我目前正在将我的auto_ptr
实例转换为unique_ptr
,但我遇到了一个问题。在C++部分的代码中它运行得很好,但是当我在我的托管C++/CLI层(软件同时使用C#和C++)中进行时,我会遇到链接错误。它可以编译,但在链接时会出现错误。使用auto_ptr
从未出现过任何问题。
我目前正在使用Visual Studio 2010。有人知道在C++/CLI中使用unique_ptr
是否存在任何问题吗?
我尝试在下面的代码片段中总结我的问题,但请注意,下面的代码实际上可以编译和工作(我检查了指针所有权的移动是否正确)。编译这个代码时我没有得到链接错误,但下面的代码是纯C++而不是C++/CLI。我只是想有一个最小的例子来说明代码的构造方式,以便链接器错误更容易理解。
#include "stdafx.h"
#include <vector>
#include <memory>
#include <utility>
using namespace std;
namespace Test {
template< class T >
struct LinAlgPoint3 {
LinAlgPoint3() { x = y = z = 0; };
union {
struct {T x,y,z;} ;
T data_[3];
};
};
class ContainerClass
{
public:
void setUniquePtr(
unique_ptr< vector< LinAlgPoint3< float > > > newUniquePtr1 ,
unique_ptr< vector< unsigned char > > newUniquePtr2 )
{
m_uniquePtr1 = move(newUniquePtr1);
m_uniquePtr2 = move(newUniquePtr2);
}
private:
unique_ptr< vector< LinAlgPoint3< float > > > m_uniquePtr1;
unique_ptr< vector< unsigned char > > m_uniquePtr2;
};
int main(int argc, char** argv)
{
auto pos = unique_ptr< vector< LinAlgPoint3< float > > >( new vector< LinAlgPoint3< float > >() );
auto name = unique_ptr< vector< unsigned char > >(new vector< unsigned char >());
ContainerClass container;
container.setUniquePtr(move(pos), move(name));
}
} //namespace Test
我在链接时遇到的错误如下:
error LNK2028: unresolved token (0A0018A5) "private: __cdecl std::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > >::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > >(class std::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > > const &)" (??0?$unique_ptr@V?$vector@U?$LinAlgPoint3@M@Test@@V?$allocator@U?$LinAlgPoint3@M@Test@@@std@@@std@@U?$default_delete@V?$vector@U?$LinAlgPoint3@M@Test@@V?$allocator@U?$LinAlgPoint3@M@Test@@@std@@@std@@@2@@std@@$$FAEAA@AEBV01@@Z) referenced in function "public: static void __clrcall std::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > >::<MarshalCopy>(class std::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > > *,class std::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > > *)" (?<MarshalCopy>@?$unique_ptr@V?$vector@U?$LinAlgPoint3@M@Test@@V?$allocator@U?$LinAlgPoint3@M@Test@@@std@@@std@@U?$default_delete@V?$vector@U?$LinAlgPoint3@M@Test@@V?$allocator@U?$LinAlgPoint3@M@Test@@@std@@@std@@@2@@std@@$$FSMXPEAV12@0@Z)
1>TestClass.obj : error LNK2028: unresolved token (0A0018A6) "private: __cdecl std::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > >::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > >(class std::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > > const &)" (??0?$unique_ptr@V?$vector@EV?$allocator@E@std@@@std@@U?$default_delete@V?$vector@EV?$allocator@E@std@@@std@@@2@@std@@$$FAEAA@AEBV01@@Z) referenced in function "public: static void __clrcall std::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > >::<MarshalCopy>(class std::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > > *,class std::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > > *)" (?<MarshalCopy>@?$unique_ptr@V?$vector@EV?$allocator@E@std@@@std@@U?$default_delete@V?$vector@EV?$allocator@E@std@@@std@@@2@@std@@$$FSMXPEAV12@0@Z)
1>TestClass.obj : error LNK2019: unresolved external symbol "private: __cdecl std::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > >::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > >(class std::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > > const &)" (??0?$unique_ptr@V?$vector@EV?$allocator@E@std@@@std@@U?$default_delete@V?$vector@EV?$allocator@E@std@@@std@@@2@@std@@$$FAEAA@AEBV01@@Z) referenced in function "public: static void __clrcall std::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > >::<MarshalCopy>(class std::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > > *,class std::unique_ptr<class std::vector<unsigned char,class std::allocator<unsigned char> >,struct std::default_delete<class std::vector<unsigned char,class std::allocator<unsigned char> > > > *)" (?<MarshalCopy>@?$unique_ptr@V?$vector@EV?$allocator@E@std@@@std@@U?$default_delete@V?$vector@EV?$allocator@E@std@@@std@@@2@@std@@$$FSMXPEAV12@0@Z)
1>TestClass.obj : error LNK2019: unresolved external symbol "private: __cdecl std::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > >::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > >(class std::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > > const &)" (??0?$unique_ptr@V?$vector@U?$LinAlgPoint3@M@Test@@V?$allocator@U?$LinAlgPoint3@M@Test@@@std@@@std@@U?$default_delete@V?$vector@U?$LinAlgPoint3@M@Test@@V?$allocator@U?$LinAlgPoint3@M@Test@@@std@@@std@@@2@@std@@$$FAEAA@AEBV01@@Z) referenced in function "public: static void __clrcall std::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > >::<MarshalCopy>(class std::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > > *,class std::unique_ptr<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > >,struct std::default_delete<class std::vector<struct LinAlgPoint3<float>,class std::allocator<struct LinAlgPoint3<float> > > > > *)" (?<MarshalCopy>@?$unique_ptr@V?$vector@U?$LinAlgPoint3@M@Test@@V?$allocator@U?$LinAlgPoint3@M@Test@@@std@@@std@@U?$default_delete@V?$vector@U?$LinAlgPoint3@M@Test@@V?$allocator@U?$LinAlgPoint3@M@Test@@@std@@@std@@@2@@std@@$$FSMXPEAV12@0@Z)
1>D:\Test\Test.dll : fatal error LNK1120: 4 unresolved externals
正如你所看到的(如果你能忍受那些极其糟糕的信息),有一些关于MarshalCopy的引用,这让我担心C++/CLI可能还不支持unique_ptr。
软件的布局是
C# executable -> C++/CLI translation layer (dll) -> C++ dll
所以使用unique_ptr编译C++ dll没有问题,但是C++/CLI dll无法正确链接。
我忘记提到一些非常重要的事情:如果我使用unique_ptr指向一个更简单的数据类型,比如字符串,它可以成功链接。例如:
auto string1= unique_ptr< string >(new string(20000, 'S'));
auto string2 = unique_ptr< string >(new string(20000, 'A'));
string1= std::move(string2);
我也尝试确保使用变量,以便编译器不会将其优化掉。
编辑:我刚刚测试了添加另一个接受unique_ptr<string>
的外部函数,并尝试发送上面的string1
,但仍然出现错误!因此,问题必须在生成的DLL之间,因为std::move()在每个文件/类中都可以正常工作。
unique_ptr
就不可能工作。 - Puppyerror C2248: 'std::unique_ptr<_Ty>::unique_ptr' : cannot access private member declared in class 'std::unique_ptr<_Ty>'
,就像我在上面的小例子中添加move()调用之前遇到的一样。还有一件事我忘了提到的是,如果我使用unique_ptr<double>
而不是上面更高级的类型,代码可以编译通过。不过我需要再次确认一下。 - AzP