isIterable redux

/// Determine whether some type can be iterated over using foreach.
/// Will not evaluate true for types such as tuples where all elements may
/// not be of the same type.
enum bool isIterable(alias T) = isIterable!(typeof(T));
/// ditto
enum bool isIterable(T) = (
    is(typeof({
        // Must be iterable
        foreach(e; T.init){}
        // Indexes must not be known at compile-time
        // Because if they are, this is a tuple
        static if(is(typeof({foreach(i, e; T.init){}}))){
            foreach(i, e; T.init){
                static assert(!is(typeof({enum x = i;})));
            }
        }
    })) && !is(typeof({
        // Must not be an empty tuple
        foreach(e; T.init){
            static assert(false);
        }
    }))
);