Fix a bug in the main C++ JSON parser/serializer camelcasing of certain non-style-compliant names incorrectly, in a way that would prevent it from interoperating with any other implementation on those fields.

Before this fix, the camelcasing that it would use under certain non-style compliant names like `_field` are mutually incompatible with any other implementation.

This case was already covered by the conformance test suite but was not hooked up to this implementation and instead used a lesser-used path in the same JSON package which is based on type.proto instead of Descriptor. A subsequent CL will switch the cc conformance testee to use this implementation as it is the primary one that our customers.

PiperOrigin-RevId: 798047846

Author: protobuf-github-bot

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

@@ -178,7 +178,7 @@ struct Proto2Descriptor {
 
     for (int i = 0; i < d.field_count(); ++i) {
       const auto* field = d.field(i);
-      if (field->has_json_name() && field->json_name() == name) {
+      if (field->json_name() == name) {
         return field;
       }
     }
@@ -206,9 +206,7 @@ struct Proto2Descriptor {
   /// Functions for introspecting fields. ///
 
   static absl::string_view FieldName(Field f) { return f->name(); }
-  static absl::string_view FieldJsonName(Field f) {
-    return f->has_json_name() ? f->json_name() : f->camelcase_name();
-  }
+  static absl::string_view FieldJsonName(Field f) { return f->json_name(); }
   static absl::string_view FieldFullName(Field f) { return f->full_name(); }
 
   static absl::string_view FieldTypeName(Field f) {

src/google/protobuf/json/json_test.cc

@@ -7,12 +7,9 @@
 
 #include "google/protobuf/json/json.h"
 
-#include <algorithm>
 #include <cstdint>
-#include <list>
 #include <memory>
 #include <string>
-#include <vector>
 
 #include "google/protobuf/duration.pb.h"
 #include "google/protobuf/field_mask.pb.h"
@@ -23,11 +20,11 @@
 #include <gtest/gtest.h>
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
+#include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 #include "google/protobuf/descriptor_database.h"
 #include "google/protobuf/dynamic_message.h"
 #include "google/protobuf/io/test_zero_copy_stream.h"
-#include "google/protobuf/io/zero_copy_stream.h"
 #include "google/protobuf/io/zero_copy_stream_impl_lite.h"
 #include "google/protobuf/util/json_format.pb.h"
 #include "google/protobuf/util/json_format_proto3.pb.h"
@@ -68,6 +65,7 @@ MATCHER_P(IsOkAndHolds, inner,
 }
 
 absl::Status GetStatus(const absl::Status& s) { return s; }
+
 template <typename T>
 absl::Status GetStatus(const absl::StatusOr<T>& s) {
   return s.status();
@@ -200,7 +198,8 @@ TEST_P(JsonTest, TestAlwaysPrintFieldsWithNoPresence) {
                                                R"("repeatedStringValue":[],)"
                                                R"("repeatedBytesValue":[],)"
                                                R"("repeatedEnumValue":[],)"
-                                               R"("repeatedMessageValue":[])"
+                                               R"("repeatedMessageValue":[],)"
+                                               R"("NonStandardName":0)"
                                                "}"));
 
   m.set_string_value("i am a test string value");
@@ -232,7 +231,8 @@ TEST_P(JsonTest, TestAlwaysPrintFieldsWithNoPresence) {
                            R"("repeatedMessageValue":[],)"
                            R"("optionalBoolValue":false,)"
                            R"("optionalStringValue":"",)"
-                           R"("optionalBytesValue":"")"
+                           R"("optionalBytesValue":"",)"
+                           R"("NonStandardName":0)"
                            "}"));
 
   EXPECT_THAT(

src/google/protobuf/util/json_format_proto3.proto

@@ -5,6 +5,8 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
+// LINT: LEGACY_NAMES
+
 syntax = "proto3";
 
 package proto3;
@@ -66,6 +68,8 @@ message TestMessage {
   optional bytes optional_bytes_value = 49;
   optional EnumType optional_enum_value = 50;
   optional MessageType optional_message_value = 51;
+
+  int32 _nonStandard_name_ = 52;
 }
 
 message TestOneof {