comprehensive-rust/src/chromium/interoperability-with-cpp/example-bindings.md

Example Bindings

CXX requires that the whole C++/Rust boundary is declared in cxx::bridge modules inside .rs source code.

{{#include ../../../third_party/cxx/book/snippets.rs:cxx_overview}}

Point out:

• Although this looks like a regular Rust mod, the #[cxx::bridge] procedural macro does complex things to it. The generated code is quite a bit more sophisticated - though this does still result in a mod called ffi in your code.
• Native support for C++'s std::unique_ptr in Rust
• Native support for Rust slices in C++
• Calls from C++ to Rust, and Rust types (in the top part)
• Calls from Rust to C++, and C++ types (in the bottom part)

Common misconception: It looks like a C++ header is being parsed by Rust, but this is misleading. This header is never interpreted by Rust, but simply #included in the generated C++ code for the benefit of C++ compilers.