[class.inhctor.init]
Change:
Inheriting a constructor no longer injects a constructor into the derived class
.  Rationale:
Better interaction with other language features
.  Effect on original feature:
Valid C++ 2014 code that uses inheriting constructors may not be valid
or may have different semantics
.  A 
using-declaration
that names a constructor now makes the corresponding base class constructors
visible to initializations of the derived class
rather than declaring additional derived class constructors
.  
struct A {
  template<typename T> A(T, typename T::type = 0);
  A(int);
};
struct B : A {
  using A::A;
  B(int);
};
B b(42L);