• Minimum Rust version now 1.55
• Added rust_type! to allow passing references to Rust types within C++ APIs
• Added support for rust::Box to allow passing opaque Rust types into and out of C++ APIs
• Added very early support for creating Rust subclasses of C++ superclasses, subject to a bunch of constraints. See examples/subclass/src/main.rs.
• Upgrade to cxx 1.0.54