Only consider scalar submessages eligible for explicit lazy.

While other fields can be tagged "lazy", they do not impact codegen.

PiperOrigin-RevId: 604443879

src/google/protobuf/compiler/cpp/helpers.h

@@ -383,6 +383,14 @@ bool IsLazy(const FieldDescriptor* field, const Options& options,
 // Is this an explicit (non-profile driven) lazy field, as denoted by
 // lazy/unverified_lazy in the descriptor?
 inline bool IsExplicitLazy(const FieldDescriptor* field) {
+  if (field->is_map() || field->is_repeated()) {
+    return false;
+  }
+
+  if (field->cpp_type() != FieldDescriptor::CPPTYPE_MESSAGE) {
+    return false;
+  }
+
   return field->options().lazy() || field->options().unverified_lazy();
 }