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diff --git a/absl/container/internal/test_allocator.h b/absl/container/internal/test_allocator.h
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+// Copyright 2018 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_CONTAINER_INTERNAL_TEST_ALLOCATOR_H_
+#define ABSL_CONTAINER_INTERNAL_TEST_ALLOCATOR_H_
+
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <type_traits>
+
+#include "gtest/gtest.h"
+#include "absl/base/config.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace container_internal {
+
+// This is a stateful allocator, but the state lives outside of the
+// allocator (in whatever test is using the allocator). This is odd
+// but helps in tests where the allocator is propagated into nested
+// containers - that chain of allocators uses the same state and is
+// thus easier to query for aggregate allocation information.
+template <typename T>
+class CountingAllocator {
+ public:
+  using Allocator = std::allocator<T>;
+  using AllocatorTraits = std::allocator_traits<Allocator>;
+  using value_type = typename AllocatorTraits::value_type;
+  using pointer = typename AllocatorTraits::pointer;
+  using const_pointer = typename AllocatorTraits::const_pointer;
+  using size_type = typename AllocatorTraits::size_type;
+  using difference_type = typename AllocatorTraits::difference_type;
+
+  CountingAllocator() = default;
+  explicit CountingAllocator(int64_t* bytes_used) : bytes_used_(bytes_used) {}
+  CountingAllocator(int64_t* bytes_used, int64_t* instance_count)
+      : bytes_used_(bytes_used), instance_count_(instance_count) {}
+
+  template <typename U>
+  CountingAllocator(const CountingAllocator<U>& x)
+      : bytes_used_(x.bytes_used_), instance_count_(x.instance_count_) {}
+
+  pointer allocate(
+      size_type n,
+      typename AllocatorTraits::const_void_pointer hint = nullptr) {
+    Allocator allocator;
+    pointer ptr = AllocatorTraits::allocate(allocator, n, hint);
+    if (bytes_used_ != nullptr) {
+      *bytes_used_ += n * sizeof(T);
+    }
+    return ptr;
+  }
+
+  void deallocate(pointer p, size_type n) {
+    Allocator allocator;
+    AllocatorTraits::deallocate(allocator, p, n);
+    if (bytes_used_ != nullptr) {
+      *bytes_used_ -= n * sizeof(T);
+    }
+  }
+
+  template <typename U, typename... Args>
+  void construct(U* p, Args&&... args) {
+    Allocator allocator;
+    AllocatorTraits::construct(allocator, p, std::forward<Args>(args)...);
+    if (instance_count_ != nullptr) {
+      *instance_count_ += 1;
+    }
+  }
+
+  template <typename U>
+  void destroy(U* p) {
+    Allocator allocator;
+    // Ignore GCC warning bug.
+#if ABSL_INTERNAL_HAVE_MIN_GNUC_VERSION(12, 0)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wuse-after-free"
+#endif
+    AllocatorTraits::destroy(allocator, p);
+#if ABSL_INTERNAL_HAVE_MIN_GNUC_VERSION(12, 0)
+#pragma GCC diagnostic pop
+#endif
+    if (instance_count_ != nullptr) {
+      *instance_count_ -= 1;
+    }
+  }
+
+  template <typename U>
+  class rebind {
+   public:
+    using other = CountingAllocator<U>;
+  };
+
+  friend bool operator==(const CountingAllocator& a,
+                         const CountingAllocator& b) {
+    return a.bytes_used_ == b.bytes_used_ &&
+           a.instance_count_ == b.instance_count_;
+  }
+
+  friend bool operator!=(const CountingAllocator& a,
+                         const CountingAllocator& b) {
+    return !(a == b);
+  }
+
+  int64_t* bytes_used_ = nullptr;
+  int64_t* instance_count_ = nullptr;
+};
+
+template <typename T>
+struct CopyAssignPropagatingCountingAlloc : public CountingAllocator<T> {
+  using propagate_on_container_copy_assignment = std::true_type;
+
+  using Base = CountingAllocator<T>;
+  using Base::Base;
+
+  template <typename U>
+  explicit CopyAssignPropagatingCountingAlloc(
+      const CopyAssignPropagatingCountingAlloc<U>& other)
+      : Base(other.bytes_used_, other.instance_count_) {}
+
+  template <typename U>
+  struct rebind {
+    using other = CopyAssignPropagatingCountingAlloc<U>;
+  };
+};
+
+template <typename T>
+struct MoveAssignPropagatingCountingAlloc : public CountingAllocator<T> {
+  using propagate_on_container_move_assignment = std::true_type;
+
+  using Base = CountingAllocator<T>;
+  using Base::Base;
+
+  template <typename U>
+  explicit MoveAssignPropagatingCountingAlloc(
+      const MoveAssignPropagatingCountingAlloc<U>& other)
+      : Base(other.bytes_used_, other.instance_count_) {}
+
+  template <typename U>
+  struct rebind {
+    using other = MoveAssignPropagatingCountingAlloc<U>;
+  };
+};
+
+template <typename T>
+struct SwapPropagatingCountingAlloc : public CountingAllocator<T> {
+  using propagate_on_container_swap = std::true_type;
+
+  using Base = CountingAllocator<T>;
+  using Base::Base;
+
+  template <typename U>
+  explicit SwapPropagatingCountingAlloc(
+      const SwapPropagatingCountingAlloc<U>& other)
+      : Base(other.bytes_used_, other.instance_count_) {}
+
+  template <typename U>
+  struct rebind {
+    using other = SwapPropagatingCountingAlloc<U>;
+  };
+};
+
+// Tries to allocate memory at the minimum alignment even when the default
+// allocator uses a higher alignment.
+template <typename T>
+struct MinimumAlignmentAlloc : std::allocator<T> {
+  MinimumAlignmentAlloc() = default;
+
+  template <typename U>
+  explicit MinimumAlignmentAlloc(const MinimumAlignmentAlloc<U>& /*other*/) {}
+
+  template <class U>
+  struct rebind {
+    using other = MinimumAlignmentAlloc<U>;
+  };
+
+  T* allocate(size_t n) {
+    T* ptr = std::allocator<T>::allocate(n + 1);
+    char* cptr = reinterpret_cast<char*>(ptr);
+    cptr += alignof(T);
+    return reinterpret_cast<T*>(cptr);
+  }
+
+  void deallocate(T* ptr, size_t n) {
+    char* cptr = reinterpret_cast<char*>(ptr);
+    cptr -= alignof(T);
+    std::allocator<T>::deallocate(reinterpret_cast<T*>(cptr), n + 1);
+  }
+};
+
+inline bool IsAssertEnabled() {
+  // Use an assert with side-effects to figure out if they are actually enabled.
+  bool assert_enabled = false;
+  assert([&]() {  // NOLINT
+    assert_enabled = true;
+    return true;
+  }());
+  return assert_enabled;
+}
+
+template <template <class Alloc> class Container>
+void TestCopyAssignAllocPropagation() {
+  int64_t bytes1 = 0, instances1 = 0, bytes2 = 0, instances2 = 0;
+  CopyAssignPropagatingCountingAlloc<int> allocator1(&bytes1, &instances1);
+  CopyAssignPropagatingCountingAlloc<int> allocator2(&bytes2, &instances2);
+
+  // Test propagating allocator_type.
+  {
+    Container<CopyAssignPropagatingCountingAlloc<int>> c1(allocator1);
+    Container<CopyAssignPropagatingCountingAlloc<int>> c2(allocator2);
+
+    for (int i = 0; i < 100; ++i) c1.insert(i);
+
+    EXPECT_NE(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+
+    c2 = c1;
+
+    EXPECT_EQ(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 200);
+    EXPECT_EQ(instances2, 0);
+  }
+  // Test non-propagating allocator_type with different allocators.
+  {
+    Container<CountingAllocator<int>> c1(allocator1), c2(allocator2);
+
+    for (int i = 0; i < 100; ++i) c1.insert(i);
+
+    EXPECT_EQ(c2.get_allocator(), allocator2);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+
+    c2 = c1;
+
+    EXPECT_EQ(c2.get_allocator(), allocator2);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 100);
+  }
+  EXPECT_EQ(bytes1, 0);
+  EXPECT_EQ(instances1, 0);
+  EXPECT_EQ(bytes2, 0);
+  EXPECT_EQ(instances2, 0);
+}
+
+template <template <class Alloc> class Container>
+void TestMoveAssignAllocPropagation() {
+  int64_t bytes1 = 0, instances1 = 0, bytes2 = 0, instances2 = 0;
+  MoveAssignPropagatingCountingAlloc<int> allocator1(&bytes1, &instances1);
+  MoveAssignPropagatingCountingAlloc<int> allocator2(&bytes2, &instances2);
+
+  // Test propagating allocator_type.
+  {
+    Container<MoveAssignPropagatingCountingAlloc<int>> c1(allocator1);
+    Container<MoveAssignPropagatingCountingAlloc<int>> c2(allocator2);
+
+    for (int i = 0; i < 100; ++i) c1.insert(i);
+
+    EXPECT_NE(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+
+    c2 = std::move(c1);
+
+    EXPECT_EQ(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+  }
+  // Test non-propagating allocator_type with equal allocators.
+  {
+    Container<CountingAllocator<int>> c1(allocator1), c2(allocator1);
+
+    for (int i = 0; i < 100; ++i) c1.insert(i);
+
+    EXPECT_EQ(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+
+    c2 = std::move(c1);
+
+    EXPECT_EQ(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+  }
+  // Test non-propagating allocator_type with different allocators.
+  {
+    Container<CountingAllocator<int>> c1(allocator1), c2(allocator2);
+
+    for (int i = 0; i < 100; ++i) c1.insert(i);
+
+    EXPECT_NE(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+
+    c2 = std::move(c1);
+
+    EXPECT_EQ(c2.get_allocator(), allocator2);
+    EXPECT_LE(instances1, 100);  // The values in c1 may or may not have been
+                                 // destroyed at this point.
+    EXPECT_EQ(instances2, 100);
+  }
+  EXPECT_EQ(bytes1, 0);
+  EXPECT_EQ(instances1, 0);
+  EXPECT_EQ(bytes2, 0);
+  EXPECT_EQ(instances2, 0);
+}
+
+template <template <class Alloc> class Container>
+void TestSwapAllocPropagation() {
+  int64_t bytes1 = 0, instances1 = 0, bytes2 = 0, instances2 = 0;
+  SwapPropagatingCountingAlloc<int> allocator1(&bytes1, &instances1);
+  SwapPropagatingCountingAlloc<int> allocator2(&bytes2, &instances2);
+
+  // Test propagating allocator_type.
+  {
+    Container<SwapPropagatingCountingAlloc<int>> c1(allocator1), c2(allocator2);
+
+    for (int i = 0; i < 100; ++i) c1.insert(i);
+
+    EXPECT_NE(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+
+    c2.swap(c1);
+
+    EXPECT_EQ(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+  }
+  // Test non-propagating allocator_type with equal allocators.
+  {
+    Container<CountingAllocator<int>> c1(allocator1), c2(allocator1);
+
+    for (int i = 0; i < 100; ++i) c1.insert(i);
+
+    EXPECT_EQ(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+
+    c2.swap(c1);
+
+    EXPECT_EQ(c2.get_allocator(), allocator1);
+    EXPECT_EQ(instances1, 100);
+    EXPECT_EQ(instances2, 0);
+  }
+  // Test non-propagating allocator_type with different allocators.
+  {
+    Container<CountingAllocator<int>> c1(allocator1), c2(allocator2);
+
+    for (int i = 0; i < 100; ++i) c1.insert(i);
+
+    EXPECT_NE(c1.get_allocator(), c2.get_allocator());
+    if (IsAssertEnabled()) {
+      EXPECT_DEATH_IF_SUPPORTED(c2.swap(c1), "");
+    }
+  }
+  EXPECT_EQ(bytes1, 0);
+  EXPECT_EQ(instances1, 0);
+  EXPECT_EQ(bytes2, 0);
+  EXPECT_EQ(instances2, 0);
+}
+
+template <template <class Alloc> class Container>
+void TestAllocPropagation() {
+  TestCopyAssignAllocPropagation<Container>();
+  TestMoveAssignAllocPropagation<Container>();
+  TestSwapAllocPropagation<Container>();
+}
+
+}  // namespace container_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_CONTAINER_INTERNAL_TEST_ALLOCATOR_H_