Fixed move constructor in generated union class (#4192)

* Fixed move constructor in generated union class

* Removed delegating constructor

samples/monster_generated.h

@@ -75,7 +75,8 @@ struct EquipmentUnion {
 
   EquipmentUnion() : type(Equipment_NONE), table(nullptr) {}
   EquipmentUnion(EquipmentUnion&& u):
-    type(std::move(u.type)), table(std::move(u.table)) {}
+    type(Equipment_NONE), table(nullptr)
+    { std::swap(type, u.type); std::swap(table, u.table); }
   EquipmentUnion(const EquipmentUnion &);
   EquipmentUnion &operator=(const EquipmentUnion &);
   ~EquipmentUnion() { Reset(); }

src/idl_gen_cpp.cpp

@@ -652,7 +652,8 @@ class CppGenerator : public BaseGenerator {
       code_ += "";
       code_ += "  {{NAME}}Union() : type({{NONE}}), table(nullptr) {}";
       code_ += "  {{NAME}}Union({{NAME}}Union&& u):";
-      code_ += "    type(std::move(u.type)), table(std::move(u.table)) {}";
+      code_ += "    type({{NONE}}), table(nullptr)";
+      code_ += "    { std::swap(type, u.type); std::swap(table, u.table); }";
       code_ += "  {{NAME}}Union(const {{NAME}}Union &);";
       code_ += "  {{NAME}}Union &operator=(const {{NAME}}Union &);";
       code_ += "  ~{{NAME}}Union() { Reset(); }";

tests/monster_test_generated.h

@@ -104,7 +104,8 @@ struct AnyUnion {
 
   AnyUnion() : type(Any_NONE), table(nullptr) {}
   AnyUnion(AnyUnion&& u):
-    type(std::move(u.type)), table(std::move(u.table)) {}
+    type(Any_NONE), table(nullptr)
+    { std::swap(type, u.type); std::swap(table, u.table); }
   AnyUnion(const AnyUnion &);
   AnyUnion &operator=(const AnyUnion &);
   ~AnyUnion() { Reset(); }