Unwrapping variadic template structs

I'm trying to create an any struct, i.e. a struct that contains one of so many types. Here is my attempt so far:

template <typename Type, typename... Rest> struct OneOf {
    union {
        Type value;
        OneOf<Rest...> rest;
    };
};

template <typename Type> struct OneOf {
    Type value;
};

Sadly, this doesn't compile. When I try to instantiate it, I get:

one_of.h:34:33: error: redeclared with 1 template parameter template struct OneOf {

Is there a way to terminate a self referencing recursion with structs?