Suggested resolution [SUPERSEDED]:

1. Change in 9.10 [namespace.udecl] paragraph 4 as follows:

   If a constructor or assignment operator brought from a base class into a derived class has the signature of a default constructor or copy/move constructor or assignment operator for the derived class (11.4.5.2 [class.default.ctor], 11.4.5.3 [class.copy.ctor], 11.4.6 [class.copy.assign]), the using-declaration does not by itself suppress the implicit declaration of the derived class member; the member from the base class is hidden or overridden by the implicitly-declared copy/move constructor or assignment operator special member function of the derived class, as described below.

2. Change in 11.4.5.2 [class.default.ctor] paragraph 1 as follows:

   A default constructor for a class X is a constructor of class X for which each parameter that is not a function parameter pack has a default argument (including the case of a constructor with no parameters). If there is no user-declared constructor for class X, or if X inherits (9.10 [namespace.udecl]) one or more default constructors and there is no user-declared default constructor for X, a non-explicit constructor having no parameters is implicitly declared as defaulted (9.6 [dcl.fct.def]). An implicitly-declared default constructor is an inline public member of its class.