Do perfect forwarding to avoid unnecessary extra instances of UntypedMessage,

reducing runtime costs and stack usage.

PiperOrigin-RevId: 570169961

src/google/protobuf/json/internal/untyped_message.cc

@@ -300,7 +300,7 @@ absl::Status UntypedMessage::Decode(io::CodedInputStream& stream,
 
         UntypedMessage group(*group_desc);
         RETURN_IF_ERROR(group.Decode(stream, field_number));
-        RETURN_IF_ERROR(InsertField<UntypedMessage>(*field, std::move(group)));
+        RETURN_IF_ERROR(InsertField(*field, std::move(group)));
         break;
       }
       case WireFormatLite::WIRETYPE_END_GROUP:
@@ -473,7 +473,7 @@ absl::Status UntypedMessage::DecodeDelimited(io::CodedInputStream& stream,
         }
       }
 
-      RETURN_IF_ERROR(InsertField<std::string>(field, std::move(buf)));
+      RETURN_IF_ERROR(InsertField(field, std::move(buf)));
       break;
     }
     case Field::TYPE_MESSAGE: {
@@ -482,7 +482,7 @@ absl::Status UntypedMessage::DecodeDelimited(io::CodedInputStream& stream,
 
       auto inner = ParseFromStream(*inner_desc, stream);
       RETURN_IF_ERROR(inner.status());
-      RETURN_IF_ERROR(InsertField<UntypedMessage>(field, std::move(*inner)));
+      RETURN_IF_ERROR(InsertField(field, std::move(*inner)));
       break;
     }
     default: {
@@ -523,9 +523,9 @@ absl::Status UntypedMessage::DecodeDelimited(io::CodedInputStream& stream,
 
 template <typename T>
 absl::Status UntypedMessage::InsertField(const ResolverPool::Field& field,
-                                         T value) {
+                                         T&& value) {
   int32_t number = field.proto().number();
-  auto emplace_result = fields_.try_emplace(number, std::move(value));
+  auto emplace_result = fields_.try_emplace(number, std::forward<T>(value));
   if (emplace_result.second) {
     return absl::OkStatus();
   }
@@ -537,17 +537,18 @@ absl::Status UntypedMessage::InsertField(const ResolverPool::Field& field,
   }
 
   Value& slot = emplace_result.first->second;
-  if (auto* extant = absl::get_if<T>(&slot)) {
-    std::vector<T> repeated;
+  using value_type = std::decay_t<T>;
+  if (auto* extant = absl::get_if<value_type>(&slot)) {
+    std::vector<value_type> repeated;
     repeated.push_back(std::move(*extant));
-    repeated.push_back(std::move(value));
+    repeated.push_back(std::forward<T>(value));
 
     slot = std::move(repeated);
-  } else if (auto* extant = absl::get_if<std::vector<T>>(&slot)) {
-    extant->push_back(std::move(value));
+  } else if (auto* extant = absl::get_if<std::vector<value_type>>(&slot)) {
+    extant->push_back(std::forward<T>(value));
   } else {
     absl::optional<absl::string_view> name =
-        google::protobuf::internal::RttiTypeName<T>();
+        google::protobuf::internal::RttiTypeName<value_type>();
     if (!name.has_value()) {
       name = "<unknown>";
     }

src/google/protobuf/json/internal/untyped_message.h

@@ -224,7 +224,7 @@ class UntypedMessage final {
                                const ResolverPool::Field& field);
 
   template <typename T>
-  absl::Status InsertField(const ResolverPool::Field& field, T value);
+  absl::Status InsertField(const ResolverPool::Field& field, T&& value);
 
   const ResolverPool::Message* desc_;
   absl::flat_hash_map<int32_t, Value> fields_;