Annex C (informative) Compatibility [diff]

C.4 C++ and ISO C++ 2014 [diff.cpp14]

C.4.5 [special]: special member functions [diff.cpp14.special]

[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); // now calls B(int), used to call B<long>(long),
          // which called A(int) due to substitution failure
          // in A<long>(long).