Compiler Error C2139
'type' : an undefined class is not allowed as an argument to compiler intrinsic type trait 'trait'
An invalid argument was passed to a type trait.
Remarks
For more information, see Compiler Support for Type Traits.
Example
The following sample generates C2139.
// C2139.cpp
// compile with: /EHsc
#include <iostream>
using namespace std;
template <class T>
struct is_polymorphic {
static const bool value = __is_polymorphic(T);
};
class C;
class D {};
class E {
public:
virtual void Test() {}
};
int main() {
cout << is_polymorphic<C>::value << endl; // C2139
cout << is_polymorphic<D>::value << endl; // OK
cout << is_polymorphic<E>::value << endl; // OK
}