Add internally visible Arena enabled copy constructor

PiperOrigin-RevId: 547364398

src/google/protobuf/repeated_field_unittest.cc

@@ -1795,12 +1795,30 @@ TEST(RepeatedPtrField, Erase) {
 }
 
 TEST(RepeatedPtrField, CopyConstruct) {
+  auto token = internal::InternalVisibilityForTesting{};
   RepeatedPtrField<std::string> source;
   source.Add()->assign("1");
   source.Add()->assign("2");
 
-  RepeatedPtrField<std::string> destination(source);
+  RepeatedPtrField<std::string> destination1(source);
+  ASSERT_EQ(2, destination1.size());
+  EXPECT_EQ("1", destination1.Get(0));
+  EXPECT_EQ("2", destination1.Get(1));
+
+  RepeatedPtrField<std::string> destination2(token, nullptr, source);
+  ASSERT_EQ(2, destination2.size());
+  EXPECT_EQ("1", destination2.Get(0));
+  EXPECT_EQ("2", destination2.Get(1));
+}
 
+TEST(RepeatedPtrField, CopyConstructWithArena) {
+  auto token = internal::InternalVisibilityForTesting{};
+  RepeatedPtrField<std::string> source;
+  source.Add()->assign("1");
+  source.Add()->assign("2");
+
+  Arena arena;
+  RepeatedPtrField<std::string> destination(token, &arena, source);
   ASSERT_EQ(2, destination.size());
   EXPECT_EQ("1", destination.Get(0));
   EXPECT_EQ("2", destination.Get(1));

src/google/protobuf/repeated_ptr_field.h

@@ -60,6 +60,7 @@
 #include "google/protobuf/port.h"
 #include "absl/base/attributes.h"
 #include "absl/log/absl_check.h"
+#include "google/protobuf/internal_visibility.h"
 #include "google/protobuf/message_lite.h"
 #include "google/protobuf/port.h"
 
@@ -924,9 +925,18 @@ class RepeatedPtrField final : private internal::RepeatedPtrFieldBase {
 
  public:
   constexpr RepeatedPtrField();
-  explicit RepeatedPtrField(Arena* arena);
+  RepeatedPtrField(const RepeatedPtrField& other)
+      : RepeatedPtrField(nullptr, other) {}
+
+  // Arena enabled constructors: for internal use only.
+  RepeatedPtrField(internal::InternalVisibility, Arena* arena)
+      : RepeatedPtrField(arena) {}
+  RepeatedPtrField(internal::InternalVisibility, Arena* arena,
+                   const RepeatedPtrField& rhs)
+      : RepeatedPtrField(arena, rhs) {}
 
-  RepeatedPtrField(const RepeatedPtrField& other);
+  // TODO(b/290091828): make constructor private
+  explicit RepeatedPtrField(Arena* arena);
 
   template <typename Iter,
             typename = typename std::enable_if<std::is_constructible<
@@ -1214,6 +1224,8 @@ class RepeatedPtrField final : private internal::RepeatedPtrFieldBase {
   }
 
  private:
+  RepeatedPtrField(Arena* arena, const RepeatedPtrField& rhs);
+
   // Note:  RepeatedPtrField SHOULD NOT be subclassed by users.
   class TypeHandler;
 
@@ -1267,11 +1279,11 @@ inline RepeatedPtrField<Element>::RepeatedPtrField(Arena* arena)
 }
 
 template <typename Element>
-inline RepeatedPtrField<Element>::RepeatedPtrField(
+inline RepeatedPtrField<Element>::RepeatedPtrField(Arena* arena,
-    const RepeatedPtrField& other)
+                                                   const RepeatedPtrField& rhs)
-    : RepeatedPtrFieldBase() {
+    : RepeatedPtrFieldBase(arena) {
   StaticValidityCheck();
-  MergeFrom(other);
+  MergeFrom(rhs);
 }
 
 template <typename Element>