(copied) polymorphic clone helper

// Polymorphic clone utilities
namespace HOEngine {
    template <typename T>
    class AbstractFunc;

    template <typename T>
    class VirtualInheritFrom : public virtual T {
        using T::T;
    };

    template <typename Derived, typename... Bases>
    class CloneInherit : public Bases... {
    public:
        virtual ~CloneInherit() = default;

        std::unique_ptr<Derived> Clone() const {
            return std::unique_ptr<Derived>(static_cast<Derived*>(this->CloneImpl()));
        }

    private:
        virtual Derived* CloneImpl() const override {
            return new Derived(static_cast<const Derived&>(*this));
        }
    };

    template <typename Derived, typename... Bases>
    class CloneInherit<AbstractFunc<Derived>, Bases...> : public Bases... {
    public:
        virtual ~CloneInherit() = default;

        std::unique_ptr<Derived> Clone() const {
            return std::unique_ptr<Derived>(static_cast<Derived*>(this->CloneImpl()));
        }

    private:
        virtual Derived* CloneImpl() const = 0;
    };

    template <typename Derived>
    class CloneInherit<Derived> {
    public:
        virtual ~CloneInherit() = default;

        std::unique_ptr<Derived> Clone() const {
            return std::unique_ptr<Derived>(static_cast<Derived*>(this->CloneImpl()));
        }

    private:
        virtual Derived* CloneImpl() const override {
            return new Derived(static_cast<const Derived&>(*this));
        }
    };

    template <typename Derived>
    class CloneInherit<AbstractFunc<Derived>> {
    public:
        virtual ~CloneInherit() = default;

        std::unique_ptr<Derived> Clone() const {
            return std::unique_ptr<Derived>(static_cast<Derived*>(this->CloneImpl()));
        }

    private:
        virtual Derived* CloneImpl() const = 0;
    };
}