Unify behavior of deprecated_legacy_json_field_conflicts across upb and syntax.

This disables all checks of json_name for upb and protoc under both proto2 and proto3.  This option is deprecated that will be removed in future versions, and is only meant as a temporary solution.  This also fixes a latent bug in the calculation of camelcase name in Python/upb.

Fixes #12525

PiperOrigin-RevId: 603158026

python/descriptor.c

@@ -983,10 +983,23 @@ static PyObject* PyUpb_FieldDescriptor_GetName(PyUpb_DescriptorBase* self,
   return PyUnicode_FromString(upb_FieldDef_Name(self->def));
 }
 
+static char PyUpb_AsciiIsUpper(char ch) { return ch >= 'A' && ch <= 'Z'; }
+
+static char PyUpb_AsciiToLower(char ch) {
+  assert(PyUpb_AsciiIsUpper(ch));
+  return ch + ('a' - 'A');
+}
+
 static PyObject* PyUpb_FieldDescriptor_GetCamelCaseName(
     PyUpb_DescriptorBase* self, void* closure) {
-  // TODO: Ok to use jsonname here?
-  return PyUnicode_FromString(upb_FieldDef_JsonName(self->def));
+  // Camelcase is equivalent to JSON name except for potentially the first
+  // character.
+  const char* name = upb_FieldDef_JsonName(self->def);
+  size_t size = strlen(name);
+  return size > 0 && PyUpb_AsciiIsUpper(name[0])
+             ? PyUnicode_FromFormat("%c%s", PyUpb_AsciiToLower(name[0]),
+                                    name + 1)
+             : PyUnicode_FromStringAndSize(name, size);
 }
 
 static PyObject* PyUpb_FieldDescriptor_GetJsonName(PyUpb_DescriptorBase* self,

python/pb_unit_tests/descriptor_test_wrapper.py

@@ -31,11 +31,6 @@
 from google.protobuf.internal.descriptor_test import *
 import unittest
 
-# These fail because they attempt to add fields with conflicting JSON names.
-# We don't want to support this going forward.
-MakeDescriptorTest.testCamelcaseName.__unittest_expecting_failure__ = True
-MakeDescriptorTest.testJsonName.__unittest_expecting_failure__ = True
-
 # We pass this test, but the error message is slightly different.
 # Our error message is better.
 NewDescriptorTest.testImmutableCppDescriptor.__unittest_expecting_failure__ = True

src/google/protobuf/compiler/parser_unittest.cc

@@ -2307,15 +2307,32 @@ TEST_F(ParserValidationErrorTest, Proto2CustomJsonConflictError) {
 }
 
 TEST_F(ParserValidationErrorTest, Proto3JsonConflictLegacy) {
-  ExpectHasValidationErrors(
+  ExpectParsesTo(
       "syntax = 'proto3';\n"
       "message TestMessage {\n"
       "  option deprecated_legacy_json_field_conflicts = true;\n"
       "  uint32 fooBar = 1;\n"
       "  uint32 foo_bar = 2;\n"
       "}\n",
-      "4:9: The default JSON name of field \"foo_bar\" (\"fooBar\") conflicts "
-      "with the default JSON name of field \"fooBar\".\n");
+      "syntax: 'proto3'\n"
+      "message_type {\n"
+      "  name: 'TestMessage'\n"
+      "  field {\n"
+      "    label: LABEL_OPTIONAL type: TYPE_UINT32 name: 'fooBar' number: 1\n"
+      "  }\n"
+      "  field {\n"
+      "    label: LABEL_OPTIONAL type: TYPE_UINT32 name: 'foo_bar' number: 2\n"
+      "  }\n"
+      "  options {\n"
+      "    uninterpreted_option {\n"
+      "      name {\n"
+      "        name_part: 'deprecated_legacy_json_field_conflicts'\n"
+      "        is_extension: false\n"
+      "      }\n"
+      "      identifier_value: 'true'\n"
+      "    }\n"
+      "  }\n"
+      "}\n");
 }
 
 TEST_F(ParserValidationErrorTest, Proto2JsonConflictLegacy) {

src/google/protobuf/descriptor.cc

@@ -6186,14 +6186,8 @@ void DescriptorBuilder::BuildMessage(const DescriptorProto& proto,
 void DescriptorBuilder::CheckFieldJsonNameUniqueness(
     const DescriptorProto& proto, const Descriptor* result) {
   std::string message_name = result->full_name();
-  if (pool_->deprecated_legacy_json_field_conflicts_ ||
-      IsLegacyJsonFieldConflictEnabled(result->options())) {
-    if (result->file()->edition() == Edition::EDITION_PROTO3) {
-      // Only check default JSON names for conflicts in proto3.  This is legacy
-      // behavior that will be removed in a later version.
-      CheckFieldJsonNameUniqueness(message_name, proto, result, false);
-    }
-  } else {
+  if (!pool_->deprecated_legacy_json_field_conflicts_ &&
+      !IsLegacyJsonFieldConflictEnabled(result->options())) {
     // Check both with and without taking json_name into consideration.  This is
     // needed for field masks, which don't use json_name.
     CheckFieldJsonNameUniqueness(message_name, proto, result, false);

src/google/protobuf/descriptor_unittest.cc

@@ -7267,7 +7267,7 @@ TEST_F(ValidationErrorTest, ValidateJsonNameConflictProto2) {
 
 // Test that field names that may conflict in JSON is not allowed by protoc.
 TEST_F(ValidationErrorTest, ValidateJsonNameConflictProto3Legacy) {
-  BuildFileWithErrors(
+  BuildFile(
       "name: 'foo.proto' "
       "syntax: 'proto3' "
       "message_type {"
@@ -7275,10 +7275,7 @@ TEST_F(ValidationErrorTest, ValidateJsonNameConflictProto3Legacy) {
       "  options { deprecated_legacy_json_field_conflicts: true }"
       "  field { name:'AB' number:1 label:LABEL_OPTIONAL type:TYPE_INT32 }"
       "  field { name:'_a__b_' number:2 label:LABEL_OPTIONAL type:TYPE_INT32 }"
-      "}",
-      "foo.proto: Foo: NAME: The default JSON name of field \"_a__b_\" "
-      "(\"AB\") "
-      "conflicts with the default JSON name of field \"AB\".\n");
+      "}");
 }
 
 TEST_F(ValidationErrorTest, ValidateJsonNameConflictProto2Legacy) {

upb/reflection/message_def.c

@@ -415,7 +415,10 @@ void _upb_MessageDef_InsertField(upb_DefBuilder* ctx, upb_MessageDef* m,
       _upb_MessageDef_Insert(m, shortname, shortnamelen, field_v, ctx->arena);
   if (!ok) _upb_DefBuilder_OomErr(ctx);
 
-  if (strcmp(shortname, json_name) != 0 &&
+  bool skip_json_conflicts =
+      UPB_DESC(MessageOptions_deprecated_legacy_json_field_conflicts)(
+          upb_MessageDef_Options(m));
+  if (!skip_json_conflicts && strcmp(shortname, json_name) != 0 &&
       UPB_DESC(FeatureSet_json_format)(m->resolved_features) ==
           UPB_DESC(FeatureSet_ALLOW) &&
       upb_strtable_lookup(&m->ntof, json_name, &v)) {
@@ -425,14 +428,16 @@ void _upb_MessageDef_InsertField(upb_DefBuilder* ctx, upb_MessageDef* m,
   }
 
   if (upb_strtable_lookup(&m->jtof, json_name, &v)) {
-    _upb_DefBuilder_Errf(ctx, "duplicate json_name (%s)", json_name);
+    if (!skip_json_conflicts) {
+      _upb_DefBuilder_Errf(ctx, "duplicate json_name (%s)", json_name);
+    }
+  } else {
+    const size_t json_size = strlen(json_name);
+    ok = upb_strtable_insert(&m->jtof, json_name, json_size,
+                             upb_value_constptr(f), ctx->arena);
+    if (!ok) _upb_DefBuilder_OomErr(ctx);
   }
 
-  const size_t json_size = strlen(json_name);
-  ok = upb_strtable_insert(&m->jtof, json_name, json_size,
-                           upb_value_constptr(f), ctx->arena);
-  if (!ok) _upb_DefBuilder_OomErr(ctx);
-
   if (upb_inttable_lookup(&m->itof, field_number, NULL)) {
     _upb_DefBuilder_Errf(ctx, "duplicate field number (%u)", field_number);
   }