), and rustup (which installs the Rust toolchain from Crubit’s rust-toolchain.toml).
• Bazel: bazelisk (which downloads the Rust and Clang toolchains for you), plus a rustc on your PATH, which crubit_toolchains uses to check LLVM version compatibility.

{}

{{#tab name=“CMake”}}

git clone https://github.com/google/crubit.git
cd crubit/examples/build_systems/cmake
cmake -B build -S . -G Ninja
cmake --build build
./build/main

{}

{{#tab name=“Bazel”}}

git clone https://github.com/google/crubit.git
cd crubit/examples/build_systems/bazel
bazelisk run //:main

{}

{}

Toolchains

cpp_api_from_rust works with nightly Rust toolchains and with the two most recent stable releases, as long as the rustc-dev component is installed. It generates portable C++20 that doesn't depend on a particular C++ compiler. See Toolchain requirements for details.

Building cc_bindings_from_rs yourself

The Bazel and CMake integrations build Crubit for you. If you're integrating Crubit into another build system, see Cargo build of Crubit for how to build the cc_bindings_from_rs binary from source.