fixup! roundtrip test via reference passed to aliased class method

Author: rhaschke

tests/test_class_sh_with_alias.cpp

@@ -81,11 +81,13 @@ struct Passenger {
     Passenger(Passenger &&other) { mtxt = other.mtxt + "_MvCtor"; }
 };
 struct ConsumerBase {
+    ConsumerBase() = default;
+    ConsumerBase(const ConsumerBase&) = default;
+    ConsumerBase(ConsumerBase&&) = default;
     virtual ~ConsumerBase() = default;
     virtual void pass_uq_cref(const std::unique_ptr<Passenger>& obj) = 0;
     virtual void pass_lref(Passenger &obj)                           = 0;
     virtual void pass_cref(const Passenger &obj)                     = 0;
-
 };
 struct ConsumerBaseAlias : ConsumerBase {
     using ConsumerBase::ConsumerBase;