Don't iterate at all if unknowns are not populated

PiperOrigin-RevId: 695429913

csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs

@@ -1,17 +0,0 @@
-#region Copyright notice and license
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-#endregion
-
-namespace Google.Protobuf.Reflection;
-
-internal sealed partial class FeatureSetDescriptor
-{
-    // Canonical serialized form of the edition defaults, generated by embed_edition_defaults.
-    private const string DefaultsBase64 =
-        "ChMYhAciACoMCAEQAhgCIAMoATACChMY5wciACoMCAIQARgBIAIoATABChMY6AciDAgBEAEYASACKAEwASoAIOYHKOgH";
-}

upb/message/message.c

@@ -55,17 +55,19 @@ void _upb_Message_DiscardUnknown_shallow(upb_Message* msg) {
 
 bool upb_Message_NextUnknown(const upb_Message* msg, upb_StringView* data,
                              uintptr_t* iter) {
-  upb_Message_Internal* in = UPB_PRIVATE(_upb_Message_GetInternal)(msg);
+  const upb_Message_Internal* in = UPB_PRIVATE(_upb_Message_GetInternal)(msg);
   if (in && *iter == kUpb_Message_UnknownBegin) {
-    data->size = in->unknown_end - message_overhead;
-    data->data = (char*)(in + 1);
-    (*iter)++;
-    return true;
-  } else {
-    data->size = 0;
-    data->data = NULL;
-    return false;
+    size_t len = in->unknown_end - message_overhead;
+    if (len != 0) {
+      data->size = len;
+      data->data = (const char*)(in + 1);
+      (*iter)++;
+      return true;
+    }
   }
+  data->size = 0;
+  data->data = NULL;
+  return false;
 }
 
 const char* upb_Message_GetUnknown(const upb_Message* msg, size_t* len) {