diff --git a/csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs b/csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs
deleted file mode 100644
index 208ce1fcb6..0000000000
--- a/csharp/src/Google.Protobuf/Reflection/FeatureSetDescriptor.g.cs
+++ /dev/null
@@ -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";
-}
diff --git a/upb/mem/arena.c b/upb/mem/arena.c
index 975520b7c7..e313d605be 100644
--- a/upb/mem/arena.c
+++ b/upb/mem/arena.c
@@ -565,6 +565,11 @@ void upb_Arena_DecRefFor(const upb_Arena* a, const void* owner) {
   upb_Arena_Free((upb_Arena*)a);
 }
 
+upb_alloc* upb_Arena_GetUpbAlloc(upb_Arena* a) {
+  upb_ArenaInternal* ai = upb_Arena_Internal(a);
+  return _upb_ArenaInternal_BlockAlloc(ai);
+}
+
 void UPB_PRIVATE(_upb_Arena_SwapIn)(upb_Arena* des, const upb_Arena* src) {
   upb_ArenaInternal* desi = upb_Arena_Internal(des);
   upb_ArenaInternal* srci = upb_Arena_Internal(src);
diff --git a/upb/mem/arena.h b/upb/mem/arena.h
index 63fad6d3ff..f0d9d2d6f0 100644
--- a/upb/mem/arena.h
+++ b/upb/mem/arena.h
@@ -44,6 +44,9 @@ UPB_API void upb_Arena_Free(upb_Arena* a);
 UPB_API bool upb_Arena_Fuse(const upb_Arena* a, const upb_Arena* b);
 UPB_API bool upb_Arena_IsFused(const upb_Arena* a, const upb_Arena* b);
 
+// Returns the upb_alloc used by the arena.
+UPB_API upb_alloc* upb_Arena_GetUpbAlloc(upb_Arena* a);
+
 bool upb_Arena_IncRefFor(const upb_Arena* a, const void* owner);
 void upb_Arena_DecRefFor(const upb_Arena* a, const void* owner);