chore(3p/abseil_cpp): unvendor abseil_cpp r/3786

we weren't actually using these sources anymore, okay?

Change-Id: If701571d9716de308d3512e1eb22c35db0877a66
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5248
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: tazjin <tazjin@tvl.su>

1 files changed, 0 insertions, 2827 deletions

diff --git a/third_party/abseil_cpp/absl/container/btree_test.cc b/third_party/abseil_cpp/absl/container/btree_test.cc
deleted file mode 100644
index 9b1b6436c7ca..000000000000
--- a/third_party/abseil_cpp/absl/container/btree_test.cc
+++ /dev/null
@@ -1,2827 +0,0 @@
-// 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.
-
-#include "absl/container/btree_test.h"
-
-#include <cstdint>
-#include <limits>
-#include <map>
-#include <memory>
-#include <stdexcept>
-#include <string>
-#include <type_traits>
-#include <utility>
-
-#include "gmock/gmock.h"
-#include "gtest/gtest.h"
-#include "absl/base/internal/raw_logging.h"
-#include "absl/base/macros.h"
-#include "absl/container/btree_map.h"
-#include "absl/container/btree_set.h"
-#include "absl/container/internal/counting_allocator.h"
-#include "absl/container/internal/test_instance_tracker.h"
-#include "absl/flags/flag.h"
-#include "absl/hash/hash_testing.h"
-#include "absl/memory/memory.h"
-#include "absl/meta/type_traits.h"
-#include "absl/strings/str_cat.h"
-#include "absl/strings/str_split.h"
-#include "absl/strings/string_view.h"
-#include "absl/types/compare.h"
-
-ABSL_FLAG(int, test_values, 10000, "The number of values to use for tests");
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace container_internal {
-namespace {
-
-using ::absl::test_internal::CopyableMovableInstance;
-using ::absl::test_internal::InstanceTracker;
-using ::absl::test_internal::MovableOnlyInstance;
-using ::testing::ElementsAre;
-using ::testing::ElementsAreArray;
-using ::testing::IsEmpty;
-using ::testing::IsNull;
-using ::testing::Pair;
-using ::testing::SizeIs;
-
-template <typename T, typename U>
-void CheckPairEquals(const T &x, const U &y) {
-  ABSL_INTERNAL_CHECK(x == y, "Values are unequal.");
-}
-
-template <typename T, typename U, typename V, typename W>
-void CheckPairEquals(const std::pair<T, U> &x, const std::pair<V, W> &y) {
-  CheckPairEquals(x.first, y.first);
-  CheckPairEquals(x.second, y.second);
-}
-}  // namespace
-
-// The base class for a sorted associative container checker. TreeType is the
-// container type to check and CheckerType is the container type to check
-// against. TreeType is expected to be btree_{set,map,multiset,multimap} and
-// CheckerType is expected to be {set,map,multiset,multimap}.
-template <typename TreeType, typename CheckerType>
-class base_checker {
- public:
-  using key_type = typename TreeType::key_type;
-  using value_type = typename TreeType::value_type;
-  using key_compare = typename TreeType::key_compare;
-  using pointer = typename TreeType::pointer;
-  using const_pointer = typename TreeType::const_pointer;
-  using reference = typename TreeType::reference;
-  using const_reference = typename TreeType::const_reference;
-  using size_type = typename TreeType::size_type;
-  using difference_type = typename TreeType::difference_type;
-  using iterator = typename TreeType::iterator;
-  using const_iterator = typename TreeType::const_iterator;
-  using reverse_iterator = typename TreeType::reverse_iterator;
-  using const_reverse_iterator = typename TreeType::const_reverse_iterator;
-
- public:
-  base_checker() : const_tree_(tree_) {}
-  base_checker(const base_checker &other)
-      : tree_(other.tree_), const_tree_(tree_), checker_(other.checker_) {}
-  template <typename InputIterator>
-  base_checker(InputIterator b, InputIterator e)
-      : tree_(b, e), const_tree_(tree_), checker_(b, e) {}
-
-  iterator begin() { return tree_.begin(); }
-  const_iterator begin() const { return tree_.begin(); }
-  iterator end() { return tree_.end(); }
-  const_iterator end() const { return tree_.end(); }
-  reverse_iterator rbegin() { return tree_.rbegin(); }
-  const_reverse_iterator rbegin() const { return tree_.rbegin(); }
-  reverse_iterator rend() { return tree_.rend(); }
-  const_reverse_iterator rend() const { return tree_.rend(); }
-
-  template <typename IterType, typename CheckerIterType>
-  IterType iter_check(IterType tree_iter, CheckerIterType checker_iter) const {
-    if (tree_iter == tree_.end()) {
-      ABSL_INTERNAL_CHECK(checker_iter == checker_.end(),
-                          "Checker iterator not at end.");
-    } else {
-      CheckPairEquals(*tree_iter, *checker_iter);
-    }
-    return tree_iter;
-  }
-  template <typename IterType, typename CheckerIterType>
-  IterType riter_check(IterType tree_iter, CheckerIterType checker_iter) const {
-    if (tree_iter == tree_.rend()) {
-      ABSL_INTERNAL_CHECK(checker_iter == checker_.rend(),
-                          "Checker iterator not at rend.");
-    } else {
-      CheckPairEquals(*tree_iter, *checker_iter);
-    }
-    return tree_iter;
-  }
-  void value_check(const value_type &v) {
-    typename KeyOfValue<typename TreeType::key_type,
-                        typename TreeType::value_type>::type key_of_value;
-    const key_type &key = key_of_value(v);
-    CheckPairEquals(*find(key), v);
-    lower_bound(key);
-    upper_bound(key);
-    equal_range(key);
-    contains(key);
-    count(key);
-  }
-  void erase_check(const key_type &key) {
-    EXPECT_FALSE(tree_.contains(key));
-    EXPECT_EQ(tree_.find(key), const_tree_.end());
-    EXPECT_FALSE(const_tree_.contains(key));
-    EXPECT_EQ(const_tree_.find(key), tree_.end());
-    EXPECT_EQ(tree_.equal_range(key).first,
-              const_tree_.equal_range(key).second);
-  }
-
-  iterator lower_bound(const key_type &key) {
-    return iter_check(tree_.lower_bound(key), checker_.lower_bound(key));
-  }
-  const_iterator lower_bound(const key_type &key) const {
-    return iter_check(tree_.lower_bound(key), checker_.lower_bound(key));
-  }
-  iterator upper_bound(const key_type &key) {
-    return iter_check(tree_.upper_bound(key), checker_.upper_bound(key));
-  }
-  const_iterator upper_bound(const key_type &key) const {
-    return iter_check(tree_.upper_bound(key), checker_.upper_bound(key));
-  }
-  std::pair<iterator, iterator> equal_range(const key_type &key) {
-    std::pair<typename CheckerType::iterator, typename CheckerType::iterator>
-        checker_res = checker_.equal_range(key);
-    std::pair<iterator, iterator> tree_res = tree_.equal_range(key);
-    iter_check(tree_res.first, checker_res.first);
-    iter_check(tree_res.second, checker_res.second);
-    return tree_res;
-  }
-  std::pair<const_iterator, const_iterator> equal_range(
-      const key_type &key) const {
-    std::pair<typename CheckerType::const_iterator,
-              typename CheckerType::const_iterator>
-        checker_res = checker_.equal_range(key);
-    std::pair<const_iterator, const_iterator> tree_res = tree_.equal_range(key);
-    iter_check(tree_res.first, checker_res.first);
-    iter_check(tree_res.second, checker_res.second);
-    return tree_res;
-  }
-  iterator find(const key_type &key) {
-    return iter_check(tree_.find(key), checker_.find(key));
-  }
-  const_iterator find(const key_type &key) const {
-    return iter_check(tree_.find(key), checker_.find(key));
-  }
-  bool contains(const key_type &key) const { return find(key) != end(); }
-  size_type count(const key_type &key) const {
-    size_type res = checker_.count(key);
-    EXPECT_EQ(res, tree_.count(key));
-    return res;
-  }
-
-  base_checker &operator=(const base_checker &other) {
-    tree_ = other.tree_;
-    checker_ = other.checker_;
-    return *this;
-  }
-
-  int erase(const key_type &key) {
-    int size = tree_.size();
-    int res = checker_.erase(key);
-    EXPECT_EQ(res, tree_.count(key));
-    EXPECT_EQ(res, tree_.erase(key));
-    EXPECT_EQ(tree_.count(key), 0);
-    EXPECT_EQ(tree_.size(), size - res);
-    erase_check(key);
-    return res;
-  }
-  iterator erase(iterator iter) {
-    key_type key = iter.key();
-    int size = tree_.size();
-    int count = tree_.count(key);
-    auto checker_iter = checker_.lower_bound(key);
-    for (iterator tmp(tree_.lower_bound(key)); tmp != iter; ++tmp) {
-      ++checker_iter;
-    }
-    auto checker_next = checker_iter;
-    ++checker_next;
-    checker_.erase(checker_iter);
-    iter = tree_.erase(iter);
-    EXPECT_EQ(tree_.size(), checker_.size());
-    EXPECT_EQ(tree_.size(), size - 1);
-    EXPECT_EQ(tree_.count(key), count - 1);
-    if (count == 1) {
-      erase_check(key);
-    }
-    return iter_check(iter, checker_next);
-  }
-
-  void erase(iterator begin, iterator end) {
-    int size = tree_.size();
-    int count = std::distance(begin, end);
-    auto checker_begin = checker_.lower_bound(begin.key());
-    for (iterator tmp(tree_.lower_bound(begin.key())); tmp != begin; ++tmp) {
-      ++checker_begin;
-    }
-    auto checker_end =
-        end == tree_.end() ? checker_.end() : checker_.lower_bound(end.key());
-    if (end != tree_.end()) {
-      for (iterator tmp(tree_.lower_bound(end.key())); tmp != end; ++tmp) {
-        ++checker_end;
-      }
-    }
-    const auto checker_ret = checker_.erase(checker_begin, checker_end);
-    const auto tree_ret = tree_.erase(begin, end);
-    EXPECT_EQ(std::distance(checker_.begin(), checker_ret),
-              std::distance(tree_.begin(), tree_ret));
-    EXPECT_EQ(tree_.size(), checker_.size());
-    EXPECT_EQ(tree_.size(), size - count);
-  }
-
-  void clear() {
-    tree_.clear();
-    checker_.clear();
-  }
-  void swap(base_checker &other) {
-    tree_.swap(other.tree_);
-    checker_.swap(other.checker_);
-  }
-
-  void verify() const {
-    tree_.verify();
-    EXPECT_EQ(tree_.size(), checker_.size());
-
-    // Move through the forward iterators using increment.
-    auto checker_iter = checker_.begin();
-    const_iterator tree_iter(tree_.begin());
-    for (; tree_iter != tree_.end(); ++tree_iter, ++checker_iter) {
-      CheckPairEquals(*tree_iter, *checker_iter);
-    }
-
-    // Move through the forward iterators using decrement.
-    for (int n = tree_.size() - 1; n >= 0; --n) {
-      iter_check(tree_iter, checker_iter);
-      --tree_iter;
-      --checker_iter;
-    }
-    EXPECT_EQ(tree_iter, tree_.begin());
-    EXPECT_EQ(checker_iter, checker_.begin());
-
-    // Move through the reverse iterators using increment.
-    auto checker_riter = checker_.rbegin();
-    const_reverse_iterator tree_riter(tree_.rbegin());
-    for (; tree_riter != tree_.rend(); ++tree_riter, ++checker_riter) {
-      CheckPairEquals(*tree_riter, *checker_riter);
-    }
-
-    // Move through the reverse iterators using decrement.
-    for (int n = tree_.size() - 1; n >= 0; --n) {
-      riter_check(tree_riter, checker_riter);
-      --tree_riter;
-      --checker_riter;
-    }
-    EXPECT_EQ(tree_riter, tree_.rbegin());
-    EXPECT_EQ(checker_riter, checker_.rbegin());
-  }
-
-  const TreeType &tree() const { return tree_; }
-
-  size_type size() const {
-    EXPECT_EQ(tree_.size(), checker_.size());
-    return tree_.size();
-  }
-  size_type max_size() const { return tree_.max_size(); }
-  bool empty() const {
-    EXPECT_EQ(tree_.empty(), checker_.empty());
-    return tree_.empty();
-  }
-
- protected:
-  TreeType tree_;
-  const TreeType &const_tree_;
-  CheckerType checker_;
-};
-
-namespace {
-// A checker for unique sorted associative containers. TreeType is expected to
-// be btree_{set,map} and CheckerType is expected to be {set,map}.
-template <typename TreeType, typename CheckerType>
-class unique_checker : public base_checker<TreeType, CheckerType> {
-  using super_type = base_checker<TreeType, CheckerType>;
-
- public:
-  using iterator = typename super_type::iterator;
-  using value_type = typename super_type::value_type;
-
- public:
-  unique_checker() : super_type() {}
-  unique_checker(const unique_checker &other) : super_type(other) {}
-  template <class InputIterator>
-  unique_checker(InputIterator b, InputIterator e) : super_type(b, e) {}
-  unique_checker &operator=(const unique_checker &) = default;
-
-  // Insertion routines.
-  std::pair<iterator, bool> insert(const value_type &v) {
-    int size = this->tree_.size();
-    std::pair<typename CheckerType::iterator, bool> checker_res =
-        this->checker_.insert(v);
-    std::pair<iterator, bool> tree_res = this->tree_.insert(v);
-    CheckPairEquals(*tree_res.first, *checker_res.first);
-    EXPECT_EQ(tree_res.second, checker_res.second);
-    EXPECT_EQ(this->tree_.size(), this->checker_.size());
-    EXPECT_EQ(this->tree_.size(), size + tree_res.second);
-    return tree_res;
-  }
-  iterator insert(iterator position, const value_type &v) {
-    int size = this->tree_.size();
-    std::pair<typename CheckerType::iterator, bool> checker_res =
-        this->checker_.insert(v);
-    iterator tree_res = this->tree_.insert(position, v);
-    CheckPairEquals(*tree_res, *checker_res.first);
-    EXPECT_EQ(this->tree_.size(), this->checker_.size());
-    EXPECT_EQ(this->tree_.size(), size + checker_res.second);
-    return tree_res;
-  }
-  template <typename InputIterator>
-  void insert(InputIterator b, InputIterator e) {
-    for (; b != e; ++b) {
-      insert(*b);
-    }
-  }
-};
-
-// A checker for multiple sorted associative containers. TreeType is expected
-// to be btree_{multiset,multimap} and CheckerType is expected to be
-// {multiset,multimap}.
-template <typename TreeType, typename CheckerType>
-class multi_checker : public base_checker<TreeType, CheckerType> {
-  using super_type = base_checker<TreeType, CheckerType>;
-
- public:
-  using iterator = typename super_type::iterator;
-  using value_type = typename super_type::value_type;
-
- public:
-  multi_checker() : super_type() {}
-  multi_checker(const multi_checker &other) : super_type(other) {}
-  template <class InputIterator>
-  multi_checker(InputIterator b, InputIterator e) : super_type(b, e) {}
-  multi_checker &operator=(const multi_checker &) = default;
-
-  // Insertion routines.
-  iterator insert(const value_type &v) {
-    int size = this->tree_.size();
-    auto checker_res = this->checker_.insert(v);
-    iterator tree_res = this->tree_.insert(v);
-    CheckPairEquals(*tree_res, *checker_res);
-    EXPECT_EQ(this->tree_.size(), this->checker_.size());
-    EXPECT_EQ(this->tree_.size(), size + 1);
-    return tree_res;
-  }
-  iterator insert(iterator position, const value_type &v) {
-    int size = this->tree_.size();
-    auto checker_res = this->checker_.insert(v);
-    iterator tree_res = this->tree_.insert(position, v);
-    CheckPairEquals(*tree_res, *checker_res);
-    EXPECT_EQ(this->tree_.size(), this->checker_.size());
-    EXPECT_EQ(this->tree_.size(), size + 1);
-    return tree_res;
-  }
-  template <typename InputIterator>
-  void insert(InputIterator b, InputIterator e) {
-    for (; b != e; ++b) {
-      insert(*b);
-    }
-  }
-};
-
-template <typename T, typename V>
-void DoTest(const char *name, T *b, const std::vector<V> &values) {
-  typename KeyOfValue<typename T::key_type, V>::type key_of_value;
-
-  T &mutable_b = *b;
-  const T &const_b = *b;
-
-  // Test insert.
-  for (int i = 0; i < values.size(); ++i) {
-    mutable_b.insert(values[i]);
-    mutable_b.value_check(values[i]);
-  }
-  ASSERT_EQ(mutable_b.size(), values.size());
-
-  const_b.verify();
-
-  // Test copy constructor.
-  T b_copy(const_b);
-  EXPECT_EQ(b_copy.size(), const_b.size());
-  for (int i = 0; i < values.size(); ++i) {
-    CheckPairEquals(*b_copy.find(key_of_value(values[i])), values[i]);
-  }
-
-  // Test range constructor.
-  T b_range(const_b.begin(), const_b.end());
-  EXPECT_EQ(b_range.size(), const_b.size());
-  for (int i = 0; i < values.size(); ++i) {
-    CheckPairEquals(*b_range.find(key_of_value(values[i])), values[i]);
-  }
-
-  // Test range insertion for values that already exist.
-  b_range.insert(b_copy.begin(), b_copy.end());
-  b_range.verify();
-
-  // Test range insertion for new values.
-  b_range.clear();
-  b_range.insert(b_copy.begin(), b_copy.end());
-  EXPECT_EQ(b_range.size(), b_copy.size());
-  for (int i = 0; i < values.size(); ++i) {
-    CheckPairEquals(*b_range.find(key_of_value(values[i])), values[i]);
-  }
-
-  // Test assignment to self. Nothing should change.
-  b_range.operator=(b_range);
-  EXPECT_EQ(b_range.size(), b_copy.size());
-
-  // Test assignment of new values.
-  b_range.clear();
-  b_range = b_copy;
-  EXPECT_EQ(b_range.size(), b_copy.size());
-
-  // Test swap.
-  b_range.clear();
-  b_range.swap(b_copy);
-  EXPECT_EQ(b_copy.size(), 0);
-  EXPECT_EQ(b_range.size(), const_b.size());
-  for (int i = 0; i < values.size(); ++i) {
-    CheckPairEquals(*b_range.find(key_of_value(values[i])), values[i]);
-  }
-  b_range.swap(b_copy);
-
-  // Test non-member function swap.
-  swap(b_range, b_copy);
-  EXPECT_EQ(b_copy.size(), 0);
-  EXPECT_EQ(b_range.size(), const_b.size());
-  for (int i = 0; i < values.size(); ++i) {
-    CheckPairEquals(*b_range.find(key_of_value(values[i])), values[i]);
-  }
-  swap(b_range, b_copy);
-
-  // Test erase via values.
-  for (int i = 0; i < values.size(); ++i) {
-    mutable_b.erase(key_of_value(values[i]));
-    // Erasing a non-existent key should have no effect.
-    ASSERT_EQ(mutable_b.erase(key_of_value(values[i])), 0);
-  }
-
-  const_b.verify();
-  EXPECT_EQ(const_b.size(), 0);
-
-  // Test erase via iterators.
-  mutable_b = b_copy;
-  for (int i = 0; i < values.size(); ++i) {
-    mutable_b.erase(mutable_b.find(key_of_value(values[i])));
-  }
-
-  const_b.verify();
-  EXPECT_EQ(const_b.size(), 0);
-
-  // Test insert with hint.
-  for (int i = 0; i < values.size(); i++) {
-    mutable_b.insert(mutable_b.upper_bound(key_of_value(values[i])), values[i]);
-  }
-
-  const_b.verify();
-
-  // Test range erase.
-  mutable_b.erase(mutable_b.begin(), mutable_b.end());
-  EXPECT_EQ(mutable_b.size(), 0);
-  const_b.verify();
-
-  // First half.
-  mutable_b = b_copy;
-  typename T::iterator mutable_iter_end = mutable_b.begin();
-  for (int i = 0; i < values.size() / 2; ++i) ++mutable_iter_end;
-  mutable_b.erase(mutable_b.begin(), mutable_iter_end);
-  EXPECT_EQ(mutable_b.size(), values.size() - values.size() / 2);
-  const_b.verify();
-
-  // Second half.
-  mutable_b = b_copy;
-  typename T::iterator mutable_iter_begin = mutable_b.begin();
-  for (int i = 0; i < values.size() / 2; ++i) ++mutable_iter_begin;
-  mutable_b.erase(mutable_iter_begin, mutable_b.end());
-  EXPECT_EQ(mutable_b.size(), values.size() / 2);
-  const_b.verify();
-
-  // Second quarter.
-  mutable_b = b_copy;
-  mutable_iter_begin = mutable_b.begin();
-  for (int i = 0; i < values.size() / 4; ++i) ++mutable_iter_begin;
-  mutable_iter_end = mutable_iter_begin;
-  for (int i = 0; i < values.size() / 4; ++i) ++mutable_iter_end;
-  mutable_b.erase(mutable_iter_begin, mutable_iter_end);
-  EXPECT_EQ(mutable_b.size(), values.size() - values.size() / 4);
-  const_b.verify();
-
-  mutable_b.clear();
-}
-
-template <typename T>
-void ConstTest() {
-  using value_type = typename T::value_type;
-  typename KeyOfValue<typename T::key_type, value_type>::type key_of_value;
-
-  T mutable_b;
-  const T &const_b = mutable_b;
-
-  // Insert a single value into the container and test looking it up.
-  value_type value = Generator<value_type>(2)(2);
-  mutable_b.insert(value);
-  EXPECT_TRUE(mutable_b.contains(key_of_value(value)));
-  EXPECT_NE(mutable_b.find(key_of_value(value)), const_b.end());
-  EXPECT_TRUE(const_b.contains(key_of_value(value)));
-  EXPECT_NE(const_b.find(key_of_value(value)), mutable_b.end());
-  EXPECT_EQ(*const_b.lower_bound(key_of_value(value)), value);
-  EXPECT_EQ(const_b.upper_bound(key_of_value(value)), const_b.end());
-  EXPECT_EQ(*const_b.equal_range(key_of_value(value)).first, value);
-
-  // We can only create a non-const iterator from a non-const container.
-  typename T::iterator mutable_iter(mutable_b.begin());
-  EXPECT_EQ(mutable_iter, const_b.begin());
-  EXPECT_NE(mutable_iter, const_b.end());
-  EXPECT_EQ(const_b.begin(), mutable_iter);
-  EXPECT_NE(const_b.end(), mutable_iter);
-  typename T::reverse_iterator mutable_riter(mutable_b.rbegin());
-  EXPECT_EQ(mutable_riter, const_b.rbegin());
-  EXPECT_NE(mutable_riter, const_b.rend());
-  EXPECT_EQ(const_b.rbegin(), mutable_riter);
-  EXPECT_NE(const_b.rend(), mutable_riter);
-
-  // We can create a const iterator from a non-const iterator.
-  typename T::const_iterator const_iter(mutable_iter);
-  EXPECT_EQ(const_iter, mutable_b.begin());
-  EXPECT_NE(const_iter, mutable_b.end());
-  EXPECT_EQ(mutable_b.begin(), const_iter);
-  EXPECT_NE(mutable_b.end(), const_iter);
-  typename T::const_reverse_iterator const_riter(mutable_riter);
-  EXPECT_EQ(const_riter, mutable_b.rbegin());
-  EXPECT_NE(const_riter, mutable_b.rend());
-  EXPECT_EQ(mutable_b.rbegin(), const_riter);
-  EXPECT_NE(mutable_b.rend(), const_riter);
-
-  // Make sure various methods can be invoked on a const container.
-  const_b.verify();
-  ASSERT_TRUE(!const_b.empty());
-  EXPECT_EQ(const_b.size(), 1);
-  EXPECT_GT(const_b.max_size(), 0);
-  EXPECT_TRUE(const_b.contains(key_of_value(value)));
-  EXPECT_EQ(const_b.count(key_of_value(value)), 1);
-}
-
-template <typename T, typename C>
-void BtreeTest() {
-  ConstTest<T>();
-
-  using V = typename remove_pair_const<typename T::value_type>::type;
-  const std::vector<V> random_values = GenerateValuesWithSeed<V>(
-      absl::GetFlag(FLAGS_test_values), 4 * absl::GetFlag(FLAGS_test_values),
-      testing::GTEST_FLAG(random_seed));
-
-  unique_checker<T, C> container;
-
-  // Test key insertion/deletion in sorted order.
-  std::vector<V> sorted_values(random_values);
-  std::sort(sorted_values.begin(), sorted_values.end());
-  DoTest("sorted:    ", &container, sorted_values);
-
-  // Test key insertion/deletion in reverse sorted order.
-  std::reverse(sorted_values.begin(), sorted_values.end());
-  DoTest("rsorted:   ", &container, sorted_values);
-
-  // Test key insertion/deletion in random order.
-  DoTest("random:    ", &container, random_values);
-}
-
-template <typename T, typename C>
-void BtreeMultiTest() {
-  ConstTest<T>();
-
-  using V = typename remove_pair_const<typename T::value_type>::type;
-  const std::vector<V> random_values = GenerateValuesWithSeed<V>(
-      absl::GetFlag(FLAGS_test_values), 4 * absl::GetFlag(FLAGS_test_values),
-      testing::GTEST_FLAG(random_seed));
-
-  multi_checker<T, C> container;
-
-  // Test keys in sorted order.
-  std::vector<V> sorted_values(random_values);
-  std::sort(sorted_values.begin(), sorted_values.end());
-  DoTest("sorted:    ", &container, sorted_values);
-
-  // Test keys in reverse sorted order.
-  std::reverse(sorted_values.begin(), sorted_values.end());
-  DoTest("rsorted:   ", &container, sorted_values);
-
-  // Test keys in random order.
-  DoTest("random:    ", &container, random_values);
-
-  // Test keys in random order w/ duplicates.
-  std::vector<V> duplicate_values(random_values);
-  duplicate_values.insert(duplicate_values.end(), random_values.begin(),
-                          random_values.end());
-  DoTest("duplicates:", &container, duplicate_values);
-
-  // Test all identical keys.
-  std::vector<V> identical_values(100);
-  std::fill(identical_values.begin(), identical_values.end(),
-            Generator<V>(2)(2));
-  DoTest("identical: ", &container, identical_values);
-}
-
-template <typename T>
-struct PropagatingCountingAlloc : public CountingAllocator<T> {
-  using propagate_on_container_copy_assignment = std::true_type;
-  using propagate_on_container_move_assignment = std::true_type;
-  using propagate_on_container_swap = std::true_type;
-
-  using Base = CountingAllocator<T>;
-  using Base::Base;
-
-  template <typename U>
-  explicit PropagatingCountingAlloc(const PropagatingCountingAlloc<U> &other)
-      : Base(other.bytes_used_) {}
-
-  template <typename U>
-  struct rebind {
-    using other = PropagatingCountingAlloc<U>;
-  };
-};
-
-template <typename T>
-void BtreeAllocatorTest() {
-  using value_type = typename T::value_type;
-
-  int64_t bytes1 = 0, bytes2 = 0;
-  PropagatingCountingAlloc<T> allocator1(&bytes1);
-  PropagatingCountingAlloc<T> allocator2(&bytes2);
-  Generator<value_type> generator(1000);
-
-  // Test that we allocate properly aligned memory. If we don't, then Layout
-  // will assert fail.
-  auto unused1 = allocator1.allocate(1);
-  auto unused2 = allocator2.allocate(1);
-
-  // Test copy assignment
-  {
-    T b1(typename T::key_compare(), allocator1);
-    T b2(typename T::key_compare(), allocator2);
-
-    int64_t original_bytes1 = bytes1;
-    b1.insert(generator(0));
-    EXPECT_GT(bytes1, original_bytes1);
-
-    // This should propagate the allocator.
-    b1 = b2;
-    EXPECT_EQ(b1.size(), 0);
-    EXPECT_EQ(b2.size(), 0);
-    EXPECT_EQ(bytes1, original_bytes1);
-
-    for (int i = 1; i < 1000; i++) {
-      b1.insert(generator(i));
-    }
-
-    // We should have allocated out of allocator2.
-    EXPECT_GT(bytes2, bytes1);
-  }
-
-  // Test move assignment
-  {
-    T b1(typename T::key_compare(), allocator1);
-    T b2(typename T::key_compare(), allocator2);
-
-    int64_t original_bytes1 = bytes1;
-    b1.insert(generator(0));
-    EXPECT_GT(bytes1, original_bytes1);
-
-    // This should propagate the allocator.
-    b1 = std::move(b2);
-    EXPECT_EQ(b1.size(), 0);
-    EXPECT_EQ(bytes1, original_bytes1);
-
-    for (int i = 1; i < 1000; i++) {
-      b1.insert(generator(i));
-    }
-
-    // We should have allocated out of allocator2.
-    EXPECT_GT(bytes2, bytes1);
-  }
-
-  // Test swap
-  {
-    T b1(typename T::key_compare(), allocator1);
-    T b2(typename T::key_compare(), allocator2);
-
-    int64_t original_bytes1 = bytes1;
-    b1.insert(generator(0));
-    EXPECT_GT(bytes1, original_bytes1);
-
-    // This should swap the allocators.
-    swap(b1, b2);
-    EXPECT_EQ(b1.size(), 0);
-    EXPECT_EQ(b2.size(), 1);
-    EXPECT_GT(bytes1, original_bytes1);
-
-    for (int i = 1; i < 1000; i++) {
-      b1.insert(generator(i));
-    }
-
-    // We should have allocated out of allocator2.
-    EXPECT_GT(bytes2, bytes1);
-  }
-
-  allocator1.deallocate(unused1, 1);
-  allocator2.deallocate(unused2, 1);
-}
-
-template <typename T>
-void BtreeMapTest() {
-  using value_type = typename T::value_type;
-  using mapped_type = typename T::mapped_type;
-
-  mapped_type m = Generator<mapped_type>(0)(0);
-  (void)m;
-
-  T b;
-
-  // Verify we can insert using operator[].
-  for (int i = 0; i < 1000; i++) {
-    value_type v = Generator<value_type>(1000)(i);
-    b[v.first] = v.second;
-  }
-  EXPECT_EQ(b.size(), 1000);
-
-  // Test whether we can use the "->" operator on iterators and
-  // reverse_iterators. This stresses the btree_map_params::pair_pointer
-  // mechanism.
-  EXPECT_EQ(b.begin()->first, Generator<value_type>(1000)(0).first);
-  EXPECT_EQ(b.begin()->second, Generator<value_type>(1000)(0).second);
-  EXPECT_EQ(b.rbegin()->first, Generator<value_type>(1000)(999).first);
-  EXPECT_EQ(b.rbegin()->second, Generator<value_type>(1000)(999).second);
-}
-
-template <typename T>
-void BtreeMultiMapTest() {
-  using mapped_type = typename T::mapped_type;
-  mapped_type m = Generator<mapped_type>(0)(0);
-  (void)m;
-}
-
-template <typename K, int N = 256>
-void SetTest() {
-  EXPECT_EQ(
-      sizeof(absl::btree_set<K>),
-      2 * sizeof(void *) + sizeof(typename absl::btree_set<K>::size_type));
-  using BtreeSet = absl::btree_set<K>;
-  using CountingBtreeSet =
-      absl::btree_set<K, std::less<K>, PropagatingCountingAlloc<K>>;
-  BtreeTest<BtreeSet, std::set<K>>();
-  BtreeAllocatorTest<CountingBtreeSet>();
-}
-
-template <typename K, int N = 256>
-void MapTest() {
-  EXPECT_EQ(
-      sizeof(absl::btree_map<K, K>),
-      2 * sizeof(void *) + sizeof(typename absl::btree_map<K, K>::size_type));
-  using BtreeMap = absl::btree_map<K, K>;
-  using CountingBtreeMap =
-      absl::btree_map<K, K, std::less<K>,
-                      PropagatingCountingAlloc<std::pair<const K, K>>>;
-  BtreeTest<BtreeMap, std::map<K, K>>();
-  BtreeAllocatorTest<CountingBtreeMap>();
-  BtreeMapTest<BtreeMap>();
-}
-
-TEST(Btree, set_int32) { SetTest<int32_t>(); }
-TEST(Btree, set_int64) { SetTest<int64_t>(); }
-TEST(Btree, set_string) { SetTest<std::string>(); }
-TEST(Btree, set_cord) { SetTest<absl::Cord>(); }
-TEST(Btree, set_pair) { SetTest<std::pair<int, int>>(); }
-TEST(Btree, map_int32) { MapTest<int32_t>(); }
-TEST(Btree, map_int64) { MapTest<int64_t>(); }
-TEST(Btree, map_string) { MapTest<std::string>(); }
-TEST(Btree, map_cord) { MapTest<absl::Cord>(); }
-TEST(Btree, map_pair) { MapTest<std::pair<int, int>>(); }
-
-template <typename K, int N = 256>
-void MultiSetTest() {
-  EXPECT_EQ(
-      sizeof(absl::btree_multiset<K>),
-      2 * sizeof(void *) + sizeof(typename absl::btree_multiset<K>::size_type));
-  using BtreeMSet = absl::btree_multiset<K>;
-  using CountingBtreeMSet =
-      absl::btree_multiset<K, std::less<K>, PropagatingCountingAlloc<K>>;
-  BtreeMultiTest<BtreeMSet, std::multiset<K>>();
-  BtreeAllocatorTest<CountingBtreeMSet>();
-}
-
-template <typename K, int N = 256>
-void MultiMapTest() {
-  EXPECT_EQ(sizeof(absl::btree_multimap<K, K>),
-            2 * sizeof(void *) +
-                sizeof(typename absl::btree_multimap<K, K>::size_type));
-  using BtreeMMap = absl::btree_multimap<K, K>;
-  using CountingBtreeMMap =
-      absl::btree_multimap<K, K, std::less<K>,
-                           PropagatingCountingAlloc<std::pair<const K, K>>>;
-  BtreeMultiTest<BtreeMMap, std::multimap<K, K>>();
-  BtreeMultiMapTest<BtreeMMap>();
-  BtreeAllocatorTest<CountingBtreeMMap>();
-}
-
-TEST(Btree, multiset_int32) { MultiSetTest<int32_t>(); }
-TEST(Btree, multiset_int64) { MultiSetTest<int64_t>(); }
-TEST(Btree, multiset_string) { MultiSetTest<std::string>(); }
-TEST(Btree, multiset_cord) { MultiSetTest<absl::Cord>(); }
-TEST(Btree, multiset_pair) { MultiSetTest<std::pair<int, int>>(); }
-TEST(Btree, multimap_int32) { MultiMapTest<int32_t>(); }
-TEST(Btree, multimap_int64) { MultiMapTest<int64_t>(); }
-TEST(Btree, multimap_string) { MultiMapTest<std::string>(); }
-TEST(Btree, multimap_cord) { MultiMapTest<absl::Cord>(); }
-TEST(Btree, multimap_pair) { MultiMapTest<std::pair<int, int>>(); }
-
-struct CompareIntToString {
-  bool operator()(const std::string &a, const std::string &b) const {
-    return a < b;
-  }
-  bool operator()(const std::string &a, int b) const {
-    return a < absl::StrCat(b);
-  }
-  bool operator()(int a, const std::string &b) const {
-    return absl::StrCat(a) < b;
-  }
-  using is_transparent = void;
-};
-
-struct NonTransparentCompare {
-  template <typename T, typename U>
-  bool operator()(const T &t, const U &u) const {
-    // Treating all comparators as transparent can cause inefficiencies (see
-    // N3657 C++ proposal). Test that for comparators without 'is_transparent'
-    // alias (like this one), we do not attempt heterogeneous lookup.
-    EXPECT_TRUE((std::is_same<T, U>()));
-    return t < u;
-  }
-};
-
-template <typename T>
-bool CanEraseWithEmptyBrace(T t, decltype(t.erase({})) *) {
-  return true;
-}
-
-template <typename T>
-bool CanEraseWithEmptyBrace(T, ...) {
-  return false;
-}
-
-template <typename T>
-void TestHeterogeneous(T table) {
-  auto lb = table.lower_bound("3");
-  EXPECT_EQ(lb, table.lower_bound(3));
-  EXPECT_NE(lb, table.lower_bound(4));
-  EXPECT_EQ(lb, table.lower_bound({"3"}));
-  EXPECT_NE(lb, table.lower_bound({}));
-
-  auto ub = table.upper_bound("3");
-  EXPECT_EQ(ub, table.upper_bound(3));
-  EXPECT_NE(ub, table.upper_bound(5));
-  EXPECT_EQ(ub, table.upper_bound({"3"}));
-  EXPECT_NE(ub, table.upper_bound({}));
-
-  auto er = table.equal_range("3");
-  EXPECT_EQ(er, table.equal_range(3));
-  EXPECT_NE(er, table.equal_range(4));
-  EXPECT_EQ(er, table.equal_range({"3"}));
-  EXPECT_NE(er, table.equal_range({}));
-
-  auto it = table.find("3");
-  EXPECT_EQ(it, table.find(3));
-  EXPECT_NE(it, table.find(4));
-  EXPECT_EQ(it, table.find({"3"}));
-  EXPECT_NE(it, table.find({}));
-
-  EXPECT_TRUE(table.contains(3));
-  EXPECT_FALSE(table.contains(4));
-  EXPECT_TRUE(table.count({"3"}));
-  EXPECT_FALSE(table.contains({}));
-
-  EXPECT_EQ(1, table.count(3));
-  EXPECT_EQ(0, table.count(4));
-  EXPECT_EQ(1, table.count({"3"}));
-  EXPECT_EQ(0, table.count({}));
-
-  auto copy = table;
-  copy.erase(3);
-  EXPECT_EQ(table.size() - 1, copy.size());
-  copy.erase(4);
-  EXPECT_EQ(table.size() - 1, copy.size());
-  copy.erase({"5"});
-  EXPECT_EQ(table.size() - 2, copy.size());
-  EXPECT_FALSE(CanEraseWithEmptyBrace(table, nullptr));
-
-  // Also run it with const T&.
-  if (std::is_class<T>()) TestHeterogeneous<const T &>(table);
-}
-
-TEST(Btree, HeterogeneousLookup) {
-  TestHeterogeneous(btree_set<std::string, CompareIntToString>{"1", "3", "5"});
-  TestHeterogeneous(btree_map<std::string, int, CompareIntToString>{
-      {"1", 1}, {"3", 3}, {"5", 5}});
-  TestHeterogeneous(
-      btree_multiset<std::string, CompareIntToString>{"1", "3", "5"});
-  TestHeterogeneous(btree_multimap<std::string, int, CompareIntToString>{
-      {"1", 1}, {"3", 3}, {"5", 5}});
-
-  // Only maps have .at()
-  btree_map<std::string, int, CompareIntToString> map{
-      {"", -1}, {"1", 1}, {"3", 3}, {"5", 5}};
-  EXPECT_EQ(1, map.at(1));
-  EXPECT_EQ(3, map.at({"3"}));
-  EXPECT_EQ(-1, map.at({}));
-  const auto &cmap = map;
-  EXPECT_EQ(1, cmap.at(1));
-  EXPECT_EQ(3, cmap.at({"3"}));
-  EXPECT_EQ(-1, cmap.at({}));
-}
-
-TEST(Btree, NoHeterogeneousLookupWithoutAlias) {
-  using StringSet = absl::btree_set<std::string, NonTransparentCompare>;
-  StringSet s;
-  ASSERT_TRUE(s.insert("hello").second);
-  ASSERT_TRUE(s.insert("world").second);
-  EXPECT_TRUE(s.end() == s.find("blah"));
-  EXPECT_TRUE(s.begin() == s.lower_bound("hello"));
-  EXPECT_EQ(1, s.count("world"));
-  EXPECT_TRUE(s.contains("hello"));
-  EXPECT_TRUE(s.contains("world"));
-  EXPECT_FALSE(s.contains("blah"));
-
-  using StringMultiSet =
-      absl::btree_multiset<std::string, NonTransparentCompare>;
-  StringMultiSet ms;
-  ms.insert("hello");
-  ms.insert("world");
-  ms.insert("world");
-  EXPECT_TRUE(ms.end() == ms.find("blah"));
-  EXPECT_TRUE(ms.begin() == ms.lower_bound("hello"));
-  EXPECT_EQ(2, ms.count("world"));
-  EXPECT_TRUE(ms.contains("hello"));
-  EXPECT_TRUE(ms.contains("world"));
-  EXPECT_FALSE(ms.contains("blah"));
-}
-
-TEST(Btree, DefaultTransparent) {
-  {
-    // `int` does not have a default transparent comparator.
-    // The input value is converted to key_type.
-    btree_set<int> s = {1};
-    double d = 1.1;
-    EXPECT_EQ(s.begin(), s.find(d));
-    EXPECT_TRUE(s.contains(d));
-  }
-
-  {
-    // `std::string` has heterogeneous support.
-    btree_set<std::string> s = {"A"};
-    EXPECT_EQ(s.begin(), s.find(absl::string_view("A")));
-    EXPECT_TRUE(s.contains(absl::string_view("A")));
-  }
-}
-
-class StringLike {
- public:
-  StringLike() = default;
-
-  StringLike(const char *s) : s_(s) {  // NOLINT
-    ++constructor_calls_;
-  }
-
-  bool operator<(const StringLike &a) const { return s_ < a.s_; }
-
-  static void clear_constructor_call_count() { constructor_calls_ = 0; }
-
-  static int constructor_calls() { return constructor_calls_; }
-
- private:
-  static int constructor_calls_;
-  std::string s_;
-};
-
-int StringLike::constructor_calls_ = 0;
-
-TEST(Btree, HeterogeneousLookupDoesntDegradePerformance) {
-  using StringSet = absl::btree_set<StringLike>;
-  StringSet s;
-  for (int i = 0; i < 100; ++i) {
-    ASSERT_TRUE(s.insert(absl::StrCat(i).c_str()).second);
-  }
-  StringLike::clear_constructor_call_count();
-  s.find("50");
-  ASSERT_EQ(1, StringLike::constructor_calls());
-
-  StringLike::clear_constructor_call_count();
-  s.contains("50");
-  ASSERT_EQ(1, StringLike::constructor_calls());
-
-  StringLike::clear_constructor_call_count();
-  s.count("50");
-  ASSERT_EQ(1, StringLike::constructor_calls());
-
-  StringLike::clear_constructor_call_count();
-  s.lower_bound("50");
-  ASSERT_EQ(1, StringLike::constructor_calls());
-
-  StringLike::clear_constructor_call_count();
-  s.upper_bound("50");
-  ASSERT_EQ(1, StringLike::constructor_calls());
-
-  StringLike::clear_constructor_call_count();
-  s.equal_range("50");
-  ASSERT_EQ(1, StringLike::constructor_calls());
-
-  StringLike::clear_constructor_call_count();
-  s.erase("50");
-  ASSERT_EQ(1, StringLike::constructor_calls());
-}
-
-// Verify that swapping btrees swaps the key comparison functors and that we can
-// use non-default constructible comparators.
-struct SubstringLess {
-  SubstringLess() = delete;
-  explicit SubstringLess(int length) : n(length) {}
-  bool operator()(const std::string &a, const std::string &b) const {
-    return absl::string_view(a).substr(0, n) <
-           absl::string_view(b).substr(0, n);
-  }
-  int n;
-};
-
-TEST(Btree, SwapKeyCompare) {
-  using SubstringSet = absl::btree_set<std::string, SubstringLess>;
-  SubstringSet s1(SubstringLess(1), SubstringSet::allocator_type());
-  SubstringSet s2(SubstringLess(2), SubstringSet::allocator_type());
-
-  ASSERT_TRUE(s1.insert("a").second);
-  ASSERT_FALSE(s1.insert("aa").second);
-
-  ASSERT_TRUE(s2.insert("a").second);
-  ASSERT_TRUE(s2.insert("aa").second);
-  ASSERT_FALSE(s2.insert("aaa").second);
-
-  swap(s1, s2);
-
-  ASSERT_TRUE(s1.insert("b").second);
-  ASSERT_TRUE(s1.insert("bb").second);
-  ASSERT_FALSE(s1.insert("bbb").second);
-
-  ASSERT_TRUE(s2.insert("b").second);
-  ASSERT_FALSE(s2.insert("bb").second);
-}
-
-TEST(Btree, UpperBoundRegression) {
-  // Regress a bug where upper_bound would default-construct a new key_compare
-  // instead of copying the existing one.
-  using SubstringSet = absl::btree_set<std::string, SubstringLess>;
-  SubstringSet my_set(SubstringLess(3));
-  my_set.insert("aab");
-  my_set.insert("abb");
-  // We call upper_bound("aaa").  If this correctly uses the length 3
-  // comparator, aaa < aab < abb, so we should get aab as the result.
-  // If it instead uses the default-constructed length 2 comparator,
-  // aa == aa < ab, so we'll get abb as our result.
-  SubstringSet::iterator it = my_set.upper_bound("aaa");
-  ASSERT_TRUE(it != my_set.end());
-  EXPECT_EQ("aab", *it);
-}
-
-TEST(Btree, Comparison) {
-  const int kSetSize = 1201;
-  absl::btree_set<int64_t> my_set;
-  for (int i = 0; i < kSetSize; ++i) {
-    my_set.insert(i);
-  }
-  absl::btree_set<int64_t> my_set_copy(my_set);
-  EXPECT_TRUE(my_set_copy == my_set);
-  EXPECT_TRUE(my_set == my_set_copy);
-  EXPECT_FALSE(my_set_copy != my_set);
-  EXPECT_FALSE(my_set != my_set_copy);
-
-  my_set.insert(kSetSize);
-  EXPECT_FALSE(my_set_copy == my_set);
-  EXPECT_FALSE(my_set == my_set_copy);
-  EXPECT_TRUE(my_set_copy != my_set);
-  EXPECT_TRUE(my_set != my_set_copy);
-
-  my_set.erase(kSetSize - 1);
-  EXPECT_FALSE(my_set_copy == my_set);
-  EXPECT_FALSE(my_set == my_set_copy);
-  EXPECT_TRUE(my_set_copy != my_set);
-  EXPECT_TRUE(my_set != my_set_copy);
-
-  absl::btree_map<std::string, int64_t> my_map;
-  for (int i = 0; i < kSetSize; ++i) {
-    my_map[std::string(i, 'a')] = i;
-  }
-  absl::btree_map<std::string, int64_t> my_map_copy(my_map);
-  EXPECT_TRUE(my_map_copy == my_map);
-  EXPECT_TRUE(my_map == my_map_copy);
-  EXPECT_FALSE(my_map_copy != my_map);
-  EXPECT_FALSE(my_map != my_map_copy);
-
-  ++my_map_copy[std::string(7, 'a')];
-  EXPECT_FALSE(my_map_copy == my_map);
-  EXPECT_FALSE(my_map == my_map_copy);
-  EXPECT_TRUE(my_map_copy != my_map);
-  EXPECT_TRUE(my_map != my_map_copy);
-
-  my_map_copy = my_map;
-  my_map["hello"] = kSetSize;
-  EXPECT_FALSE(my_map_copy == my_map);
-  EXPECT_FALSE(my_map == my_map_copy);
-  EXPECT_TRUE(my_map_copy != my_map);
-  EXPECT_TRUE(my_map != my_map_copy);
-
-  my_map.erase(std::string(kSetSize - 1, 'a'));
-  EXPECT_FALSE(my_map_copy == my_map);
-  EXPECT_FALSE(my_map == my_map_copy);
-  EXPECT_TRUE(my_map_copy != my_map);
-  EXPECT_TRUE(my_map != my_map_copy);
-}
-
-TEST(Btree, RangeCtorSanity) {
-  std::vector<int> ivec;
-  ivec.push_back(1);
-  std::map<int, int> imap;
-  imap.insert(std::make_pair(1, 2));
-  absl::btree_multiset<int> tmset(ivec.begin(), ivec.end());
-  absl::btree_multimap<int, int> tmmap(imap.begin(), imap.end());
-  absl::btree_set<int> tset(ivec.begin(), ivec.end());
-  absl::btree_map<int, int> tmap(imap.begin(), imap.end());
-  EXPECT_EQ(1, tmset.size());
-  EXPECT_EQ(1, tmmap.size());
-  EXPECT_EQ(1, tset.size());
-  EXPECT_EQ(1, tmap.size());
-}
-
-}  // namespace
-
-class BtreeNodePeer {
- public:
-  // Yields the size of a leaf node with a specific number of values.
-  template <typename ValueType>
-  constexpr static size_t GetTargetNodeSize(size_t target_values_per_node) {
-    return btree_node<
-        set_params<ValueType, std::less<ValueType>, std::allocator<ValueType>,
-                   /*TargetNodeSize=*/256,  // This parameter isn't used here.
-                   /*Multi=*/false>>::SizeWithNValues(target_values_per_node);
-  }
-
-  // Yields the number of values in a (non-root) leaf node for this btree.
-  template <typename Btree>
-  constexpr static size_t GetNumValuesPerNode() {
-    return btree_node<typename Btree::params_type>::kNodeValues;
-  }
-
-  template <typename Btree>
-  constexpr static size_t GetMaxFieldType() {
-    return std::numeric_limits<
-        typename btree_node<typename Btree::params_type>::field_type>::max();
-  }
-
-  template <typename Btree>
-  constexpr static bool UsesLinearNodeSearch() {
-    return btree_node<typename Btree::params_type>::use_linear_search::value;
-  }
-};
-
-namespace {
-
-class BtreeMapTest : public ::testing::Test {
- public:
-  struct Key {};
-  struct Cmp {
-    template <typename T>
-    bool operator()(T, T) const {
-      return false;
-    }
-  };
-
-  struct KeyLin {
-    using absl_btree_prefer_linear_node_search = std::true_type;
-  };
-  struct CmpLin : Cmp {
-    using absl_btree_prefer_linear_node_search = std::true_type;
-  };
-
-  struct KeyBin {
-    using absl_btree_prefer_linear_node_search = std::false_type;
-  };
-  struct CmpBin : Cmp {
-    using absl_btree_prefer_linear_node_search = std::false_type;
-  };
-
-  template <typename K, typename C>
-  static bool IsLinear() {
-    return BtreeNodePeer::UsesLinearNodeSearch<absl::btree_map<K, int, C>>();
-  }
-};
-
-TEST_F(BtreeMapTest, TestLinearSearchPreferredForKeyLinearViaAlias) {
-  // Test requesting linear search by directly exporting an alias.
-  EXPECT_FALSE((IsLinear<Key, Cmp>()));
-  EXPECT_TRUE((IsLinear<KeyLin, Cmp>()));
-  EXPECT_TRUE((IsLinear<Key, CmpLin>()));
-  EXPECT_TRUE((IsLinear<KeyLin, CmpLin>()));
-}
-
-TEST_F(BtreeMapTest, LinearChoiceTree) {
-  // Cmp has precedence, and is forcing binary
-  EXPECT_FALSE((IsLinear<Key, CmpBin>()));
-  EXPECT_FALSE((IsLinear<KeyLin, CmpBin>()));
-  EXPECT_FALSE((IsLinear<KeyBin, CmpBin>()));
-  EXPECT_FALSE((IsLinear<int, CmpBin>()));
-  EXPECT_FALSE((IsLinear<std::string, CmpBin>()));
-  // Cmp has precedence, and is forcing linear
-  EXPECT_TRUE((IsLinear<Key, CmpLin>()));
-  EXPECT_TRUE((IsLinear<KeyLin, CmpLin>()));
-  EXPECT_TRUE((IsLinear<KeyBin, CmpLin>()));
-  EXPECT_TRUE((IsLinear<int, CmpLin>()));
-  EXPECT_TRUE((IsLinear<std::string, CmpLin>()));
-  // Cmp has no preference, Key determines linear vs binary.
-  EXPECT_FALSE((IsLinear<Key, Cmp>()));
-  EXPECT_TRUE((IsLinear<KeyLin, Cmp>()));
-  EXPECT_FALSE((IsLinear<KeyBin, Cmp>()));
-  // arithmetic key w/ std::less or std::greater: linear
-  EXPECT_TRUE((IsLinear<int, std::less<int>>()));
-  EXPECT_TRUE((IsLinear<double, std::greater<double>>()));
-  // arithmetic key w/ custom compare: binary
-  EXPECT_FALSE((IsLinear<int, Cmp>()));
-  // non-arithmetic key: binary
-  EXPECT_FALSE((IsLinear<std::string, std::less<std::string>>()));
-}
-
-TEST(Btree, BtreeMapCanHoldMoveOnlyTypes) {
-  absl::btree_map<std::string, std::unique_ptr<std::string>> m;
-
-  std::unique_ptr<std::string> &v = m["A"];
-  EXPECT_TRUE(v == nullptr);
-  v.reset(new std::string("X"));
-
-  auto iter = m.find("A");
-  EXPECT_EQ("X", *iter->second);
-}
-
-TEST(Btree, InitializerListConstructor) {
-  absl::btree_set<std::string> set({"a", "b"});
-  EXPECT_EQ(set.count("a"), 1);
-  EXPECT_EQ(set.count("b"), 1);
-
-  absl::btree_multiset<int> mset({1, 1, 4});
-  EXPECT_EQ(mset.count(1), 2);
-  EXPECT_EQ(mset.count(4), 1);
-
-  absl::btree_map<int, int> map({{1, 5}, {2, 10}});
-  EXPECT_EQ(map[1], 5);
-  EXPECT_EQ(map[2], 10);
-
-  absl::btree_multimap<int, int> mmap({{1, 5}, {1, 10}});
-  auto range = mmap.equal_range(1);
-  auto it = range.first;
-  ASSERT_NE(it, range.second);
-  EXPECT_EQ(it->second, 5);
-  ASSERT_NE(++it, range.second);
-  EXPECT_EQ(it->second, 10);
-  EXPECT_EQ(++it, range.second);
-}
-
-TEST(Btree, InitializerListInsert) {
-  absl::btree_set<std::string> set;
-  set.insert({"a", "b"});
-  EXPECT_EQ(set.count("a"), 1);
-  EXPECT_EQ(set.count("b"), 1);
-
-  absl::btree_multiset<int> mset;
-  mset.insert({1, 1, 4});
-  EXPECT_EQ(mset.count(1), 2);
-  EXPECT_EQ(mset.count(4), 1);
-
-  absl::btree_map<int, int> map;
-  map.insert({{1, 5}, {2, 10}});
-  // Test that inserting one element using an initializer list also works.
-  map.insert({3, 15});
-  EXPECT_EQ(map[1], 5);
-  EXPECT_EQ(map[2], 10);
-  EXPECT_EQ(map[3], 15);
-
-  absl::btree_multimap<int, int> mmap;
-  mmap.insert({{1, 5}, {1, 10}});
-  auto range = mmap.equal_range(1);
-  auto it = range.first;
-  ASSERT_NE(it, range.second);
-  EXPECT_EQ(it->second, 5);
-  ASSERT_NE(++it, range.second);
-  EXPECT_EQ(it->second, 10);
-  EXPECT_EQ(++it, range.second);
-}
-
-template <typename Compare, typename K>
-void AssertKeyCompareToAdapted() {
-  using Adapted = typename key_compare_to_adapter<Compare>::type;
-  static_assert(!std::is_same<Adapted, Compare>::value,
-                "key_compare_to_adapter should have adapted this comparator.");
-  static_assert(
-      std::is_same<absl::weak_ordering,
-                   absl::result_of_t<Adapted(const K &, const K &)>>::value,
-      "Adapted comparator should be a key-compare-to comparator.");
-}
-template <typename Compare, typename K>
-void AssertKeyCompareToNotAdapted() {
-  using Unadapted = typename key_compare_to_adapter<Compare>::type;
-  static_assert(
-      std::is_same<Unadapted, Compare>::value,
-      "key_compare_to_adapter shouldn't have adapted this comparator.");
-  static_assert(
-      std::is_same<bool,
-                   absl::result_of_t<Unadapted(const K &, const K &)>>::value,
-      "Un-adapted comparator should return bool.");
-}
-
-TEST(Btree, KeyCompareToAdapter) {
-  AssertKeyCompareToAdapted<std::less<std::string>, std::string>();
-  AssertKeyCompareToAdapted<std::greater<std::string>, std::string>();
-  AssertKeyCompareToAdapted<std::less<absl::string_view>, absl::string_view>();
-  AssertKeyCompareToAdapted<std::greater<absl::string_view>,
-                            absl::string_view>();
-  AssertKeyCompareToAdapted<std::less<absl::Cord>, absl::Cord>();
-  AssertKeyCompareToAdapted<std::greater<absl::Cord>, absl::Cord>();
-  AssertKeyCompareToNotAdapted<std::less<int>, int>();
-  AssertKeyCompareToNotAdapted<std::greater<int>, int>();
-}
-
-TEST(Btree, RValueInsert) {
-  InstanceTracker tracker;
-
-  absl::btree_set<MovableOnlyInstance> set;
-  set.insert(MovableOnlyInstance(1));
-  set.insert(MovableOnlyInstance(3));
-  MovableOnlyInstance two(2);
-  set.insert(set.find(MovableOnlyInstance(3)), std::move(two));
-  auto it = set.find(MovableOnlyInstance(2));
-  ASSERT_NE(it, set.end());
-  ASSERT_NE(++it, set.end());
-  EXPECT_EQ(it->value(), 3);
-
-  absl::btree_multiset<MovableOnlyInstance> mset;
-  MovableOnlyInstance zero(0);
-  MovableOnlyInstance zero2(0);
-  mset.insert(std::move(zero));
-  mset.insert(mset.find(MovableOnlyInstance(0)), std::move(zero2));
-  EXPECT_EQ(mset.count(MovableOnlyInstance(0)), 2);
-
-  absl::btree_map<int, MovableOnlyInstance> map;
-  std::pair<const int, MovableOnlyInstance> p1 = {1, MovableOnlyInstance(5)};
-  std::pair<const int, MovableOnlyInstance> p2 = {2, MovableOnlyInstance(10)};
-  std::pair<const int, MovableOnlyInstance> p3 = {3, MovableOnlyInstance(15)};
-  map.insert(std::move(p1));
-  map.insert(std::move(p3));
-  map.insert(map.find(3), std::move(p2));
-  ASSERT_NE(map.find(2), map.end());
-  EXPECT_EQ(map.find(2)->second.value(), 10);
-
-  absl::btree_multimap<int, MovableOnlyInstance> mmap;
-  std::pair<const int, MovableOnlyInstance> p4 = {1, MovableOnlyInstance(5)};
-  std::pair<const int, MovableOnlyInstance> p5 = {1, MovableOnlyInstance(10)};
-  mmap.insert(std::move(p4));
-  mmap.insert(mmap.find(1), std::move(p5));
-  auto range = mmap.equal_range(1);
-  auto it1 = range.first;
-  ASSERT_NE(it1, range.second);
-  EXPECT_EQ(it1->second.value(), 10);
-  ASSERT_NE(++it1, range.second);
-  EXPECT_EQ(it1->second.value(), 5);
-  EXPECT_EQ(++it1, range.second);
-
-  EXPECT_EQ(tracker.copies(), 0);
-  EXPECT_EQ(tracker.swaps(), 0);
-}
-
-// A btree set with a specific number of values per node.
-template <typename Key, int TargetValuesPerNode, typename Cmp = std::less<Key>>
-class SizedBtreeSet
-    : public btree_set_container<btree<
-          set_params<Key, Cmp, std::allocator<Key>,
-                     BtreeNodePeer::GetTargetNodeSize<Key>(TargetValuesPerNode),
-                     /*Multi=*/false>>> {
-  using Base = typename SizedBtreeSet::btree_set_container;
-
- public:
-  SizedBtreeSet() {}
-  using Base::Base;
-};
-
-template <typename Set>
-void ExpectOperationCounts(const int expected_moves,
-                           const int expected_comparisons,
-                           const std::vector<int> &values,
-                           InstanceTracker *tracker, Set *set) {
-  for (const int v : values) set->insert(MovableOnlyInstance(v));
-  set->clear();
-  EXPECT_EQ(tracker->moves(), expected_moves);
-  EXPECT_EQ(tracker->comparisons(), expected_comparisons);
-  EXPECT_EQ(tracker->copies(), 0);
-  EXPECT_EQ(tracker->swaps(), 0);
-  tracker->ResetCopiesMovesSwaps();
-}
-
-// Note: when the values in this test change, it is expected to have an impact
-// on performance.
-TEST(Btree, MovesComparisonsCopiesSwapsTracking) {
-  InstanceTracker tracker;
-  // Note: this is minimum number of values per node.
-  SizedBtreeSet<MovableOnlyInstance, /*TargetValuesPerNode=*/3> set3;
-  // Note: this is the default number of values per node for a set of int32s
-  // (with 64-bit pointers).
-  SizedBtreeSet<MovableOnlyInstance, /*TargetValuesPerNode=*/61> set61;
-  SizedBtreeSet<MovableOnlyInstance, /*TargetValuesPerNode=*/100> set100;
-
-  // Don't depend on flags for random values because then the expectations will
-  // fail if the flags change.
-  std::vector<int> values =
-      GenerateValuesWithSeed<int>(10000, 1 << 22, /*seed=*/23);
-
-  EXPECT_EQ(BtreeNodePeer::GetNumValuesPerNode<decltype(set3)>(), 3);
-  EXPECT_EQ(BtreeNodePeer::GetNumValuesPerNode<decltype(set61)>(), 61);
-  EXPECT_EQ(BtreeNodePeer::GetNumValuesPerNode<decltype(set100)>(), 100);
-  if (sizeof(void *) == 8) {
-    EXPECT_EQ(BtreeNodePeer::GetNumValuesPerNode<absl::btree_set<int32_t>>(),
-              BtreeNodePeer::GetNumValuesPerNode<decltype(set61)>());
-  }
-
-  // Test key insertion/deletion in random order.
-  ExpectOperationCounts(45281, 132551, values, &tracker, &set3);
-  ExpectOperationCounts(386718, 129807, values, &tracker, &set61);
-  ExpectOperationCounts(586761, 130310, values, &tracker, &set100);
-
-  // Test key insertion/deletion in sorted order.
-  std::sort(values.begin(), values.end());
-  ExpectOperationCounts(26638, 92134, values, &tracker, &set3);
-  ExpectOperationCounts(20208, 87757, values, &tracker, &set61);
-  ExpectOperationCounts(20124, 96583, values, &tracker, &set100);
-
-  // Test key insertion/deletion in reverse sorted order.
-  std::reverse(values.begin(), values.end());
-  ExpectOperationCounts(49951, 119325, values, &tracker, &set3);
-  ExpectOperationCounts(338813, 118266, values, &tracker, &set61);
-  ExpectOperationCounts(534529, 125279, values, &tracker, &set100);
-}
-
-struct MovableOnlyInstanceThreeWayCompare {
-  absl::weak_ordering operator()(const MovableOnlyInstance &a,
-                                 const MovableOnlyInstance &b) const {
-    return a.compare(b);
-  }
-};
-
-// Note: when the values in this test change, it is expected to have an impact
-// on performance.
-TEST(Btree, MovesComparisonsCopiesSwapsTrackingThreeWayCompare) {
-  InstanceTracker tracker;
-  // Note: this is minimum number of values per node.
-  SizedBtreeSet<MovableOnlyInstance, /*TargetValuesPerNode=*/3,
-                MovableOnlyInstanceThreeWayCompare>
-      set3;
-  // Note: this is the default number of values per node for a set of int32s
-  // (with 64-bit pointers).
-  SizedBtreeSet<MovableOnlyInstance, /*TargetValuesPerNode=*/61,
-                MovableOnlyInstanceThreeWayCompare>
-      set61;
-  SizedBtreeSet<MovableOnlyInstance, /*TargetValuesPerNode=*/100,
-                MovableOnlyInstanceThreeWayCompare>
-      set100;
-
-  // Don't depend on flags for random values because then the expectations will
-  // fail if the flags change.
-  std::vector<int> values =
-      GenerateValuesWithSeed<int>(10000, 1 << 22, /*seed=*/23);
-
-  EXPECT_EQ(BtreeNodePeer::GetNumValuesPerNode<decltype(set3)>(), 3);
-  EXPECT_EQ(BtreeNodePeer::GetNumValuesPerNode<decltype(set61)>(), 61);
-  EXPECT_EQ(BtreeNodePeer::GetNumValuesPerNode<decltype(set100)>(), 100);
-  if (sizeof(void *) == 8) {
-    EXPECT_EQ(BtreeNodePeer::GetNumValuesPerNode<absl::btree_set<int32_t>>(),
-              BtreeNodePeer::GetNumValuesPerNode<decltype(set61)>());
-  }
-
-  // Test key insertion/deletion in random order.
-  ExpectOperationCounts(45281, 122560, values, &tracker, &set3);
-  ExpectOperationCounts(386718, 119816, values, &tracker, &set61);
-  ExpectOperationCounts(586761, 120319, values, &tracker, &set100);
-
-  // Test key insertion/deletion in sorted order.
-  std::sort(values.begin(), values.end());
-  ExpectOperationCounts(26638, 92134, values, &tracker, &set3);
-  ExpectOperationCounts(20208, 87757, values, &tracker, &set61);
-  ExpectOperationCounts(20124, 96583, values, &tracker, &set100);
-
-  // Test key insertion/deletion in reverse sorted order.
-  std::reverse(values.begin(), values.end());
-  ExpectOperationCounts(49951, 109326, values, &tracker, &set3);
-  ExpectOperationCounts(338813, 108267, values, &tracker, &set61);
-  ExpectOperationCounts(534529, 115280, values, &tracker, &set100);
-}
-
-struct NoDefaultCtor {
-  int num;
-  explicit NoDefaultCtor(int i) : num(i) {}
-
-  friend bool operator<(const NoDefaultCtor &a, const NoDefaultCtor &b) {
-    return a.num < b.num;
-  }
-};
-
-TEST(Btree, BtreeMapCanHoldNoDefaultCtorTypes) {
-  absl::btree_map<NoDefaultCtor, NoDefaultCtor> m;
-
-  for (int i = 1; i <= 99; ++i) {
-    SCOPED_TRACE(i);
-    EXPECT_TRUE(m.emplace(NoDefaultCtor(i), NoDefaultCtor(100 - i)).second);
-  }
-  EXPECT_FALSE(m.emplace(NoDefaultCtor(78), NoDefaultCtor(0)).second);
-
-  auto iter99 = m.find(NoDefaultCtor(99));
-  ASSERT_NE(iter99, m.end());
-  EXPECT_EQ(iter99->second.num, 1);
-
-  auto iter1 = m.find(NoDefaultCtor(1));
-  ASSERT_NE(iter1, m.end());
-  EXPECT_EQ(iter1->second.num, 99);
-
-  auto iter50 = m.find(NoDefaultCtor(50));
-  ASSERT_NE(iter50, m.end());
-  EXPECT_EQ(iter50->second.num, 50);
-
-  auto iter25 = m.find(NoDefaultCtor(25));
-  ASSERT_NE(iter25, m.end());
-  EXPECT_EQ(iter25->second.num, 75);
-}
-
-TEST(Btree, BtreeMultimapCanHoldNoDefaultCtorTypes) {
-  absl::btree_multimap<NoDefaultCtor, NoDefaultCtor> m;
-
-  for (int i = 1; i <= 99; ++i) {
-    SCOPED_TRACE(i);
-    m.emplace(NoDefaultCtor(i), NoDefaultCtor(100 - i));
-  }
-
-  auto iter99 = m.find(NoDefaultCtor(99));
-  ASSERT_NE(iter99, m.end());
-  EXPECT_EQ(iter99->second.num, 1);
-
-  auto iter1 = m.find(NoDefaultCtor(1));
-  ASSERT_NE(iter1, m.end());
-  EXPECT_EQ(iter1->second.num, 99);
-
-  auto iter50 = m.find(NoDefaultCtor(50));
-  ASSERT_NE(iter50, m.end());
-  EXPECT_EQ(iter50->second.num, 50);
-
-  auto iter25 = m.find(NoDefaultCtor(25));
-  ASSERT_NE(iter25, m.end());
-  EXPECT_EQ(iter25->second.num, 75);
-}
-
-TEST(Btree, MapAt) {
-  absl::btree_map<int, int> map = {{1, 2}, {2, 4}};
-  EXPECT_EQ(map.at(1), 2);
-  EXPECT_EQ(map.at(2), 4);
-  map.at(2) = 8;
-  const absl::btree_map<int, int> &const_map = map;
-  EXPECT_EQ(const_map.at(1), 2);
-  EXPECT_EQ(const_map.at(2), 8);
-#ifdef ABSL_HAVE_EXCEPTIONS
-  EXPECT_THROW(map.at(3), std::out_of_range);
-#else
-  EXPECT_DEATH_IF_SUPPORTED(map.at(3), "absl::btree_map::at");
-#endif
-}
-
-TEST(Btree, BtreeMultisetEmplace) {
-  const int value_to_insert = 123456;
-  absl::btree_multiset<int> s;
-  auto iter = s.emplace(value_to_insert);
-  ASSERT_NE(iter, s.end());
-  EXPECT_EQ(*iter, value_to_insert);
-  auto iter2 = s.emplace(value_to_insert);
-  EXPECT_NE(iter2, iter);
-  ASSERT_NE(iter2, s.end());
-  EXPECT_EQ(*iter2, value_to_insert);
-  auto result = s.equal_range(value_to_insert);
-  EXPECT_EQ(std::distance(result.first, result.second), 2);
-}
-
-TEST(Btree, BtreeMultisetEmplaceHint) {
-  const int value_to_insert = 123456;
-  absl::btree_multiset<int> s;
-  auto iter = s.emplace(value_to_insert);
-  ASSERT_NE(iter, s.end());
-  EXPECT_EQ(*iter, value_to_insert);
-  auto emplace_iter = s.emplace_hint(iter, value_to_insert);
-  EXPECT_NE(emplace_iter, iter);
-  ASSERT_NE(emplace_iter, s.end());
-  EXPECT_EQ(*emplace_iter, value_to_insert);
-}
-
-TEST(Btree, BtreeMultimapEmplace) {
-  const int key_to_insert = 123456;
-  const char value0[] = "a";
-  absl::btree_multimap<int, std::string> s;
-  auto iter = s.emplace(key_to_insert, value0);
-  ASSERT_NE(iter, s.end());
-  EXPECT_EQ(iter->first, key_to_insert);
-  EXPECT_EQ(iter->second, value0);
-  const char value1[] = "b";
-  auto iter2 = s.emplace(key_to_insert, value1);
-  EXPECT_NE(iter2, iter);
-  ASSERT_NE(iter2, s.end());
-  EXPECT_EQ(iter2->first, key_to_insert);
-  EXPECT_EQ(iter2->second, value1);
-  auto result = s.equal_range(key_to_insert);
-  EXPECT_EQ(std::distance(result.first, result.second), 2);
-}
-
-TEST(Btree, BtreeMultimapEmplaceHint) {
-  const int key_to_insert = 123456;
-  const char value0[] = "a";
-  absl::btree_multimap<int, std::string> s;
-  auto iter = s.emplace(key_to_insert, value0);
-  ASSERT_NE(iter, s.end());
-  EXPECT_EQ(iter->first, key_to_insert);
-  EXPECT_EQ(iter->second, value0);
-  const char value1[] = "b";
-  auto emplace_iter = s.emplace_hint(iter, key_to_insert, value1);
-  EXPECT_NE(emplace_iter, iter);
-  ASSERT_NE(emplace_iter, s.end());
-  EXPECT_EQ(emplace_iter->first, key_to_insert);
-  EXPECT_EQ(emplace_iter->second, value1);
-}
-
-TEST(Btree, ConstIteratorAccessors) {
-  absl::btree_set<int> set;
-  for (int i = 0; i < 100; ++i) {
-    set.insert(i);
-  }
-
-  auto it = set.cbegin();
-  auto r_it = set.crbegin();
-  for (int i = 0; i < 100; ++i, ++it, ++r_it) {
-    ASSERT_EQ(*it, i);
-    ASSERT_EQ(*r_it, 99 - i);
-  }
-  EXPECT_EQ(it, set.cend());
-  EXPECT_EQ(r_it, set.crend());
-}
-
-TEST(Btree, StrSplitCompatible) {
-  const absl::btree_set<std::string> split_set = absl::StrSplit("a,b,c", ',');
-  const absl::btree_set<std::string> expected_set = {"a", "b", "c"};
-
-  EXPECT_EQ(split_set, expected_set);
-}
-
-// We can't use EXPECT_EQ/etc. to compare absl::weak_ordering because they
-// convert literal 0 to int and absl::weak_ordering can only be compared with
-// literal 0. Defining this function allows for avoiding ClangTidy warnings.
-bool Identity(const bool b) { return b; }
-
-TEST(Btree, ValueComp) {
-  absl::btree_set<int> s;
-  EXPECT_TRUE(s.value_comp()(1, 2));
-  EXPECT_FALSE(s.value_comp()(2, 2));
-  EXPECT_FALSE(s.value_comp()(2, 1));
-
-  absl::btree_map<int, int> m1;
-  EXPECT_TRUE(m1.value_comp()(std::make_pair(1, 0), std::make_pair(2, 0)));
-  EXPECT_FALSE(m1.value_comp()(std::make_pair(2, 0), std::make_pair(2, 0)));
-  EXPECT_FALSE(m1.value_comp()(std::make_pair(2, 0), std::make_pair(1, 0)));
-
-  absl::btree_map<std::string, int> m2;
-  EXPECT_TRUE(Identity(
-      m2.value_comp()(std::make_pair("a", 0), std::make_pair("b", 0)) < 0));
-  EXPECT_TRUE(Identity(
-      m2.value_comp()(std::make_pair("b", 0), std::make_pair("b", 0)) == 0));
-  EXPECT_TRUE(Identity(
-      m2.value_comp()(std::make_pair("b", 0), std::make_pair("a", 0)) > 0));
-}
-
-TEST(Btree, DefaultConstruction) {
-  absl::btree_set<int> s;
-  absl::btree_map<int, int> m;
-  absl::btree_multiset<int> ms;
-  absl::btree_multimap<int, int> mm;
-
-  EXPECT_TRUE(s.empty());
-  EXPECT_TRUE(m.empty());
-  EXPECT_TRUE(ms.empty());
-  EXPECT_TRUE(mm.empty());
-}
-
-TEST(Btree, SwissTableHashable) {
-  static constexpr int kValues = 10000;
-  std::vector<int> values(kValues);
-  std::iota(values.begin(), values.end(), 0);
-  std::vector<std::pair<int, int>> map_values;
-  for (int v : values) map_values.emplace_back(v, -v);
-
-  using set = absl::btree_set<int>;
-  EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly({
-      set{},
-      set{1},
-      set{2},
-      set{1, 2},
-      set{2, 1},
-      set(values.begin(), values.end()),
-      set(values.rbegin(), values.rend()),
-  }));
-
-  using mset = absl::btree_multiset<int>;
-  EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly({
-      mset{},
-      mset{1},
-      mset{1, 1},
-      mset{2},
-      mset{2, 2},
-      mset{1, 2},
-      mset{1, 1, 2},
-      mset{1, 2, 2},
-      mset{1, 1, 2, 2},
-      mset(values.begin(), values.end()),
-      mset(values.rbegin(), values.rend()),
-  }));
-
-  using map = absl::btree_map<int, int>;
-  EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly({
-      map{},
-      map{{1, 0}},
-      map{{1, 1}},
-      map{{2, 0}},
-      map{{2, 2}},
-      map{{1, 0}, {2, 1}},
-      map(map_values.begin(), map_values.end()),
-      map(map_values.rbegin(), map_values.rend()),
-  }));
-
-  using mmap = absl::btree_multimap<int, int>;
-  EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly({
-      mmap{},
-      mmap{{1, 0}},
-      mmap{{1, 1}},
-      mmap{{1, 0}, {1, 1}},
-      mmap{{1, 1}, {1, 0}},
-      mmap{{2, 0}},
-      mmap{{2, 2}},
-      mmap{{1, 0}, {2, 1}},
-      mmap(map_values.begin(), map_values.end()),
-      mmap(map_values.rbegin(), map_values.rend()),
-  }));
-}
-
-TEST(Btree, ComparableSet) {
-  absl::btree_set<int> s1 = {1, 2};
-  absl::btree_set<int> s2 = {2, 3};
-  EXPECT_LT(s1, s2);
-  EXPECT_LE(s1, s2);
-  EXPECT_LE(s1, s1);
-  EXPECT_GT(s2, s1);
-  EXPECT_GE(s2, s1);
-  EXPECT_GE(s1, s1);
-}
-
-TEST(Btree, ComparableSetsDifferentLength) {
-  absl::btree_set<int> s1 = {1, 2};
-  absl::btree_set<int> s2 = {1, 2, 3};
-  EXPECT_LT(s1, s2);
-  EXPECT_LE(s1, s2);
-  EXPECT_GT(s2, s1);
-  EXPECT_GE(s2, s1);
-}
-
-TEST(Btree, ComparableMultiset) {
-  absl::btree_multiset<int> s1 = {1, 2};
-  absl::btree_multiset<int> s2 = {2, 3};
-  EXPECT_LT(s1, s2);
-  EXPECT_LE(s1, s2);
-  EXPECT_LE(s1, s1);
-  EXPECT_GT(s2, s1);
-  EXPECT_GE(s2, s1);
-  EXPECT_GE(s1, s1);
-}
-
-TEST(Btree, ComparableMap) {
-  absl::btree_map<int, int> s1 = {{1, 2}};
-  absl::btree_map<int, int> s2 = {{2, 3}};
-  EXPECT_LT(s1, s2);
-  EXPECT_LE(s1, s2);
-  EXPECT_LE(s1, s1);
-  EXPECT_GT(s2, s1);
-  EXPECT_GE(s2, s1);
-  EXPECT_GE(s1, s1);
-}
-
-TEST(Btree, ComparableMultimap) {
-  absl::btree_multimap<int, int> s1 = {{1, 2}};
-  absl::btree_multimap<int, int> s2 = {{2, 3}};
-  EXPECT_LT(s1, s2);
-  EXPECT_LE(s1, s2);
-  EXPECT_LE(s1, s1);
-  EXPECT_GT(s2, s1);
-  EXPECT_GE(s2, s1);
-  EXPECT_GE(s1, s1);
-}
-
-TEST(Btree, ComparableSetWithCustomComparator) {
-  // As specified by
-  // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3337.pdf section
-  // [container.requirements.general].12, ordering associative containers always
-  // uses default '<' operator
-  // - even if otherwise the container uses custom functor.
-  absl::btree_set<int, std::greater<int>> s1 = {1, 2};
-  absl::btree_set<int, std::greater<int>> s2 = {2, 3};
-  EXPECT_LT(s1, s2);
-  EXPECT_LE(s1, s2);
-  EXPECT_LE(s1, s1);
-  EXPECT_GT(s2, s1);
-  EXPECT_GE(s2, s1);
-  EXPECT_GE(s1, s1);
-}
-
-TEST(Btree, EraseReturnsIterator) {
-  absl::btree_set<int> set = {1, 2, 3, 4, 5};
-  auto result_it = set.erase(set.begin(), set.find(3));
-  EXPECT_EQ(result_it, set.find(3));
-  result_it = set.erase(set.find(5));
-  EXPECT_EQ(result_it, set.end());
-}
-
-TEST(Btree, ExtractAndInsertNodeHandleSet) {
-  absl::btree_set<int> src1 = {1, 2, 3, 4, 5};
-  auto nh = src1.extract(src1.find(3));
-  EXPECT_THAT(src1, ElementsAre(1, 2, 4, 5));
-  absl::btree_set<int> other;
-  absl::btree_set<int>::insert_return_type res = other.insert(std::move(nh));
-  EXPECT_THAT(other, ElementsAre(3));
-  EXPECT_EQ(res.position, other.find(3));
-  EXPECT_TRUE(res.inserted);
-  EXPECT_TRUE(res.node.empty());
-
-  absl::btree_set<int> src2 = {3, 4};
-  nh = src2.extract(src2.find(3));
-  EXPECT_THAT(src2, ElementsAre(4));
-  res = other.insert(std::move(nh));
-  EXPECT_THAT(other, ElementsAre(3));
-  EXPECT_EQ(res.position, other.find(3));
-  EXPECT_FALSE(res.inserted);
-  ASSERT_FALSE(res.node.empty());
-  EXPECT_EQ(res.node.value(), 3);
-}
-
-template <typename Set>
-void TestExtractWithTrackingForSet() {
-  InstanceTracker tracker;
-  {
-    Set s;
-    // Add enough elements to make sure we test internal nodes too.
-    const size_t kSize = 1000;
-    while (s.size() < kSize) {
-      s.insert(MovableOnlyInstance(s.size()));
-    }
-    for (int i = 0; i < kSize; ++i) {
-      // Extract with key
-      auto nh = s.extract(MovableOnlyInstance(i));
-      EXPECT_EQ(s.size(), kSize - 1);
-      EXPECT_EQ(nh.value().value(), i);
-      // Insert with node
-      s.insert(std::move(nh));
-      EXPECT_EQ(s.size(), kSize);
-
-      // Extract with iterator
-      auto it = s.find(MovableOnlyInstance(i));
-      nh = s.extract(it);
-      EXPECT_EQ(s.size(), kSize - 1);
-      EXPECT_EQ(nh.value().value(), i);
-      // Insert with node and hint
-      s.insert(s.begin(), std::move(nh));
-      EXPECT_EQ(s.size(), kSize);
-    }
-  }
-  EXPECT_EQ(0, tracker.instances());
-}
-
-template <typename Map>
-void TestExtractWithTrackingForMap() {
-  InstanceTracker tracker;
-  {
-    Map m;
-    // Add enough elements to make sure we test internal nodes too.
-    const size_t kSize = 1000;
-    while (m.size() < kSize) {
-      m.insert(
-          {CopyableMovableInstance(m.size()), MovableOnlyInstance(m.size())});
-    }
-    for (int i = 0; i < kSize; ++i) {
-      // Extract with key
-      auto nh = m.extract(CopyableMovableInstance(i));
-      EXPECT_EQ(m.size(), kSize - 1);
-      EXPECT_EQ(nh.key().value(), i);
-      EXPECT_EQ(nh.mapped().value(), i);
-      // Insert with node
-      m.insert(std::move(nh));
-      EXPECT_EQ(m.size(), kSize);
-
-      // Extract with iterator
-      auto it = m.find(CopyableMovableInstance(i));
-      nh = m.extract(it);
-      EXPECT_EQ(m.size(), kSize - 1);
-      EXPECT_EQ(nh.key().value(), i);
-      EXPECT_EQ(nh.mapped().value(), i);
-      // Insert with node and hint
-      m.insert(m.begin(), std::move(nh));
-      EXPECT_EQ(m.size(), kSize);
-    }
-  }
-  EXPECT_EQ(0, tracker.instances());
-}
-
-TEST(Btree, ExtractTracking) {
-  TestExtractWithTrackingForSet<absl::btree_set<MovableOnlyInstance>>();
-  TestExtractWithTrackingForSet<absl::btree_multiset<MovableOnlyInstance>>();
-  TestExtractWithTrackingForMap<
-      absl::btree_map<CopyableMovableInstance, MovableOnlyInstance>>();
-  TestExtractWithTrackingForMap<
-      absl::btree_multimap<CopyableMovableInstance, MovableOnlyInstance>>();
-}
-
-TEST(Btree, ExtractAndInsertNodeHandleMultiSet) {
-  absl::btree_multiset<int> src1 = {1, 2, 3, 3, 4, 5};
-  auto nh = src1.extract(src1.find(3));
-  EXPECT_THAT(src1, ElementsAre(1, 2, 3, 4, 5));
-  absl::btree_multiset<int> other;
-  auto res = other.insert(std::move(nh));
-  EXPECT_THAT(other, ElementsAre(3));
-  EXPECT_EQ(res, other.find(3));
-
-  absl::btree_multiset<int> src2 = {3, 4};
-  nh = src2.extract(src2.find(3));
-  EXPECT_THAT(src2, ElementsAre(4));
-  res = other.insert(std::move(nh));
-  EXPECT_THAT(other, ElementsAre(3, 3));
-  EXPECT_EQ(res, ++other.find(3));
-}
-
-TEST(Btree, ExtractAndInsertNodeHandleMap) {
-  absl::btree_map<int, int> src1 = {{1, 2}, {3, 4}, {5, 6}};
-  auto nh = src1.extract(src1.find(3));
-  EXPECT_THAT(src1, ElementsAre(Pair(1, 2), Pair(5, 6)));
-  absl::btree_map<int, int> other;
-  absl::btree_map<int, int>::insert_return_type res =
-      other.insert(std::move(nh));
-  EXPECT_THAT(other, ElementsAre(Pair(3, 4)));
-  EXPECT_EQ(res.position, other.find(3));
-  EXPECT_TRUE(res.inserted);
-  EXPECT_TRUE(res.node.empty());
-
-  absl::btree_map<int, int> src2 = {{3, 6}};
-  nh = src2.extract(src2.find(3));
-  EXPECT_TRUE(src2.empty());
-  res = other.insert(std::move(nh));
-  EXPECT_THAT(other, ElementsAre(Pair(3, 4)));
-  EXPECT_EQ(res.position, other.find(3));
-  EXPECT_FALSE(res.inserted);
-  ASSERT_FALSE(res.node.empty());
-  EXPECT_EQ(res.node.key(), 3);
-  EXPECT_EQ(res.node.mapped(), 6);
-}
-
-TEST(Btree, ExtractAndInsertNodeHandleMultiMap) {
-  absl::btree_multimap<int, int> src1 = {{1, 2}, {3, 4}, {5, 6}};
-  auto nh = src1.extract(src1.find(3));
-  EXPECT_THAT(src1, ElementsAre(Pair(1, 2), Pair(5, 6)));
-  absl::btree_multimap<int, int> other;
-  auto res = other.insert(std::move(nh));
-  EXPECT_THAT(other, ElementsAre(Pair(3, 4)));
-  EXPECT_EQ(res, other.find(3));
-
-  absl::btree_multimap<int, int> src2 = {{3, 6}};
-  nh = src2.extract(src2.find(3));
-  EXPECT_TRUE(src2.empty());
-  res = other.insert(std::move(nh));
-  EXPECT_THAT(other, ElementsAre(Pair(3, 4), Pair(3, 6)));
-  EXPECT_EQ(res, ++other.begin());
-}
-
-// For multisets, insert with hint also affects correctness because we need to
-// insert immediately before the hint if possible.
-struct InsertMultiHintData {
-  int key;
-  int not_key;
-  bool operator==(const InsertMultiHintData other) const {
-    return key == other.key && not_key == other.not_key;
-  }
-};
-
-struct InsertMultiHintDataKeyCompare {
-  using is_transparent = void;
-  bool operator()(const InsertMultiHintData a,
-                  const InsertMultiHintData b) const {
-    return a.key < b.key;
-  }
-  bool operator()(const int a, const InsertMultiHintData b) const {
-    return a < b.key;
-  }
-  bool operator()(const InsertMultiHintData a, const int b) const {
-    return a.key < b;
-  }
-};
-
-TEST(Btree, InsertHintNodeHandle) {
-  // For unique sets, insert with hint is just a performance optimization.
-  // Test that insert works correctly when the hint is right or wrong.
-  {
-    absl::btree_set<int> src = {1, 2, 3, 4, 5};
-    auto nh = src.extract(src.find(3));
-    EXPECT_THAT(src, ElementsAre(1, 2, 4, 5));
-    absl::btree_set<int> other = {0, 100};
-    // Test a correct hint.
-    auto it = other.insert(other.lower_bound(3), std::move(nh));
-    EXPECT_THAT(other, ElementsAre(0, 3, 100));
-    EXPECT_EQ(it, other.find(3));
-
-    nh = src.extract(src.find(5));
-    // Test an incorrect hint.
-    it = other.insert(other.end(), std::move(nh));
-    EXPECT_THAT(other, ElementsAre(0, 3, 5, 100));
-    EXPECT_EQ(it, other.find(5));
-  }
-
-  absl::btree_multiset<InsertMultiHintData, InsertMultiHintDataKeyCompare> src =
-      {{1, 2}, {3, 4}, {3, 5}};
-  auto nh = src.extract(src.lower_bound(3));
-  EXPECT_EQ(nh.value(), (InsertMultiHintData{3, 4}));
-  absl::btree_multiset<InsertMultiHintData, InsertMultiHintDataKeyCompare>
-      other = {{3, 1}, {3, 2}, {3, 3}};
-  auto it = other.insert(--other.end(), std::move(nh));
-  EXPECT_THAT(
-      other, ElementsAre(InsertMultiHintData{3, 1}, InsertMultiHintData{3, 2},
-                         InsertMultiHintData{3, 4}, InsertMultiHintData{3, 3}));
-  EXPECT_EQ(it, --(--other.end()));
-
-  nh = src.extract(src.find(3));
-  EXPECT_EQ(nh.value(), (InsertMultiHintData{3, 5}));
-  it = other.insert(other.begin(), std::move(nh));
-  EXPECT_THAT(other,
-              ElementsAre(InsertMultiHintData{3, 5}, InsertMultiHintData{3, 1},
-                          InsertMultiHintData{3, 2}, InsertMultiHintData{3, 4},
-                          InsertMultiHintData{3, 3}));
-  EXPECT_EQ(it, other.begin());
-}
-
-struct IntCompareToCmp {
-  absl::weak_ordering operator()(int a, int b) const {
-    if (a < b) return absl::weak_ordering::less;
-    if (a > b) return absl::weak_ordering::greater;
-    return absl::weak_ordering::equivalent;
-  }
-};
-
-TEST(Btree, MergeIntoUniqueContainers) {
-  absl::btree_set<int, IntCompareToCmp> src1 = {1, 2, 3};
-  absl::btree_multiset<int> src2 = {3, 4, 4, 5};
-  absl::btree_set<int> dst;
-
-  dst.merge(src1);
-  EXPECT_TRUE(src1.empty());
-  EXPECT_THAT(dst, ElementsAre(1, 2, 3));
-  dst.merge(src2);
-  EXPECT_THAT(src2, ElementsAre(3, 4));
-  EXPECT_THAT(dst, ElementsAre(1, 2, 3, 4, 5));
-}
-
-TEST(Btree, MergeIntoUniqueContainersWithCompareTo) {
-  absl::btree_set<int, IntCompareToCmp> src1 = {1, 2, 3};
-  absl::btree_multiset<int> src2 = {3, 4, 4, 5};
-  absl::btree_set<int, IntCompareToCmp> dst;
-
-  dst.merge(src1);
-  EXPECT_TRUE(src1.empty());
-  EXPECT_THAT(dst, ElementsAre(1, 2, 3));
-  dst.merge(src2);
-  EXPECT_THAT(src2, ElementsAre(3, 4));
-  EXPECT_THAT(dst, ElementsAre(1, 2, 3, 4, 5));
-}
-
-TEST(Btree, MergeIntoMultiContainers) {
-  absl::btree_set<int, IntCompareToCmp> src1 = {1, 2, 3};
-  absl::btree_multiset<int> src2 = {3, 4, 4, 5};
-  absl::btree_multiset<int> dst;
-
-  dst.merge(src1);
-  EXPECT_TRUE(src1.empty());
-  EXPECT_THAT(dst, ElementsAre(1, 2, 3));
-  dst.merge(src2);
-  EXPECT_TRUE(src2.empty());
-  EXPECT_THAT(dst, ElementsAre(1, 2, 3, 3, 4, 4, 5));
-}
-
-TEST(Btree, MergeIntoMultiContainersWithCompareTo) {
-  absl::btree_set<int, IntCompareToCmp> src1 = {1, 2, 3};
-  absl::btree_multiset<int> src2 = {3, 4, 4, 5};
-  absl::btree_multiset<int, IntCompareToCmp> dst;
-
-  dst.merge(src1);
-  EXPECT_TRUE(src1.empty());
-  EXPECT_THAT(dst, ElementsAre(1, 2, 3));
-  dst.merge(src2);
-  EXPECT_TRUE(src2.empty());
-  EXPECT_THAT(dst, ElementsAre(1, 2, 3, 3, 4, 4, 5));
-}
-
-TEST(Btree, MergeIntoMultiMapsWithDifferentComparators) {
-  absl::btree_map<int, int, IntCompareToCmp> src1 = {{1, 1}, {2, 2}, {3, 3}};
-  absl::btree_multimap<int, int, std::greater<int>> src2 = {
-      {5, 5}, {4, 1}, {4, 4}, {3, 2}};
-  absl::btree_multimap<int, int> dst;
-
-  dst.merge(src1);
-  EXPECT_TRUE(src1.empty());
-  EXPECT_THAT(dst, ElementsAre(Pair(1, 1), Pair(2, 2), Pair(3, 3)));
-  dst.merge(src2);
-  EXPECT_TRUE(src2.empty());
-  EXPECT_THAT(dst, ElementsAre(Pair(1, 1), Pair(2, 2), Pair(3, 3), Pair(3, 2),
-                               Pair(4, 1), Pair(4, 4), Pair(5, 5)));
-}
-
-TEST(Btree, MergeIntoSetMovableOnly) {
-  absl::btree_set<MovableOnlyInstance> src;
-  src.insert(MovableOnlyInstance(1));
-  absl::btree_multiset<MovableOnlyInstance> dst1;
-  dst1.insert(MovableOnlyInstance(2));
-  absl::btree_set<MovableOnlyInstance> dst2;
-
-  // Test merge into multiset.
-  dst1.merge(src);
-
-  EXPECT_TRUE(src.empty());
-  // ElementsAre/ElementsAreArray don't work with move-only types.
-  ASSERT_THAT(dst1, SizeIs(2));
-  EXPECT_EQ(*dst1.begin(), MovableOnlyInstance(1));
-  EXPECT_EQ(*std::next(dst1.begin()), MovableOnlyInstance(2));
-
-  // Test merge into set.
-  dst2.merge(dst1);
-
-  EXPECT_TRUE(dst1.empty());
-  ASSERT_THAT(dst2, SizeIs(2));
-  EXPECT_EQ(*dst2.begin(), MovableOnlyInstance(1));
-  EXPECT_EQ(*std::next(dst2.begin()), MovableOnlyInstance(2));
-}
-
-struct KeyCompareToWeakOrdering {
-  template <typename T>
-  absl::weak_ordering operator()(const T &a, const T &b) const {
-    return a < b ? absl::weak_ordering::less
-                 : a == b ? absl::weak_ordering::equivalent
-                          : absl::weak_ordering::greater;
-  }
-};
-
-struct KeyCompareToStrongOrdering {
-  template <typename T>
-  absl::strong_ordering operator()(const T &a, const T &b) const {
-    return a < b ? absl::strong_ordering::less
-                 : a == b ? absl::strong_ordering::equal
-                          : absl::strong_ordering::greater;
-  }
-};
-
-TEST(Btree, UserProvidedKeyCompareToComparators) {
-  absl::btree_set<int, KeyCompareToWeakOrdering> weak_set = {1, 2, 3};
-  EXPECT_TRUE(weak_set.contains(2));
-  EXPECT_FALSE(weak_set.contains(4));
-
-  absl::btree_set<int, KeyCompareToStrongOrdering> strong_set = {1, 2, 3};
-  EXPECT_TRUE(strong_set.contains(2));
-  EXPECT_FALSE(strong_set.contains(4));
-}
-
-TEST(Btree, TryEmplaceBasicTest) {
-  absl::btree_map<int, std::string> m;
-
-  // Should construct a string from the literal.
-  m.try_emplace(1, "one");
-  EXPECT_EQ(1, m.size());
-
-  // Try other string constructors and const lvalue key.
-  const int key(42);
-  m.try_emplace(key, 3, 'a');
-  m.try_emplace(2, std::string("two"));
-
-  EXPECT_TRUE(std::is_sorted(m.begin(), m.end()));
-  EXPECT_THAT(m, ElementsAreArray(std::vector<std::pair<int, std::string>>{
-                     {1, "one"}, {2, "two"}, {42, "aaa"}}));
-}
-
-TEST(Btree, TryEmplaceWithHintWorks) {
-  // Use a counting comparator here to verify that hint is used.
-  int calls = 0;
-  auto cmp = [&calls](int x, int y) {
-    ++calls;
-    return x < y;
-  };
-  using Cmp = decltype(cmp);
-
-  absl::btree_map<int, int, Cmp> m(cmp);
-  for (int i = 0; i < 128; ++i) {
-    m.emplace(i, i);
-  }
-
-  // Sanity check for the comparator
-  calls = 0;
-  m.emplace(127, 127);
-  EXPECT_GE(calls, 4);
-
-  // Try with begin hint:
-  calls = 0;
-  auto it = m.try_emplace(m.begin(), -1, -1);
-  EXPECT_EQ(129, m.size());
-  EXPECT_EQ(it, m.begin());
-  EXPECT_LE(calls, 2);
-
-  // Try with end hint:
-  calls = 0;
-  std::pair<int, int> pair1024 = {1024, 1024};
-  it = m.try_emplace(m.end(), pair1024.first, pair1024.second);
-  EXPECT_EQ(130, m.size());
-  EXPECT_EQ(it, --m.end());
-  EXPECT_LE(calls, 2);
-
-  // Try value already present, bad hint; ensure no duplicate added:
-  calls = 0;
-  it = m.try_emplace(m.end(), 16, 17);
-  EXPECT_EQ(130, m.size());
-  EXPECT_GE(calls, 4);
-  EXPECT_EQ(it, m.find(16));
-
-  // Try value already present, hint points directly to it:
-  calls = 0;
-  it = m.try_emplace(it, 16, 17);
-  EXPECT_EQ(130, m.size());
-  EXPECT_LE(calls, 2);
-  EXPECT_EQ(it, m.find(16));
-
-  m.erase(2);
-  EXPECT_EQ(129, m.size());
-  auto hint = m.find(3);
-  // Try emplace in the middle of two other elements.
-  calls = 0;
-  m.try_emplace(hint, 2, 2);
-  EXPECT_EQ(130, m.size());
-  EXPECT_LE(calls, 2);
-
-  EXPECT_TRUE(std::is_sorted(m.begin(), m.end()));
-}
-
-TEST(Btree, TryEmplaceWithBadHint) {
-  absl::btree_map<int, int> m = {{1, 1}, {9, 9}};
-
-  // Bad hint (too small), should still emplace:
-  auto it = m.try_emplace(m.begin(), 2, 2);
-  EXPECT_EQ(it, ++m.begin());
-  EXPECT_THAT(m, ElementsAreArray(
-                     std::vector<std::pair<int, int>>{{1, 1}, {2, 2}, {9, 9}}));
-
-  // Bad hint, too large this time:
-  it = m.try_emplace(++(++m.begin()), 0, 0);
-  EXPECT_EQ(it, m.begin());
-  EXPECT_THAT(m, ElementsAreArray(std::vector<std::pair<int, int>>{
-                     {0, 0}, {1, 1}, {2, 2}, {9, 9}}));
-}
-
-TEST(Btree, TryEmplaceMaintainsSortedOrder) {
-  absl::btree_map<int, std::string> m;
-  std::pair<int, std::string> pair5 = {5, "five"};
-
-  // Test both lvalue & rvalue emplace.
-  m.try_emplace(10, "ten");
-  m.try_emplace(pair5.first, pair5.second);
-  EXPECT_EQ(2, m.size());
-  EXPECT_TRUE(std::is_sorted(m.begin(), m.end()));
-
-  int int100{100};
-  m.try_emplace(int100, "hundred");
-  m.try_emplace(1, "one");
-  EXPECT_EQ(4, m.size());
-  EXPECT_TRUE(std::is_sorted(m.begin(), m.end()));
-}
-
-TEST(Btree, TryEmplaceWithHintAndNoValueArgsWorks) {
-  absl::btree_map<int, int> m;
-  m.try_emplace(m.end(), 1);
-  EXPECT_EQ(0, m[1]);
-}
-
-TEST(Btree, TryEmplaceWithHintAndMultipleValueArgsWorks) {
-  absl::btree_map<int, std::string> m;
-  m.try_emplace(m.end(), 1, 10, 'a');
-  EXPECT_EQ(std::string(10, 'a'), m[1]);
-}
-
-TEST(Btree, MoveAssignmentAllocatorPropagation) {
-  InstanceTracker tracker;
-
-  int64_t bytes1 = 0, bytes2 = 0;
-  PropagatingCountingAlloc<MovableOnlyInstance> allocator1(&bytes1);
-  PropagatingCountingAlloc<MovableOnlyInstance> allocator2(&bytes2);
-  std::less<MovableOnlyInstance> cmp;
-
-  // Test propagating allocator_type.
-  {
-    absl::btree_set<MovableOnlyInstance, std::less<MovableOnlyInstance>,
-                    PropagatingCountingAlloc<MovableOnlyInstance>>
-        set1(cmp, allocator1), set2(cmp, allocator2);
-
-    for (int i = 0; i < 100; ++i) set1.insert(MovableOnlyInstance(i));
-
-    tracker.ResetCopiesMovesSwaps();
-    set2 = std::move(set1);
-    EXPECT_EQ(tracker.moves(), 0);
-  }
-  // Test non-propagating allocator_type with equal allocators.
-  {
-    absl::btree_set<MovableOnlyInstance, std::less<MovableOnlyInstance>,
-                    CountingAllocator<MovableOnlyInstance>>
-        set1(cmp, allocator1), set2(cmp, allocator1);
-
-    for (int i = 0; i < 100; ++i) set1.insert(MovableOnlyInstance(i));
-
-    tracker.ResetCopiesMovesSwaps();
-    set2 = std::move(set1);
-    EXPECT_EQ(tracker.moves(), 0);
-  }
-  // Test non-propagating allocator_type with different allocators.
-  {
-    absl::btree_set<MovableOnlyInstance, std::less<MovableOnlyInstance>,
-                    CountingAllocator<MovableOnlyInstance>>
-        set1(cmp, allocator1), set2(cmp, allocator2);
-
-    for (int i = 0; i < 100; ++i) set1.insert(MovableOnlyInstance(i));
-
-    tracker.ResetCopiesMovesSwaps();
-    set2 = std::move(set1);
-    EXPECT_GE(tracker.moves(), 100);
-  }
-}
-
-TEST(Btree, EmptyTree) {
-  absl::btree_set<int> s;
-  EXPECT_TRUE(s.empty());
-  EXPECT_EQ(s.size(), 0);
-  EXPECT_GT(s.max_size(), 0);
-}
-
-bool IsEven(int k) { return k % 2 == 0; }
-
-TEST(Btree, EraseIf) {
-  // Test that erase_if works with all the container types and supports lambdas.
-  {
-    absl::btree_set<int> s = {1, 3, 5, 6, 100};
-    erase_if(s, [](int k) { return k > 3; });
-    EXPECT_THAT(s, ElementsAre(1, 3));
-  }
-  {
-    absl::btree_multiset<int> s = {1, 3, 3, 5, 6, 6, 100};
-    erase_if(s, [](int k) { return k <= 3; });
-    EXPECT_THAT(s, ElementsAre(5, 6, 6, 100));
-  }
-  {
-    absl::btree_map<int, int> m = {{1, 1}, {3, 3}, {6, 6}, {100, 100}};
-    erase_if(m, [](std::pair<const int, int> kv) { return kv.first > 3; });
-    EXPECT_THAT(m, ElementsAre(Pair(1, 1), Pair(3, 3)));
-  }
-  {
-    absl::btree_multimap<int, int> m = {{1, 1}, {3, 3}, {3, 6},
-                                        {6, 6}, {6, 7}, {100, 6}};
-    erase_if(m, [](std::pair<const int, int> kv) { return kv.second == 6; });
-    EXPECT_THAT(m, ElementsAre(Pair(1, 1), Pair(3, 3), Pair(6, 7)));
-  }
-  // Test that erasing all elements from a large set works and test support for
-  // function pointers.
-  {
-    absl::btree_set<int> s;
-    for (int i = 0; i < 1000; ++i) s.insert(2 * i);
-    erase_if(s, IsEven);
-    EXPECT_THAT(s, IsEmpty());
-  }
-  // Test that erase_if supports other format of function pointers.
-  {
-    absl::btree_set<int> s = {1, 3, 5, 6, 100};
-    erase_if(s, &IsEven);
-    EXPECT_THAT(s, ElementsAre(1, 3, 5));
-  }
-}
-
-TEST(Btree, InsertOrAssign) {
-  absl::btree_map<int, int> m = {{1, 1}, {3, 3}};
-  using value_type = typename decltype(m)::value_type;
-
-  auto ret = m.insert_or_assign(4, 4);
-  EXPECT_EQ(*ret.first, value_type(4, 4));
-  EXPECT_TRUE(ret.second);
-  ret = m.insert_or_assign(3, 100);
-  EXPECT_EQ(*ret.first, value_type(3, 100));
-  EXPECT_FALSE(ret.second);
-
-  auto hint_ret = m.insert_or_assign(ret.first, 3, 200);
-  EXPECT_EQ(*hint_ret, value_type(3, 200));
-  hint_ret = m.insert_or_assign(m.find(1), 0, 1);
-  EXPECT_EQ(*hint_ret, value_type(0, 1));
-  // Test with bad hint.
-  hint_ret = m.insert_or_assign(m.end(), -1, 1);
-  EXPECT_EQ(*hint_ret, value_type(-1, 1));
-
-  EXPECT_THAT(m, ElementsAre(Pair(-1, 1), Pair(0, 1), Pair(1, 1), Pair(3, 200),
-                             Pair(4, 4)));
-}
-
-TEST(Btree, InsertOrAssignMovableOnly) {
-  absl::btree_map<int, MovableOnlyInstance> m;
-  using value_type = typename decltype(m)::value_type;
-
-  auto ret = m.insert_or_assign(4, MovableOnlyInstance(4));
-  EXPECT_EQ(*ret.first, value_type(4, MovableOnlyInstance(4)));
-  EXPECT_TRUE(ret.second);
-  ret = m.insert_or_assign(4, MovableOnlyInstance(100));
-  EXPECT_EQ(*ret.first, value_type(4, MovableOnlyInstance(100)));
-  EXPECT_FALSE(ret.second);
-
-  auto hint_ret = m.insert_or_assign(ret.first, 3, MovableOnlyInstance(200));
-  EXPECT_EQ(*hint_ret, value_type(3, MovableOnlyInstance(200)));
-
-  EXPECT_EQ(m.size(), 2);
-}
-
-TEST(Btree, BitfieldArgument) {
-  union {
-    int n : 1;
-  };
-  n = 0;
-  absl::btree_map<int, int> m;
-  m.erase(n);
-  m.count(n);
-  m.find(n);
-  m.contains(n);
-  m.equal_range(n);
-  m.insert_or_assign(n, n);
-  m.insert_or_assign(m.end(), n, n);
-  m.try_emplace(n);
-  m.try_emplace(m.end(), n);
-  m.at(n);
-  m[n];
-}
-
-TEST(Btree, SetRangeConstructorAndInsertSupportExplicitConversionComparable) {
-  const absl::string_view names[] = {"n1", "n2"};
-
-  absl::btree_set<std::string> name_set1{std::begin(names), std::end(names)};
-  EXPECT_THAT(name_set1, ElementsAreArray(names));
-
-  absl::btree_set<std::string> name_set2;
-  name_set2.insert(std::begin(names), std::end(names));
-  EXPECT_THAT(name_set2, ElementsAreArray(names));
-}
-
-// A type that is explicitly convertible from int and counts constructor calls.
-struct ConstructorCounted {
-  explicit ConstructorCounted(int i) : i(i) { ++constructor_calls; }
-  bool operator==(int other) const { return i == other; }
-
-  int i;
-  static int constructor_calls;
-};
-int ConstructorCounted::constructor_calls = 0;
-
-struct ConstructorCountedCompare {
-  bool operator()(int a, const ConstructorCounted &b) const { return a < b.i; }
-  bool operator()(const ConstructorCounted &a, int b) const { return a.i < b; }
-  bool operator()(const ConstructorCounted &a,
-                  const ConstructorCounted &b) const {
-    return a.i < b.i;
-  }
-  using is_transparent = void;
-};
-
-TEST(Btree,
-     SetRangeConstructorAndInsertExplicitConvComparableLimitConstruction) {
-  const int i[] = {0, 1, 1};
-  ConstructorCounted::constructor_calls = 0;
-
-  absl::btree_set<ConstructorCounted, ConstructorCountedCompare> set{
-      std::begin(i), std::end(i)};
-  EXPECT_THAT(set, ElementsAre(0, 1));
-  EXPECT_EQ(ConstructorCounted::constructor_calls, 2);
-
-  set.insert(std::begin(i), std::end(i));
-  EXPECT_THAT(set, ElementsAre(0, 1));
-  EXPECT_EQ(ConstructorCounted::constructor_calls, 2);
-}
-
-TEST(Btree,
-     SetRangeConstructorAndInsertSupportExplicitConversionNonComparable) {
-  const int i[] = {0, 1};
-
-  absl::btree_set<std::vector<void *>> s1{std::begin(i), std::end(i)};
-  EXPECT_THAT(s1, ElementsAre(IsEmpty(), ElementsAre(IsNull())));
-
-  absl::btree_set<std::vector<void *>> s2;
-  s2.insert(std::begin(i), std::end(i));
-  EXPECT_THAT(s2, ElementsAre(IsEmpty(), ElementsAre(IsNull())));
-}
-
-// libstdc++ included with GCC 4.9 has a bug in the std::pair constructors that
-// prevents explicit conversions between pair types.
-// We only run this test for the libstdc++ from GCC 7 or newer because we can't
-// reliably check the libstdc++ version prior to that release.
-#if !defined(__GLIBCXX__) || \
-    (defined(_GLIBCXX_RELEASE) && _GLIBCXX_RELEASE >= 7)
-TEST(Btree, MapRangeConstructorAndInsertSupportExplicitConversionComparable) {
-  const std::pair<absl::string_view, int> names[] = {{"n1", 1}, {"n2", 2}};
-
-  absl::btree_map<std::string, int> name_map1{std::begin(names),
-                                              std::end(names)};
-  EXPECT_THAT(name_map1, ElementsAre(Pair("n1", 1), Pair("n2", 2)));
-
-  absl::btree_map<std::string, int> name_map2;
-  name_map2.insert(std::begin(names), std::end(names));
-  EXPECT_THAT(name_map2, ElementsAre(Pair("n1", 1), Pair("n2", 2)));
-}
-
-TEST(Btree,
-     MapRangeConstructorAndInsertExplicitConvComparableLimitConstruction) {
-  const std::pair<int, int> i[] = {{0, 1}, {1, 2}, {1, 3}};
-  ConstructorCounted::constructor_calls = 0;
-
-  absl::btree_map<ConstructorCounted, int, ConstructorCountedCompare> map{
-      std::begin(i), std::end(i)};
-  EXPECT_THAT(map, ElementsAre(Pair(0, 1), Pair(1, 2)));
-  EXPECT_EQ(ConstructorCounted::constructor_calls, 2);
-
-  map.insert(std::begin(i), std::end(i));
-  EXPECT_THAT(map, ElementsAre(Pair(0, 1), Pair(1, 2)));
-  EXPECT_EQ(ConstructorCounted::constructor_calls, 2);
-}
-
-TEST(Btree,
-     MapRangeConstructorAndInsertSupportExplicitConversionNonComparable) {
-  const std::pair<int, int> i[] = {{0, 1}, {1, 2}};
-
-  absl::btree_map<std::vector<void *>, int> m1{std::begin(i), std::end(i)};
-  EXPECT_THAT(m1,
-              ElementsAre(Pair(IsEmpty(), 1), Pair(ElementsAre(IsNull()), 2)));
-
-  absl::btree_map<std::vector<void *>, int> m2;
-  m2.insert(std::begin(i), std::end(i));
-  EXPECT_THAT(m2,
-              ElementsAre(Pair(IsEmpty(), 1), Pair(ElementsAre(IsNull()), 2)));
-}
-
-TEST(Btree, HeterogeneousTryEmplace) {
-  absl::btree_map<std::string, int> m;
-  std::string s = "key";
-  absl::string_view sv = s;
-  m.try_emplace(sv, 1);
-  EXPECT_EQ(m[s], 1);
-
-  m.try_emplace(m.end(), sv, 2);
-  EXPECT_EQ(m[s], 1);
-}
-
-TEST(Btree, HeterogeneousOperatorMapped) {
-  absl::btree_map<std::string, int> m;
-  std::string s = "key";
-  absl::string_view sv = s;
-  m[sv] = 1;
-  EXPECT_EQ(m[s], 1);
-
-  m[sv] = 2;
-  EXPECT_EQ(m[s], 2);
-}
-
-TEST(Btree, HeterogeneousInsertOrAssign) {
-  absl::btree_map<std::string, int> m;
-  std::string s = "key";
-  absl::string_view sv = s;
-  m.insert_or_assign(sv, 1);
-  EXPECT_EQ(m[s], 1);
-
-  m.insert_or_assign(m.end(), sv, 2);
-  EXPECT_EQ(m[s], 2);
-}
-#endif
-
-// This test requires std::launder for mutable key access in node handles.
-#if defined(__cpp_lib_launder) && __cpp_lib_launder >= 201606
-TEST(Btree, NodeHandleMutableKeyAccess) {
-  {
-    absl::btree_map<std::string, std::string> map;
-
-    map["key1"] = "mapped";
-
-    auto nh = map.extract(map.begin());
-    nh.key().resize(3);
-    map.insert(std::move(nh));
-
-    EXPECT_THAT(map, ElementsAre(Pair("key", "mapped")));
-  }
-  // Also for multimap.
-  {
-    absl::btree_multimap<std::string, std::string> map;
-
-    map.emplace("key1", "mapped");
-
-    auto nh = map.extract(map.begin());
-    nh.key().resize(3);
-    map.insert(std::move(nh));
-
-    EXPECT_THAT(map, ElementsAre(Pair("key", "mapped")));
-  }
-}
-#endif
-
-struct MultiKey {
-  int i1;
-  int i2;
-};
-
-bool operator==(const MultiKey a, const MultiKey b) {
-  return a.i1 == b.i1 && a.i2 == b.i2;
-}
-
-// A heterogeneous comparator that has different equivalence classes for
-// different lookup types.
-struct MultiKeyComp {
-  using is_transparent = void;
-  bool operator()(const MultiKey a, const MultiKey b) const {
-    if (a.i1 != b.i1) return a.i1 < b.i1;
-    return a.i2 < b.i2;
-  }
-  bool operator()(const int a, const MultiKey b) const { return a < b.i1; }
-  bool operator()(const MultiKey a, const int b) const { return a.i1 < b; }
-};
-
-TEST(Btree, MultiKeyEqualRange) {
-  absl::btree_set<MultiKey, MultiKeyComp> set;
-
-  for (int i = 0; i < 100; ++i) {
-    for (int j = 0; j < 100; ++j) {
-      set.insert({i, j});
-    }
-  }
-
-  for (int i = 0; i < 100; ++i) {
-    auto equal_range = set.equal_range(i);
-    EXPECT_EQ(equal_range.first->i1, i);
-    EXPECT_EQ(equal_range.first->i2, 0);
-    EXPECT_EQ(std::distance(equal_range.first, equal_range.second), 100) << i;
-  }
-}
-
-TEST(Btree, MultiKeyErase) {
-  absl::btree_set<MultiKey, MultiKeyComp> set = {
-      {1, 1}, {2, 1}, {2, 2}, {3, 1}};
-  EXPECT_EQ(set.erase(2), 2);
-  EXPECT_THAT(set, ElementsAre(MultiKey{1, 1}, MultiKey{3, 1}));
-}
-
-TEST(Btree, MultiKeyCount) {
-  const absl::btree_set<MultiKey, MultiKeyComp> set = {
-      {1, 1}, {2, 1}, {2, 2}, {3, 1}};
-  EXPECT_EQ(set.count(2), 2);
-}
-
-TEST(Btree, AllocConstructor) {
-  using Alloc = CountingAllocator<int>;
-  using Set = absl::btree_set<int, std::less<int>, Alloc>;
-  int64_t bytes_used = 0;
-  Alloc alloc(&bytes_used);
-  Set set(alloc);
-
-  set.insert({1, 2, 3});
-
-  EXPECT_THAT(set, ElementsAre(1, 2, 3));
-  EXPECT_GT(bytes_used, set.size() * sizeof(int));
-}
-
-TEST(Btree, AllocInitializerListConstructor) {
-  using Alloc = CountingAllocator<int>;
-  using Set = absl::btree_set<int, std::less<int>, Alloc>;
-  int64_t bytes_used = 0;
-  Alloc alloc(&bytes_used);
-  Set set({1, 2, 3}, alloc);
-
-  EXPECT_THAT(set, ElementsAre(1, 2, 3));
-  EXPECT_GT(bytes_used, set.size() * sizeof(int));
-}
-
-TEST(Btree, AllocRangeConstructor) {
-  using Alloc = CountingAllocator<int>;
-  using Set = absl::btree_set<int, std::less<int>, Alloc>;
-  int64_t bytes_used = 0;
-  Alloc alloc(&bytes_used);
-  std::vector<int> v = {1, 2, 3};
-  Set set(v.begin(), v.end(), alloc);
-
-  EXPECT_THAT(set, ElementsAre(1, 2, 3));
-  EXPECT_GT(bytes_used, set.size() * sizeof(int));
-}
-
-TEST(Btree, AllocCopyConstructor) {
-  using Alloc = CountingAllocator<int>;
-  using Set = absl::btree_set<int, std::less<int>, Alloc>;
-  int64_t bytes_used1 = 0;
-  Alloc alloc1(&bytes_used1);
-  Set set1(alloc1);
-
-  set1.insert({1, 2, 3});
-
-  int64_t bytes_used2 = 0;
-  Alloc alloc2(&bytes_used2);
-  Set set2(set1, alloc2);
-
-  EXPECT_THAT(set1, ElementsAre(1, 2, 3));
-  EXPECT_THAT(set2, ElementsAre(1, 2, 3));
-  EXPECT_GT(bytes_used1, set1.size() * sizeof(int));
-  EXPECT_EQ(bytes_used1, bytes_used2);
-}
-
-TEST(Btree, AllocMoveConstructor_SameAlloc) {
-  using Alloc = CountingAllocator<int>;
-  using Set = absl::btree_set<int, std::less<int>, Alloc>;
-  int64_t bytes_used = 0;
-  Alloc alloc(&bytes_used);
-  Set set1(alloc);
-
-  set1.insert({1, 2, 3});
-
-  const int64_t original_bytes_used = bytes_used;
-  EXPECT_GT(original_bytes_used, set1.size() * sizeof(int));
-
-  Set set2(std::move(set1), alloc);
-
-  EXPECT_THAT(set2, ElementsAre(1, 2, 3));
-  EXPECT_EQ(bytes_used, original_bytes_used);
-}
-
-TEST(Btree, AllocMoveConstructor_DifferentAlloc) {
-  using Alloc = CountingAllocator<int>;
-  using Set = absl::btree_set<int, std::less<int>, Alloc>;
-  int64_t bytes_used1 = 0;
-  Alloc alloc1(&bytes_used1);
-  Set set1(alloc1);
-
-  set1.insert({1, 2, 3});
-
-  const int64_t original_bytes_used = bytes_used1;
-  EXPECT_GT(original_bytes_used, set1.size() * sizeof(int));
-
-  int64_t bytes_used2 = 0;
-  Alloc alloc2(&bytes_used2);
-  Set set2(std::move(set1), alloc2);
-
-  EXPECT_THAT(set2, ElementsAre(1, 2, 3));
-  // We didn't free these bytes allocated by `set1` yet.
-  EXPECT_EQ(bytes_used1, original_bytes_used);
-  EXPECT_EQ(bytes_used2, original_bytes_used);
-}
-
-}  // namespace
-}  // namespace container_internal
-ABSL_NAMESPACE_END
-}  // namespace absl