Fix delimited inheritance in all languages.

This was previously fixed in C++ (https://github.com/protocolbuffers/protobuf/issues/16549), but not ported to other languages.  Delimited field encoding can be inherited by fields where it's invalid, such as non-messages and maps.  In these cases, the encoding should be ignored and length-prefixed should be used.

PiperOrigin-RevId: 642792988

conformance/binary_json_conformance_suite.cc

@@ -155,6 +155,11 @@ std::string group(uint32_t fieldnum, std::string content) {
                       tag(fieldnum, WireFormatLite::WIRETYPE_END_GROUP));
 }
 
+std::string len(uint32_t fieldnum, std::string content) {
+  return absl::StrCat(tag(fieldnum, WireFormatLite::WIRETYPE_LENGTH_DELIMITED),
+                      delim(content));
+}
+
 std::string GetDefaultValue(FieldDescriptor::Type type) {
   switch (type) {
     case FieldDescriptor::TYPE_INT32:
@@ -363,6 +368,33 @@ void BinaryAndJsonConformanceSuite::RunDelimitedFieldTests() {
   TestAllTypesEdition2023 prototype;
   SetTypeUrl(GetTypeUrl(TestAllTypesEdition2023::GetDescriptor()));
 
+  RunValidProtobufTest<TestAllTypesEdition2023>(
+      absl::StrCat("ValidNonMessage"), REQUIRED,
+      field(1, WireFormatLite::WIRETYPE_VARINT, varint(99)),
+      R"pb(optional_int32: 99)pb");
+
+  RunValidProtobufTest<TestAllTypesEdition2023>(
+      absl::StrCat("ValidLengthPrefixedField"), REQUIRED,
+      len(18, field(1, WireFormatLite::WIRETYPE_VARINT, varint(99))),
+      R"pb(optional_nested_message { a: 99 })pb");
+
+  RunValidProtobufTest<TestAllTypesEdition2023>(
+      absl::StrCat("ValidMap.Integer"), REQUIRED,
+      len(56,
+          absl::StrCat(field(1, WireFormatLite::WIRETYPE_VARINT, varint(99)),
+                       field(2, WireFormatLite::WIRETYPE_VARINT, varint(87)))),
+      R"pb(map_int32_int32 { key: 99 value: 87 })pb");
+
+  RunValidProtobufTest<TestAllTypesEdition2023>(
+      absl::StrCat("ValidMap.LengthPrefixed"), REQUIRED,
+      len(71, absl::StrCat(len(1, "a"),
+                           len(2, field(1, WireFormatLite::WIRETYPE_VARINT,
+                                        varint(87))))),
+      R"pb(map_string_nested_message {
+             key: "a"
+             value: { a: 87 }
+           })pb");
+
   RunValidProtobufTest<TestAllTypesEdition2023>(
       absl::StrCat("ValidDelimitedField.GroupLike"), REQUIRED,
       group(201, field(202, WireFormatLite::WIRETYPE_VARINT, varint(99))),

conformance/test_protos/test_messages_edition2023.proto

@@ -2,6 +2,7 @@ edition = "2023";
 
 package protobuf_test_messages.editions;
 
+option features.message_encoding = DELIMITED;
 option java_package = "com.google.protobuf_test_messages.edition2023";
 option java_multiple_files = true;
 option objc_class_prefix = "Editions";
@@ -9,7 +10,8 @@ option objc_class_prefix = "Editions";
 message TestAllTypesEdition2023 {
   message NestedMessage {
     int32 a = 1;
-    TestAllTypesEdition2023 corecursive = 2;
+    TestAllTypesEdition2023 corecursive = 2
+        [features.message_encoding = LENGTH_PREFIXED];
   }
 
   enum NestedEnum {
@@ -36,8 +38,10 @@ message TestAllTypesEdition2023 {
   string optional_string = 14;
   bytes optional_bytes = 15;
 
-  NestedMessage optional_nested_message = 18;
-  ForeignMessageEdition2023 optional_foreign_message = 19;
+  NestedMessage optional_nested_message = 18
+      [features.message_encoding = LENGTH_PREFIXED];
+  ForeignMessageEdition2023 optional_foreign_message = 19
+      [features.message_encoding = LENGTH_PREFIXED];
 
   NestedEnum optional_nested_enum = 21;
   ForeignEnumEdition2023 optional_foreign_enum = 22;
@@ -45,7 +49,8 @@ message TestAllTypesEdition2023 {
   string optional_string_piece = 24 [ctype = STRING_PIECE];
   string optional_cord = 25 [ctype = CORD];
 
-  TestAllTypesEdition2023 recursive_message = 27;
+  TestAllTypesEdition2023 recursive_message = 27
+      [features.message_encoding = LENGTH_PREFIXED];
 
   // Repeated
   repeated int32 repeated_int32 = 31;
@@ -64,8 +69,10 @@ message TestAllTypesEdition2023 {
   repeated string repeated_string = 44;
   repeated bytes repeated_bytes = 45;
 
-  repeated NestedMessage repeated_nested_message = 48;
-  repeated ForeignMessageEdition2023 repeated_foreign_message = 49;
+  repeated NestedMessage repeated_nested_message = 48
+      [features.message_encoding = LENGTH_PREFIXED];
+  repeated ForeignMessageEdition2023 repeated_foreign_message = 49
+      [features.message_encoding = LENGTH_PREFIXED];
 
   repeated NestedEnum repeated_nested_enum = 51;
   repeated ForeignEnumEdition2023 repeated_foreign_enum = 52;
@@ -152,7 +159,8 @@ message TestAllTypesEdition2023 {
 
   oneof oneof_field {
     uint32 oneof_uint32 = 111;
-    NestedMessage oneof_nested_message = 112;
+    NestedMessage oneof_nested_message = 112
+        [features.message_encoding = LENGTH_PREFIXED];
     string oneof_string = 113;
     bytes oneof_bytes = 114;
     bool oneof_bool = 115;
@@ -170,8 +178,8 @@ message TestAllTypesEdition2023 {
     int32 group_int32 = 202;
     uint32 group_uint32 = 203;
   }
-  GroupLikeType groupliketype = 201 [features.message_encoding = DELIMITED];
-  GroupLikeType delimited_field = 202 [features.message_encoding = DELIMITED];
+  GroupLikeType groupliketype = 201;
+  GroupLikeType delimited_field = 202;
 }
 
 message ForeignMessageEdition2023 {
@@ -193,6 +201,6 @@ message GroupLikeType {
 }
 
 extend TestAllTypesEdition2023 {
-  GroupLikeType groupliketype = 121 [features.message_encoding = DELIMITED];
-  GroupLikeType delimited_ext = 122 [features.message_encoding = DELIMITED];
+  GroupLikeType groupliketype = 121;
+  GroupLikeType delimited_ext = 122;
 }

csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs

@@ -407,6 +407,11 @@ namespace Google.Protobuf.Reflection
                         throw new DescriptorValidationException(this, $"\"{Proto.TypeName}\" is not a message type.");
                     }
                     messageType = m;
+                    if (m.Proto.Options?.MapEntry == true || ContainingType?.Proto.Options?.MapEntry == true)
+                    {
+                        // Maps can't inherit delimited encoding.
+                        FieldType = FieldType.Message;
+                    }
 
                     if (Proto.HasDefaultValue)
                     {

java/core/src/main/java/com/google/protobuf/Descriptors.java

@@ -1297,6 +1297,8 @@ public final class Descriptors {
       // since these are used before feature resolution when parsing java feature set defaults
       // (custom options) into unknown fields.
       if (type == Type.MESSAGE
+          && !(messageType != null && messageType.toProto().getOptions().getMapEntry())
+          && !(containingType != null && containingType.toProto().getOptions().getMapEntry())
           && this.features != null
           && getFeatures().getMessageEncoding() == FeatureSet.MessageEncoding.DELIMITED) {
         return Type.GROUP;
@@ -1476,8 +1478,7 @@ public final class Descriptors {
      * been upgraded to editions.
      */
     boolean isGroupLike() {
-      if (getFeatures().getMessageEncoding()
-          != DescriptorProtos.FeatureSet.MessageEncoding.DELIMITED) {
+      if (getType() != Type.GROUP) {
         // Groups are always tag-delimited.
         return false;
       }

python/google/protobuf/descriptor.py

@@ -708,6 +708,9 @@ class FieldDescriptor(DescriptorBase):
     if (
         self._GetFeatures().message_encoding
         == _FEATURESET_MESSAGE_ENCODING_DELIMITED
+        and self.message_type
+        and not self.message_type.GetOptions().map_entry
+        and not self.containing_type.GetOptions().map_entry
     ):
       return FieldDescriptor.TYPE_GROUP
     return self._type

python/google/protobuf/text_format.py

@@ -195,10 +195,7 @@ def _IsGroupLike(field):
     True if this field is group-like, false otherwise.
   """
   # Groups are always tag-delimited.
-  if (
-      field._GetFeatures().message_encoding
-      != descriptor._FEATURESET_MESSAGE_ENCODING_DELIMITED
-  ):
+  if field.type != descriptor.FieldDescriptor.TYPE_GROUP:
     return False
 
   # Group fields always are always the lowercase type name.

upb/reflection/field_def.c

@@ -252,8 +252,7 @@ bool _upb_FieldDef_ValidateUtf8(const upb_FieldDef* f) {
 
 bool _upb_FieldDef_IsGroupLike(const upb_FieldDef* f) {
   // Groups are always tag-delimited.
-  if (UPB_DESC(FeatureSet_message_encoding)(upb_FieldDef_ResolvedFeatures(f)) !=
-      UPB_DESC(FeatureSet_DELIMITED)) {
+  if (f->type_ != kUpb_FieldType_Group) {
     return false;
   }
 
@@ -687,12 +686,6 @@ static void _upb_FieldDef_Create(upb_DefBuilder* ctx, const char* prefix,
       UPB_DESC(FieldDescriptorProto_has_type_name)(field_proto);
 
   f->type_ = (int)UPB_DESC(FieldDescriptorProto_type)(field_proto);
-  if (f->type_ == kUpb_FieldType_Message &&
-      // TODO: remove once we can deprecate kUpb_FieldType_Group.
-      UPB_DESC(FeatureSet_message_encoding)(f->resolved_features) ==
-          UPB_DESC(FeatureSet_DELIMITED)) {
-    f->type_ = kUpb_FieldType_Group;
-  }
 
   if (has_type) {
     switch (f->type_) {
@@ -713,7 +706,7 @@ static void _upb_FieldDef_Create(upb_DefBuilder* ctx, const char* prefix,
     }
   }
 
-  if (!has_type && has_type_name) {
+  if ((!has_type && has_type_name) || f->type_ == kUpb_FieldType_Message) {
     f->type_ =
         UPB_FIELD_TYPE_UNSPECIFIED;  // We'll assign this in resolve_subdef()
   } else {
@@ -863,8 +856,15 @@ static void resolve_subdef(upb_DefBuilder* ctx, const char* prefix,
           break;
         case UPB_DEFTYPE_MSG:
           f->sub.msgdef = def;
-          f->type_ = kUpb_FieldType_Message;  // It appears there is no way of
-                                              // this being a group.
+          f->type_ = kUpb_FieldType_Message;
+          // TODO: remove once we can deprecate
+          // kUpb_FieldType_Group.
+          if (UPB_DESC(FeatureSet_message_encoding)(f->resolved_features) ==
+                  UPB_DESC(FeatureSet_DELIMITED) &&
+              !upb_MessageDef_IsMapEntry(def) &&
+              !(f->msgdef && upb_MessageDef_IsMapEntry(f->msgdef))) {
+            f->type_ = kUpb_FieldType_Group;
+          }
           f->has_presence = !upb_FieldDef_IsRepeated(f);
           break;
         default: