upb: add upb_FieldDef_LayoutIndex()

PiperOrigin-RevId: 618007325

upb/reflection/def.hpp

@@ -18,6 +18,7 @@
 #include "upb/base/status.hpp"
 #include "upb/base/string_view.h"
 #include "upb/mem/arena.hpp"
+#include "upb/message/value.h"
 #include "upb/mini_descriptor/decode.h"
 #include "upb/mini_table/enum.h"
 #include "upb/mini_table/field.h"
@@ -87,6 +88,9 @@ class FieldDefPtr {
   // been finalized.
   uint32_t index() const { return upb_FieldDef_Index(ptr_); }
 
+  // Index into msgdef->layout->fields or file->exts
+  uint32_t layout_index() const { return upb_FieldDef_LayoutIndex(ptr_); }
+
   // The MessageDef to which this field belongs (for extensions, the extended
   // message).
   MessageDefPtr containing_type() const;

upb/reflection/field_def.c

@@ -122,6 +122,10 @@ upb_FieldType upb_FieldDef_Type(const upb_FieldDef* f) {
 
 uint32_t upb_FieldDef_Index(const upb_FieldDef* f) { return f->index_; }
 
+uint32_t upb_FieldDef_LayoutIndex(const upb_FieldDef* f) {
+  return f->layout_index;
+}
+
 upb_Label upb_FieldDef_Label(const upb_FieldDef* f) {
   // TODO: remove once we can deprecate kUpb_Label_Required.
   if (UPB_DESC(FeatureSet_field_presence)(f->resolved_features) ==

upb/reflection/field_def.h

@@ -14,6 +14,7 @@
 
 #include "upb/base/descriptor_constants.h"
 #include "upb/base/string_view.h"
+#include "upb/message/value.h"
 #include "upb/mini_table/extension.h"
 #include "upb/mini_table/field.h"
 #include "upb/reflection/common.h"
@@ -55,6 +56,7 @@ bool upb_FieldDef_IsString(const upb_FieldDef* f);
 UPB_API bool upb_FieldDef_IsSubMessage(const upb_FieldDef* f);
 UPB_API const char* upb_FieldDef_JsonName(const upb_FieldDef* f);
 UPB_API upb_Label upb_FieldDef_Label(const upb_FieldDef* f);
+uint32_t upb_FieldDef_LayoutIndex(const upb_FieldDef* f);
 UPB_API const upb_MessageDef* upb_FieldDef_MessageSubDef(const upb_FieldDef* f);
 bool _upb_FieldDef_ValidateUtf8(const upb_FieldDef* f);