Chromium Docs

Rust FFI

This document tries to provide guidance for C++/Rust FFI. CLs to improve this guidance are welcomed.

General guidance

Chromium recommends using the cxx crate for C++/Rust FFI. For introductory guidance, please see the cxx chapter in the Chromium day of the Comprehensive Rust course.

Chromium also supports the following tools:

  • bindgen - see //build/rust/rust_bindgen.gni for usage instructions.

At this point Chromium's //build/rust/*.gni templates do not support other FFI tools like:

cxx guidance

Best practices

  • Generate C++ side of bindings into a project-specific or crate-specific namespace. For example: #[cxx::bridge(namespace = "some_cpp_namespace")].
  • Maintain binding declarations in a single #[cxx::bridge] declaration. cxx supports reusing types across multiple bridges, but there are some rough edges.

Suggestions

TODO: Provide some examples or suggestions on how to structure FFI bindings (even if these suggestions wouldn't necessarily rise to the level of “best practices”).