Rust and C++: Together on the way to better programming integration

Rust and C++: Together on the way to better programming integration

The Rust Foundation recently published an important document on GitHub that highlights the challenges in the interaction between the Rust and C++ programming languages. The foundation outlines both short-term and long-term solutions for improved interoperability between these two programming languages. This is particularly relevant because Rust, although established in low-level programming, often encounters existing C++ applications.

Interoperability between Rust and C++ is a key issue, especially when developing embedded systems or other resource-limited environments. The use cases mentioned by the Rust Foundation are exemplary of practice: C++ systems that implement new functions with Rust, Rust-based systems that rely on existing C++ code, and systems that use multiple programming languages. C++ has a much longer history, which is why many projects often have to work with existing C++ code.

Challenges of integration

A major obstacle to using Rust and C++ together is the lack of a toolchain that allows mixing C++ and Rust code in the same file. An FFI-based (Foreign Function Interface) approach is currently necessary to connect the two programming languages. This is typically done via C's Application Binary Interface (ABI), which is more stable and platform independent than the more complex C++ ABIs.

Another big problem is that many of Rust's security features are largely lost when interacting with C. This therefore poses a serious challenge for developers who want to take advantage of Rust's strong security measures while also interacting with C. The Rust Foundation describes C as the “lingua franca” for FFI integration, and the difficulties in creating a common basis for communication severely limit the use of specific Rust features.

Strategies for improvement

In its “C++/Rust Interoperability Problem Statement,” the Rust Foundation has defined three key strategies to optimize interoperability between these languages. First, the foundation plans to improve tools and fix fundamental problems within the Rust project that make integration difficult.

In addition, the aim is to find a consensus on a strategy to identify and implement the necessary changes for Rust to increase interoperability. Another important point is collaboration with the C++ community and the C++ Standards Committee to pursue common security and performance goals.

These approaches come as Google made a generous $1 million grant to the Rust Foundation in February 2024. These funds are intended to further advance the collaboration between Rust and C++.

For more information, the details can be found in the C++/Rust Problem Statement on GitHub and in the Rust Foundation announcements. These initiatives could potentially have a significant impact on software development and integration in the future, particularly in areas where Rust and C++ are used together.