Rusty cmake

Integrate Rust in a Cmake project with Corrosion and Cxx.

Usage

Rust_CARGO_TARGET needs to be defined before calling add_library_rust, which takes a PATH to the root of a rust crate along with a required NAMESPACE to use for the created target.
add_library_rust(PATH some/path/to/rustycrate NAMESPACE my [CXX_BRIDGE_SOURCE_FILE src/lib.rs]) will result in a target my::rustycrate that includes both the crate itself and the generated cxxbridge header and source to be linked into another target. The optional parameter CXX_BRIDGE_SOURCE_FILE defaults to src/lib.rs and allows you to change the source of the #[cxx::bridge] implementation within the rust crate.

Windows + Clang issue

Building with Clang on Windows in debug mode creates a mismatch between the c runtime being dynamic release for the rust lib and dynamic debug for cpp code. No clean solution have been found to this issue. Using the -gnu target on Windows for the Rust lib and building with mingw bypasses this.

Other notes

• This has only been tested with calling Rust from Cpp, and not the other way around.
• For some reason the `lib.rs.cpp' file gets compliled twice, not sure why.
• Clean up how the bindings are placed #include "rustycrate/src/lib.rs.h" is a bit ugly.