{{#title std::shared_ptr — Rust ♡ C++}}
The Rust binding of std::shared_ptr<T> is called SharedPtr<T>
. See the link for documentation of the Rust API.
SharedPtr<T> does not support T being an opaque Rust type. You should use a Box<T> (C++ rust::Box<T>) instead for transferring ownership of opaque Rust types on the language boundary.
// src/main.rs use std::ops::Deref; use std::ptr; #[cxx::bridge] mod ffi { unsafe extern "C++" { include!("example/include/example.h"); type Object; fn create_shared_ptr() -> SharedPtr<Object>; } } fn main() { let ptr1 = ffi::create_shared_ptr(); { // Create a second shared_ptr holding shared ownership of the same // object. There is still only one Object but two SharedPtr<Object>. // Both pointers point to the same object on the heap. let ptr2 = ptr1.clone(); assert!(ptr::eq(ptr1.deref(), ptr2.deref())); // ptr2 goes out of scope, but Object is not destroyed yet. } println!("say goodbye to Object"); // ptr1 goes out of scope and Object is destroyed. }
// include/example.h #pragma once #include <memory> class Object { public: Object(); ~Object(); }; std::shared_ptr<Object> create_shared_ptr();
// src/example.cc #include "example/include/example.h" #include <iostream> Object::Object() { std::cout << "construct Object" << std::endl; } Object::~Object() { std::cout << "~Object" << std::endl; } std::shared_ptr<Object> create_shared_ptr() { return std::make_shared<Object>(); }