Hello, I've been looking at ABIs and such (various unpleasant reasons). But I recently created the following code: #include <iostream> struct Base { virtual void check() = 0; template<typename T> T* IsDerivedFrom() { try { check(); } catch(T* p) { return p; } catch(...) { return nullptr; } return nullptr; } }; template<typename T> struct Derived : public Base { Derived(T obj) : t(obj) {} T t; void check() override final { throw &t; } }; struct A { virtual ~A() {} virtual void print() = 0;}; struct B : public A { int x; B(int y) : x(y) {} void print() override final { std::cout << x; } }; int main() { Base* b = new Derived<B>(B(5)); A* p = b->IsDerivedFrom<A>(); p->print(); } Whilst this is hardly the cleanest piece of code I've ever written, it also provides a base for implementing a more generic any_cast<ValueType>, which could succeed if ValueType is a base class of the stored type. Amazingly, the Standard requires the code to work but does not provide a cleaner means of implementation. I also note that, for some configurations, you could fall back to the Itanium ABI provided function directly, which would presumably be substantially faster and cleaner. Enabling this variety of any_cast would substantially improve the composability of boost::any. For example, it's arguable that std::function is merely boost::any but with additional interface requirements. With such an any_cast enhancement, it would be quite trivial to compose std::function implementations or similar concepts on top of boost::any.