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Compiler Error C2140

  • Artikkeli

'type' : a type that is dependent on a generic type parameter is not allowed as an argument to compiler intrinsic type trait 'trait'

An invalid type specifier was passed to a type trait.

For more information, see Compiler Support for Type Traits.

Example

The following sample generates C2140.

// C2140.cpp
// compile with: /clr /c
template <class T>

struct is_polymorphic {
   static const bool value = __is_polymorphic(T);
};

class x {};

generic <class T>
ref class C {
   void f() {
      System::Console::WriteLine(__is_polymorphic(T));   // C2140
      System::Console::WriteLine(is_polymorphic<T>::value);   // C2140

      System::Console::WriteLine(__is_polymorphic(x));   // OK
      System::Console::WriteLine(is_polymorphic<x>::value);   // OK
   }
};