3 files changed, 37 insertions, 73 deletions

diff --git a/absl/memory/memory.h b/absl/memory/memory.h
index f207169a6885..c7caf8b94dc9 100644
--- a/absl/memory/memory.h
+++ b/absl/memory/memory.h
@@ -641,38 +641,56 @@ struct default_allocator_is_nothrow : std::false_type {};
 #endif
 
 namespace memory_internal {
-// TODO(b110200014): Implement proper backports
-template <typename ForwardIt>
-void DefaultConstruct(ForwardIt it) {
-  using value_type = typename std::iterator_traits<ForwardIt>::value_type;
-  ::new (static_cast<void*>(std::addressof(*it))) value_type;
-}  // namespace memory_internal
-
 #ifdef ABSL_HAVE_EXCEPTIONS
-template <typename ForwardIt, typename Size>
-void uninitialized_default_construct_n(ForwardIt first, Size size) {
-  for (ForwardIt cur = first; size > 0; static_cast<void>(++cur), --size) {
+template <typename Allocator, typename StorageElement, typename... Args>
+void ConstructStorage(Allocator* alloc, StorageElement* first,
+                      StorageElement* last, const Args&... args) {
+  for (StorageElement* cur = first; cur != last; ++cur) {
+    try {
+      std::allocator_traits<Allocator>::construct(*alloc, cur, args...);
+    } catch (...) {
+      while (cur != first) {
+        --cur;
+        std::allocator_traits<Allocator>::destroy(*alloc, cur);
+      }
+      throw;
+    }
+  }
+}
+template <typename Allocator, typename StorageElement, typename Iterator>
+void CopyToStorageFromRange(Allocator* alloc, StorageElement* destination,
+                            Iterator first, Iterator last) {
+  for (StorageElement* cur = destination; first != last;
+       static_cast<void>(++cur), static_cast<void>(++first)) {
     try {
-      absl::memory_internal::DefaultConstruct(cur);
+      std::allocator_traits<Allocator>::construct(*alloc, cur, *first);
     } catch (...) {
-      using value_type = typename std::iterator_traits<ForwardIt>::value_type;
-      for (; first != cur; ++first) {
-        first->~value_type();
+      while (cur != destination) {
+        --cur;
+        std::allocator_traits<Allocator>::destroy(*alloc, cur);
       }
       throw;
     }
   }
 }
 #else   // ABSL_HAVE_EXCEPTIONS
-template <typename ForwardIt, typename Size>
-void uninitialized_default_construct_n(ForwardIt first, Size size) {
-  for (; size > 0; static_cast<void>(++first), --size) {
-    absl::memory_internal::DefaultConstruct(first);
+template <typename Allocator, typename StorageElement, typename... Args>
+void ConstructStorage(Allocator* alloc, StorageElement* first,
+                      StorageElement* last, const Args&... args) {
+  for (; first != last; ++first) {
+    std::allocator_traits<Allocator>::construct(*alloc, first, args...);
+  }
+}
+template <typename Allocator, typename StorageElement, typename Iterator>
+void CopyToStorageFromRange(Allocator* alloc, StorageElement* destination,
+                            Iterator first, Iterator last) {
+  for (; first != last;
+       static_cast<void>(++destination), static_cast<void>(++first)) {
+    std::allocator_traits<Allocator>::construct(*alloc, destination, *first);
   }
 }
 #endif  // ABSL_HAVE_EXCEPTIONS
 }  // namespace memory_internal
-
 }  // namespace absl
 
 #endif  // ABSL_MEMORY_MEMORY_H_
diff --git a/absl/memory/memory_exception_safety_test.cc b/absl/memory/memory_exception_safety_test.cc
index fb8b561d59fb..d1f6e84f10f8 100644
--- a/absl/memory/memory_exception_safety_test.cc
+++ b/absl/memory/memory_exception_safety_test.cc
@@ -48,16 +48,5 @@ TEST(MakeUnique, CheckForLeaks) {
   }));
 }
 
-TEST(MemoryInternal, UninitDefaultConstructNNonTrivial) {
-  EXPECT_TRUE(testing::MakeExceptionSafetyTester()
-                  .WithInitialValue(ThrowerList{})
-                  .WithOperation([&](ThrowerList* list_ptr) {
-                    absl::memory_internal::uninitialized_default_construct_n(
-                        list_ptr->data(), kLength);
-                  })
-                  .WithInvariants([&](...) { return true; })
-                  .Test());
-}
-
 }  // namespace
 }  // namespace absl
diff --git a/absl/memory/memory_test.cc b/absl/memory/memory_test.cc
index 8ff1945debe5..dee9b486a30d 100644
--- a/absl/memory/memory_test.cc
+++ b/absl/memory/memory_test.cc
@@ -611,47 +611,4 @@ TEST(AllocatorNoThrowTest, CustomAllocator) {
   EXPECT_FALSE(absl::allocator_is_nothrow<UnspecifiedAllocator>::value);
 }
 
-TEST(MemoryInternal, UninitDefaultConstructNTrivial) {
-  constexpr int kInitialValue = 123;
-  constexpr int kExpectedValue = kInitialValue;  // Expect no-op behavior
-  constexpr int len = 5;
-
-  struct TestObj {
-    int val;
-  };
-  static_assert(absl::is_trivially_default_constructible<TestObj>::value, "");
-  static_assert(absl::is_trivially_destructible<TestObj>::value, "");
-
-  TestObj objs[len];
-  for (auto& obj : objs) {
-    obj.val = kInitialValue;
-  }
-
-  absl::memory_internal::uninitialized_default_construct_n(objs, len);
-  for (auto& obj : objs) {
-    EXPECT_EQ(obj.val, kExpectedValue);
-  }
-}
-
-TEST(MemoryInternal, UninitDefaultConstructNNonTrivial) {
-  constexpr int kInitialValue = 123;
-  constexpr int kExpectedValue = 0;  // Expect value-construction behavior
-  constexpr int len = 5;
-
-  struct TestObj {
-    int val{kExpectedValue};
-  };
-  static_assert(absl::is_trivially_destructible<TestObj>::value, "");
-
-  TestObj objs[len];
-  for (auto& obj : objs) {
-    obj.val = kInitialValue;
-  }
-
-  absl::memory_internal::uninitialized_default_construct_n(objs, len);
-  for (auto& obj : objs) {
-    EXPECT_EQ(obj.val, kExpectedValue);
-  }
-}
-
 }  // namespace