使用std :: move发送std :: unique_ptr到VS1012中的std :: thread [英] Using std::move to send a std::unique_ptr to std::thread in VS1012

问题描述

以下是Visual Studio 2012中的错误。

The following gives me an error in visual studio 2012.

void do_something(std::unique_ptr<int> i);
std::unique_ptr<int> i(new int);
std::thread(do_something, std::move(i));

错误3错误C2248：'std :: unique_ptr< _Ty>： ：unique_ptr'：无法访问在'std :: unique_ptr< _Ty>'c：\program文件（x86）中声明的私有成员\microsoft visual studio 11.0 \vc\include\functional 1152 1 scratch
在功能上有助于指定这个定义：
_VARIADIC_EXPAND_0X（_CLASS_BIND，，，）

Error 3 error C2248: 'std::unique_ptr<_Ty>::unique_ptr' : cannot access private member declared in class 'std::unique_ptr<_Ty>' c:\program files (x86)\microsoft visual studio 11.0\vc\include\functional 1152 1 scratch It is helpfully(!) pointing at this definition in functional: _VARIADIC_EXPAND_0X(_CLASS_BIND, , , , )

是很好的：

do_something(std::move(i));

我做错了什么？

推荐答案

我做错了什么？

What am I doing wrong?

没有。事实上，你的程序是合法的，它的行为是明确定义的。

Almost nothing. In fact, your program is legal and its behavior is well defined.

你得到的编译器错误必然是在执行标准库编译器，或许与VC11不支持可变参数模板，并且用于伪造它们的基于宏的机器不完美的事实有关。

The compiler error you are getting is necessarily a bug in the implementation of the Standard Library that ships with your compiler, perhaps connected with the fact that VC11 does not support variadic templates, and the macro-based machinery used to fake them is not perfect.

这说，即使你的程序编译，你仍然必须加入你的线程或分离之前， std :: thread RAII包装器被销毁 - 抛出一个异常，如果析构函数 std :: thread 在被封装的线程仍在运行时被调用（除非它被分离）。

This said, even if your program did compile, you would still have to join your thread or detach from it before the std::thread RAII wrapper gets destroyed - an exception is thrown if the destructor of std::thread is invoked while the encapsulated thread is still running (unless it was detached).

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