使用std :: shared_ptr与clang ++和libstdc ++ [英] Using std::shared_ptr with clang++ and libstdc++

问题描述

我想使用clst ++的std :: shared_ptr（clang版本3.1（trunk 143100））使用libstdc ++（4.6.1）。我有一个小演示程序：

I'm trying to use the std::shared_ptr in clang++(clang version 3.1 (trunk 143100)) using libstdc++(4.6.1). I have a little demo program:

#include <memory>

int main()
{
    std::shared_ptr<int> some(new int);
    std::shared_ptr<int> other(some);
    return 0;
}

可以使用以下命令生成：

which can be build using:

clang++ -std=c++0x -o main main.cpp

并给出以下错误输出：

main.cpp:6:23: error: call to deleted constructor of 'std::shared_ptr<int>'
    std::shared_ptr<int> other(some);
                         ^     ~~~~
/usr/include/c++/4.6/bits/shared_ptr.h:93:11: note: function has been explicitly marked
deleted here
class shared_ptr : public __shared_ptr<_Tp>

由于某种原因，它需要被删除的构造函数，因为提供了一个移动构造函数）。
但是为什么它工作编译（g ++（Ubuntu / Linaro 4.6.1-9ubuntu3）4.6.1。）？

For some reason it needs the constructor which is deleted because a move constructor is provided (which is correct behaviour). But why does it work compile with (g++ (Ubuntu/Linaro 4.6.1-9ubuntu3) 4.6.1.)? Somebody any ideas on how to fix this?

推荐答案

shared_ptr的隐式声明的拷贝构造函数被删除，因为shared_ptr有一个move构造函数或者一个移动赋值运算符（或两者），每个C ++ 11 12.8p7：

The implicitly-declared copy constructor for shared_ptr is deleted because shared_ptr has a move constructor or a move assignment operator (or both), per C++11 12.8p7:

如果类定义没有显式声明一个拷贝构造函数，如果类定义声明了move构造函数或move赋值运算符，则隐式声明的拷贝构造函数定义为deleted;

If the class definition does not explicitly declare a copy constructor, one is declared implicitly. If the class definition declares a move constructor or move assignment operator, the implicitly declared copy constructor is defined as deleted; otherwise, it is defined as defaulted (8.4).

GCC 4.6.x没有实现这个规则，它在C ++ 11的工作文件中作为 N3203 = 10-0193 处理。 libstdc ++ 4.6.x中的shared_ptr在写入时是正确的，但是C ++ 11之后改变了.. Boost有完全相同的问题和它的shared_ptr，这是常见的不兼容性 GCC和Clang之间。

GCC 4.6.x does not implement this rule, which came into the C++11 working paper very late in the process as N3203=10-0193. The shared_ptr in libstdc++ 4.6.x was correct at the time it was written, but C++11 changed after that.. Boost had exactly the same issue with it's shared_ptr, and this is one of the common incompatibilities between GCC and Clang.

向shared_ptr添加默认的复制构造函数和复制赋值操作符将解决问题。

Adding a defaulted copy constructor and copy assignment operator to shared_ptr will fix the problem.

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