Export of internal Abseil changes

--
23500704dd7c2642fad49f88c07ce41ebaab12e4 by Abseil Team <absl-team@google.com>:

Change fetch_add() to store(1 + load())

As there is only one concurrent writer to the Info struct, we can avoid using
the more expensive fetch_add() function.

PiperOrigin-RevId: 329523785

--
79e5018dba2e117ad89b76367165a604b3f24045 by Abseil Team <absl-team@google.com>:

Record rehash count in hashtablez

This will help identify which containers could benefit from a reserve call.

PiperOrigin-RevId: 329510552

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e327e54b805d67556f934fa7f7dc2d4e72fa066a by Abseil Team <absl-team@google.com>:

Fix -Wsign-compare issues.

These lines could theoretically have overflowed in cases of very large stack
traces etc. Very unlikely, but this was causing warnings when built with
-Wsign-compare, which we intend to enable with Chromium.

In none of these three cases is it trivial to switch to a range-based for loop.

PiperOrigin-RevId: 329415195

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08aca2fc75e8b3ad1201849987b64148fe48f283 by Xiaoyi Zhang <zhangxy@google.com>:

Release absl::StatusOr.

PiperOrigin-RevId: 329353348

--
bf4d2a7f8b089e2adf14d32b0e39de0a981005c3 by Xiaoyi Zhang <zhangxy@google.com>:

Internal change

PiperOrigin-RevId: 329337031

--
42fa7d2fb993bbfc344954227cf1eeb801eca065 by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 329099807
GitOrigin-RevId: 23500704dd7c2642fad49f88c07ce41ebaab12e4
Change-Id: I6713e4ca3bb0ab2ced5e487827ae036ab8ac61f1

1 files changed, 1800 insertions, 0 deletions

diff --git a/absl/status/statusor_test.cc b/absl/status/statusor_test.cc
new file mode 100644
index 00000000..5e4b2687
--- /dev/null
+++ b/absl/status/statusor_test.cc
@@ -0,0 +1,1800 @@
+// Copyright 2020 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/status/statusor.h"
+
+#include <array>
+#include <initializer_list>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/base/casts.h"
+#include "absl/memory/memory.h"
+#include "absl/status/status.h"
+#include "absl/types/any.h"
+#include "absl/utility/utility.h"
+
+namespace {
+
+using ::testing::AllOf;
+using ::testing::AnyWith;
+using ::testing::ElementsAre;
+using ::testing::Field;
+using ::testing::Ne;
+using ::testing::Not;
+using ::testing::Pointee;
+using ::testing::VariantWith;
+
+#ifdef GTEST_HAS_STATUS_MATCHERS
+using ::testing::status::IsOk;
+using ::testing::status::IsOkAndHolds;
+#else  // GTEST_HAS_STATUS_MATCHERS
+inline const ::absl::Status& GetStatus(const ::absl::Status& status) {
+  return status;
+}
+
+template <typename T>
+inline const ::absl::Status& GetStatus(const ::absl::StatusOr<T>& status) {
+  return status.status();
+}
+
+// Monomorphic implementation of matcher IsOkAndHolds(m).  StatusOrType is a
+// reference to StatusOr<T>.
+template <typename StatusOrType>
+class IsOkAndHoldsMatcherImpl
+    : public ::testing::MatcherInterface<StatusOrType> {
+ public:
+  typedef
+      typename std::remove_reference<StatusOrType>::type::value_type value_type;
+
+  template <typename InnerMatcher>
+  explicit IsOkAndHoldsMatcherImpl(InnerMatcher&& inner_matcher)
+      : inner_matcher_(::testing::SafeMatcherCast<const value_type&>(
+            std::forward<InnerMatcher>(inner_matcher))) {}
+
+  void DescribeTo(std::ostream* os) const override {
+    *os << "is OK and has a value that ";
+    inner_matcher_.DescribeTo(os);
+  }
+
+  void DescribeNegationTo(std::ostream* os) const override {
+    *os << "isn't OK or has a value that ";
+    inner_matcher_.DescribeNegationTo(os);
+  }
+
+  bool MatchAndExplain(
+      StatusOrType actual_value,
+      ::testing::MatchResultListener* result_listener) const override {
+    if (!actual_value.ok()) {
+      *result_listener << "which has status " << actual_value.status();
+      return false;
+    }
+
+    ::testing::StringMatchResultListener inner_listener;
+    const bool matches =
+        inner_matcher_.MatchAndExplain(*actual_value, &inner_listener);
+    const std::string inner_explanation = inner_listener.str();
+    if (!inner_explanation.empty()) {
+      *result_listener << "which contains value "
+                       << ::testing::PrintToString(*actual_value) << ", "
+                       << inner_explanation;
+    }
+    return matches;
+  }
+
+ private:
+  const ::testing::Matcher<const value_type&> inner_matcher_;
+};
+
+// Implements IsOkAndHolds(m) as a polymorphic matcher.
+template <typename InnerMatcher>
+class IsOkAndHoldsMatcher {
+ public:
+  explicit IsOkAndHoldsMatcher(InnerMatcher inner_matcher)
+      : inner_matcher_(std::move(inner_matcher)) {}
+
+  // Converts this polymorphic matcher to a monomorphic matcher of the
+  // given type.  StatusOrType can be either StatusOr<T> or a
+  // reference to StatusOr<T>.
+  template <typename StatusOrType>
+  operator ::testing::Matcher<StatusOrType>() const {  // NOLINT
+    return ::testing::Matcher<StatusOrType>(
+        new IsOkAndHoldsMatcherImpl<const StatusOrType&>(inner_matcher_));
+  }
+
+ private:
+  const InnerMatcher inner_matcher_;
+};
+
+// Monomorphic implementation of matcher IsOk() for a given type T.
+// T can be Status, StatusOr<>, or a reference to either of them.
+template <typename T>
+class MonoIsOkMatcherImpl : public ::testing::MatcherInterface<T> {
+ public:
+  void DescribeTo(std::ostream* os) const override { *os << "is OK"; }
+  void DescribeNegationTo(std::ostream* os) const override {
+    *os << "is not OK";
+  }
+  bool MatchAndExplain(T actual_value,
+                       ::testing::MatchResultListener*) const override {
+    return GetStatus(actual_value).ok();
+  }
+};
+
+// Implements IsOk() as a polymorphic matcher.
+class IsOkMatcher {
+ public:
+  template <typename T>
+  operator ::testing::Matcher<T>() const {  // NOLINT
+    return ::testing::Matcher<T>(new MonoIsOkMatcherImpl<T>());
+  }
+};
+
+// Macros for testing the results of functions that return absl::Status or
+// absl::StatusOr<T> (for any type T).
+#define EXPECT_OK(expression) EXPECT_THAT(expression, IsOk())
+
+// Returns a gMock matcher that matches a StatusOr<> whose status is
+// OK and whose value matches the inner matcher.
+template <typename InnerMatcher>
+IsOkAndHoldsMatcher<typename std::decay<InnerMatcher>::type> IsOkAndHolds(
+    InnerMatcher&& inner_matcher) {
+  return IsOkAndHoldsMatcher<typename std::decay<InnerMatcher>::type>(
+      std::forward<InnerMatcher>(inner_matcher));
+}
+
+// Returns a gMock matcher that matches a Status or StatusOr<> which is OK.
+inline IsOkMatcher IsOk() { return IsOkMatcher(); }
+#endif  // GTEST_HAS_STATUS_MATCHERS
+
+struct CopyDetector {
+  CopyDetector() = default;
+  explicit CopyDetector(int xx) : x(xx) {}
+  CopyDetector(CopyDetector&& d) noexcept
+      : x(d.x), copied(false), moved(true) {}
+  CopyDetector(const CopyDetector& d) : x(d.x), copied(true), moved(false) {}
+  CopyDetector& operator=(const CopyDetector& c) {
+    x = c.x;
+    copied = true;
+    moved = false;
+    return *this;
+  }
+  CopyDetector& operator=(CopyDetector&& c) noexcept {
+    x = c.x;
+    copied = false;
+    moved = true;
+    return *this;
+  }
+  int x = 0;
+  bool copied = false;
+  bool moved = false;
+};
+
+testing::Matcher<const CopyDetector&> CopyDetectorHas(int a, bool b, bool c) {
+  return AllOf(Field(&CopyDetector::x, a), Field(&CopyDetector::moved, b),
+               Field(&CopyDetector::copied, c));
+}
+
+class Base1 {
+ public:
+  virtual ~Base1() {}
+  int pad;
+};
+
+class Base2 {
+ public:
+  virtual ~Base2() {}
+  int yetotherpad;
+};
+
+class Derived : public Base1, public Base2 {
+ public:
+  virtual ~Derived() {}
+  int evenmorepad;
+};
+
+class CopyNoAssign {
+ public:
+  explicit CopyNoAssign(int value) : foo(value) {}
+  CopyNoAssign(const CopyNoAssign& other) : foo(other.foo) {}
+  int foo;
+
+ private:
+  const CopyNoAssign& operator=(const CopyNoAssign&);
+};
+
+absl::StatusOr<std::unique_ptr<int>> ReturnUniquePtr() {
+  // Uses implicit constructor from T&&
+  return absl::make_unique<int>(0);
+}
+
+TEST(StatusOr, ElementType) {
+  static_assert(std::is_same<absl::StatusOr<int>::value_type, int>(), "");
+  static_assert(std::is_same<absl::StatusOr<char>::value_type, char>(), "");
+}
+
+TEST(StatusOr, TestMoveOnlyInitialization) {
+  absl::StatusOr<std::unique_ptr<int>> thing(ReturnUniquePtr());
+  ASSERT_TRUE(thing.ok());
+  EXPECT_EQ(0, **thing);
+  int* previous = thing->get();
+
+  thing = ReturnUniquePtr();
+  EXPECT_TRUE(thing.ok());
+  EXPECT_EQ(0, **thing);
+  EXPECT_NE(previous, thing->get());
+}
+
+TEST(StatusOr, TestMoveOnlyValueExtraction) {
+  absl::StatusOr<std::unique_ptr<int>> thing(ReturnUniquePtr());
+  ASSERT_TRUE(thing.ok());
+  std::unique_ptr<int> ptr = *std::move(thing);
+  EXPECT_EQ(0, *ptr);
+
+  thing = std::move(ptr);
+  ptr = std::move(*thing);
+  EXPECT_EQ(0, *ptr);
+}
+
+TEST(StatusOr, TestMoveOnlyInitializationFromTemporaryByValueOrDie) {
+  std::unique_ptr<int> ptr(*ReturnUniquePtr());
+  EXPECT_EQ(0, *ptr);
+}
+
+TEST(StatusOr, TestValueOrDieOverloadForConstTemporary) {
+  static_assert(
+      std::is_same<const int&&,
+                   decltype(
+                       std::declval<const absl::StatusOr<int>&&>().value())>(),
+      "value() for const temporaries should return const T&&");
+}
+
+TEST(StatusOr, TestMoveOnlyConversion) {
+  absl::StatusOr<std::unique_ptr<const int>> const_thing(ReturnUniquePtr());
+  EXPECT_TRUE(const_thing.ok());
+  EXPECT_EQ(0, **const_thing);
+
+  // Test rvalue converting assignment
+  const int* const_previous = const_thing->get();
+  const_thing = ReturnUniquePtr();
+  EXPECT_TRUE(const_thing.ok());
+  EXPECT_EQ(0, **const_thing);
+  EXPECT_NE(const_previous, const_thing->get());
+}
+
+TEST(StatusOr, TestMoveOnlyVector) {
+  // Sanity check that absl::StatusOr<MoveOnly> works in vector.
+  std::vector<absl::StatusOr<std::unique_ptr<int>>> vec;
+  vec.push_back(ReturnUniquePtr());
+  vec.resize(2);
+  auto another_vec = std::move(vec);
+  EXPECT_EQ(0, **another_vec[0]);
+  EXPECT_EQ(absl::UnknownError(""), another_vec[1].status());
+}
+
+TEST(StatusOr, TestDefaultCtor) {
+  absl::StatusOr<int> thing;
+  EXPECT_FALSE(thing.ok());
+  EXPECT_EQ(thing.status().code(), absl::StatusCode::kUnknown);
+}
+
+// Define `EXPECT_DEATH_OR_THROW` to test the behavior of `StatusOr::value`,
+// which either throws `BadStatusOrAccess` or `LOG(FATAL)` based on whether
+// exceptions are enabled.
+#ifdef ABSL_HAVE_EXCEPTIONS
+#define EXPECT_DEATH_OR_THROW(statement, status_)    \
+  EXPECT_THROW(                                      \
+      {                                              \
+        try {                                        \
+          statement;                                 \
+        } catch (const absl::BadStatusOrAccess& e) { \
+          EXPECT_EQ(e.status(), status_);            \
+          throw;                                     \
+        }                                            \
+      },                                             \
+      absl::BadStatusOrAccess);
+#else  // ABSL_HAVE_EXCEPTIONS
+#define EXPECT_DEATH_OR_THROW(statement, status) \
+  EXPECT_DEATH_IF_SUPPORTED(statement, status.ToString());
+#endif  // ABSL_HAVE_EXCEPTIONS
+
+TEST(StatusOrDeathTest, TestDefaultCtorValue) {
+  absl::StatusOr<int> thing;
+  EXPECT_DEATH_OR_THROW(thing.value(), absl::UnknownError(""));
+  const absl::StatusOr<int> thing2;
+  EXPECT_DEATH_OR_THROW(thing2.value(), absl::UnknownError(""));
+}
+
+TEST(StatusOrDeathTest, TestValueNotOk) {
+  absl::StatusOr<int> thing(absl::CancelledError());
+  EXPECT_DEATH_OR_THROW(thing.value(), absl::CancelledError());
+}
+
+TEST(StatusOrDeathTest, TestValueNotOkConst) {
+  const absl::StatusOr<int> thing(absl::UnknownError(""));
+  EXPECT_DEATH_OR_THROW(thing.value(), absl::UnknownError(""));
+}
+
+TEST(StatusOrDeathTest, TestPointerDefaultCtorValue) {
+  absl::StatusOr<int*> thing;
+  EXPECT_DEATH_OR_THROW(thing.value(), absl::UnknownError(""));
+}
+
+TEST(StatusOrDeathTest, TestPointerValueNotOk) {
+  absl::StatusOr<int*> thing(absl::CancelledError());
+  EXPECT_DEATH_OR_THROW(thing.value(), absl::CancelledError());
+}
+
+TEST(StatusOrDeathTest, TestPointerValueNotOkConst) {
+  const absl::StatusOr<int*> thing(absl::CancelledError());
+  EXPECT_DEATH_OR_THROW(thing.value(), absl::CancelledError());
+}
+
+#if GTEST_HAS_DEATH_TEST
+TEST(StatusOrDeathTest, TestStatusCtorStatusOk) {
+  EXPECT_DEBUG_DEATH(
+      {
+        // This will DCHECK
+        absl::StatusOr<int> thing(absl::OkStatus());
+        // In optimized mode, we are actually going to get error::INTERNAL for
+        // status here, rather than crashing, so check that.
+        EXPECT_FALSE(thing.ok());
+        EXPECT_EQ(thing.status().code(), absl::StatusCode::kInternal);
+      },
+      "An OK status is not a valid constructor argument");
+}
+
+TEST(StatusOrDeathTest, TestPointerStatusCtorStatusOk) {
+  EXPECT_DEBUG_DEATH(
+      {
+        absl::StatusOr<int*> thing(absl::OkStatus());
+        // In optimized mode, we are actually going to get error::INTERNAL for
+        // status here, rather than crashing, so check that.
+        EXPECT_FALSE(thing.ok());
+        EXPECT_EQ(thing.status().code(), absl::StatusCode::kInternal);
+      },
+      "An OK status is not a valid constructor argument");
+}
+#endif
+
+TEST(StatusOr, ValueAccessor) {
+  const int kIntValue = 110;
+  {
+    absl::StatusOr<int> status_or(kIntValue);
+    EXPECT_EQ(kIntValue, status_or.value());
+    EXPECT_EQ(kIntValue, std::move(status_or).value());
+  }
+  {
+    absl::StatusOr<CopyDetector> status_or(kIntValue);
+    EXPECT_THAT(status_or,
+                IsOkAndHolds(CopyDetectorHas(kIntValue, false, false)));
+    CopyDetector copy_detector = status_or.value();
+    EXPECT_THAT(copy_detector, CopyDetectorHas(kIntValue, false, true));
+    copy_detector = std::move(status_or).value();
+    EXPECT_THAT(copy_detector, CopyDetectorHas(kIntValue, true, false));
+  }
+}
+
+TEST(StatusOr, BadValueAccess) {
+  const absl::Status kError = absl::CancelledError("message");
+  absl::StatusOr<int> status_or(kError);
+  EXPECT_DEATH_OR_THROW(status_or.value(), kError);
+}
+
+TEST(StatusOr, TestStatusCtor) {
+  absl::StatusOr<int> thing(absl::CancelledError());
+  EXPECT_FALSE(thing.ok());
+  EXPECT_EQ(thing.status().code(), absl::StatusCode::kCancelled);
+}
+
+
+
+TEST(StatusOr, TestValueCtor) {
+  const int kI = 4;
+  const absl::StatusOr<int> thing(kI);
+  EXPECT_TRUE(thing.ok());
+  EXPECT_EQ(kI, *thing);
+}
+
+struct Foo {
+  const int x;
+  explicit Foo(int y) : x(y) {}
+};
+
+TEST(StatusOr, InPlaceConstruction) {
+  EXPECT_THAT(absl::StatusOr<Foo>(absl::in_place, 10),
+              IsOkAndHolds(Field(&Foo::x, 10)));
+}
+
+struct InPlaceHelper {
+  InPlaceHelper(std::initializer_list<int> xs, std::unique_ptr<int> yy)
+      : x(xs), y(std::move(yy)) {}
+  const std::vector<int> x;
+  std::unique_ptr<int> y;
+};
+
+TEST(StatusOr, InPlaceInitListConstruction) {
+  absl::StatusOr<InPlaceHelper> status_or(absl::in_place, {10, 11, 12},
+                                          absl::make_unique<int>(13));
+  EXPECT_THAT(status_or, IsOkAndHolds(AllOf(
+                             Field(&InPlaceHelper::x, ElementsAre(10, 11, 12)),
+                             Field(&InPlaceHelper::y, Pointee(13)))));
+}
+
+TEST(StatusOr, Emplace) {
+  absl::StatusOr<Foo> status_or_foo(10);
+  status_or_foo.emplace(20);
+  EXPECT_THAT(status_or_foo, IsOkAndHolds(Field(&Foo::x, 20)));
+  status_or_foo = absl::InvalidArgumentError("msg");
+  EXPECT_FALSE(status_or_foo.ok());
+  EXPECT_EQ(status_or_foo.status().code(), absl::StatusCode::kInvalidArgument);
+  EXPECT_EQ(status_or_foo.status().message(), "msg");
+  status_or_foo.emplace(20);
+  EXPECT_THAT(status_or_foo, IsOkAndHolds(Field(&Foo::x, 20)));
+}
+
+TEST(StatusOr, EmplaceInitializerList) {
+  absl::StatusOr<InPlaceHelper> status_or(absl::in_place, {10, 11, 12},
+                                          absl::make_unique<int>(13));
+  status_or.emplace({1, 2, 3}, absl::make_unique<int>(4));
+  EXPECT_THAT(status_or,
+              IsOkAndHolds(AllOf(Field(&InPlaceHelper::x, ElementsAre(1, 2, 3)),
+                                 Field(&InPlaceHelper::y, Pointee(4)))));
+  status_or = absl::InvalidArgumentError("msg");
+  EXPECT_FALSE(status_or.ok());
+  EXPECT_EQ(status_or.status().code(), absl::StatusCode::kInvalidArgument);
+  EXPECT_EQ(status_or.status().message(), "msg");
+  status_or.emplace({1, 2, 3}, absl::make_unique<int>(4));
+  EXPECT_THAT(status_or,
+              IsOkAndHolds(AllOf(Field(&InPlaceHelper::x, ElementsAre(1, 2, 3)),
+                                 Field(&InPlaceHelper::y, Pointee(4)))));
+}
+
+TEST(StatusOr, TestCopyCtorStatusOk) {
+  const int kI = 4;
+  const absl::StatusOr<int> original(kI);
+  const absl::StatusOr<int> copy(original);
+  EXPECT_OK(copy.status());
+  EXPECT_EQ(*original, *copy);
+}
+
+TEST(StatusOr, TestCopyCtorStatusNotOk) {
+  absl::StatusOr<int> original(absl::CancelledError());
+  absl::StatusOr<int> copy(original);
+  EXPECT_EQ(copy.status().code(), absl::StatusCode::kCancelled);
+}
+
+TEST(StatusOr, TestCopyCtorNonAssignable) {
+  const int kI = 4;
+  CopyNoAssign value(kI);
+  absl::StatusOr<CopyNoAssign> original(value);
+  absl::StatusOr<CopyNoAssign> copy(original);
+  EXPECT_OK(copy.status());
+  EXPECT_EQ(original->foo, copy->foo);
+}
+
+TEST(StatusOr, TestCopyCtorStatusOKConverting) {
+  const int kI = 4;
+  absl::StatusOr<int> original(kI);
+  absl::StatusOr<double> copy(original);
+  EXPECT_OK(copy.status());
+  EXPECT_DOUBLE_EQ(*original, *copy);
+}
+
+TEST(StatusOr, TestCopyCtorStatusNotOkConverting) {
+  absl::StatusOr<int> original(absl::CancelledError());
+  absl::StatusOr<double> copy(original);
+  EXPECT_EQ(copy.status(), original.status());
+}
+
+TEST(StatusOr, TestAssignmentStatusOk) {
+  // Copy assignmment
+  {
+    const auto p = std::make_shared<int>(17);
+    absl::StatusOr<std::shared_ptr<int>> source(p);
+
+    absl::StatusOr<std::shared_ptr<int>> target;
+    target = source;
+
+    ASSERT_TRUE(target.ok());
+    EXPECT_OK(target.status());
+    EXPECT_EQ(p, *target);
+
+    ASSERT_TRUE(source.ok());
+    EXPECT_OK(source.status());
+    EXPECT_EQ(p, *source);
+  }
+
+  // Move asssignment
+  {
+    const auto p = std::make_shared<int>(17);
+    absl::StatusOr<std::shared_ptr<int>> source(p);
+
+    absl::StatusOr<std::shared_ptr<int>> target;
+    target = std::move(source);
+
+    ASSERT_TRUE(target.ok());
+    EXPECT_OK(target.status());
+    EXPECT_EQ(p, *target);
+
+    ASSERT_TRUE(source.ok());
+    EXPECT_OK(source.status());
+    EXPECT_EQ(nullptr, *source);
+  }
+}
+
+TEST(StatusOr, TestAssignmentStatusNotOk) {
+  // Copy assignment
+  {
+    const absl::Status expected = absl::CancelledError();
+    absl::StatusOr<int> source(expected);
+
+    absl::StatusOr<int> target;
+    target = source;
+
+    EXPECT_FALSE(target.ok());
+    EXPECT_EQ(expected, target.status());
+
+    EXPECT_FALSE(source.ok());
+    EXPECT_EQ(expected, source.status());
+  }
+
+  // Move assignment
+  {
+    const absl::Status expected = absl::CancelledError();
+    absl::StatusOr<int> source(expected);
+
+    absl::StatusOr<int> target;
+    target = std::move(source);
+
+    EXPECT_FALSE(target.ok());
+    EXPECT_EQ(expected, target.status());
+
+    EXPECT_FALSE(source.ok());
+    EXPECT_EQ(source.status().code(), absl::StatusCode::kInternal);
+  }
+}
+
+TEST(StatusOr, TestAssignmentStatusOKConverting) {
+  // Copy assignment
+  {
+    const int kI = 4;
+    absl::StatusOr<int> source(kI);
+
+    absl::StatusOr<double> target;
+    target = source;
+
+    ASSERT_TRUE(target.ok());
+    EXPECT_OK(target.status());
+    EXPECT_DOUBLE_EQ(kI, *target);
+
+    ASSERT_TRUE(source.ok());
+    EXPECT_OK(source.status());
+    EXPECT_DOUBLE_EQ(kI, *source);
+  }
+
+  // Move assignment
+  {
+    const auto p = new int(17);
+    absl::StatusOr<std::unique_ptr<int>> source(absl::WrapUnique(p));
+
+    absl::StatusOr<std::shared_ptr<int>> target;
+    target = std::move(source);
+
+    ASSERT_TRUE(target.ok());
+    EXPECT_OK(target.status());
+    EXPECT_EQ(p, target->get());
+
+    ASSERT_TRUE(source.ok());
+    EXPECT_OK(source.status());
+    EXPECT_EQ(nullptr, source->get());
+  }
+}
+
+struct A {
+  int x;
+};
+
+struct ImplicitConstructibleFromA {
+  int x;
+  bool moved;
+  ImplicitConstructibleFromA(const A& a)  // NOLINT
+      : x(a.x), moved(false) {}
+  ImplicitConstructibleFromA(A&& a)  // NOLINT
+      : x(a.x), moved(true) {}
+};
+
+TEST(StatusOr, ImplicitConvertingConstructor) {
+  EXPECT_THAT(
+      absl::implicit_cast<absl::StatusOr<ImplicitConstructibleFromA>>(
+          absl::StatusOr<A>(A{11})),
+      IsOkAndHolds(AllOf(Field(&ImplicitConstructibleFromA::x, 11),
+                         Field(&ImplicitConstructibleFromA::moved, true))));
+  absl::StatusOr<A> a(A{12});
+  EXPECT_THAT(
+      absl::implicit_cast<absl::StatusOr<ImplicitConstructibleFromA>>(a),
+      IsOkAndHolds(AllOf(Field(&ImplicitConstructibleFromA::x, 12),
+                         Field(&ImplicitConstructibleFromA::moved, false))));
+}
+
+struct ExplicitConstructibleFromA {
+  int x;
+  bool moved;
+  explicit ExplicitConstructibleFromA(const A& a) : x(a.x), moved(false) {}
+  explicit ExplicitConstructibleFromA(A&& a) : x(a.x), moved(true) {}
+};
+
+TEST(StatusOr, ExplicitConvertingConstructor) {
+  EXPECT_FALSE(
+      (std::is_convertible<const absl::StatusOr<A>&,
+                           absl::StatusOr<ExplicitConstructibleFromA>>::value));
+  EXPECT_FALSE(
+      (std::is_convertible<absl::StatusOr<A>&&,
+                           absl::StatusOr<ExplicitConstructibleFromA>>::value));
+  EXPECT_THAT(
+      absl::StatusOr<ExplicitConstructibleFromA>(absl::StatusOr<A>(A{11})),
+      IsOkAndHolds(AllOf(Field(&ExplicitConstructibleFromA::x, 11),
+                         Field(&ExplicitConstructibleFromA::moved, true))));
+  absl::StatusOr<A> a(A{12});
+  EXPECT_THAT(
+      absl::StatusOr<ExplicitConstructibleFromA>(a),
+      IsOkAndHolds(AllOf(Field(&ExplicitConstructibleFromA::x, 12),
+                         Field(&ExplicitConstructibleFromA::moved, false))));
+}
+
+struct ImplicitConstructibleFromBool {
+  ImplicitConstructibleFromBool(bool y) : x(y) {}  // NOLINT
+  bool x = false;
+};
+
+struct ConvertibleToBool {
+  explicit ConvertibleToBool(bool y) : x(y) {}
+  operator bool() const { return x; }  // NOLINT
+  bool x = false;
+};
+
+TEST(StatusOr, ImplicitBooleanConstructionWithImplicitCasts) {
+  EXPECT_THAT(absl::StatusOr<bool>(absl::StatusOr<ConvertibleToBool>(true)),
+              IsOkAndHolds(true));
+  EXPECT_THAT(absl::StatusOr<bool>(absl::StatusOr<ConvertibleToBool>(false)),
+              IsOkAndHolds(false));
+  EXPECT_THAT(
+      absl::implicit_cast<absl::StatusOr<ImplicitConstructibleFromBool>>(
+          absl::StatusOr<bool>(false)),
+      IsOkAndHolds(Field(&ImplicitConstructibleFromBool::x, false)));
+  EXPECT_FALSE((std::is_convertible<
+                absl::StatusOr<ConvertibleToBool>,
+                absl::StatusOr<ImplicitConstructibleFromBool>>::value));
+}
+
+TEST(StatusOr, BooleanConstructionWithImplicitCasts) {
+  EXPECT_THAT(absl::StatusOr<bool>(absl::StatusOr<ConvertibleToBool>(true)),
+              IsOkAndHolds(true));
+  EXPECT_THAT(absl::StatusOr<bool>(absl::StatusOr<ConvertibleToBool>(false)),
+              IsOkAndHolds(false));
+  EXPECT_THAT(
+      absl::StatusOr<ImplicitConstructibleFromBool>{
+          absl::StatusOr<bool>(false)},
+      IsOkAndHolds(Field(&ImplicitConstructibleFromBool::x, false)));
+  EXPECT_THAT(
+      absl::StatusOr<ImplicitConstructibleFromBool>{
+          absl::StatusOr<bool>(absl::InvalidArgumentError(""))},
+      Not(IsOk()));
+
+  EXPECT_THAT(
+      absl::StatusOr<ImplicitConstructibleFromBool>{
+          absl::StatusOr<ConvertibleToBool>(ConvertibleToBool{false})},
+      IsOkAndHolds(Field(&ImplicitConstructibleFromBool::x, false)));
+  EXPECT_THAT(
+      absl::StatusOr<ImplicitConstructibleFromBool>{
+          absl::StatusOr<ConvertibleToBool>(absl::InvalidArgumentError(""))},
+      Not(IsOk()));
+}
+
+TEST(StatusOr, ConstImplicitCast) {
+  EXPECT_THAT(absl::implicit_cast<absl::StatusOr<bool>>(
+                  absl::StatusOr<const bool>(true)),
+              IsOkAndHolds(true));
+  EXPECT_THAT(absl::implicit_cast<absl::StatusOr<bool>>(
+                  absl::StatusOr<const bool>(false)),
+              IsOkAndHolds(false));
+  EXPECT_THAT(absl::implicit_cast<absl::StatusOr<const bool>>(
+                  absl::StatusOr<bool>(true)),
+              IsOkAndHolds(true));
+  EXPECT_THAT(absl::implicit_cast<absl::StatusOr<const bool>>(
+                  absl::StatusOr<bool>(false)),
+              IsOkAndHolds(false));
+  EXPECT_THAT(absl::implicit_cast<absl::StatusOr<const std::string>>(
+                  absl::StatusOr<std::string>("foo")),
+              IsOkAndHolds("foo"));
+  EXPECT_THAT(absl::implicit_cast<absl::StatusOr<std::string>>(
+                  absl::StatusOr<const std::string>("foo")),
+              IsOkAndHolds("foo"));
+  EXPECT_THAT(
+      absl::implicit_cast<absl::StatusOr<std::shared_ptr<const std::string>>>(
+          absl::StatusOr<std::shared_ptr<std::string>>(
+              std::make_shared<std::string>("foo"))),
+      IsOkAndHolds(Pointee(std::string("foo"))));
+}
+
+TEST(StatusOr, ConstExplicitConstruction) {
+  EXPECT_THAT(absl::StatusOr<bool>(absl::StatusOr<const bool>(true)),
+              IsOkAndHolds(true));
+  EXPECT_THAT(absl::StatusOr<bool>(absl::StatusOr<const bool>(false)),
+              IsOkAndHolds(false));
+  EXPECT_THAT(absl::StatusOr<const bool>(absl::StatusOr<bool>(true)),
+              IsOkAndHolds(true));
+  EXPECT_THAT(absl::StatusOr<const bool>(absl::StatusOr<bool>(false)),
+              IsOkAndHolds(false));
+}
+
+struct ExplicitConstructibleFromInt {
+  int x;
+  explicit ExplicitConstructibleFromInt(int y) : x(y) {}
+};
+
+TEST(StatusOr, ExplicitConstruction) {
+  EXPECT_THAT(absl::StatusOr<ExplicitConstructibleFromInt>(10),
+              IsOkAndHolds(Field(&ExplicitConstructibleFromInt::x, 10)));
+}
+
+TEST(StatusOr, ImplicitConstruction) {
+  // Check implicit casting works.
+  auto status_or =
+      absl::implicit_cast<absl::StatusOr<absl::variant<int, std::string>>>(10);
+  EXPECT_THAT(status_or, IsOkAndHolds(VariantWith<int>(10)));
+}
+
+TEST(StatusOr, ImplicitConstructionFromInitliazerList) {
+  // Note: dropping the explicit std::initializer_list<int> is not supported
+  // by absl::StatusOr or absl::optional.
+  auto status_or =
+      absl::implicit_cast<absl::StatusOr<std::vector<int>>>({{10, 20, 30}});
+  EXPECT_THAT(status_or, IsOkAndHolds(ElementsAre(10, 20, 30)));
+}
+
+TEST(StatusOr, UniquePtrImplicitConstruction) {
+  auto status_or = absl::implicit_cast<absl::StatusOr<std::unique_ptr<Base1>>>(
+      absl::make_unique<Derived>());
+  EXPECT_THAT(status_or, IsOkAndHolds(Ne(nullptr)));
+}
+
+TEST(StatusOr, NestedStatusOrCopyAndMoveConstructorTests) {
+  absl::StatusOr<absl::StatusOr<CopyDetector>> status_or = CopyDetector(10);
+  absl::StatusOr<absl::StatusOr<CopyDetector>> status_error =
+      absl::InvalidArgumentError("foo");
+  EXPECT_THAT(status_or,
+              IsOkAndHolds(IsOkAndHolds(CopyDetectorHas(10, true, false))));
+  absl::StatusOr<absl::StatusOr<CopyDetector>> a = status_or;
+  EXPECT_THAT(a, IsOkAndHolds(IsOkAndHolds(CopyDetectorHas(10, false, true))));
+  absl::StatusOr<absl::StatusOr<CopyDetector>> a_err = status_error;
+  EXPECT_THAT(a_err, Not(IsOk()));
+
+  const absl::StatusOr<absl::StatusOr<CopyDetector>>& cref = status_or;
+  absl::StatusOr<absl::StatusOr<CopyDetector>> b = cref;  // NOLINT
+  EXPECT_THAT(b, IsOkAndHolds(IsOkAndHolds(CopyDetectorHas(10, false, true))));
+  const absl::StatusOr<absl::StatusOr<CopyDetector>>& cref_err = status_error;
+  absl::StatusOr<absl::StatusOr<CopyDetector>> b_err = cref_err;  // NOLINT
+  EXPECT_THAT(b_err, Not(IsOk()));
+
+  absl::StatusOr<absl::StatusOr<CopyDetector>> c = std::move(status_or);
+  EXPECT_THAT(c, IsOkAndHolds(IsOkAndHolds(CopyDetectorHas(10, true, false))));
+  absl::StatusOr<absl::StatusOr<CopyDetector>> c_err = std::move(status_error);
+  EXPECT_THAT(c_err, Not(IsOk()));
+}
+
+TEST(StatusOr, NestedStatusOrCopyAndMoveAssignment) {
+  absl::StatusOr<absl::StatusOr<CopyDetector>> status_or = CopyDetector(10);
+  absl::StatusOr<absl::StatusOr<CopyDetector>> status_error =
+      absl::InvalidArgumentError("foo");
+  absl::StatusOr<absl::StatusOr<CopyDetector>> a;
+  a = status_or;
+  EXPECT_THAT(a, IsOkAndHolds(IsOkAndHolds(CopyDetectorHas(10, false, true))));
+  a = status_error;
+  EXPECT_THAT(a, Not(IsOk()));
+
+  const absl::StatusOr<absl::StatusOr<CopyDetector>>& cref = status_or;
+  a = cref;
+  EXPECT_THAT(a, IsOkAndHolds(IsOkAndHolds(CopyDetectorHas(10, false, true))));
+  const absl::StatusOr<absl::StatusOr<CopyDetector>>& cref_err = status_error;
+  a = cref_err;
+  EXPECT_THAT(a, Not(IsOk()));
+  a = std::move(status_or);
+  EXPECT_THAT(a, IsOkAndHolds(IsOkAndHolds(CopyDetectorHas(10, true, false))));
+  a = std::move(status_error);
+  EXPECT_THAT(a, Not(IsOk()));
+}
+
+struct Copyable {
+  Copyable() {}
+  Copyable(const Copyable&) {}
+  Copyable& operator=(const Copyable&) { return *this; }
+};
+
+struct MoveOnly {
+  MoveOnly() {}
+  MoveOnly(MoveOnly&&) {}
+  MoveOnly& operator=(MoveOnly&&) { return *this; }
+};
+
+struct NonMovable {
+  NonMovable() {}
+  NonMovable(const NonMovable&) = delete;
+  NonMovable(NonMovable&&) = delete;
+  NonMovable& operator=(const NonMovable&) = delete;
+  NonMovable& operator=(NonMovable&&) = delete;
+};
+
+TEST(StatusOr, CopyAndMoveAbility) {
+  EXPECT_TRUE(std::is_copy_constructible<Copyable>::value);
+  EXPECT_TRUE(std::is_copy_assignable<Copyable>::value);
+  EXPECT_TRUE(std::is_move_constructible<Copyable>::value);
+  EXPECT_TRUE(std::is_move_assignable<Copyable>::value);
+  EXPECT_FALSE(std::is_copy_constructible<MoveOnly>::value);
+  EXPECT_FALSE(std::is_copy_assignable<MoveOnly>::value);
+  EXPECT_TRUE(std::is_move_constructible<MoveOnly>::value);
+  EXPECT_TRUE(std::is_move_assignable<MoveOnly>::value);
+  EXPECT_FALSE(std::is_copy_constructible<NonMovable>::value);
+  EXPECT_FALSE(std::is_copy_assignable<NonMovable>::value);
+  EXPECT_FALSE(std::is_move_constructible<NonMovable>::value);
+  EXPECT_FALSE(std::is_move_assignable<NonMovable>::value);
+}
+
+TEST(StatusOr, StatusOrAnyCopyAndMoveConstructorTests) {
+  absl::StatusOr<absl::any> status_or = CopyDetector(10);
+  absl::StatusOr<absl::any> status_error = absl::InvalidArgumentError("foo");
+  EXPECT_THAT(
+      status_or,
+      IsOkAndHolds(AnyWith<CopyDetector>(CopyDetectorHas(10, true, false))));
+  absl::StatusOr<absl::any> a = status_or;
+  EXPECT_THAT(
+      a, IsOkAndHolds(AnyWith<CopyDetector>(CopyDetectorHas(10, false, true))));
+  absl::StatusOr<absl::any> a_err = status_error;
+  EXPECT_THAT(a_err, Not(IsOk()));
+
+  const absl::StatusOr<absl::any>& cref = status_or;
+  // No lint for no-change copy.
+  absl::StatusOr<absl::any> b = cref;  // NOLINT
+  EXPECT_THAT(
+      b, IsOkAndHolds(AnyWith<CopyDetector>(CopyDetectorHas(10, false, true))));
+  const absl::StatusOr<absl::any>& cref_err = status_error;
+  // No lint for no-change copy.
+  absl::StatusOr<absl::any> b_err = cref_err;  // NOLINT
+  EXPECT_THAT(b_err, Not(IsOk()));
+
+  absl::StatusOr<absl::any> c = std::move(status_or);
+  EXPECT_THAT(
+      c, IsOkAndHolds(AnyWith<CopyDetector>(CopyDetectorHas(10, true, false))));
+  absl::StatusOr<absl::any> c_err = std::move(status_error);
+  EXPECT_THAT(c_err, Not(IsOk()));
+}
+
+TEST(StatusOr, StatusOrAnyCopyAndMoveAssignment) {
+  absl::StatusOr<absl::any> status_or = CopyDetector(10);
+  absl::StatusOr<absl::any> status_error = absl::InvalidArgumentError("foo");
+  absl::StatusOr<absl::any> a;
+  a = status_or;
+  EXPECT_THAT(
+      a, IsOkAndHolds(AnyWith<CopyDetector>(CopyDetectorHas(10, false, true))));
+  a = status_error;
+  EXPECT_THAT(a, Not(IsOk()));
+
+  const absl::StatusOr<absl::any>& cref = status_or;
+  a = cref;
+  EXPECT_THAT(
+      a, IsOkAndHolds(AnyWith<CopyDetector>(CopyDetectorHas(10, false, true))));
+  const absl::StatusOr<absl::any>& cref_err = status_error;
+  a = cref_err;
+  EXPECT_THAT(a, Not(IsOk()));
+  a = std::move(status_or);
+  EXPECT_THAT(
+      a, IsOkAndHolds(AnyWith<CopyDetector>(CopyDetectorHas(10, true, false))));
+  a = std::move(status_error);
+  EXPECT_THAT(a, Not(IsOk()));
+}
+
+TEST(StatusOr, StatusOrCopyAndMoveTestsConstructor) {
+  absl::StatusOr<CopyDetector> status_or(10);
+  ASSERT_THAT(status_or, IsOkAndHolds(CopyDetectorHas(10, false, false)));
+  absl::StatusOr<CopyDetector> a(status_or);
+  EXPECT_THAT(a, IsOkAndHolds(CopyDetectorHas(10, false, true)));
+  const absl::StatusOr<CopyDetector>& cref = status_or;
+  absl::StatusOr<CopyDetector> b(cref);  // NOLINT
+  EXPECT_THAT(b, IsOkAndHolds(CopyDetectorHas(10, false, true)));
+  absl::StatusOr<CopyDetector> c(std::move(status_or));
+  EXPECT_THAT(c, IsOkAndHolds(CopyDetectorHas(10, true, false)));
+}
+
+TEST(StatusOr, StatusOrCopyAndMoveTestsAssignment) {
+  absl::StatusOr<CopyDetector> status_or(10);
+  ASSERT_THAT(status_or, IsOkAndHolds(CopyDetectorHas(10, false, false)));
+  absl::StatusOr<CopyDetector> a;
+  a = status_or;
+  EXPECT_THAT(a, IsOkAndHolds(CopyDetectorHas(10, false, true)));
+  const absl::StatusOr<CopyDetector>& cref = status_or;
+  absl::StatusOr<CopyDetector> b;
+  b = cref;
+  EXPECT_THAT(b, IsOkAndHolds(CopyDetectorHas(10, false, true)));
+  absl::StatusOr<CopyDetector> c;
+  c = std::move(status_or);
+  EXPECT_THAT(c, IsOkAndHolds(CopyDetectorHas(10, true, false)));
+}
+
+TEST(StatusOr, AbslAnyAssignment) {
+  EXPECT_FALSE((std::is_assignable<absl::StatusOr<absl::any>,
+                                   absl::StatusOr<int>>::value));
+  absl::StatusOr<absl::any> status_or;
+  status_or = absl::InvalidArgumentError("foo");
+  EXPECT_THAT(status_or, Not(IsOk()));
+}
+
+TEST(StatusOr, ImplicitAssignment) {
+  absl::StatusOr<absl::variant<int, std::string>> status_or;
+  status_or = 10;
+  EXPECT_THAT(status_or, IsOkAndHolds(VariantWith<int>(10)));
+}
+
+TEST(StatusOr, SelfDirectInitAssignment) {
+  absl::StatusOr<std::vector<int>> status_or = {{10, 20, 30}};
+  status_or = *status_or;
+  EXPECT_THAT(status_or, IsOkAndHolds(ElementsAre(10, 20, 30)));
+}
+
+TEST(StatusOr, ImplicitCastFromInitializerList) {
+  absl::StatusOr<std::vector<int>> status_or = {{10, 20, 30}};
+  EXPECT_THAT(status_or, IsOkAndHolds(ElementsAre(10, 20, 30)));
+}
+
+TEST(StatusOr, UniquePtrImplicitAssignment) {
+  absl::StatusOr<std::unique_ptr<Base1>> status_or;
+  status_or = absl::make_unique<Derived>();
+  EXPECT_THAT(status_or, IsOkAndHolds(Ne(nullptr)));
+}
+
+TEST(StatusOr, Pointer) {
+  struct A {};
+  struct B : public A {};
+  struct C : private A {};
+
+  EXPECT_TRUE((std::is_constructible<absl::StatusOr<A*>, B*>::value));
+  EXPECT_TRUE((std::is_convertible<B*, absl::StatusOr<A*>>::value));
+  EXPECT_FALSE((std::is_constructible<absl::StatusOr<A*>, C*>::value));
+  EXPECT_FALSE((std::is_convertible<C*, absl::StatusOr<A*>>::value));
+}
+
+TEST(StatusOr, TestAssignmentStatusNotOkConverting) {
+  // Copy assignment
+  {
+    const absl::Status expected = absl::CancelledError();
+    absl::StatusOr<int> source(expected);
+
+    absl::StatusOr<double> target;
+    target = source;
+
+    EXPECT_FALSE(target.ok());
+    EXPECT_EQ(expected, target.status());
+
+    EXPECT_FALSE(source.ok());
+    EXPECT_EQ(expected, source.status());
+  }
+
+  // Move assignment
+  {
+    const absl::Status expected = absl::CancelledError();
+    absl::StatusOr<int> source(expected);
+
+    absl::StatusOr<double> target;
+    target = std::move(source);
+
+    EXPECT_FALSE(target.ok());
+    EXPECT_EQ(expected, target.status());
+
+    EXPECT_FALSE(source.ok());
+    EXPECT_EQ(source.status().code(), absl::StatusCode::kInternal);
+  }
+}
+
+TEST(StatusOr, SelfAssignment) {
+  // Copy-assignment, status OK
+  {
+    // A string long enough that it's likely to defeat any inline representation
+    // optimization.
+    const std::string long_str(128, 'a');
+
+    absl::StatusOr<std::string> so = long_str;
+    so = *&so;
+
+    ASSERT_TRUE(so.ok());
+    EXPECT_OK(so.status());
+    EXPECT_EQ(long_str, *so);
+  }
+
+  // Copy-assignment, error status
+  {
+    absl::StatusOr<int> so = absl::NotFoundError("taco");
+    so = *&so;
+
+    EXPECT_FALSE(so.ok());
+    EXPECT_EQ(so.status().code(), absl::StatusCode::kNotFound);
+    EXPECT_EQ(so.status().message(), "taco");
+  }
+
+  // Move-assignment with copyable type, status OK
+  {
+    absl::StatusOr<int> so = 17;
+
+    // Fool the compiler, which otherwise complains.
+    auto& same = so;
+    so = std::move(same);
+
+    ASSERT_TRUE(so.ok());
+    EXPECT_OK(so.status());
+    EXPECT_EQ(17, *so);
+  }
+
+  // Move-assignment with copyable type, error status
+  {
+    absl::StatusOr<int> so = absl::NotFoundError("taco");
+
+    // Fool the compiler, which otherwise complains.
+    auto& same = so;
+    so = std::move(same);
+
+    EXPECT_FALSE(so.ok());
+    EXPECT_EQ(so.status().code(), absl::StatusCode::kNotFound);
+    EXPECT_EQ(so.status().message(), "taco");
+  }
+
+  // Move-assignment with non-copyable type, status OK
+  {
+    const auto raw = new int(17);
+    absl::StatusOr<std::unique_ptr<int>> so = absl::WrapUnique(raw);
+
+    // Fool the compiler, which otherwise complains.
+    auto& same = so;
+    so = std::move(same);
+
+    ASSERT_TRUE(so.ok());
+    EXPECT_OK(so.status());
+    EXPECT_EQ(raw, so->get());
+  }
+
+  // Move-assignment with non-copyable type, error status
+  {
+    absl::StatusOr<std::unique_ptr<int>> so = absl::NotFoundError("taco");
+
+    // Fool the compiler, which otherwise complains.
+    auto& same = so;
+    so = std::move(same);
+
+    EXPECT_FALSE(so.ok());
+    EXPECT_EQ(so.status().code(), absl::StatusCode::kNotFound);
+    EXPECT_EQ(so.status().message(), "taco");
+  }
+}
+
+// These types form the overload sets of the constructors and the assignment
+// operators of `MockValue`. They distinguish construction from assignment,
+// lvalue from rvalue.
+struct FromConstructibleAssignableLvalue {};
+struct FromConstructibleAssignableRvalue {};
+struct FromImplicitConstructibleOnly {};
+struct FromAssignableOnly {};
+
+// This class is for testing the forwarding value assignments of `StatusOr`.
+// `from_rvalue` indicates whether the constructor or the assignment taking
+// rvalue reference is called. `from_assignment` indicates whether any
+// assignment is called.
+struct MockValue {
+  // Constructs `MockValue` from `FromConstructibleAssignableLvalue`.
+  MockValue(const FromConstructibleAssignableLvalue&)  // NOLINT
+      : from_rvalue(false), assigned(false) {}
+  // Constructs `MockValue` from `FromConstructibleAssignableRvalue`.
+  MockValue(FromConstructibleAssignableRvalue&&)  // NOLINT
+      : from_rvalue(true), assigned(false) {}
+  // Constructs `MockValue` from `FromImplicitConstructibleOnly`.
+  // `MockValue` is not assignable from `FromImplicitConstructibleOnly`.
+  MockValue(const FromImplicitConstructibleOnly&)  // NOLINT
+      : from_rvalue(false), assigned(false) {}
+  // Assigns `FromConstructibleAssignableLvalue`.
+  MockValue& operator=(const FromConstructibleAssignableLvalue&) {
+    from_rvalue = false;
+    assigned = true;
+    return *this;
+  }
+  // Assigns `FromConstructibleAssignableRvalue` (rvalue only).
+  MockValue& operator=(FromConstructibleAssignableRvalue&&) {
+    from_rvalue = true;
+    assigned = true;
+    return *this;
+  }
+  // Assigns `FromAssignableOnly`, but not constructible from
+  // `FromAssignableOnly`.
+  MockValue& operator=(const FromAssignableOnly&) {
+    from_rvalue = false;
+    assigned = true;
+    return *this;
+  }
+  bool from_rvalue;
+  bool assigned;
+};
+
+// operator=(U&&)
+TEST(StatusOr, PerfectForwardingAssignment) {
+  // U == T
+  constexpr int kValue1 = 10, kValue2 = 20;
+  absl::StatusOr<CopyDetector> status_or;
+  CopyDetector lvalue(kValue1);
+  status_or = lvalue;
+  EXPECT_THAT(status_or, IsOkAndHolds(CopyDetectorHas(kValue1, false, true)));
+  status_or = CopyDetector(kValue2);
+  EXPECT_THAT(status_or, IsOkAndHolds(CopyDetectorHas(kValue2, true, false)));
+
+  // U != T
+  EXPECT_TRUE(
+      (std::is_assignable<absl::StatusOr<MockValue>&,
+                          const FromConstructibleAssignableLvalue&>::value));
+  EXPECT_TRUE((std::is_assignable<absl::StatusOr<MockValue>&,
+                                  FromConstructibleAssignableLvalue&&>::value));
+  EXPECT_FALSE(
+      (std::is_assignable<absl::StatusOr<MockValue>&,
+                          const FromConstructibleAssignableRvalue&>::value));
+  EXPECT_TRUE((std::is_assignable<absl::StatusOr<MockValue>&,
+                                  FromConstructibleAssignableRvalue&&>::value));
+  EXPECT_TRUE(
+      (std::is_assignable<absl::StatusOr<MockValue>&,
+                          const FromImplicitConstructibleOnly&>::value));
+  EXPECT_FALSE((std::is_assignable<absl::StatusOr<MockValue>&,
+                                   const FromAssignableOnly&>::value));
+
+  absl::StatusOr<MockValue> from_lvalue(FromConstructibleAssignableLvalue{});
+  EXPECT_FALSE(from_lvalue->from_rvalue);
+  EXPECT_FALSE(from_lvalue->assigned);
+  from_lvalue = FromConstructibleAssignableLvalue{};
+  EXPECT_FALSE(from_lvalue->from_rvalue);
+  EXPECT_TRUE(from_lvalue->assigned);
+
+  absl::StatusOr<MockValue> from_rvalue(FromConstructibleAssignableRvalue{});
+  EXPECT_TRUE(from_rvalue->from_rvalue);
+  EXPECT_FALSE(from_rvalue->assigned);
+  from_rvalue = FromConstructibleAssignableRvalue{};
+  EXPECT_TRUE(from_rvalue->from_rvalue);
+  EXPECT_TRUE(from_rvalue->assigned);
+
+  absl::StatusOr<MockValue> from_implicit_constructible(
+      FromImplicitConstructibleOnly{});
+  EXPECT_FALSE(from_implicit_constructible->from_rvalue);
+  EXPECT_FALSE(from_implicit_constructible->assigned);
+  // construct a temporary `StatusOr` object and invoke the `StatusOr` move
+  // assignment operator.
+  from_implicit_constructible = FromImplicitConstructibleOnly{};
+  EXPECT_FALSE(from_implicit_constructible->from_rvalue);
+  EXPECT_FALSE(from_implicit_constructible->assigned);
+}
+
+TEST(StatusOr, TestStatus) {
+  absl::StatusOr<int> good(4);
+  EXPECT_TRUE(good.ok());
+  absl::StatusOr<int> bad(absl::CancelledError());
+  EXPECT_FALSE(bad.ok());
+  EXPECT_EQ(bad.status().code(), absl::StatusCode::kCancelled);
+}
+
+TEST(StatusOr, OperatorStarRefQualifiers) {
+  static_assert(
+      std::is_same<const int&,
+                   decltype(*std::declval<const absl::StatusOr<int>&>())>(),
+      "Unexpected ref-qualifiers");
+  static_assert(
+      std::is_same<int&, decltype(*std::declval<absl::StatusOr<int>&>())>(),
+      "Unexpected ref-qualifiers");
+  static_assert(
+      std::is_same<const int&&,
+                   decltype(*std::declval<const absl::StatusOr<int>&&>())>(),
+      "Unexpected ref-qualifiers");
+  static_assert(
+      std::is_same<int&&, decltype(*std::declval<absl::StatusOr<int>&&>())>(),
+      "Unexpected ref-qualifiers");
+}
+
+TEST(StatusOr, OperatorStar) {
+  const absl::StatusOr<std::string> const_lvalue("hello");
+  EXPECT_EQ("hello", *const_lvalue);
+
+  absl::StatusOr<std::string> lvalue("hello");
+  EXPECT_EQ("hello", *lvalue);
+
+  // Note: Recall that std::move() is equivalent to a static_cast to an rvalue
+  // reference type.
+  const absl::StatusOr<std::string> const_rvalue("hello");
+  EXPECT_EQ("hello", *std::move(const_rvalue));  // NOLINT
+
+  absl::StatusOr<std::string> rvalue("hello");
+  EXPECT_EQ("hello", *std::move(rvalue));
+}
+
+TEST(StatusOr, OperatorArrowQualifiers) {
+  static_assert(
+      std::is_same<
+          const int*,
+          decltype(std::declval<const absl::StatusOr<int>&>().operator->())>(),
+      "Unexpected qualifiers");
+  static_assert(
+      std::is_same<
+          int*, decltype(std::declval<absl::StatusOr<int>&>().operator->())>(),
+      "Unexpected qualifiers");
+  static_assert(
+      std::is_same<
+          const int*,
+          decltype(std::declval<const absl::StatusOr<int>&&>().operator->())>(),
+      "Unexpected qualifiers");
+  static_assert(
+      std::is_same<
+          int*, decltype(std::declval<absl::StatusOr<int>&&>().operator->())>(),
+      "Unexpected qualifiers");
+}
+
+TEST(StatusOr, OperatorArrow) {
+  const absl::StatusOr<std::string> const_lvalue("hello");
+  EXPECT_EQ(std::string("hello"), const_lvalue->c_str());
+
+  absl::StatusOr<std::string> lvalue("hello");
+  EXPECT_EQ(std::string("hello"), lvalue->c_str());
+}
+
+TEST(StatusOr, RValueStatus) {
+  absl::StatusOr<int> so(absl::NotFoundError("taco"));
+  const absl::Status s = std::move(so).status();
+
+  EXPECT_EQ(s.code(), absl::StatusCode::kNotFound);
+  EXPECT_EQ(s.message(), "taco");
+
+  // Check that !ok() still implies !status().ok(), even after moving out of the
+  // object. See the note on the rvalue ref-qualified status method.
+  EXPECT_FALSE(so.ok());  // NOLINT
+  EXPECT_FALSE(so.status().ok());
+  EXPECT_EQ(so.status().code(), absl::StatusCode::kInternal);
+  EXPECT_EQ(so.status().message(), "Status accessed after move.");
+}
+
+TEST(StatusOr, TestValue) {
+  const int kI = 4;
+  absl::StatusOr<int> thing(kI);
+  EXPECT_EQ(kI, *thing);
+}
+
+TEST(StatusOr, TestValueConst) {
+  const int kI = 4;
+  const absl::StatusOr<int> thing(kI);
+  EXPECT_EQ(kI, *thing);
+}
+
+TEST(StatusOr, TestPointerDefaultCtor) {
+  absl::StatusOr<int*> thing;
+  EXPECT_FALSE(thing.ok());
+  EXPECT_EQ(thing.status().code(), absl::StatusCode::kUnknown);
+}
+
+
+
+TEST(StatusOr, TestPointerStatusCtor) {
+  absl::StatusOr<int*> thing(absl::CancelledError());
+  EXPECT_FALSE(thing.ok());
+  EXPECT_EQ(thing.status().code(), absl::StatusCode::kCancelled);
+}
+
+TEST(StatusOr, TestPointerValueCtor) {
+  const int kI = 4;
+
+  // Construction from a non-null pointer
+  {
+    absl::StatusOr<const int*> so(&kI);
+    EXPECT_TRUE(so.ok());
+    EXPECT_OK(so.status());
+    EXPECT_EQ(&kI, *so);
+  }
+
+  // Construction from a null pointer constant
+  {
+    absl::StatusOr<const int*> so(nullptr);
+    EXPECT_TRUE(so.ok());
+    EXPECT_OK(so.status());
+    EXPECT_EQ(nullptr, *so);
+  }
+
+  // Construction from a non-literal null pointer
+  {
+    const int* const p = nullptr;
+
+    absl::StatusOr<const int*> so(p);
+    EXPECT_TRUE(so.ok());
+    EXPECT_OK(so.status());
+    EXPECT_EQ(nullptr, *so);
+  }
+}
+
+TEST(StatusOr, TestPointerCopyCtorStatusOk) {
+  const int kI = 0;
+  absl::StatusOr<const int*> original(&kI);
+  absl::StatusOr<const int*> copy(original);
+  EXPECT_OK(copy.status());
+  EXPECT_EQ(*original, *copy);
+}
+
+TEST(StatusOr, TestPointerCopyCtorStatusNotOk) {
+  absl::StatusOr<int*> original(absl::CancelledError());
+  absl::StatusOr<int*> copy(original);
+  EXPECT_EQ(copy.status().code(), absl::StatusCode::kCancelled);
+}
+
+TEST(StatusOr, TestPointerCopyCtorStatusOKConverting) {
+  Derived derived;
+  absl::StatusOr<Derived*> original(&derived);
+  absl::StatusOr<Base2*> copy(original);
+  EXPECT_OK(copy.status());
+  EXPECT_EQ(static_cast<const Base2*>(*original), *copy);
+}
+
+TEST(StatusOr, TestPointerCopyCtorStatusNotOkConverting) {
+  absl::StatusOr<Derived*> original(absl::CancelledError());
+  absl::StatusOr<Base2*> copy(original);
+  EXPECT_EQ(copy.status().code(), absl::StatusCode::kCancelled);
+}
+
+TEST(StatusOr, TestPointerAssignmentStatusOk) {
+  const int kI = 0;
+  absl::StatusOr<const int*> source(&kI);
+  absl::StatusOr<const int*> target;
+  target = source;
+  EXPECT_OK(target.status());
+  EXPECT_EQ(*source, *target);
+}
+
+TEST(StatusOr, TestPointerAssignmentStatusNotOk) {
+  absl::StatusOr<int*> source(absl::CancelledError());
+  absl::StatusOr<int*> target;
+  target = source;
+  EXPECT_EQ(target.status().code(), absl::StatusCode::kCancelled);
+}
+
+TEST(StatusOr, TestPointerAssignmentStatusOKConverting) {
+  Derived derived;
+  absl::StatusOr<Derived*> source(&derived);
+  absl::StatusOr<Base2*> target;
+  target = source;
+  EXPECT_OK(target.status());
+  EXPECT_EQ(static_cast<const Base2*>(*source), *target);
+}
+
+TEST(StatusOr, TestPointerAssignmentStatusNotOkConverting) {
+  absl::StatusOr<Derived*> source(absl::CancelledError());
+  absl::StatusOr<Base2*> target;
+  target = source;
+  EXPECT_EQ(target.status(), source.status());
+}
+
+TEST(StatusOr, TestPointerStatus) {
+  const int kI = 0;
+  absl::StatusOr<const int*> good(&kI);
+  EXPECT_TRUE(good.ok());
+  absl::StatusOr<const int*> bad(absl::CancelledError());
+  EXPECT_EQ(bad.status().code(), absl::StatusCode::kCancelled);
+}
+
+TEST(StatusOr, TestPointerValue) {
+  const int kI = 0;
+  absl::StatusOr<const int*> thing(&kI);
+  EXPECT_EQ(&kI, *thing);
+}
+
+TEST(StatusOr, TestPointerValueConst) {
+  const int kI = 0;
+  const absl::StatusOr<const int*> thing(&kI);
+  EXPECT_EQ(&kI, *thing);
+}
+
+TEST(StatusOr, StatusOrVectorOfUniquePointerCanReserveAndResize) {
+  using EvilType = std::vector<std::unique_ptr<int>>;
+  static_assert(std::is_copy_constructible<EvilType>::value, "");
+  std::vector<::absl::StatusOr<EvilType>> v(5);
+  v.reserve(v.capacity() + 10);
+  v.resize(v.capacity() + 10);
+}
+
+TEST(StatusOr, ConstPayload) {
+  // A reduced version of a problematic type found in the wild. All of the
+  // operations below should compile.
+  absl::StatusOr<const int> a;
+
+  // Copy-construction
+  absl::StatusOr<const int> b(a);
+
+  // Copy-assignment
+  EXPECT_FALSE(std::is_copy_assignable<absl::StatusOr<const int>>::value);
+
+  // Move-construction
+  absl::StatusOr<const int> c(std::move(a));
+
+  // Move-assignment
+  EXPECT_FALSE(std::is_move_assignable<absl::StatusOr<const int>>::value);
+}
+
+TEST(StatusOr, MapToStatusOrUniquePtr) {
+  // A reduced version of a problematic type found in the wild. All of the
+  // operations below should compile.
+  using MapType = std::map<std::string, absl::StatusOr<std::unique_ptr<int>>>;
+
+  MapType a;
+
+  // Move-construction
+  MapType b(std::move(a));
+
+  // Move-assignment
+  a = std::move(b);
+}
+
+TEST(StatusOr, ValueOrOk) {
+  const absl::StatusOr<int> status_or = 0;
+  EXPECT_EQ(status_or.value_or(-1), 0);
+}
+
+TEST(StatusOr, ValueOrDefault) {
+  const absl::StatusOr<int> status_or = absl::CancelledError();
+  EXPECT_EQ(status_or.value_or(-1), -1);
+}
+
+TEST(StatusOr, MoveOnlyValueOrOk) {
+  EXPECT_THAT(absl::StatusOr<std::unique_ptr<int>>(absl::make_unique<int>(0))
+                  .value_or(absl::make_unique<int>(-1)),
+              Pointee(0));
+}
+
+TEST(StatusOr, MoveOnlyValueOrDefault) {
+  EXPECT_THAT(absl::StatusOr<std::unique_ptr<int>>(absl::CancelledError())
+                  .value_or(absl::make_unique<int>(-1)),
+              Pointee(-1));
+}
+
+static absl::StatusOr<int> MakeStatus() { return 100; }
+
+TEST(StatusOr, TestIgnoreError) { MakeStatus().IgnoreError(); }
+
+TEST(StatusOr, EqualityOperator) {
+  constexpr int kNumCases = 4;
+  std::array<absl::StatusOr<int>, kNumCases> group1 = {
+      absl::StatusOr<int>(1), absl::StatusOr<int>(2),
+      absl::StatusOr<int>(absl::InvalidArgumentError("msg")),
+      absl::StatusOr<int>(absl::InternalError("msg"))};
+  std::array<absl::StatusOr<int>, kNumCases> group2 = {
+      absl::StatusOr<int>(1), absl::StatusOr<int>(2),
+      absl::StatusOr<int>(absl::InvalidArgumentError("msg")),
+      absl::StatusOr<int>(absl::InternalError("msg"))};
+  for (int i = 0; i < kNumCases; ++i) {
+    for (int j = 0; j < kNumCases; ++j) {
+      if (i == j) {
+        EXPECT_TRUE(group1[i] == group2[j]);
+        EXPECT_FALSE(group1[i] != group2[j]);
+      } else {
+        EXPECT_FALSE(group1[i] == group2[j]);
+        EXPECT_TRUE(group1[i] != group2[j]);
+      }
+    }
+  }
+}
+
+struct MyType {
+  bool operator==(const MyType&) const { return true; }
+};
+
+enum class ConvTraits { kNone = 0, kImplicit = 1, kExplicit = 2 };
+
+// This class has conversion operator to `StatusOr<T>` based on value of
+// `conv_traits`.
+template <typename T, ConvTraits conv_traits = ConvTraits::kNone>
+struct StatusOrConversionBase {};
+
+template <typename T>
+struct StatusOrConversionBase<T, ConvTraits::kImplicit> {
+  operator absl::StatusOr<T>() const& {  // NOLINT
+    return absl::InvalidArgumentError("conversion to absl::StatusOr");
+  }
+  operator absl::StatusOr<T>() && {  // NOLINT
+    return absl::InvalidArgumentError("conversion to absl::StatusOr");
+  }
+};
+
+template <typename T>
+struct StatusOrConversionBase<T, ConvTraits::kExplicit> {
+  explicit operator absl::StatusOr<T>() const& {
+    return absl::InvalidArgumentError("conversion to absl::StatusOr");
+  }
+  explicit operator absl::StatusOr<T>() && {
+    return absl::InvalidArgumentError("conversion to absl::StatusOr");
+  }
+};
+
+// This class has conversion operator to `T` based on the value of
+// `conv_traits`.
+template <typename T, ConvTraits conv_traits = ConvTraits::kNone>
+struct ConversionBase {};
+
+template <typename T>
+struct ConversionBase<T, ConvTraits::kImplicit> {
+  operator T() const& { return t; }         // NOLINT
+  operator T() && { return std::move(t); }  // NOLINT
+  T t;
+};
+
+template <typename T>
+struct ConversionBase<T, ConvTraits::kExplicit> {
+  explicit operator T() const& { return t; }
+  explicit operator T() && { return std::move(t); }
+  T t;
+};
+
+// This class has conversion operator to `absl::Status` based on the value of
+// `conv_traits`.
+template <ConvTraits conv_traits = ConvTraits::kNone>
+struct StatusConversionBase {};
+
+template <>
+struct StatusConversionBase<ConvTraits::kImplicit> {
+  operator absl::Status() const& {  // NOLINT
+    return absl::InternalError("conversion to Status");
+  }
+  operator absl::Status() && {  // NOLINT
+    return absl::InternalError("conversion to Status");
+  }
+};
+
+template <>
+struct StatusConversionBase<ConvTraits::kExplicit> {
+  explicit operator absl::Status() const& {  // NOLINT
+    return absl::InternalError("conversion to Status");
+  }
+  explicit operator absl::Status() && {  // NOLINT
+    return absl::InternalError("conversion to Status");
+  }
+};
+
+static constexpr int kConvToStatus = 1;
+static constexpr int kConvToStatusOr = 2;
+static constexpr int kConvToT = 4;
+static constexpr int kConvExplicit = 8;
+
+constexpr ConvTraits GetConvTraits(int bit, int config) {
+  return (config & bit) == 0
+             ? ConvTraits::kNone
+             : ((config & kConvExplicit) == 0 ? ConvTraits::kImplicit
+                                              : ConvTraits::kExplicit);
+}
+
+// This class conditionally has conversion operator to `absl::Status`, `T`,
+// `StatusOr<T>`, based on values of the template parameters.
+template <typename T, int config>
+struct CustomType
+    : StatusOrConversionBase<T, GetConvTraits(kConvToStatusOr, config)>,
+      ConversionBase<T, GetConvTraits(kConvToT, config)>,
+      StatusConversionBase<GetConvTraits(kConvToStatus, config)> {};
+
+struct ConvertibleToAnyStatusOr {
+  template <typename T>
+  operator absl::StatusOr<T>() const {  // NOLINT
+    return absl::InvalidArgumentError("Conversion to absl::StatusOr");
+  }
+};
+
+// Test the rank of overload resolution for `StatusOr<T>` constructor and
+// assignment, from highest to lowest:
+// 1. T/Status
+// 2. U that has conversion operator to absl::StatusOr<T>
+// 3. U that is convertible to Status
+// 4. U that is convertible to T
+TEST(StatusOr, ConstructionFromT) {
+  // Construct absl::StatusOr<T> from T when T is convertible to
+  // absl::StatusOr<T>
+  {
+    ConvertibleToAnyStatusOr v;
+    absl::StatusOr<ConvertibleToAnyStatusOr> statusor(v);
+    EXPECT_TRUE(statusor.ok());
+  }
+  {
+    ConvertibleToAnyStatusOr v;
+    absl::StatusOr<ConvertibleToAnyStatusOr> statusor = v;
+    EXPECT_TRUE(statusor.ok());
+  }
+  // Construct absl::StatusOr<T> from T when T is explicitly convertible to
+  // Status
+  {
+    CustomType<MyType, kConvToStatus | kConvExplicit> v;
+    absl::StatusOr<CustomType<MyType, kConvToStatus | kConvExplicit>> statusor(
+        v);
+    EXPECT_TRUE(statusor.ok());
+  }
+  {
+    CustomType<MyType, kConvToStatus | kConvExplicit> v;
+    absl::StatusOr<CustomType<MyType, kConvToStatus | kConvExplicit>> statusor =
+        v;
+    EXPECT_TRUE(statusor.ok());
+  }
+}
+
+// Construct absl::StatusOr<T> from U when U is explicitly convertible to T
+TEST(StatusOr, ConstructionFromTypeConvertibleToT) {
+  {
+    CustomType<MyType, kConvToT | kConvExplicit> v;
+    absl::StatusOr<MyType> statusor(v);
+    EXPECT_TRUE(statusor.ok());
+  }
+  {
+    CustomType<MyType, kConvToT> v;
+    absl::StatusOr<MyType> statusor = v;
+    EXPECT_TRUE(statusor.ok());
+  }
+}
+
+// Construct absl::StatusOr<T> from U when U has explicit conversion operator to
+// absl::StatusOr<T>
+TEST(StatusOr, ConstructionFromTypeWithConversionOperatorToStatusOrT) {
+  {
+    CustomType<MyType, kConvToStatusOr | kConvExplicit> v;
+    absl::StatusOr<MyType> statusor(v);
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+  {
+    CustomType<MyType, kConvToT | kConvToStatusOr | kConvExplicit> v;
+    absl::StatusOr<MyType> statusor(v);
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+  {
+    CustomType<MyType, kConvToStatusOr | kConvToStatus | kConvExplicit> v;
+    absl::StatusOr<MyType> statusor(v);
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+  {
+    CustomType<MyType,
+               kConvToT | kConvToStatusOr | kConvToStatus | kConvExplicit>
+        v;
+    absl::StatusOr<MyType> statusor(v);
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+  {
+    CustomType<MyType, kConvToStatusOr> v;
+    absl::StatusOr<MyType> statusor = v;
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+  {
+    CustomType<MyType, kConvToT | kConvToStatusOr> v;
+    absl::StatusOr<MyType> statusor = v;
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+  {
+    CustomType<MyType, kConvToStatusOr | kConvToStatus> v;
+    absl::StatusOr<MyType> statusor = v;
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+  {
+    CustomType<MyType, kConvToT | kConvToStatusOr | kConvToStatus> v;
+    absl::StatusOr<MyType> statusor = v;
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+}
+
+TEST(StatusOr, ConstructionFromTypeConvertibleToStatus) {
+  // Construction fails because conversion to `Status` is explicit.
+  {
+    CustomType<MyType, kConvToStatus | kConvExplicit> v;
+    absl::StatusOr<MyType> statusor(v);
+    EXPECT_FALSE(statusor.ok());
+    EXPECT_EQ(statusor.status(), static_cast<absl::Status>(v));
+  }
+  {
+    CustomType<MyType, kConvToT | kConvToStatus | kConvExplicit> v;
+    absl::StatusOr<MyType> statusor(v);
+    EXPECT_FALSE(statusor.ok());
+    EXPECT_EQ(statusor.status(), static_cast<absl::Status>(v));
+  }
+  {
+    CustomType<MyType, kConvToStatus> v;
+    absl::StatusOr<MyType> statusor = v;
+    EXPECT_FALSE(statusor.ok());
+    EXPECT_EQ(statusor.status(), static_cast<absl::Status>(v));
+  }
+  {
+    CustomType<MyType, kConvToT | kConvToStatus> v;
+    absl::StatusOr<MyType> statusor = v;
+    EXPECT_FALSE(statusor.ok());
+    EXPECT_EQ(statusor.status(), static_cast<absl::Status>(v));
+  }
+}
+
+TEST(StatusOr, AssignmentFromT) {
+  // Assign to absl::StatusOr<T> from T when T is convertible to
+  // absl::StatusOr<T>
+  {
+    ConvertibleToAnyStatusOr v;
+    absl::StatusOr<ConvertibleToAnyStatusOr> statusor;
+    statusor = v;
+    EXPECT_TRUE(statusor.ok());
+  }
+  // Assign to absl::StatusOr<T> from T when T is convertible to Status
+  {
+    CustomType<MyType, kConvToStatus> v;
+    absl::StatusOr<CustomType<MyType, kConvToStatus>> statusor;
+    statusor = v;
+    EXPECT_TRUE(statusor.ok());
+  }
+}
+
+TEST(StatusOr, AssignmentFromTypeConvertibleToT) {
+  // Assign to absl::StatusOr<T> from U when U is convertible to T
+  {
+    CustomType<MyType, kConvToT> v;
+    absl::StatusOr<MyType> statusor;
+    statusor = v;
+    EXPECT_TRUE(statusor.ok());
+  }
+}
+
+TEST(StatusOr, AssignmentFromTypeWithConversionOperatortoStatusOrT) {
+  // Assign to absl::StatusOr<T> from U when U has conversion operator to
+  // absl::StatusOr<T>
+  {
+    CustomType<MyType, kConvToStatusOr> v;
+    absl::StatusOr<MyType> statusor;
+    statusor = v;
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+  {
+    CustomType<MyType, kConvToT | kConvToStatusOr> v;
+    absl::StatusOr<MyType> statusor;
+    statusor = v;
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+  {
+    CustomType<MyType, kConvToStatusOr | kConvToStatus> v;
+    absl::StatusOr<MyType> statusor;
+    statusor = v;
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+  {
+    CustomType<MyType, kConvToT | kConvToStatusOr | kConvToStatus> v;
+    absl::StatusOr<MyType> statusor;
+    statusor = v;
+    EXPECT_EQ(statusor, v.operator absl::StatusOr<MyType>());
+  }
+}
+
+TEST(StatusOr, AssignmentFromTypeConvertibleToStatus) {
+  // Assign to absl::StatusOr<T> from U when U is convertible to Status
+  {
+    CustomType<MyType, kConvToStatus> v;
+    absl::StatusOr<MyType> statusor;
+    statusor = v;
+    EXPECT_FALSE(statusor.ok());
+    EXPECT_EQ(statusor.status(), static_cast<absl::Status>(v));
+  }
+  {
+    CustomType<MyType, kConvToT | kConvToStatus> v;
+    absl::StatusOr<MyType> statusor;
+    statusor = v;
+    EXPECT_FALSE(statusor.ok());
+    EXPECT_EQ(statusor.status(), static_cast<absl::Status>(v));
+  }
+}
+
+}  // namespace