Export of internal Abseil changes

--
c68f1886f5e8fd90eb0c2d2e68feaf00a7cdacda by CJ Johnson <johnsoncj@google.com>:

Introduce absl::Cleanup to the OSS repo

PiperOrigin-RevId: 354583156

--
17030cf388e10f7eb959e3e566326d1072ce392e by Abseil Team <absl-team@google.com>:

Internal change only

PiperOrigin-RevId: 354574953

--
e979d7236d4f3252e79ddda6739b67a9a326bf6d by CJ Johnson <johnsoncj@google.com>:

Internal change

PiperOrigin-RevId: 354545297

--
7ea02b3783f7f49ef97d86a8f6580a19cc57df14 by Abseil Team <absl-team@google.com>:

Pre-allocate memory for vectors where the size is known.

PiperOrigin-RevId: 354344576

--
9246c7cb11f1d6444f79ebe25acc69a8a9b870e0 by Matt Kulukundis <kfm@google.com>:

Add support for Elbrus 2000 (e2k)

Import of https://github.com/abseil/abseil-cpp/pull/889

PiperOrigin-RevId: 354344013

--
0fc93d359cc1fb307552e917b37b7b2e7eed822f by Abseil Team <absl-team@google.com>:

Integrate CordRepRing logic into cord (but do not enable it)

PiperOrigin-RevId: 354312238

--
eda05622f7da71466723acb33403f783529df24b by Abseil Team <absl-team@google.com>:

Protect ignore diagnostic with "__has_warning".

PiperOrigin-RevId: 354112334

--
47716c5d8fb10efa4fdd801d28bac414c6f8ec32 by Abseil Team <absl-team@google.com>:

Rearrange InlinedVector copy constructor and destructor to treat
a few special cases inline and then tail-call a non-inlined routine
for the rest.  In particular, we optimize for empty vectors in both
cases.

Added a couple of benchmarks that copy either an InlVec<int64> or
an InlVec<InlVec<int64>>.

Speed difference:
```
BM_CopyTrivial/0                                    0.92ns +- 0%   0.47ns +- 0%  -48.91%  (p=0.000 n=11+12)
BM_CopyTrivial/1                                    0.92ns +- 0%   1.15ns +- 0%  +25.00%  (p=0.000 n=10+9)
BM_CopyTrivial/8                                    8.57ns +- 0%  10.72ns +- 1%  +25.16%  (p=0.000 n=10+12)
BM_CopyNonTrivial/0                                 3.21ns +- 0%   0.70ns +- 0%  -78.23%  (p=0.000 n=12+10)
BM_CopyNonTrivial/1                                 5.88ns +- 1%   5.51ns +- 0%   -6.28%  (p=0.000 n=10+8)
BM_CopyNonTrivial/8                                 21.5ns +- 1%   15.2ns +- 2%  -29.23%  (p=0.000 n=12+12)
```

Note: the slowdowns are a few cycles which is expected given the procedure
call added in that case. We decided this is a good tradeoff given the code
size reductions and the more significant speedups for empty vectors.

Size difference (as measured by nm):
```
BM_CopyTrivial     from 1048 bytes to 326 bytes.
BM_CopyNonTrivial  from  749 bytes to 470 bytes.
```

Code size for a large binary drops by ~500KB (from 349415719 to 348906015 348906191).

All of the benchmarks that showed a significant difference:

Ones that improve with this CL:
```
BM_CopyNonTrivial/0                                 3.21ns +- 0%   0.70ns +- 0%  -78.23%  (p=0.000 n=12+10)
BM_InlinedVectorFillString/0                        0.93ns +- 0%   0.24ns +- 0%  -74.19%  (p=0.000 n=12+10)
BM_InlinedVectorAssignments/1                       10.5ns +- 0%    4.1ns +- 0%  -60.64%  (p=0.000 n=11+10)
BM_InlinedVectorAssignments/2                       10.7ns +- 0%    4.4ns +- 0%  -59.08%  (p=0.000 n=11+11)
BM_CopyTrivial/0                                    0.92ns +- 0%   0.47ns +- 0%  -48.91%  (p=0.000 n=11+12)
BM_CopyNonTrivial/8                                 21.5ns +- 1%   15.2ns +- 2%  -29.23%  (p=0.000 n=12+12)
BM_StdVectorEmpty                                   0.47ns +- 1%   0.35ns +- 0%  -24.73%  (p=0.000 n=12+12)
BM_StdVectorSize                                    0.46ns +- 2%   0.35ns +- 0%  -24.32%  (p=0.000 n=12+12)
BM_SwapElements<LargeCopyableOnly>/0                3.44ns +- 0%   2.76ns +- 1%  -19.83%  (p=0.000 n=11+11)
BM_InlinedVectorFillRange/256                       20.7ns +- 1%   17.8ns +- 0%  -14.08%  (p=0.000 n=12+9)
BM_CopyNonTrivial/1                                 5.88ns +- 1%   5.51ns +- 0%   -6.28%  (p=0.000 n=10+8)
BM_SwapElements<LargeCopyableMovable>/1             4.19ns +- 0%   3.95ns +- 1%   -5.63%  (p=0.000 n=11+12)
BM_SwapElements<LargeCopyableMovableSwappable>/1    4.18ns +- 0%   3.99ns +- 0%   -4.70%  (p=0.000 n=9+11)
BM_SwapElements<LargeCopyableMovable>/0             2.41ns +- 0%   2.31ns +- 0%   -4.45%  (p=0.000 n=12+12)
BM_InlinedVectorFillRange/64                        8.25ns +- 0%   8.04ns +- 0%   -2.51%  (p=0.000 n=12+11)
BM_SwapElements<LargeCopyableOnly>/1                82.4ns +- 0%   81.5ns +- 0%   -1.06%  (p=0.000 n=12+12)
```

Ones that get worse with this CL:
```
BM_CopyTrivial/1                                    0.92ns +- 0%   1.15ns +- 0%  +25.00%  (p=0.000 n=10+9)
BM_CopyTrivial/8                                    8.57ns +- 0%  10.72ns +- 1%  +25.16%  (p=0.000 n=10+12)
BM_SwapElements<LargeCopyableMovableSwappable>/512  1.48ns +- 1%   1.66ns +- 1%  +11.88%  (p=0.000 n=12+12)
BM_InlinedVectorFillString/1                        11.5ns +- 0%   12.8ns +- 1%  +11.62%  (p=0.000 n=12+11)
BM_SwapElements<LargeCopyableMovableSwappable>/64   1.48ns +- 2%   1.66ns +- 1%  +11.66%  (p=0.000 n=12+11)
BM_SwapElements<LargeCopyableMovableSwappable>/1k   1.48ns +- 1%   1.65ns +- 2%  +11.32%  (p=0.000 n=12+12)
BM_SwapElements<LargeCopyableMovable>/512           1.48ns +- 2%   1.58ns +- 4%   +6.62%  (p=0.000 n=11+12)
BM_SwapElements<LargeCopyableMovable>/1k            1.49ns +- 2%   1.58ns +- 3%   +6.05%  (p=0.000 n=12+12)
BM_SwapElements<LargeCopyableMovable>/64            1.48ns +- 2%   1.57ns +- 4%   +6.04%  (p=0.000 n=11+12)
BM_InlinedVectorFillRange/1                         4.81ns +- 0%   5.05ns +- 0%   +4.83%  (p=0.000 n=11+11)
BM_InlinedVectorFillString/8                        79.4ns +- 1%   83.1ns +- 1%   +4.64%  (p=0.000 n=10+12)
BM_StdVectorFillString/1                            16.3ns +- 0%   16.6ns +- 0%   +2.13%  (p=0.000 n=11+8)
```

PiperOrigin-RevId: 353906786

--
8e26518b3cec9c598e5e9573c46c3bd1b03a67ef by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 353737330

--
f206ae0983e58c9904ed8b8f05f9caf564a446be by Matt Kulukundis <kfm@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 353682256
GitOrigin-RevId: c68f1886f5e8fd90eb0c2d2e68feaf00a7cdacda
Change-Id: I5790c1036c4f543c701d1039848fabf7ae881ad8

5 files changed, 567 insertions, 0 deletions

diff --git a/absl/cleanup/BUILD.bazel b/absl/cleanup/BUILD.bazel
new file mode 100644
index 00000000..5cca898f
--- /dev/null
+++ b/absl/cleanup/BUILD.bazel
@@ -0,0 +1,66 @@
+# Copyright 2021 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.
+
+load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
+load(
+    "//absl:copts/configure_copts.bzl",
+    "ABSL_DEFAULT_COPTS",
+    "ABSL_DEFAULT_LINKOPTS",
+    "ABSL_TEST_COPTS",
+)
+
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+cc_library(
+    name = "cleanup_internal",
+    hdrs = ["internal/cleanup.h"],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        "//absl/base:base_internal",
+        "//absl/base:core_headers",
+        "//absl/utility",
+    ],
+)
+
+cc_library(
+    name = "cleanup",
+    hdrs = [
+        "cleanup.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        ":cleanup_internal",
+        "//absl/base:config",
+        "//absl/base:core_headers",
+    ],
+)
+
+cc_test(
+    name = "cleanup_test",
+    size = "small",
+    srcs = [
+        "cleanup_test.cc",
+    ],
+    copts = ABSL_TEST_COPTS,
+    deps = [
+        ":cleanup",
+        "//absl/base:config",
+        "//absl/utility",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
diff --git a/absl/cleanup/CMakeLists.txt b/absl/cleanup/CMakeLists.txt
new file mode 100644
index 00000000..a2dd78a8
--- /dev/null
+++ b/absl/cleanup/CMakeLists.txt
@@ -0,0 +1,55 @@
+# Copyright 2021 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.
+
+absl_cc_library(
+  NAME
+    cleanup_internal
+  HDRS
+    "internal/cleanup.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  DEPS
+    absl::base_internal
+    absl::core_headers
+    absl::utility
+  PUBLIC
+)
+
+absl_cc_library(
+  NAME
+    cleanup
+  HDRS
+    "cleanup.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  DEPS
+    absl::cleanup_internal
+    absl::config
+    absl::core_headers
+  PUBLIC
+)
+
+absl_cc_test(
+  NAME
+    cleanup_test
+  SRCS
+    "cleanup_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::cleanup
+    absl::config
+    absl::utility
+    gmock_main
+)
diff --git a/absl/cleanup/cleanup.h b/absl/cleanup/cleanup.h
new file mode 100644
index 00000000..eba04b33
--- /dev/null
+++ b/absl/cleanup/cleanup.h
@@ -0,0 +1,129 @@
+// Copyright 2021 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.
+//
+// -----------------------------------------------------------------------------
+// File: cleanup.h
+// -----------------------------------------------------------------------------
+//
+// `absl::Cleanup` implements the scope guard idiom, invoking `operator()() &&`
+// on the callback it was constructed with, on scope exit.
+//
+// Example:
+//
+// ```
+//   void CopyGoodData(const char* input_path, const char* output_path) {
+//     FILE* in_file = fopen(input_path, "r");
+//     FILE* out_file = fopen(output_path, "w");
+//     if (in_file == nullptr || out_file == nullptr) return;
+//
+//     // C++17 style using class template argument deduction
+//     absl::Cleanup in_closer = [&in_file] { fclose(in_file); };
+//
+//     // C++11 style using the factory function
+//     auto out_closer = absl::MakeCleanup([&out_file] { fclose(out_file); });
+//
+//     // `fclose` will be called on all exit paths by the cleanup instances
+//
+//     Data data;
+//     while (ReadData(in_file, &data)) {
+//       if (data.IsBad()) {
+//         LOG(ERROR) << "Found bad data.";
+//         return;  // `in_closer` and `out_closer` will call their callbacks
+//       }
+//       SaveData(out_file, &data);
+//     }
+//     return;  // `in_closer` and `out_closer` will call their callbacks
+//   }
+// ```
+//
+// `std::move(cleanup).Invoke()` will execute the callback early, before
+// destruction, and prevent the callback from executing in the destructor.
+//
+// Alternatively, `std::move(cleanup).Cancel()` will prevent the callback from
+// ever executing at all.
+//
+// Once a cleanup object has been `std::move(...)`-ed, it may not be used again.
+
+#ifndef ABSL_CLEANUP_CLEANUP_H_
+#define ABSL_CLEANUP_CLEANUP_H_
+
+#include <utility>
+
+#include "absl/base/config.h"
+#include "absl/base/macros.h"
+#include "absl/cleanup/internal/cleanup.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+template <typename Arg, typename Callback = void()>
+class ABSL_MUST_USE_RESULT Cleanup {
+  static_assert(cleanup_internal::WasDeduced<Arg>(),
+                "Explicit template parameters are not supported.");
+
+  static_assert(cleanup_internal::ReturnsVoid<Callback>(),
+                "Callbacks that return values are not supported.");
+
+ public:
+  Cleanup(Callback callback) : storage_(std::move(callback)) {}  // NOLINT
+
+  Cleanup(Cleanup&& other) : storage_(std::move(other.storage_)) {}
+
+  void Cancel() && {
+    ABSL_HARDENING_ASSERT(storage_.IsCallbackEngaged());
+    storage_.DisengageCallback();
+  }
+
+  void Invoke() && {
+    ABSL_HARDENING_ASSERT(storage_.IsCallbackEngaged());
+    storage_.DisengageCallback();
+    storage_.InvokeCallback();
+  }
+
+  ~Cleanup() {
+    if (storage_.IsCallbackEngaged()) {
+      storage_.InvokeCallback();
+    }
+  }
+
+ private:
+  cleanup_internal::Storage<Callback> storage_;
+};
+
+// `auto c = absl::MakeCleanup(/* callback */);`
+//
+// C++11 type deduction API for creating an instance of `absl::Cleanup`.
+template <typename... Args, typename Callback>
+absl::Cleanup<cleanup_internal::Tag, Callback> MakeCleanup(Callback callback) {
+  static_assert(cleanup_internal::WasDeduced<cleanup_internal::Tag, Args...>(),
+                "Explicit template parameters are not supported.");
+
+  static_assert(cleanup_internal::ReturnsVoid<Callback>(),
+                "Callbacks that return values are not supported.");
+
+  return {std::move(callback)};
+}
+
+// `absl::Cleanup c = /* callback */;`
+//
+// C++17 type deduction API for creating an instance of `absl::Cleanup`.
+#if defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
+template <typename Callback>
+Cleanup(Callback callback) -> Cleanup<cleanup_internal::Tag, Callback>;
+#endif  // defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_CLEANUP_CLEANUP_H_
diff --git a/absl/cleanup/cleanup_test.cc b/absl/cleanup/cleanup_test.cc
new file mode 100644
index 00000000..34e3bfad
--- /dev/null
+++ b/absl/cleanup/cleanup_test.cc
@@ -0,0 +1,240 @@
+// Copyright 2021 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/cleanup/cleanup.h"
+
+#include <functional>
+#include <type_traits>
+#include <utility>
+
+#include "gtest/gtest.h"
+#include "absl/base/config.h"
+#include "absl/utility/utility.h"
+
+namespace {
+
+using Tag = absl::cleanup_internal::Tag;
+
+template <typename Type1, typename Type2>
+void AssertSameType() {
+  static_assert(std::is_same<Type1, Type2>::value, "");
+}
+
+struct IdentityFactory {
+  template <typename Callback>
+  static Callback AsCallback(Callback callback) {
+    return Callback(std::move(callback));
+  }
+};
+
+// `FunctorClass` is a type used for testing `absl::Cleanup`. It is intended to
+// represent users that make their own move-only callback types outside of
+// `std::function` and lambda literals.
+class FunctorClass {
+  using Callback = std::function<void()>;
+
+ public:
+  explicit FunctorClass(Callback callback) : callback_(std::move(callback)) {}
+
+  FunctorClass(FunctorClass&& other)
+      : callback_(absl::exchange(other.callback_, Callback())) {}
+
+  FunctorClass(const FunctorClass&) = delete;
+
+  FunctorClass& operator=(const FunctorClass&) = delete;
+
+  FunctorClass& operator=(FunctorClass&&) = delete;
+
+  void operator()() const& = delete;
+
+  void operator()() && {
+    ASSERT_TRUE(callback_);
+    callback_();
+    callback_ = nullptr;
+  }
+
+ private:
+  Callback callback_;
+};
+
+struct FunctorClassFactory {
+  template <typename Callback>
+  static FunctorClass AsCallback(Callback callback) {
+    return FunctorClass(std::move(callback));
+  }
+};
+
+struct StdFunctionFactory {
+  template <typename Callback>
+  static std::function<void()> AsCallback(Callback callback) {
+    return std::function<void()>(std::move(callback));
+  }
+};
+
+using CleanupTestParams =
+    ::testing::Types<IdentityFactory, FunctorClassFactory, StdFunctionFactory>;
+template <typename>
+struct CleanupTest : public ::testing::Test {};
+TYPED_TEST_SUITE(CleanupTest, CleanupTestParams);
+
+bool function_pointer_called = false;
+void FunctionPointerFunction() { function_pointer_called = true; }
+
+TYPED_TEST(CleanupTest, FactoryProducesCorrectType) {
+  {
+    auto callback = TypeParam::AsCallback([] {});
+    auto cleanup = absl::MakeCleanup(std::move(callback));
+
+    AssertSameType<absl::Cleanup<Tag, decltype(callback)>, decltype(cleanup)>();
+  }
+
+  {
+    auto cleanup = absl::MakeCleanup(&FunctionPointerFunction);
+
+    AssertSameType<absl::Cleanup<Tag, void (*)()>, decltype(cleanup)>();
+  }
+
+  {
+    auto cleanup = absl::MakeCleanup(FunctionPointerFunction);
+
+    AssertSameType<absl::Cleanup<Tag, void (*)()>, decltype(cleanup)>();
+  }
+}
+
+#if defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
+TYPED_TEST(CleanupTest, CTADProducesCorrectType) {
+  {
+    auto callback = TypeParam::AsCallback([] {});
+    absl::Cleanup cleanup = std::move(callback);
+
+    AssertSameType<absl::Cleanup<Tag, decltype(callback)>, decltype(cleanup)>();
+  }
+
+  {
+    absl::Cleanup cleanup = &FunctionPointerFunction;
+
+    AssertSameType<absl::Cleanup<Tag, void (*)()>, decltype(cleanup)>();
+  }
+
+  {
+    absl::Cleanup cleanup = FunctionPointerFunction;
+
+    AssertSameType<absl::Cleanup<Tag, void (*)()>, decltype(cleanup)>();
+  }
+}
+
+TYPED_TEST(CleanupTest, FactoryAndCTADProduceSameType) {
+  {
+    auto callback = IdentityFactory::AsCallback([] {});
+    auto factory_cleanup = absl::MakeCleanup(callback);
+    absl::Cleanup deduction_cleanup = callback;
+
+    AssertSameType<decltype(factory_cleanup), decltype(deduction_cleanup)>();
+  }
+
+  {
+    auto factory_cleanup =
+        absl::MakeCleanup(FunctorClassFactory::AsCallback([] {}));
+    absl::Cleanup deduction_cleanup = FunctorClassFactory::AsCallback([] {});
+
+    AssertSameType<decltype(factory_cleanup), decltype(deduction_cleanup)>();
+  }
+
+  {
+    auto factory_cleanup =
+        absl::MakeCleanup(StdFunctionFactory::AsCallback([] {}));
+    absl::Cleanup deduction_cleanup = StdFunctionFactory::AsCallback([] {});
+
+    AssertSameType<decltype(factory_cleanup), decltype(deduction_cleanup)>();
+  }
+
+  {
+    auto factory_cleanup = absl::MakeCleanup(&FunctionPointerFunction);
+    absl::Cleanup deduction_cleanup = &FunctionPointerFunction;
+
+    AssertSameType<decltype(factory_cleanup), decltype(deduction_cleanup)>();
+  }
+
+  {
+    auto factory_cleanup = absl::MakeCleanup(FunctionPointerFunction);
+    absl::Cleanup deduction_cleanup = FunctionPointerFunction;
+
+    AssertSameType<decltype(factory_cleanup), decltype(deduction_cleanup)>();
+  }
+}
+#endif  // defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
+
+TYPED_TEST(CleanupTest, BasicUsage) {
+  bool called = false;
+
+  {
+    EXPECT_FALSE(called);
+
+    auto cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback([&called] { called = true; }));
+
+    EXPECT_FALSE(called);
+  }
+
+  EXPECT_TRUE(called);
+}
+
+TYPED_TEST(CleanupTest, BasicUsageWithFunctionPointer) {
+  function_pointer_called = false;
+
+  {
+    EXPECT_FALSE(function_pointer_called);
+
+    auto cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback(&FunctionPointerFunction));
+
+    EXPECT_FALSE(function_pointer_called);
+  }
+
+  EXPECT_TRUE(function_pointer_called);
+}
+
+TYPED_TEST(CleanupTest, Cancel) {
+  bool called = false;
+
+  {
+    EXPECT_FALSE(called);
+
+    auto cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback([&called] { called = true; }));
+    std::move(cleanup).Cancel();
+
+    EXPECT_FALSE(called);
+  }
+
+  EXPECT_FALSE(called);
+}
+
+TYPED_TEST(CleanupTest, Invoke) {
+  bool called = false;
+
+  {
+    EXPECT_FALSE(called);
+
+    auto cleanup =
+        absl::MakeCleanup(TypeParam::AsCallback([&called] { called = true; }));
+    std::move(cleanup).Invoke();
+
+    EXPECT_TRUE(called);
+  }
+
+  EXPECT_TRUE(called);
+}
+
+}  // namespace
diff --git a/absl/cleanup/internal/cleanup.h b/absl/cleanup/internal/cleanup.h
new file mode 100644
index 00000000..a126ff30
--- /dev/null
+++ b/absl/cleanup/internal/cleanup.h
@@ -0,0 +1,77 @@
+// Copyright 2021 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef ABSL_CLEANUP_INTERNAL_CLEANUP_H_
+#define ABSL_CLEANUP_INTERNAL_CLEANUP_H_
+
+#include <type_traits>
+#include <utility>
+
+#include "absl/base/internal/invoke.h"
+#include "absl/base/thread_annotations.h"
+#include "absl/utility/utility.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+namespace cleanup_internal {
+
+struct Tag {};
+
+template <typename Arg, typename... Args>
+constexpr bool WasDeduced() {
+  return (std::is_same<cleanup_internal::Tag, Arg>::value) &&
+         (sizeof...(Args) == 0);
+}
+
+template <typename Callback>
+constexpr bool ReturnsVoid() {
+  return (std::is_same<base_internal::invoke_result_t<Callback>, void>::value);
+}
+
+template <typename Callback>
+class Storage {
+ public:
+  explicit Storage(Callback callback)
+      : engaged_(true), callback_(std::move(callback)) {}
+
+  Storage(Storage&& other)
+      : engaged_(absl::exchange(other.engaged_, false)),
+        callback_(std::move(other.callback_)) {}
+
+  Storage(const Storage& other) = delete;
+
+  Storage& operator=(Storage&& other) = delete;
+
+  Storage& operator=(const Storage& other) = delete;
+
+  bool IsCallbackEngaged() const { return engaged_; }
+
+  void DisengageCallback() { engaged_ = false; }
+
+  void InvokeCallback() ABSL_NO_THREAD_SAFETY_ANALYSIS {
+    std::move(callback_)();
+  }
+
+ private:
+  bool engaged_;
+  Callback callback_;
+};
+
+}  // namespace cleanup_internal
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_CLEANUP_INTERNAL_CLEANUP_H_