What is the standard conform syntax for template constructor inheritance?

Question

GCC 4.8.1 accepts

template 
class Subclass : public Baseclass
{
public:
    using typename Baseclass::Baseclass;
};


        

Answer 1

The answer is a bit buried in the standard. A using declaration is defined as (7.3.3):

using [typename] nested-name-specifier unqualified-id;

The nested-name-specifier resolves after some steps into simple-template-id which is defined as

template-name < [template-argument-list] >

In short, the standard conforming syntax is

template <typename T>
class Subclass : public Baseclass<T>
{
public:
    using typename Baseclass<T>::Baseclass;
};