Compiler Error C3420
'finalizer' : a finalizer cannot be virtual
A finalizer can only be called non-virtually from its enclosing type. Therefore, it is an error to declare a virtual finalizer.
For more information, see Destructors and finalizers in How to: Define and consume classes and structs (C++/CLI).
Example
The following sample generates C3420.
// C3420.cpp
// compile with: /clr /c
ref class R {
virtual !R() {} // C3420
};