Breaking change: remove const GetArena method on RepeatedPtrField

PiperOrigin-RevId: 597349773

src/google/protobuf/port_def.inc

@@ -163,10 +163,6 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 // Owner: shaod@, gberg@
 #define PROTOBUF_FUTURE_DESCRIPTOR_EXTENSION_DECL 1
 
-// Used to remove `RepeatedPtrField::GetArena() const`.
-// Owner: ezb@
-#define PROTOBUF_FUTURE_REMOVE_CONST_REPEATEDFIELD_GETARENA_API 1
-
 #endif
 
 // Defines the Protobuf C++ Version for checking version compatibility at

src/google/protobuf/repeated_ptr_field.h

@@ -1175,11 +1175,6 @@ class RepeatedPtrField final : private internal::RepeatedPtrFieldBase {
   // Gets the arena on which this RepeatedPtrField stores its elements.
   inline Arena* GetArena();
 
-#ifndef PROTOBUF_FUTURE_REMOVE_CONST_REPEATEDFIELD_GETARENA_API
-  ABSL_DEPRECATED("This will be removed in a future release")
-  inline Arena* GetArena() const;
-#endif  // !PROTOBUF_FUTURE_REMOVE_CONST_REPEATEDFIELD_GETARENA_API
-
   // For internal use only.
   //
   // This is public due to it being called by generated code.
@@ -1512,13 +1507,6 @@ inline Arena* RepeatedPtrField<Element>::GetArena() {
   return RepeatedPtrFieldBase::GetArena();
 }
 
-#ifndef PROTOBUF_FUTURE_REMOVE_CONST_REPEATEDFIELD_GETARENA_API
-template <typename Element>
-inline Arena* RepeatedPtrField<Element>::GetArena() const {
-  return RepeatedPtrFieldBase::GetArena();
-}
-#endif  // !PROTOBUF_FUTURE_REMOVE_CONST_REPEATEDFIELD_GETARENA_API
-
 template <typename Element>
 inline size_t RepeatedPtrField<Element>::SpaceUsedExcludingSelfLong() const {
   // `google::protobuf::Message` has a virtual method `SpaceUsedLong`, hence we can