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将std::vector<unique\u ptr<…>>声明为“dllexport”类中的成员变量

c++

Sonicsmooth · 技术社区 · 6 年前

一个简单的例子

class __declspec(dllexport) A
{
public:
    vector<unique_ptr<int>> v;
};

的已删除副本构造函数的VS2013编译错误 unique_ptr . 如果我移除 __declspec(dllexport) unique_ptr<int> v ,也很好。这是编译器错误吗?有办法解决吗?谢谢。

http://webcompiler.cloudapp.net/ 有以下完整的代码

#include <iostream>
#include <vector>
#include <memory>
using namespace std;

class __declspec(dllexport) A
{
public:
    vector<unique_ptr<int>> v;
};

int main()
{
   cout << "Hello World" << endl; 
}

产生编译器错误:

Compiled with /EHsc /nologo /W4 /c
main.cpp
main.cpp(9): warning C4251: 'A::v': class 'std::vector<std::unique_ptr<int,std::default_delete<_Ty>>,std::allocator<std::unique_ptr<_Ty,std::default_delete<_Ty>>>>' needs to have dll-interface to be used by clients of class 'A'
        with
        [
            _Ty=int
        ]
c:\tools_root\cl\inc\xutility(2144): error C2280: 'std::unique_ptr<int,std::default_delete<_Ty>> &std::unique_ptr<_Ty,std::default_delete<_Ty>>::operator =(const std::unique_ptr<_Ty,std::default_delete<_Ty>> &)': attempting to reference a deleted function
        with
        [
            _Ty=int
        ]
c:\tools_root\cl\inc\memory(1430): note: see declaration of 'std::unique_ptr<int,std::default_delete<_Ty>>::operator ='
        with
        [
            _Ty=int
        ]
c:\tools_root\cl\inc\xutility(2165): note: see reference to function template instantiation '_OutIt std::_Copy_impl<_InIt,_OutIt>(_InIt,_InIt,_OutIt,std::_Nonscalar_ptr_iterator_tag)' being compiled
        with
        [
            _OutIt=std::unique_ptr<int,std::default_delete<int>> *,
            _InIt=std::unique_ptr<int,std::default_delete<int>> *
        ]
c:\tools_root\cl\inc\vector(973): note: see reference to function template instantiation '_OutIt std::_Copy_impl<std::unique_ptr<int,std::default_delete<_Ty>>,std::unique_ptr<_Ty,std::default_delete<_Ty>>*>(_InIt,_InIt,_OutIt)' being compiled
        with
        [
            _OutIt=std::unique_ptr<int,std::default_delete<int>> *,
            _Ty=int,
            _InIt=std::unique_ptr<int,std::default_delete<int>> *
        ]
c:\tools_root\cl\inc\vector(956): note: while compiling class template member function 'std::vector<std::unique_ptr<int,std::default_delete<_Ty>>,std::allocator<std::unique_ptr<_Ty,std::default_delete<_Ty>>>> &std::vector<std::unique_ptr<_Ty,std::default_delete<_Ty>>,std::allocator<std::unique_ptr<_Ty,std::default_delete<_Ty>>>>::operator =(const std::vector<std::unique_ptr<_Ty,std::default_delete<_Ty>>,std::allocator<std::unique_ptr<_Ty,std::default_delete<_Ty>>>> &)'
        with
        [
            _Ty=int
        ]
main.cpp(10): note: see reference to function template instantiation 'std::vector<std::unique_ptr<int,std::default_delete<_Ty>>,std::allocator<std::unique_ptr<_Ty,std::default_delete<_Ty>>>> &std::vector<std::unique_ptr<_Ty,std::default_delete<_Ty>>,std::allocator<std::unique_ptr<_Ty,std::default_delete<_Ty>>>>::operator =(const std::vector<std::unique_ptr<_Ty,std::default_delete<_Ty>>,std::allocator<std::unique_ptr<_Ty,std::default_delete<_Ty>>>> &)' being compiled
        with
        [
            _Ty=int
        ]
main.cpp(9): note: see reference to class template instantiation 'std::vector<std::unique_ptr<int,std::default_delete<_Ty>>,std::allocator<std::unique_ptr<_Ty,std::default_delete<_Ty>>>>' being compiled
        with
        [
            _Ty=int
        ]

0 回复 | 直到 11 年前

Angew is no longer proud of SO 11 年前

它似乎在增加 __declspec(dllexport) 强制编译器定义隐式声明的复制构造函数和复制赋值运算符(通常,只有在使用它们时才会发生这种情况)。它们反过来调用的复制构造函数/赋值运算符 v std::vector<T> 不可复制的 T ,例如 std::unique_ptr

A 也会被删除。

class __declspec(dllexport) A
{
public:
    A(const A&) = delete;
    A& operator=(const A&) = delete;
    vector<unique_ptr<int>> v;
};

当然,如果你希望复制功能,自己定义也会有帮助。