Specialization of template variable (for template template class)

When I try specialize a template variable for a generic container (e.g. std::list<...>, and not for an specific one, e.g. std::list<double>) I get a link error with gcc 5.3 (but not with clang 3.5)

/tmp/ccvxFv3R.s: Assembler messages:
/tmp/ccvxFv3R.s:206: Error: symbol `_ZL9separator' is already defined

http://ift.tt/1nO7Q00

#include<string>
#include<iostream>
#include<list>
#include<forward_list>
#include<vector>

template<typename T> std::string const separator = ", ";
template<typename... Ts> std::string const separator<std::list<Ts...>        > = "<->";
template<typename... Ts> std::string const separator<std::forward_list<Ts...>> = "->";

int main(){

    std::cout << separator<std::vector<double>> << '\n';
    std::cout << separator<std::list<double>> << '\n';
    std::cout << separator<std::forward_list<double>> << '\n';

}

This compiles well with clang 3.5 and works as expected.

If this is not a bug in gcc, do you think is there a work around? I tried to use class specialization but it is not possible either:

template<class T>
struct separator{
    static std::string const value;
};
template<class T>
std::string const separator<T>::value = ", ";
template<typename... Ts>
std::string const separator<std::list<Ts...>>::value = "<->";
template<typename... Ts>
std::string const sep<std::forward_list<Ts...>>::value = "->";