Remove unused internal::DownCast

src/google/protobuf/extension_set_unittest.cc

@@ -52,7 +52,6 @@ extern bool fully_verify_message_sets_opt_out;
 
 namespace {
 
-using ::google::protobuf::internal::DownCast;
 using TestUtil::EqualsToSerialized;
 
 // This test closely mirrors google/protobuf/compiler/cpp/unittest.cc

src/google/protobuf/map_test.inc

@@ -217,7 +217,6 @@ struct MapTestPeer {
 };
 
 namespace {
-using internal::DownCast;
 
 // Map API Test =====================================================
 

src/google/protobuf/message_lite.h

@@ -1200,11 +1200,6 @@ T* OnShutdownDelete(T* p) {
   return p;
 }
 
-inline void AssertDownCast(const MessageLite& from, const MessageLite& to) {
-  ABSL_DCHECK(TypeId::Get(from) == TypeId::Get(to))
-      << "Cannot downcast " << from.GetTypeName() << " to " << to.GetTypeName();
-}
-
 template <bool test_call, typename MessageLite>
 PROTOBUF_ALWAYS_INLINE MessageLite* MessageCreator::PlacementNew(
     const MessageLite* prototype_for_func,

src/google/protobuf/port.h

@@ -174,37 +174,6 @@ struct ArenaInitialized {
   explicit ArenaInitialized() = default;
 };
 
-template <typename To, typename From>
-void AssertDownCast(From* from) {
-  static_assert(std::is_base_of<From, To>::value, "illegal DownCast");
-
-#if defined(__cpp_concepts)
-  // Check that this function is not used to downcast message types.
-  // For those we should use {Down,Dynamic}CastTo{Message,Generated}.
-  static_assert(!requires {
-    std::derived_from<std::remove_pointer_t<To>,
-                      typename std::remove_pointer_t<To>::MessageLite>;
-  });
-#endif
-
-#if PROTOBUF_RTTI
-  // RTTI: debug mode only!
-  assert(from == nullptr || dynamic_cast<To*>(from) != nullptr);
-#endif
-}
-
-template <typename To, typename From>
-inline To DownCast(From* f) {
-  AssertDownCast<std::remove_pointer_t<To>>(f);
-  return static_cast<To>(f);
-}
-
-template <typename ToRef, typename From>
-inline ToRef DownCast(From& f) {
-  AssertDownCast<std::remove_reference_t<ToRef>>(&f);
-  return static_cast<ToRef>(f);
-}
-
 // Looks up the name of `T` via RTTI, if RTTI is available.
 template <typename T>
 inline absl::optional<absl::string_view> RttiTypeName() {

src/google/protobuf/repeated_field_reflection_unittest.inc

@@ -22,7 +22,6 @@ namespace protobuf {
 namespace {
 
 
-using internal::DownCast;
 using UNITTEST::ForeignMessage;
 using UNITTEST::TestAllExtensions;
 using UNITTEST::TestAllTypes;