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Pods/abseil/absl/status/internal/status_internal.cc

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+// Copyright 2023 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/internal/status_internal.h"
+
+#include <atomic>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <cstring>
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
+#include "absl/base/macros.h"
+#include "absl/base/nullability.h"
+#include "absl/debugging/stacktrace.h"
+#include "absl/debugging/symbolize.h"
+#include "absl/memory/memory.h"
+#include "absl/status/status.h"
+#include "absl/status/status_payload_printer.h"
+#include "absl/strings/cord.h"
+#include "absl/strings/escaping.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+#include "absl/strings/str_split.h"
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace status_internal {
+
+void StatusRep::Unref() const {
+  // Fast path: if ref==1, there is no need for a RefCountDec (since
+  // this is the only reference and therefore no other thread is
+  // allowed to be mucking with r).
+  if (ref_.load(std::memory_order_acquire) == 1 ||
+      ref_.fetch_sub(1, std::memory_order_acq_rel) - 1 == 0) {
+    delete this;
+  }
+}
+
+static absl::optional<size_t> FindPayloadIndexByUrl(
+    const Payloads* payloads, absl::string_view type_url) {
+  if (payloads == nullptr) return absl::nullopt;
+
+  for (size_t i = 0; i < payloads->size(); ++i) {
+    if ((*payloads)[i].type_url == type_url) return i;
+  }
+
+  return absl::nullopt;
+}
+
+absl::optional<absl::Cord> StatusRep::GetPayload(
+    absl::string_view type_url) const {
+  absl::optional<size_t> index =
+      status_internal::FindPayloadIndexByUrl(payloads_.get(), type_url);
+  if (index.has_value()) return (*payloads_)[index.value()].payload;
+
+  return absl::nullopt;
+}
+
+void StatusRep::SetPayload(absl::string_view type_url, absl::Cord payload) {
+  if (payloads_ == nullptr) {
+    payloads_ = absl::make_unique<status_internal::Payloads>();
+  }
+
+  absl::optional<size_t> index =
+      status_internal::FindPayloadIndexByUrl(payloads_.get(), type_url);
+  if (index.has_value()) {
+    (*payloads_)[index.value()].payload = std::move(payload);
+    return;
+  }
+
+  payloads_->push_back({std::string(type_url), std::move(payload)});
+}
+
+StatusRep::EraseResult StatusRep::ErasePayload(absl::string_view type_url) {
+  absl::optional<size_t> index =
+      status_internal::FindPayloadIndexByUrl(payloads_.get(), type_url);
+  if (!index.has_value()) return {false, Status::PointerToRep(this)};
+  payloads_->erase(payloads_->begin() + index.value());
+  if (payloads_->empty() && message_.empty()) {
+    // Special case: If this can be represented inlined, it MUST be inlined
+    // (== depends on this behavior).
+    EraseResult result = {true, Status::CodeToInlinedRep(code_)};
+    Unref();
+    return result;
+  }
+  return {true, Status::PointerToRep(this)};
+}
+
+void StatusRep::ForEachPayload(
+    absl::FunctionRef<void(absl::string_view, const absl::Cord&)> visitor)
+    const {
+  if (auto* payloads = payloads_.get()) {
+    bool in_reverse =
+        payloads->size() > 1 && reinterpret_cast<uintptr_t>(payloads) % 13 > 6;
+
+    for (size_t index = 0; index < payloads->size(); ++index) {
+      const auto& elem =
+          (*payloads)[in_reverse ? payloads->size() - 1 - index : index];
+
+#ifdef NDEBUG
+      visitor(elem.type_url, elem.payload);
+#else
+      // In debug mode invalidate the type url to prevent users from relying on
+      // this string lifetime.
+
+      // NOLINTNEXTLINE intentional extra conversion to force temporary.
+      visitor(std::string(elem.type_url), elem.payload);
+#endif  // NDEBUG
+    }
+  }
+}
+
+std::string StatusRep::ToString(StatusToStringMode mode) const {
+  std::string text;
+  absl::StrAppend(&text, absl::StatusCodeToString(code()), ": ", message());
+
+  const bool with_payload = (mode & StatusToStringMode::kWithPayload) ==
+                            StatusToStringMode::kWithPayload;
+
+  if (with_payload) {
+    status_internal::StatusPayloadPrinter printer =
+        status_internal::GetStatusPayloadPrinter();
+    this->ForEachPayload([&](absl::string_view type_url,
+                             const absl::Cord& payload) {
+      absl::optional<std::string> result;
+      if (printer) result = printer(type_url, payload);
+      absl::StrAppend(
+          &text, " [", type_url, "='",
+          result.has_value() ? *result : absl::CHexEscape(std::string(payload)),
+          "']");
+    });
+  }
+
+  return text;
+}
+
+bool StatusRep::operator==(const StatusRep& other) const {
+  assert(this != &other);
+  if (code_ != other.code_) return false;
+  if (message_ != other.message_) return false;
+  const status_internal::Payloads* this_payloads = payloads_.get();
+  const status_internal::Payloads* other_payloads = other.payloads_.get();
+
+  const status_internal::Payloads no_payloads;
+  const status_internal::Payloads* larger_payloads =
+      this_payloads ? this_payloads : &no_payloads;
+  const status_internal::Payloads* smaller_payloads =
+      other_payloads ? other_payloads : &no_payloads;
+  if (larger_payloads->size() < smaller_payloads->size()) {
+    std::swap(larger_payloads, smaller_payloads);
+  }
+  if ((larger_payloads->size() - smaller_payloads->size()) > 1) return false;
+  // Payloads can be ordered differently, so we can't just compare payload
+  // vectors.
+  for (const auto& payload : *larger_payloads) {
+
+    bool found = false;
+    for (const auto& other_payload : *smaller_payloads) {
+      if (payload.type_url == other_payload.type_url) {
+        if (payload.payload != other_payload.payload) {
+          return false;
+        }
+        found = true;
+        break;
+      }
+    }
+    if (!found) return false;
+  }
+  return true;
+}
+
+absl::Nonnull<StatusRep*> StatusRep::CloneAndUnref() const {
+  // Optimization: no need to create a clone if we already have a refcount of 1.
+  if (ref_.load(std::memory_order_acquire) == 1) {
+    // All StatusRep instances are heap allocated and mutable, therefore this
+    // const_cast will never cast away const from a stack instance.
+    //
+    // CloneAndUnref is the only method that doesn't involve an external cast to
+    // get a mutable StatusRep* from the uintptr_t rep stored in Status.
+    return const_cast<StatusRep*>(this);
+  }
+  std::unique_ptr<status_internal::Payloads> payloads;
+  if (payloads_) {
+    payloads = absl::make_unique<status_internal::Payloads>(*payloads_);
+  }
+  auto* new_rep = new StatusRep(code_, message_, std::move(payloads));
+  Unref();
+  return new_rep;
+}
+
+// Convert canonical code to a value known to this binary.
+absl::StatusCode MapToLocalCode(int value) {
+  absl::StatusCode code = static_cast<absl::StatusCode>(value);
+  switch (code) {
+    case absl::StatusCode::kOk:
+    case absl::StatusCode::kCancelled:
+    case absl::StatusCode::kUnknown:
+    case absl::StatusCode::kInvalidArgument:
+    case absl::StatusCode::kDeadlineExceeded:
+    case absl::StatusCode::kNotFound:
+    case absl::StatusCode::kAlreadyExists:
+    case absl::StatusCode::kPermissionDenied:
+    case absl::StatusCode::kResourceExhausted:
+    case absl::StatusCode::kFailedPrecondition:
+    case absl::StatusCode::kAborted:
+    case absl::StatusCode::kOutOfRange:
+    case absl::StatusCode::kUnimplemented:
+    case absl::StatusCode::kInternal:
+    case absl::StatusCode::kUnavailable:
+    case absl::StatusCode::kDataLoss:
+    case absl::StatusCode::kUnauthenticated:
+      return code;
+    default:
+      return absl::StatusCode::kUnknown;
+  }
+}
+
+absl::Nonnull<std::string*> MakeCheckFailString(
+    absl::Nonnull<const absl::Status*> status,
+    absl::Nonnull<const char*> prefix) {
+  return new std::string(
+      absl::StrCat(prefix, " (",
+                   status->ToString(StatusToStringMode::kWithEverything), ")"));
+}
+
+}  // namespace status_internal
+
+ABSL_NAMESPACE_END
+}  // namespace absl

Pods/abseil/absl/status/internal/status_internal.h

@@ -0,0 +1,132 @@
+// Copyright 2019 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_STATUS_INTERNAL_STATUS_INTERNAL_H_
+#define ABSL_STATUS_INTERNAL_STATUS_INTERNAL_H_
+
+#include <atomic>
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
+#include "absl/base/nullability.h"
+#include "absl/container/inlined_vector.h"
+#include "absl/strings/cord.h"
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+
+#ifndef SWIG
+// Disabled for SWIG as it doesn't parse attributes correctly.
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+// Returned Status objects may not be ignored. Codesearch doesn't handle ifdefs
+// as part of a class definitions (b/6995610), so we use a forward declaration.
+//
+// TODO(b/176172494): ABSL_MUST_USE_RESULT should expand to the more strict
+// [[nodiscard]]. For now, just use [[nodiscard]] directly when it is available.
+#if ABSL_HAVE_CPP_ATTRIBUTE(nodiscard)
+class [[nodiscard]] ABSL_ATTRIBUTE_TRIVIAL_ABI Status;
+#else
+class ABSL_MUST_USE_RESULT ABSL_ATTRIBUTE_TRIVIAL_ABI Status;
+#endif
+ABSL_NAMESPACE_END
+}  // namespace absl
+#endif  // !SWIG
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+enum class StatusCode : int;
+enum class StatusToStringMode : int;
+
+namespace status_internal {
+
+// Container for status payloads.
+struct Payload {
+  std::string type_url;
+  absl::Cord payload;
+};
+
+using Payloads = absl::InlinedVector<Payload, 1>;
+
+// Reference-counted representation of Status data.
+class StatusRep {
+ public:
+  StatusRep(absl::StatusCode code_arg, absl::string_view message_arg,
+            std::unique_ptr<status_internal::Payloads> payloads_arg)
+      : ref_(int32_t{1}),
+        code_(code_arg),
+        message_(message_arg),
+        payloads_(std::move(payloads_arg)) {}
+
+  absl::StatusCode code() const { return code_; }
+  const std::string& message() const { return message_; }
+
+  // Ref and unref are const to allow access through a const pointer, and are
+  // used during copying operations.
+  void Ref() const { ref_.fetch_add(1, std::memory_order_relaxed); }
+  void Unref() const;
+
+  // Payload methods correspond to the same methods in absl::Status.
+  absl::optional<absl::Cord> GetPayload(absl::string_view type_url) const;
+  void SetPayload(absl::string_view type_url, absl::Cord payload);
+  struct EraseResult {
+    bool erased;
+    uintptr_t new_rep;
+  };
+  EraseResult ErasePayload(absl::string_view type_url);
+  void ForEachPayload(
+      absl::FunctionRef<void(absl::string_view, const absl::Cord&)> visitor)
+      const;
+
+  std::string ToString(StatusToStringMode mode) const;
+
+  bool operator==(const StatusRep& other) const;
+  bool operator!=(const StatusRep& other) const { return !(*this == other); }
+
+  // Returns an equivalent heap allocated StatusRep with refcount 1.
+  //
+  // `this` is not safe to be used after calling as it may have been deleted.
+  absl::Nonnull<StatusRep*> CloneAndUnref() const;
+
+ private:
+  mutable std::atomic<int32_t> ref_;
+  absl::StatusCode code_;
+
+  // As an internal implementation detail, we guarantee that if status.message()
+  // is non-empty, then the resulting string_view is null terminated.
+  // This is required to implement 'StatusMessageAsCStr(...)'
+  std::string message_;
+  std::unique_ptr<status_internal::Payloads> payloads_;
+};
+
+absl::StatusCode MapToLocalCode(int value);
+
+// Returns a pointer to a newly-allocated string with the given `prefix`,
+// suitable for output as an error message in assertion/`CHECK()` failures.
+//
+// This is an internal implementation detail for Abseil logging.
+ABSL_ATTRIBUTE_PURE_FUNCTION
+absl::Nonnull<std::string*> MakeCheckFailString(
+    absl::Nonnull<const absl::Status*> status,
+    absl::Nonnull<const char*> prefix);
+
+}  // namespace status_internal
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STATUS_INTERNAL_STATUS_INTERNAL_H_

Pods/abseil/absl/status/internal/statusor_internal.h

@@ -0,0 +1,435 @@
+// 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.
+#ifndef ABSL_STATUS_INTERNAL_STATUSOR_INTERNAL_H_
+#define ABSL_STATUS_INTERNAL_STATUSOR_INTERNAL_H_
+
+#include <cstdint>
+#include <type_traits>
+#include <utility>
+
+#include "absl/base/attributes.h"
+#include "absl/base/nullability.h"
+#include "absl/meta/type_traits.h"
+#include "absl/status/status.h"
+#include "absl/strings/string_view.h"
+#include "absl/utility/utility.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+template <typename T>
+class ABSL_MUST_USE_RESULT StatusOr;
+
+namespace internal_statusor {
+
+// Detects whether `U` has conversion operator to `StatusOr<T>`, i.e. `operator
+// StatusOr<T>()`.
+template <typename T, typename U, typename = void>
+struct HasConversionOperatorToStatusOr : std::false_type {};
+
+template <typename T, typename U>
+void test(char (*)[sizeof(std::declval<U>().operator absl::StatusOr<T>())]);
+
+template <typename T, typename U>
+struct HasConversionOperatorToStatusOr<T, U, decltype(test<T, U>(0))>
+    : std::true_type {};
+
+// Detects whether `T` is constructible or convertible from `StatusOr<U>`.
+template <typename T, typename U>
+using IsConstructibleOrConvertibleFromStatusOr =
+    absl::disjunction<std::is_constructible<T, StatusOr<U>&>,
+                      std::is_constructible<T, const StatusOr<U>&>,
+                      std::is_constructible<T, StatusOr<U>&&>,
+                      std::is_constructible<T, const StatusOr<U>&&>,
+                      std::is_convertible<StatusOr<U>&, T>,
+                      std::is_convertible<const StatusOr<U>&, T>,
+                      std::is_convertible<StatusOr<U>&&, T>,
+                      std::is_convertible<const StatusOr<U>&&, T>>;
+
+// Detects whether `T` is constructible or convertible or assignable from
+// `StatusOr<U>`.
+template <typename T, typename U>
+using IsConstructibleOrConvertibleOrAssignableFromStatusOr =
+    absl::disjunction<IsConstructibleOrConvertibleFromStatusOr<T, U>,
+                      std::is_assignable<T&, StatusOr<U>&>,
+                      std::is_assignable<T&, const StatusOr<U>&>,
+                      std::is_assignable<T&, StatusOr<U>&&>,
+                      std::is_assignable<T&, const StatusOr<U>&&>>;
+
+// Detects whether direct initializing `StatusOr<T>` from `U` is ambiguous, i.e.
+// when `U` is `StatusOr<V>` and `T` is constructible or convertible from `V`.
+template <typename T, typename U>
+struct IsDirectInitializationAmbiguous
+    : public absl::conditional_t<
+          std::is_same<absl::remove_cvref_t<U>, U>::value, std::false_type,
+          IsDirectInitializationAmbiguous<T, absl::remove_cvref_t<U>>> {};
+
+template <typename T, typename V>
+struct IsDirectInitializationAmbiguous<T, absl::StatusOr<V>>
+    : public IsConstructibleOrConvertibleFromStatusOr<T, V> {};
+
+// Checks against the constraints of the direction initialization, i.e. when
+// `StatusOr<T>::StatusOr(U&&)` should participate in overload resolution.
+template <typename T, typename U>
+using IsDirectInitializationValid = absl::disjunction<
+    // Short circuits if T is basically U.
+    std::is_same<T, absl::remove_cvref_t<U>>,
+    absl::negation<absl::disjunction<
+        std::is_same<absl::StatusOr<T>, absl::remove_cvref_t<U>>,
+        std::is_same<absl::Status, absl::remove_cvref_t<U>>,
+        std::is_same<absl::in_place_t, absl::remove_cvref_t<U>>,
+        IsDirectInitializationAmbiguous<T, U>>>>;
+
+// This trait detects whether `StatusOr<T>::operator=(U&&)` is ambiguous, which
+// is equivalent to whether all the following conditions are met:
+// 1. `U` is `StatusOr<V>`.
+// 2. `T` is constructible and assignable from `V`.
+// 3. `T` is constructible and assignable from `U` (i.e. `StatusOr<V>`).
+// For example, the following code is considered ambiguous:
+// (`T` is `bool`, `U` is `StatusOr<bool>`, `V` is `bool`)
+//   StatusOr<bool> s1 = true;  // s1.ok() && s1.ValueOrDie() == true
+//   StatusOr<bool> s2 = false;  // s2.ok() && s2.ValueOrDie() == false
+//   s1 = s2;  // ambiguous, `s1 = s2.ValueOrDie()` or `s1 = bool(s2)`?
+template <typename T, typename U>
+struct IsForwardingAssignmentAmbiguous
+    : public absl::conditional_t<
+          std::is_same<absl::remove_cvref_t<U>, U>::value, std::false_type,
+          IsForwardingAssignmentAmbiguous<T, absl::remove_cvref_t<U>>> {};
+
+template <typename T, typename U>
+struct IsForwardingAssignmentAmbiguous<T, absl::StatusOr<U>>
+    : public IsConstructibleOrConvertibleOrAssignableFromStatusOr<T, U> {};
+
+// Checks against the constraints of the forwarding assignment, i.e. whether
+// `StatusOr<T>::operator(U&&)` should participate in overload resolution.
+template <typename T, typename U>
+using IsForwardingAssignmentValid = absl::disjunction<
+    // Short circuits if T is basically U.
+    std::is_same<T, absl::remove_cvref_t<U>>,
+    absl::negation<absl::disjunction<
+        std::is_same<absl::StatusOr<T>, absl::remove_cvref_t<U>>,
+        std::is_same<absl::Status, absl::remove_cvref_t<U>>,
+        std::is_same<absl::in_place_t, absl::remove_cvref_t<U>>,
+        IsForwardingAssignmentAmbiguous<T, U>>>>;
+
+class Helper {
+ public:
+  // Move type-agnostic error handling to the .cc.
+  static void HandleInvalidStatusCtorArg(absl::Nonnull<Status*>);
+  ABSL_ATTRIBUTE_NORETURN static void Crash(const absl::Status& status);
+};
+
+// Construct an instance of T in `p` through placement new, passing Args... to
+// the constructor.
+// This abstraction is here mostly for the gcc performance fix.
+template <typename T, typename... Args>
+ABSL_ATTRIBUTE_NONNULL(1)
+void PlacementNew(absl::Nonnull<void*> p, Args&&... args) {
+  new (p) T(std::forward<Args>(args)...);
+}
+
+// Helper base class to hold the data and all operations.
+// We move all this to a base class to allow mixing with the appropriate
+// TraitsBase specialization.
+template <typename T>
+class StatusOrData {
+  template <typename U>
+  friend class StatusOrData;
+
+ public:
+  StatusOrData() = delete;
+
+  StatusOrData(const StatusOrData& other) {
+    if (other.ok()) {
+      MakeValue(other.data_);
+      MakeStatus();
+    } else {
+      MakeStatus(other.status_);
+    }
+  }
+
+  StatusOrData(StatusOrData&& other) noexcept {
+    if (other.ok()) {
+      MakeValue(std::move(other.data_));
+      MakeStatus();
+    } else {
+      MakeStatus(std::move(other.status_));
+    }
+  }
+
+  template <typename U>
+  explicit StatusOrData(const StatusOrData<U>& other) {
+    if (other.ok()) {
+      MakeValue(other.data_);
+      MakeStatus();
+    } else {
+      MakeStatus(other.status_);
+    }
+  }
+
+  template <typename U>
+  explicit StatusOrData(StatusOrData<U>&& other) {
+    if (other.ok()) {
+      MakeValue(std::move(other.data_));
+      MakeStatus();
+    } else {
+      MakeStatus(std::move(other.status_));
+    }
+  }
+
+  template <typename... Args>
+  explicit StatusOrData(absl::in_place_t, Args&&... args)
+      : data_(std::forward<Args>(args)...) {
+    MakeStatus();
+  }
+
+  explicit StatusOrData(const T& value) : data_(value) {
+    MakeStatus();
+  }
+  explicit StatusOrData(T&& value) : data_(std::move(value)) {
+    MakeStatus();
+  }
+
+  template <typename U,
+            absl::enable_if_t<std::is_constructible<absl::Status, U&&>::value,
+                              int> = 0>
+  explicit StatusOrData(U&& v) : status_(std::forward<U>(v)) {
+    EnsureNotOk();
+  }
+
+  StatusOrData& operator=(const StatusOrData& other) {
+    if (this == &other) return *this;
+    if (other.ok())
+      Assign(other.data_);
+    else
+      AssignStatus(other.status_);
+    return *this;
+  }
+
+  StatusOrData& operator=(StatusOrData&& other) {
+    if (this == &other) return *this;
+    if (other.ok())
+      Assign(std::move(other.data_));
+    else
+      AssignStatus(std::move(other.status_));
+    return *this;
+  }
+
+  ~StatusOrData() {
+    if (ok()) {
+      status_.~Status();
+      data_.~T();
+    } else {
+      status_.~Status();
+    }
+  }
+
+  template <typename U>
+  void Assign(U&& value) {
+    if (ok()) {
+      data_ = std::forward<U>(value);
+    } else {
+      MakeValue(std::forward<U>(value));
+      status_ = OkStatus();
+    }
+  }
+
+  template <typename U>
+  void AssignStatus(U&& v) {
+    Clear();
+    status_ = static_cast<absl::Status>(std::forward<U>(v));
+    EnsureNotOk();
+  }
+
+  bool ok() const { return status_.ok(); }
+
+ protected:
+  // status_ will always be active after the constructor.
+  // We make it a union to be able to initialize exactly how we need without
+  // waste.
+  // Eg. in the copy constructor we use the default constructor of Status in
+  // the ok() path to avoid an extra Ref call.
+  union {
+    Status status_;
+  };
+
+  // data_ is active iff status_.ok()==true
+  struct Dummy {};
+  union {
+    // When T is const, we need some non-const object we can cast to void* for
+    // the placement new. dummy_ is that object.
+    Dummy dummy_;
+    T data_;
+  };
+
+  void Clear() {
+    if (ok()) data_.~T();
+  }
+
+  void EnsureOk() const {
+    if (ABSL_PREDICT_FALSE(!ok())) Helper::Crash(status_);
+  }
+
+  void EnsureNotOk() {
+    if (ABSL_PREDICT_FALSE(ok())) Helper::HandleInvalidStatusCtorArg(&status_);
+  }
+
+  // Construct the value (ie. data_) through placement new with the passed
+  // argument.
+  template <typename... Arg>
+  void MakeValue(Arg&&... arg) {
+    internal_statusor::PlacementNew<T>(&dummy_, std::forward<Arg>(arg)...);
+  }
+
+  // Construct the status (ie. status_) through placement new with the passed
+  // argument.
+  template <typename... Args>
+  void MakeStatus(Args&&... args) {
+    internal_statusor::PlacementNew<Status>(&status_,
+                                            std::forward<Args>(args)...);
+  }
+};
+
+// Helper base classes to allow implicitly deleted constructors and assignment
+// operators in `StatusOr`. For example, `CopyCtorBase` will explicitly delete
+// the copy constructor when T is not copy constructible and `StatusOr` will
+// inherit that behavior implicitly.
+template <typename T, bool = std::is_copy_constructible<T>::value>
+struct CopyCtorBase {
+  CopyCtorBase() = default;
+  CopyCtorBase(const CopyCtorBase&) = default;
+  CopyCtorBase(CopyCtorBase&&) = default;
+  CopyCtorBase& operator=(const CopyCtorBase&) = default;
+  CopyCtorBase& operator=(CopyCtorBase&&) = default;
+};
+
+template <typename T>
+struct CopyCtorBase<T, false> {
+  CopyCtorBase() = default;
+  CopyCtorBase(const CopyCtorBase&) = delete;
+  CopyCtorBase(CopyCtorBase&&) = default;
+  CopyCtorBase& operator=(const CopyCtorBase&) = default;
+  CopyCtorBase& operator=(CopyCtorBase&&) = default;
+};
+
+template <typename T, bool = std::is_move_constructible<T>::value>
+struct MoveCtorBase {
+  MoveCtorBase() = default;
+  MoveCtorBase(const MoveCtorBase&) = default;
+  MoveCtorBase(MoveCtorBase&&) = default;
+  MoveCtorBase& operator=(const MoveCtorBase&) = default;
+  MoveCtorBase& operator=(MoveCtorBase&&) = default;
+};
+
+template <typename T>
+struct MoveCtorBase<T, false> {
+  MoveCtorBase() = default;
+  MoveCtorBase(const MoveCtorBase&) = default;
+  MoveCtorBase(MoveCtorBase&&) = delete;
+  MoveCtorBase& operator=(const MoveCtorBase&) = default;
+  MoveCtorBase& operator=(MoveCtorBase&&) = default;
+};
+
+template <typename T, bool = std::is_copy_constructible<T>::value&&
+                          std::is_copy_assignable<T>::value>
+struct CopyAssignBase {
+  CopyAssignBase() = default;
+  CopyAssignBase(const CopyAssignBase&) = default;
+  CopyAssignBase(CopyAssignBase&&) = default;
+  CopyAssignBase& operator=(const CopyAssignBase&) = default;
+  CopyAssignBase& operator=(CopyAssignBase&&) = default;
+};
+
+template <typename T>
+struct CopyAssignBase<T, false> {
+  CopyAssignBase() = default;
+  CopyAssignBase(const CopyAssignBase&) = default;
+  CopyAssignBase(CopyAssignBase&&) = default;
+  CopyAssignBase& operator=(const CopyAssignBase&) = delete;
+  CopyAssignBase& operator=(CopyAssignBase&&) = default;
+};
+
+template <typename T, bool = std::is_move_constructible<T>::value&&
+                          std::is_move_assignable<T>::value>
+struct MoveAssignBase {
+  MoveAssignBase() = default;
+  MoveAssignBase(const MoveAssignBase&) = default;
+  MoveAssignBase(MoveAssignBase&&) = default;
+  MoveAssignBase& operator=(const MoveAssignBase&) = default;
+  MoveAssignBase& operator=(MoveAssignBase&&) = default;
+};
+
+template <typename T>
+struct MoveAssignBase<T, false> {
+  MoveAssignBase() = default;
+  MoveAssignBase(const MoveAssignBase&) = default;
+  MoveAssignBase(MoveAssignBase&&) = default;
+  MoveAssignBase& operator=(const MoveAssignBase&) = default;
+  MoveAssignBase& operator=(MoveAssignBase&&) = delete;
+};
+
+ABSL_ATTRIBUTE_NORETURN void ThrowBadStatusOrAccess(absl::Status status);
+
+// Used to introduce jitter into the output of printing functions for
+// `StatusOr` (i.e. `AbslStringify` and `operator<<`).
+class StringifyRandom {
+  enum BracesType {
+    kBareParens = 0,
+    kSpaceParens,
+    kBareBrackets,
+    kSpaceBrackets,
+  };
+
+  // Returns a random `BracesType` determined once per binary load.
+  static BracesType RandomBraces() {
+    static const BracesType kRandomBraces = static_cast<BracesType>(
+        (reinterpret_cast<uintptr_t>(&kRandomBraces) >> 4) % 4);
+    return kRandomBraces;
+  }
+
+ public:
+  static inline absl::string_view OpenBrackets() {
+    switch (RandomBraces()) {
+      case kBareParens:
+        return "(";
+      case kSpaceParens:
+        return "( ";
+      case kBareBrackets:
+        return "[";
+      case kSpaceBrackets:
+        return "[ ";
+    }
+    return "(";
+  }
+
+  static inline absl::string_view CloseBrackets() {
+    switch (RandomBraces()) {
+      case kBareParens:
+        return ")";
+      case kSpaceParens:
+        return " )";
+      case kBareBrackets:
+        return "]";
+      case kSpaceBrackets:
+        return " ]";
+    }
+    return ")";
+  }
+};
+
+}  // namespace internal_statusor
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STATUS_INTERNAL_STATUSOR_INTERNAL_H_