CXX

CXX is a library that offers safe interop between Rust and C++. It provides a safe mechanism for calling C++ code from Rust and vice versa, one that is protected from the many possible things that can go wrong when bindgen or cbindgen is used to generate unsafe C-style bindings.

The general idea of CXX is to define the signatures of both sides of the FFI boundary embedded together in one Rust module. CXX gets a complete picture from this of the boundary, and through it is able to perform static analyses against the types and function signatures, ensuring that both Rust's and C++'s invariants and requirements are upheld. CXX then emits the relevant extern "C" signatures on both sides through a pair of code generators. This is done together with any necessary static assertions needed for later in the build process to verify correctness. The result is an FFI bridge that operates at zero or negligible overhead, with no copying, serialization or memory allocation needed.