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Compiler Error C3073

Error Message

'type' : ref class does not have a user-defined copy constructor

In a /clr (Common Language Runtime Compilation) compilation, the compiler will not generate a copy constructor for a reference type. In any /clr compilation, you must define your own copy constructor for a reference type if you expect an instance of the type to be copied.

For more information, see C++ Stack Semantics for Reference Types.


The following sample generates C3073.

// C3073.cpp
// compile with: /clr
ref class R {
   R(int) {}

ref class S {
   S(int) {}
   S(const S %rhs) {}   // copy constructor

void f(R) {}
void f2(S) {}
void f3(R%){}

int main() {
   R r(1);
   f(r);   // C3073
   f3(r);   // OK

   S s(1);
   f2(s);   // OK