[Upb C++]Add ::protos::ClearMessage and DeepCopy apis.

PiperOrigin-RevId: 542903995

protos/protos.h

@@ -124,6 +124,39 @@ typename T::Proxy CloneMessage(Ptr<T> message, upb::Arena& arena) {
       arena.ptr());
 }
 
+template <typename T>
+void DeepCopy(Ptr<const T> source_message, Ptr<T> target_message) {
+  upb_Message_DeepCopy(
+      target_message->msg(), source_message->msg(), T::minitable(),
+      static_cast<upb_Arena*>(target_message->GetInternalArena()));
+}
+
+template <typename T>
+void DeepCopy(Ptr<const T> source_message, T* target_message) {
+  DeepCopy(source_message, protos::Ptr(target_message));
+}
+
+template <typename T>
+void DeepCopy(const T* source_message, Ptr<T> target_message) {
+  DeepCopy(protos::Ptr(source_message), target_message);
+}
+
+template <typename T>
+void DeepCopy(const T* source_message, T* target_message) {
+  DeepCopy(protos::Ptr(source_message), protos::Ptr(target_message));
+}
+
+template <typename T>
+void ClearMessage(Ptr<T> message) {
+  static_assert(!std::is_const_v<T>, "");
+  upb_Message_Clear(message->msg(), T::minitable());
+}
+
+template <typename T>
+void ClearMessage(T* message) {
+  ClearMessage(protos::Ptr(message));
+}
+
 // begin:github_only
 // This type exists to work around an absl type that has not yet been
 // released.

protos_generator/gen_messages.cc

@@ -245,6 +245,10 @@ void WriteModelProxyDeclaration(const protobuf::Descriptor* descriptor,
             msg_ = m.msg_;
             arena_ = m.arena_;
           }
+          $0Proxy($0* m) : internal::$0Access() {
+            msg_ = m->msg_;
+            arena_ = m->arena_;
+          }
           $0Proxy operator=(const $0Proxy& m) {
             msg_ = m.msg_;
             arena_ = m.arena_;

protos_generator/tests/test_generated.cc

@@ -882,3 +882,76 @@ TEST(CppGeneratedCode, PassProxyToCProxy) {
   model.mutable_child_model_1()->set_child_str1("text in child");
   EXPECT_TRUE(ProxyToCProxyMethod(model.mutable_child_model_1()));
 }
+
+TEST(CppGeneratedCode, PtrImplicitConversion) {
+  TestModel model;
+  model.set_int64(5);
+  ::protos::Ptr<TestModel> model_ptr = &model;
+  EXPECT_EQ(model_ptr->int64(), 5);
+}
+
+TEST(CppGeneratedCode, ClearSubMessage) {
+  // Fill model.
+  TestModel model;
+  model.set_int64(5);
+  auto new_child = model.mutable_child_model_1();
+  new_child->set_child_str1("text in child");
+  ThemeExtension extension1;
+  extension1.set_ext_name("name in extension");
+  EXPECT_TRUE(::protos::SetExtension(model, theme, extension1).ok());
+  EXPECT_TRUE(model.mutable_child_model_1()->has_child_str1());
+  // Clear using Ptr<T>
+  ::protos::ClearMessage(model.mutable_child_model_1());
+  EXPECT_FALSE(model.mutable_child_model_1()->has_child_str1());
+}
+
+TEST(CppGeneratedCode, ClearMessage) {
+  // Fill model.
+  TestModel model;
+  model.set_int64(5);
+  model.set_str2("Hello");
+  auto new_child = model.add_child_models();
+  ASSERT_TRUE(new_child.ok());
+  new_child.value()->set_child_str1("text in child");
+  ThemeExtension extension1;
+  extension1.set_ext_name("name in extension");
+  EXPECT_TRUE(::protos::SetExtension(model, theme, extension1).ok());
+  // Clear using T*
+  ::protos::ClearMessage(&model);
+  // Verify that scalars, repeated fields and extensions are cleared.
+  EXPECT_FALSE(model.has_int64());
+  EXPECT_FALSE(model.has_str2());
+  EXPECT_TRUE(model.child_models().empty());
+  EXPECT_FALSE(::protos::HasExtension(model, theme));
+}
+
+TEST(CppGeneratedCode, DeepCopy) {
+  // Fill model.
+  TestModel model;
+  model.set_int64(5);
+  model.set_str2("Hello");
+  auto new_child = model.add_child_models();
+  ASSERT_TRUE(new_child.ok());
+  new_child.value()->set_child_str1("text in child");
+  ThemeExtension extension1;
+  extension1.set_ext_name("name in extension");
+  EXPECT_TRUE(::protos::SetExtension(model, theme, extension1).ok());
+  TestModel target;
+  target.set_b1(true);
+  ::protos::DeepCopy(&model, &target);
+  EXPECT_FALSE(target.b1()) << "Target was not cleared before copying content";
+  EXPECT_EQ(target.str2(), "Hello");
+  EXPECT_TRUE(::protos::HasExtension(target, theme));
+}
+
+// TODO(b/288491350) : Add BUILD rule to test failures below.
+#ifdef TEST_CLEAR_MESSAGE_FAILURE
+TEST(CppGeneratedCode, ClearConstMessageShouldFail) {
+  // Fill model.
+  TestModel model;
+  model.set_int64(5);
+  model.set_str2("Hello");
+  // Only mutable_ can be cleared not Ptr<const T>.
+  ::protos::ClearMessage(model.child_model_1());
+}
+#endif