Calling Rust from C++

build_win32.bat

call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64

mkdir build
cl /nologo /Zi /MD /EHsc /I third_party\sdl\include shell/main.cpp /Febuild/win32_main2.exe /Fobuild/ /link /libpath:third_party\sdl\lib\win_x64 SDL2.lib SDL2main.lib /subsystem:console
cp third_party\sdl\lib\win_x64\SDL2.dll build

Cargo.toml

[package]
name = "vec"
version = "0.1.0"
authors = ["Frederik De Bleser <frederik@debleser.be>"]

[lib]
name = "vec"
crate-type = ["dylib"]

[dependencies]

lib.rs

#[repr(C)]
pub struct Vec2 {
    x: f32,
    y: f32,

    // Adding a constructor here makes the code crash on Windows! :-O
    // Vec2(f32 x_, f32 y_) : x(x_), y(y_) {}
}

#[repr(C)]
pub struct Vec4 {
    x: f32,
    y: f32,
    z: f32,
    w: f32,

    // Adding a constructor here is no problem.
    // Vec4(f32 x_, f32 y_, f32 z_, f32 w_) : x(x_), y(y_), z(z_), w(w_) {}
}

#[no_mangle]
pub extern "C" fn vec2_init() -> Vec2 {
	Vec2 { x: 3.0, y: 5.0 }
}


#[no_mangle]
pub extern "C" fn vec4_init() -> Vec4 {
	Vec4 { x: 3.0, y: 5.0, z: 7.0, w: 9.0 }
}

main.cpp

#include <SDL.h>
#include <stdint.h>
#include <stdio.h>

typedef int32_t i32;
typedef uint32_t u32;
typedef float f32;

struct Vec4 {
    f32 x;
    f32 y;
    f32 z;
    f32 w;
};

struct Vec2 {
    f32 x;
    f32 y;
};


#ifdef _WIN32
#define LIBRARY_FILENAME "target/debug/vec.dll"
#endif

typedef Vec4 (*vec4_init_t)();
typedef Vec2 (*vec2_init_t)();


int main(int, char**)
{
    void *library_handle = SDL_LoadObject(LIBRARY_FILENAME);
    if (library_handle == NULL) {
        printf("COULD NOT LOAD LIB\n");
        exit(-1);
    }

    auto vec4_init = (vec4_init_t) SDL_LoadFunction(library_handle, "vec4_init");
    if (vec4_init == NULL) {
        printf("COULD NOT FIND FN vec4_init\n");
        exit(-1);
    }
    auto v4 = vec4_init();
    printf("v4: %.2f %.2f %.2f %.2f\n", v4.x, v4.y, v4.z, v4.w);

    auto vec2_init = (vec2_init_t) SDL_LoadFunction(library_handle, "vec2_init");
    if (vec2_init == NULL) {
        printf("COULD NOT FIND FN vec2_init\n");
        exit(-1);
    }
    auto v2 = vec2_init();
    printf("v2: %.2f %.2f \n", v2.x, v2.y);

    return 0;
}

Is this still valid for 2019, and is there a package to allow me to automatically generate bindings like this?