main.rs

#[macro_use]
extern crate cpp;

cpp! {{
    #include <numeric>
    #include <vector>
}}

fn main() {
    let y = 3;
    let x = unsafe {
        cpp!([y as "int32_t"] -> i32 as "int32_t" {
            auto x = std::vector<int32_t>{1, y, 3};
            return std::accumulate(x.begin(), x.end(), 0);
        })
    };
    println!("{}", x);
}