编译器错误 C2392

“method1”：托管或 WinRT 类型中不支持协变返回类型，否则“method2”将被重写

对于 Windows 运行时成员函数或使用 /clr（公共语言运行时编译）选项进行编译时，不允许协变返回类型。

示例

下面的示例生成了 C2392，并演示了如何修复此错误。

// C2392.cpp
// compile with: /clr
public ref struct B {
public:
   int i;
};

public ref struct D: public B{};

public ref struct B1 {
public:
   virtual B^ mf() {
      B^ pB = gcnew B;
      pB->i = 11;
      return pB;
   }
};

public ref struct D1: public B1 {
public:
   virtual D^ mf() override {  // C2392
   // try the following line instead
   // virtual B^ mf() override {
   // return type D^ is covariant with B^, not allowed with CLR types
      D^ pD = gcnew D;
      pD->i = 12;
      return pD;
   }
};

int main() {
   B1^ pB1 = gcnew D1;
   B^ pB = pB1->mf();
   D^ pD = dynamic_cast<D^>(pB);
}