dtolnay/cxx

Box clone() member function to call Clone on opaque Rust types

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#105 创建于 2020年4月11日

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 (3 评论) (0 反应) (0 负责人)Rust (4,472 star) (253 fork)batch import
help wanted

描述

We should provide a way to constrain that some opaque Rust type implements Clone and then expose the Clone impl to C++ via a clone() member function on rust::Box.

Something like:

mod ffi {
    extern "Rust" {
        type ClonableR: Clone;
    }

    extern "C++" {
        fn f(b: Box<ClonableR>); // C++ will be able to clone b
    }
}

  template <typename T>
  class Box {
+   Box clone() const noexcept;
  };

贡献者指南

技术栈
rustcpp
领域
backendapi
议题类型
feature
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
4
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
3-5 days
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
clear
前置要求
RustC++cxx librarytrait system
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
30
研究方向
Investigate how cxx currently handles opaque Rust types and the Box class template. The goal is to add a clone() member function to Box that calls Clone on the underlying Rust type. Examine existing Box member functions (e.g., from Rust, into raw) to follow the pattern. The implementation will require modifying the Rust side to generate C++ bindings that expose Clone, and updating the C++ header for Box. Check issue comments for any prior discussion; there are 3 comments that may contain additional constraints. No linked PRs or assignees, so the issue is available for contribution.