18 struct Base {  struct
19   Base(int) {}  in Base()  argument
22   Base(T) {}  in Base()  function
25 struct Test : Base {
26   using Base::Base;
30 struct Test2 : Base {
31   using Base::Base;
46 Test3<Base> test3a(42);
47 Test3<Base> test3b(nullptr);
58 Test3<Base> retest3a(42);
59 Test3<Base> retest3b(nullptr);