Edit

Share via

Compiler Error C3217

  • Article

'param' : generic parameter cannot be constrained in this declaration

A constraint was ill formed; the constraint generic parameter must agree with the generic class template parameter.

The following sample generates C3217:

// C3217.cpp
// compile with: /clr
interface struct A {};

generic <class T>
ref class C {
   generic <class T1>
   where T : A   // C3217
   void f();
};

The following sample demonstrates a possible resolution:

// C3217b.cpp
// compile with: /clr /c
interface struct A {};

generic <class T>
ref class C {
   generic <class T1>
   where T1 : A
   void f();
};