Rust Error Handling

#[cxx::bridge]
mod ffi {
    extern "Rust" {
        fn fallible(depth: usize) -> Result<String>;
    }
}
fn fallible(depth: usize) -> anyhow::Result<String> {
    if depth == 0 {
        return Err(anyhow::Error::msg("fallible1 requires depth > 0"));
    }
    Ok("Success!".into())
}

• Rust functions that return Result are translated to exceptions on the C++ side.
• The exception thrown will always be of type rust::Error, which primarily exposes a way to get the error message string. The error message will come from the error type’s Display impl.
• A panic unwinding from Rust to C++ will always cause the process to immediately terminate.