Internal change

PiperOrigin-RevId: 484509863

src/google/protobuf/compiler/objectivec/map_field.cc

@@ -163,20 +163,24 @@ void MapFieldGenerator::DetermineForwardDeclarations(
     std::set<std::string>* fwd_decls, bool include_external_types) const {
   RepeatedFieldGenerator::DetermineForwardDeclarations(fwd_decls,
                                                        include_external_types);
+  const FieldDescriptor* value_descriptor =
+      descriptor_->message_type()->map_value();
   // NOTE: Maps with values of enums don't have to worry about adding the
   // forward declaration because `GPB*EnumDictionary` isn't generic to the
   // specific enum (like say `NSDictionary<String, MyMessage>`) and thus doesn't
   // reference the type in the header.
+  if (GetObjectiveCType(value_descriptor) != OBJECTIVECTYPE_MESSAGE) {
+    return;
+  }
+
+  const Descriptor* value_msg_descriptor = value_descriptor->message_type();
 
-  const FieldDescriptor* value_descriptor =
-      descriptor_->message_type()->map_value();
   // Within a file there is no requirement on the order of the messages, so
   // local references need a forward declaration. External files (not WKTs),
   // need one when requested.
-  if (GetObjectiveCType(value_descriptor) == OBJECTIVECTYPE_MESSAGE &&
-      ((include_external_types &&
-        !IsProtobufLibraryBundledProtoFile(value_descriptor->file())) ||
-       descriptor_->file() == value_descriptor->file())) {
+  if ((include_external_types &&
+       !IsProtobufLibraryBundledProtoFile(value_msg_descriptor->file())) ||
+      descriptor_->file() == value_msg_descriptor->file()) {
     const std::string& value_storage_type =
         value_field_generator_->variable("storage_type");
     fwd_decls->insert("@class " + value_storage_type);