"Template argument for template template parameter must be a class template or type alias template"

c++, c++11, clang, templates, variadic-templates

Solution

You have a template template parameter. You must pass a template as its argument. You instead pass a template instantiation as its argument - which is a concrete class, not a template (all its parameters are bound).

Consider:

template <template<typename> typename X>
class WantsTemplate {};

template <typename>
class ATemplate {};

WantsTemplate<ATemplate> wt1;  // OK
WantsTemplate<ATemplate<int> > wt2;  // not OK

Problem

Original source