我目前正在转换我的 auto_ptr 实例至 unique_ptr ，但我遇到了一个问题。它在代码的 C++ 部分工作得很好，但在我的托管 C++/CLI 层(该软件同时使用 C# 和 C++)中执行它时，我遇到链接错误。它编译得很好，但在链接时会中断。 auto_ptr 从来没有任何问题.

我目前正在使用 Visual Studio 2010。有人知道使用 unique_ptr 时遇到的任何问题吗？在 C++/CLI 中？

我试图在下面的一段代码中总结我的问题，但请注意下面的代码实际上可以编译和工作(我检查了指针的所有权是否正确移动).编译时我没有收到链接错误，但下面的代码是纯 C++ 而不是 C++/CLI。我只是想提供一个代码构建方式的最小示例，以便链接器错误更易于阅读。

#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

链接时出现的错误如下:

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

如您所见(如果您能读懂那些令人难以置信的可怕消息)，有一些对 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

因此 C++ dll 使用 unique_ptr 可以很好地编译，但 C++/CLI dll 无法正确链接。

我忘了提一些非常重要的事情:如果我将 unique_ptr 用于更简单的数据类型，例如字符串，它会成功链接。例如:

  auto string1= unique_ptr< string >(new string(20000, 'S'));
  auto string2 = unique_ptr< string >(new string(20000, 'A'));
  string1= std::move(string2);

而且我还尝试确保使用该变量，这样编译器就不会优化它。

编辑:我刚刚测试了添加另一个接受 unique_ptr<string> 的外部函数，我尝试发送上面的 string1那也坏了!所以问题一定是在生成的 DLL 之间，因为 std::move() 在每个文件/类中运行良好。

最佳答案

好吧，不知道它现在有多重要，但我在使用 C++/CLI 时遇到了完全相同的问题，并通过采用右值引用而不是值来解决它。我是说: void setUniquePtr(unique_ptr&& a, unique_ptr&& b)

虽然它不是最干净的做事方式，但它可以通过这种方式进行编译。

关于c++ - 在 C++/CLI 中使用 unique_ptr 时出现链接器错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12493203/