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diff --git a/absl/container/internal/hash_generator_testing.h b/absl/container/internal/hash_generator_testing.h
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+// Copyright 2018 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://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.
+//
+// Generates random values for testing. Specialized only for the few types we
+// care about.
+
+#ifndef ABSL_CONTAINER_INTERNAL_HASH_GENERATOR_TESTING_H_
+#define ABSL_CONTAINER_INTERNAL_HASH_GENERATOR_TESTING_H_
+
+#include <stdint.h>
+#include <algorithm>
+#include <iosfwd>
+#include <random>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+#include "absl/container/internal/hash_policy_testing.h"
+#include "absl/meta/type_traits.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+inline namespace lts_2018_12_18 {
+namespace container_internal {
+namespace hash_internal {
+namespace generator_internal {
+
+template <class Container, class = void>
+struct IsMap : std::false_type {};
+
+template <class Map>
+struct IsMap<Map, absl::void_t<typename Map::mapped_type>> : std::true_type {};
+
+}  // namespace generator_internal
+
+std::mt19937_64* GetSharedRng();
+
+enum Enum {
+  kEnumEmpty,
+  kEnumDeleted,
+};
+
+enum class EnumClass : uint64_t {
+  kEmpty,
+  kDeleted,
+};
+
+inline std::ostream& operator<<(std::ostream& o, const EnumClass& ec) {
+  return o << static_cast<uint64_t>(ec);
+}
+
+template <class T, class E = void>
+struct Generator;
+
+template <class T>
+struct Generator<T, typename std::enable_if<std::is_integral<T>::value>::type> {
+  T operator()() const {
+    std::uniform_int_distribution<T> dist;
+    return dist(*GetSharedRng());
+  }
+};
+
+template <>
+struct Generator<Enum> {
+  Enum operator()() const {
+    std::uniform_int_distribution<typename std::underlying_type<Enum>::type>
+        dist;
+    while (true) {
+      auto variate = dist(*GetSharedRng());
+      if (variate != kEnumEmpty && variate != kEnumDeleted)
+        return static_cast<Enum>(variate);
+    }
+  }
+};
+
+template <>
+struct Generator<EnumClass> {
+  EnumClass operator()() const {
+    std::uniform_int_distribution<
+        typename std::underlying_type<EnumClass>::type>
+        dist;
+    while (true) {
+      EnumClass variate = static_cast<EnumClass>(dist(*GetSharedRng()));
+      if (variate != EnumClass::kEmpty && variate != EnumClass::kDeleted)
+        return static_cast<EnumClass>(variate);
+    }
+  }
+};
+
+template <>
+struct Generator<std::string> {
+  std::string operator()() const;
+};
+
+template <>
+struct Generator<absl::string_view> {
+  absl::string_view operator()() const;
+};
+
+template <>
+struct Generator<NonStandardLayout> {
+  NonStandardLayout operator()() const {
+    return NonStandardLayout(Generator<std::string>()());
+  }
+};
+
+template <class K, class V>
+struct Generator<std::pair<K, V>> {
+  std::pair<K, V> operator()() const {
+    return std::pair<K, V>(Generator<typename std::decay<K>::type>()(),
+                           Generator<typename std::decay<V>::type>()());
+  }
+};
+
+template <class... Ts>
+struct Generator<std::tuple<Ts...>> {
+  std::tuple<Ts...> operator()() const {
+    return std::tuple<Ts...>(Generator<typename std::decay<Ts>::type>()()...);
+  }
+};
+
+template <class U>
+struct Generator<U, absl::void_t<decltype(std::declval<U&>().key()),
+                                decltype(std::declval<U&>().value())>>
+    : Generator<std::pair<
+          typename std::decay<decltype(std::declval<U&>().key())>::type,
+          typename std::decay<decltype(std::declval<U&>().value())>::type>> {};
+
+template <class Container>
+using GeneratedType = decltype(
+    std::declval<const Generator<
+        typename std::conditional<generator_internal::IsMap<Container>::value,
+                                  typename Container::value_type,
+                                  typename Container::key_type>::type>&>()());
+
+}  // namespace hash_internal
+}  // namespace container_internal
+}  // inline namespace lts_2018_12_18
+}  // namespace absl
+
+#endif  // ABSL_CONTAINER_INTERNAL_HASH_GENERATOR_TESTING_H_