virtual desctructor on pure abstract base class

I have

struct IMyInterface
{
   virtual method1() = 0;
   virtual method2() = 0;
};

GCC insists that I have

struct IMyInterface
{
   virtual method1() = 0;
   virtual method2() = 0;
   virtual ~IMyInterface(){};
};

I dont see why. A pure interface is all about the interface (duh). The destructor is part of the internal implementation details of a concrete implementer of the interface; it does not form part of the interface. I understand the whole slicing issue (or at least I think I do)

So my question is - is GCC right to insist on it and if so why?