Merge "Export of internal Abseil changes"

13 files changed, 1556 insertions, 43 deletions

diff --git a/absl/container/CMakeLists.txt b/absl/container/CMakeLists.txt
index a931f334..e702ba85 100644
--- a/absl/container/CMakeLists.txt
+++ b/absl/container/CMakeLists.txt
@@ -633,7 +633,7 @@ absl_cc_library(
   NAME
     container_common
   HDRS
-    "internal/commom.h"
+    "internal/common.h"
   COPTS
     ${ABSL_DEFAULT_COPTS}
   DEPS
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index 1c2f15dd..ec673487 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -43,10 +43,10 @@ template <typename T>
 class Flag;
 
 ///////////////////////////////////////////////////////////////////////////////
-// Type-specific operations, eg., parsing, copying, etc. are provided
+// Flag value type operations, eg., parsing, copying, etc. are provided
 // by function specific to that type with a signature matching FlagOpFn.
 
-enum FlagOp {
+enum class FlagOp {
   kDelete,
   kClone,
   kCopy,
@@ -58,26 +58,26 @@ enum FlagOp {
 };
 using FlagOpFn = void* (*)(FlagOp, const void*, void*, void*);
 
-// The per-type function
+// Flag value specific operations routine.
 template <typename T>
 void* FlagOps(FlagOp op, const void* v1, void* v2, void* v3) {
   switch (op) {
-    case flags_internal::kDelete:
+    case FlagOp::kDelete:
       delete static_cast<const T*>(v1);
       return nullptr;
-    case flags_internal::kClone:
+    case FlagOp::kClone:
       return new T(*static_cast<const T*>(v1));
-    case flags_internal::kCopy:
+    case FlagOp::kCopy:
       *static_cast<T*>(v2) = *static_cast<const T*>(v1);
       return nullptr;
-    case flags_internal::kCopyConstruct:
+    case FlagOp::kCopyConstruct:
       new (v2) T(*static_cast<const T*>(v1));
       return nullptr;
-    case flags_internal::kSizeof:
+    case FlagOp::kSizeof:
       return reinterpret_cast<void*>(sizeof(T));
-    case flags_internal::kStaticTypeId:
+    case FlagOp::kStaticTypeId:
       return reinterpret_cast<void*>(&FlagStaticTypeIdGen<T>);
-    case flags_internal::kParse: {
+    case FlagOp::kParse: {
       // Initialize the temporary instance of type T based on current value in
       // destination (which is going to be flag's default value).
       T temp(*static_cast<T*>(v2));
@@ -88,7 +88,7 @@ void* FlagOps(FlagOp op, const void* v1, void* v2, void* v3) {
       *static_cast<T*>(v2) = std::move(temp);
       return v2;
     }
-    case flags_internal::kUnparse:
+    case FlagOp::kUnparse:
       *static_cast<std::string*>(v2) =
           absl::UnparseFlag<T>(*static_cast<const T*>(v1));
       return nullptr;
@@ -97,37 +97,45 @@ void* FlagOps(FlagOp op, const void* v1, void* v2, void* v3) {
   }
 }
 
-// Functions that invoke flag-type-specific operations.
+// Deletes memory interpreting obj as flag value type pointer.
 inline void Delete(FlagOpFn op, const void* obj) {
-  op(flags_internal::kDelete, obj, nullptr, nullptr);
+  op(FlagOp::kDelete, obj, nullptr, nullptr);
 }
+// Makes a copy of flag value pointed by obj.
 inline void* Clone(FlagOpFn op, const void* obj) {
-  return op(flags_internal::kClone, obj, nullptr, nullptr);
+  return op(FlagOp::kClone, obj, nullptr, nullptr);
 }
+// Copies src to dst interpreting as flag value type pointers.
 inline void Copy(FlagOpFn op, const void* src, void* dst) {
-  op(flags_internal::kCopy, src, dst, nullptr);
+  op(FlagOp::kCopy, src, dst, nullptr);
 }
+// Construct a copy of flag value in a location pointed by dst
+// based on src - pointer to the flag's value.
 inline void CopyConstruct(FlagOpFn op, const void* src, void* dst) {
-  op(flags_internal::kCopyConstruct, src, dst, nullptr);
+  op(FlagOp::kCopyConstruct, src, dst, nullptr);
 }
+// Returns true if parsing of input text is successfull.
 inline bool Parse(FlagOpFn op, absl::string_view text, void* dst,
                   std::string* error) {
-  return op(flags_internal::kParse, &text, dst, error) != nullptr;
+  return op(FlagOp::kParse, &text, dst, error) != nullptr;
 }
+// Returns string representing supplied value.
 inline std::string Unparse(FlagOpFn op, const void* val) {
   std::string result;
-  op(flags_internal::kUnparse, val, &result, nullptr);
+  op(FlagOp::kUnparse, val, &result, nullptr);
   return result;
 }
+// Returns size of flag value type.
 inline size_t Sizeof(FlagOpFn op) {
   // This sequence of casts reverses the sequence from
   // `flags_internal::FlagOps()`
   return static_cast<size_t>(reinterpret_cast<intptr_t>(
-      op(flags_internal::kSizeof, nullptr, nullptr, nullptr)));
+      op(FlagOp::kSizeof, nullptr, nullptr, nullptr)));
 }
+// Returns static type id coresponding to the value type.
 inline FlagStaticTypeId StaticTypeId(FlagOpFn op) {
   return reinterpret_cast<FlagStaticTypeId>(
-      op(flags_internal::kStaticTypeId, nullptr, nullptr, nullptr));
+      op(FlagOp::kStaticTypeId, nullptr, nullptr, nullptr));
 }
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/absl/status/BUILD.bazel b/absl/status/BUILD.bazel
new file mode 100644
index 00000000..2b83077d
--- /dev/null
+++ b/absl/status/BUILD.bazel
@@ -0,0 +1,65 @@
+#
+# Copyright 2017 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.
+
+# This package contains `absl::Status`.
+# It will expand later to have utilities around `Status` like `StatusOr`,
+# `StatusBuilder` and macros.
+
+load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
+load(
+    "//absl:copts/configure_copts.bzl",
+    "ABSL_DEFAULT_COPTS",
+    "ABSL_TEST_COPTS",
+)
+
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])  # Apache 2.0
+
+cc_library(
+    name = "status",
+    srcs = [
+        "status.cc",
+        "status_payload_printer.cc",
+    ],
+    hdrs = [
+        "status.h",
+        "status_payload_printer.h",
+    ],
+    copts = ABSL_DEFAULT_COPTS,
+    deps = [
+        "//absl/base:config",
+        "//absl/base:core_headers",
+        "//absl/base:raw_logging_internal",
+        "//absl/container:inlined_vector",
+        "//absl/debugging:stacktrace",
+        "//absl/debugging:symbolize",
+        "//absl/strings",
+        "//absl/strings:cord",
+        "//absl/strings:str_format",
+        "//absl/types:optional",
+    ],
+)
+
+cc_test(
+    name = "status_test",
+    srcs = ["status_test.cc"],
+    copts = ABSL_TEST_COPTS,
+    deps = [
+        ":status",
+        "//absl/strings",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
diff --git a/absl/status/CMakeLists.txt b/absl/status/CMakeLists.txt
new file mode 100644
index 00000000..4f553867
--- /dev/null
+++ b/absl/status/CMakeLists.txt
@@ -0,0 +1,52 @@
+#
+# 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.
+#
+absl_cc_library(
+  NAME
+    status
+  HDRS
+    "status.h"
+  SRCS
+    "status.cc"
+    "status_payload_printer.h"
+    "status_payload_printer.cc"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
+  DEPS
+    absl::config
+    absl::core_headers
+    absl::raw_logging_internal
+    absl::inlined_vector
+    absl::stacktrace
+    absl::symbolize
+    absl::strings
+    absl::cord
+    absl::str_format
+    absl::optional
+  PUBLIC
+)
+
+absl_cc_test(
+  NAME
+    status_test
+  HDRS
+   "status_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::status
+    absl::strings
+    gmock_main
+)
diff --git a/absl/status/status.cc b/absl/status/status.cc
new file mode 100644
index 00000000..bbc1895e
--- /dev/null
+++ b/absl/status/status.cc
@@ -0,0 +1,439 @@
+// 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.
+#include "absl/status/status.h"
+
+#include <cassert>
+
+#include "absl/base/internal/raw_logging.h"
+#include "absl/debugging/stacktrace.h"
+#include "absl/debugging/symbolize.h"
+#include "absl/status/status_payload_printer.h"
+#include "absl/strings/escaping.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+#include "absl/strings/str_split.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+// The implementation was intentionally kept same as util::error::Code_Name()
+// to ease the migration.
+std::string StatusCodeToString(StatusCode code) {
+  switch (code) {
+    case StatusCode::kOk:
+      return "OK";
+    case StatusCode::kCancelled:
+      return "CANCELLED";
+    case StatusCode::kUnknown:
+      return "UNKNOWN";
+    case StatusCode::kInvalidArgument:
+      return "INVALID_ARGUMENT";
+    case StatusCode::kDeadlineExceeded:
+      return "DEADLINE_EXCEEDED";
+    case StatusCode::kNotFound:
+      return "NOT_FOUND";
+    case StatusCode::kAlreadyExists:
+      return "ALREADY_EXISTS";
+    case StatusCode::kPermissionDenied:
+      return "PERMISSION_DENIED";
+    case StatusCode::kUnauthenticated:
+      return "UNAUTHENTICATED";
+    case StatusCode::kResourceExhausted:
+      return "RESOURCE_EXHAUSTED";
+    case StatusCode::kFailedPrecondition:
+      return "FAILED_PRECONDITION";
+    case StatusCode::kAborted:
+      return "ABORTED";
+    case StatusCode::kOutOfRange:
+      return "OUT_OF_RANGE";
+    case StatusCode::kUnimplemented:
+      return "UNIMPLEMENTED";
+    case StatusCode::kInternal:
+      return "INTERNAL";
+    case StatusCode::kUnavailable:
+      return "UNAVAILABLE";
+    case StatusCode::kDataLoss:
+      return "DATA_LOSS";
+    default:
+      return "";
+  }
+}
+
+std::ostream& operator<<(std::ostream& os, StatusCode code) {
+  return os << StatusCodeToString(code);
+}
+
+namespace status_internal {
+
+static int FindPayloadIndexByUrl(const Payloads* payloads,
+                                 absl::string_view type_url) {
+  if (payloads == nullptr) return -1;
+
+  for (int i = 0; i < payloads->size(); ++i) {
+    if ((*payloads)[i].type_url == type_url) return i;
+  }
+
+  return -1;
+}
+
+// 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;
+  }
+}
+}  // namespace status_internal
+
+absl::optional<absl::Cord> Status::GetPayload(
+    absl::string_view type_url) const {
+  const auto* payloads = GetPayloads();
+  int index = status_internal::FindPayloadIndexByUrl(payloads, type_url);
+  if (index != -1) return (*payloads)[index].payload;
+
+  return absl::nullopt;
+}
+
+void Status::SetPayload(absl::string_view type_url, absl::Cord payload) {
+  if (ok()) return;
+
+  PrepareToModify();
+
+  status_internal::StatusRep* rep = RepToPointer(rep_);
+  if (!rep->payloads) {
+    rep->payloads = absl::make_unique<status_internal::Payloads>();
+  }
+
+  int index =
+      status_internal::FindPayloadIndexByUrl(rep->payloads.get(), type_url);
+  if (index != -1) {
+    (*rep->payloads)[index].payload = std::move(payload);
+    return;
+  }
+
+  rep->payloads->push_back({std::string(type_url), std::move(payload)});
+}
+
+bool Status::ErasePayload(absl::string_view type_url) {
+  int index = status_internal::FindPayloadIndexByUrl(GetPayloads(), type_url);
+  if (index != -1) {
+    GetPayloads()->erase(GetPayloads()->begin() + index);
+    return true;
+  }
+
+  return false;
+}
+
+void Status::ForEachPayload(
+    const std::function<void(absl::string_view, const absl::Cord&)>& visitor)
+    const {
+  if (auto* payloads = GetPayloads()) {
+    bool in_reverse =
+        payloads->size() > 1 && reinterpret_cast<uintptr_t>(payloads) % 13 > 6;
+
+    for (int 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 invaldiate the type url to prevent users from relying on
+      // this std::string lifetime.
+
+      // NOLINTNEXTLINE intentional extra conversion to force temporary.
+      visitor(std::string(elem.type_url), elem.payload);
+#endif  // NDEBUG
+    }
+  }
+}
+
+const std::string* Status::EmptyString() {
+  static std::string* empty_string = new std::string();
+  return empty_string;
+}
+
+constexpr const char Status::kMovedFromString[];
+
+const std::string* Status::MovedFromString() {
+  static std::string* moved_from_string = new std::string(kMovedFromString);
+  return moved_from_string;
+}
+
+void Status::UnrefNonInlined(uintptr_t rep) {
+  status_internal::StatusRep* r = RepToPointer(rep);
+  // 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 (r->ref.load(std::memory_order_acquire) == 1 ||
+      r->ref.fetch_sub(1, std::memory_order_acq_rel) - 1 == 0) {
+    delete r;
+  }
+}
+
+uintptr_t Status::NewRep(absl::StatusCode code, absl::string_view msg,
+                         std::unique_ptr<status_internal::Payloads> payloads) {
+  status_internal::StatusRep* rep = new status_internal::StatusRep;
+  rep->ref.store(1, std::memory_order_relaxed);
+  rep->code = code;
+  rep->message.assign(msg.data(), msg.size());
+  rep->payloads = std::move(payloads);
+  return PointerToRep(rep);
+}
+
+Status::Status(absl::StatusCode code, absl::string_view msg)
+    : rep_(CodeToInlinedRep(code)) {
+  if (code != absl::StatusCode::kOk && !msg.empty()) {
+    rep_ = NewRep(code, msg, nullptr);
+  }
+}
+
+int Status::raw_code() const {
+  if (IsInlined(rep_)) {
+    return static_cast<int>(InlinedRepToCode(rep_));
+  }
+  status_internal::StatusRep* rep = RepToPointer(rep_);
+  return static_cast<int>(rep->code);
+}
+
+absl::StatusCode Status::code() const {
+  return status_internal::MapToLocalCode(raw_code());
+}
+
+void Status::PrepareToModify() {
+  ABSL_RAW_CHECK(!ok(), "PrepareToModify shouldn't be called on OK status.");
+  if (IsInlined(rep_)) {
+    rep_ = NewRep(static_cast<absl::StatusCode>(raw_code()),
+                  absl::string_view(), nullptr);
+    return;
+  }
+
+  uintptr_t rep_i = rep_;
+  status_internal::StatusRep* rep = RepToPointer(rep_);
+  if (rep->ref.load(std::memory_order_acquire) != 1) {
+    std::unique_ptr<status_internal::Payloads> payloads;
+    if (rep->payloads) {
+      payloads = absl::make_unique<status_internal::Payloads>(*rep->payloads);
+    }
+    rep_ = NewRep(rep->code, message(), std::move(payloads));
+    UnrefNonInlined(rep_i);
+  }
+}
+
+bool Status::EqualsSlow(const absl::Status& a, const absl::Status& b) {
+  if (IsInlined(a.rep_) != IsInlined(b.rep_)) return false;
+  if (a.message() != b.message()) return false;
+  if (a.raw_code() != b.raw_code()) return false;
+  if (a.GetPayloads() == b.GetPayloads()) return true;
+
+  const status_internal::Payloads no_payloads;
+  const status_internal::Payloads* larger_payloads =
+      a.GetPayloads() ? a.GetPayloads() : &no_payloads;
+  const status_internal::Payloads* smaller_payloads =
+      b.GetPayloads() ? b.GetPayloads() : &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;
+}
+
+std::string Status::ToStringSlow() const {
+  std::string text;
+  absl::StrAppend(&text, absl::StatusCodeToString(code()), ": ", message());
+  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;
+}
+
+std::ostream& operator<<(std::ostream& os, const Status& x) {
+  os << x.ToString();
+  return os;
+}
+
+Status AbortedError(absl::string_view message) {
+  return Status(absl::StatusCode::kAborted, message);
+}
+
+Status AlreadyExistsError(absl::string_view message) {
+  return Status(absl::StatusCode::kAlreadyExists, message);
+}
+
+Status CancelledError(absl::string_view message) {
+  return Status(absl::StatusCode::kCancelled, message);
+}
+
+Status DataLossError(absl::string_view message) {
+  return Status(absl::StatusCode::kDataLoss, message);
+}
+
+Status DeadlineExceededError(absl::string_view message) {
+  return Status(absl::StatusCode::kDeadlineExceeded, message);
+}
+
+Status FailedPreconditionError(absl::string_view message) {
+  return Status(absl::StatusCode::kFailedPrecondition, message);
+}
+
+Status InternalError(absl::string_view message) {
+  return Status(absl::StatusCode::kInternal, message);
+}
+
+Status InvalidArgumentError(absl::string_view message) {
+  return Status(absl::StatusCode::kInvalidArgument, message);
+}
+
+Status NotFoundError(absl::string_view message) {
+  return Status(absl::StatusCode::kNotFound, message);
+}
+
+Status OutOfRangeError(absl::string_view message) {
+  return Status(absl::StatusCode::kOutOfRange, message);
+}
+
+Status PermissionDeniedError(absl::string_view message) {
+  return Status(absl::StatusCode::kPermissionDenied, message);
+}
+
+Status ResourceExhaustedError(absl::string_view message) {
+  return Status(absl::StatusCode::kResourceExhausted, message);
+}
+
+Status UnauthenticatedError(absl::string_view message) {
+  return Status(absl::StatusCode::kUnauthenticated, message);
+}
+
+Status UnavailableError(absl::string_view message) {
+  return Status(absl::StatusCode::kUnavailable, message);
+}
+
+Status UnimplementedError(absl::string_view message) {
+  return Status(absl::StatusCode::kUnimplemented, message);
+}
+
+Status UnknownError(absl::string_view message) {
+  return Status(absl::StatusCode::kUnknown, message);
+}
+
+bool IsAborted(const Status& status) {
+  return status.code() == absl::StatusCode::kAborted;
+}
+
+bool IsAlreadyExists(const Status& status) {
+  return status.code() == absl::StatusCode::kAlreadyExists;
+}
+
+bool IsCancelled(const Status& status) {
+  return status.code() == absl::StatusCode::kCancelled;
+}
+
+bool IsDataLoss(const Status& status) {
+  return status.code() == absl::StatusCode::kDataLoss;
+}
+
+bool IsDeadlineExceeded(const Status& status) {
+  return status.code() == absl::StatusCode::kDeadlineExceeded;
+}
+
+bool IsFailedPrecondition(const Status& status) {
+  return status.code() == absl::StatusCode::kFailedPrecondition;
+}
+
+bool IsInternal(const Status& status) {
+  return status.code() == absl::StatusCode::kInternal;
+}
+
+bool IsInvalidArgument(const Status& status) {
+  return status.code() == absl::StatusCode::kInvalidArgument;
+}
+
+bool IsNotFound(const Status& status) {
+  return status.code() == absl::StatusCode::kNotFound;
+}
+
+bool IsOutOfRange(const Status& status) {
+  return status.code() == absl::StatusCode::kOutOfRange;
+}
+
+bool IsPermissionDenied(const Status& status) {
+  return status.code() == absl::StatusCode::kPermissionDenied;
+}
+
+bool IsResourceExhausted(const Status& status) {
+  return status.code() == absl::StatusCode::kResourceExhausted;
+}
+
+bool IsUnauthenticated(const Status& status) {
+  return status.code() == absl::StatusCode::kUnauthenticated;
+}
+
+bool IsUnavailable(const Status& status) {
+  return status.code() == absl::StatusCode::kUnavailable;
+}
+
+bool IsUnimplemented(const Status& status) {
+  return status.code() == absl::StatusCode::kUnimplemented;
+}
+
+bool IsUnknown(const Status& status) {
+  return status.code() == absl::StatusCode::kUnknown;
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl
diff --git a/absl/status/status.h b/absl/status/status.h
new file mode 100644
index 00000000..9706d4ba
--- /dev/null
+++ b/absl/status/status.h
@@ -0,0 +1,428 @@
+// 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_STATUS_H_
+#define ABSL_STATUS_STATUS_H_
+
+#include <iostream>
+#include <string>
+
+#include "absl/container/inlined_vector.h"
+#include "absl/strings/cord.h"
+#include "absl/types/optional.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+enum class StatusCode : int {
+  kOk = 0,
+  kCancelled = 1,
+  kUnknown = 2,
+  kInvalidArgument = 3,
+  kDeadlineExceeded = 4,
+  kNotFound = 5,
+  kAlreadyExists = 6,
+  kPermissionDenied = 7,
+  kResourceExhausted = 8,
+  kFailedPrecondition = 9,
+  kAborted = 10,
+  kOutOfRange = 11,
+  kUnimplemented = 12,
+  kInternal = 13,
+  kUnavailable = 14,
+  kDataLoss = 15,
+  kUnauthenticated = 16,
+  kDoNotUseReservedForFutureExpansionUseDefaultInSwitchInstead_ = 20
+};
+
+// Returns the name for the status code, or "" if it is an unknown value.
+std::string StatusCodeToString(StatusCode code);
+
+// Streams StatusCodeToString(code) to `os`.
+std::ostream& operator<<(std::ostream& os, StatusCode code);
+
+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.
+struct StatusRep {
+  std::atomic<int32_t> ref;
+  absl::StatusCode code;
+  std::string message;
+  std::unique_ptr<status_internal::Payloads> payloads;
+};
+
+absl::StatusCode MapToLocalCode(int value);
+}  // namespace status_internal
+
+class ABSL_MUST_USE_RESULT Status final {
+ public:
+  // Creates an OK status with no message or payload.
+  Status();
+
+  // Create a status in the canonical error space with the specified code and
+  // error message.  If `code == util::error::OK`, `msg` is ignored and an
+  // object identical to an OK status is constructed.
+  //
+  // `msg` must be in UTF-8. The implementation may complain (e.g.,
+  // by printing a warning) if it is not.
+  Status(absl::StatusCode code, absl::string_view msg);
+
+  Status(const Status&);
+  Status& operator=(const Status& x);
+
+  // Move operations.
+  // The moved-from state is valid but unspecified.
+  Status(Status&&) noexcept;
+  Status& operator=(Status&&);
+
+  ~Status();
+
+  // If `this->ok()`, stores `new_status` into *this. If `!this->ok()`,
+  // preserves the current data. May, in the future, augment the current status
+  // with additional information about `new_status`.
+  //
+  // Convenient way of keeping track of the first error encountered.
+  // Instead of:
+  //   if (overall_status.ok()) overall_status = new_status
+  // Use:
+  //   overall_status.Update(new_status);
+  //
+  // Style guide exception for rvalue reference granted in CL 153567220.
+  void Update(const Status& new_status);
+  void Update(Status&& new_status);
+
+  // Returns true if the Status is OK.
+  ABSL_MUST_USE_RESULT bool ok() const;
+
+  // Returns the (canonical) error code.
+  absl::StatusCode code() const;
+
+  // Returns the raw (canonical) error code which could be out of the range of
+  // the local `absl::StatusCode` enum. NOTE: This should only be called when
+  // converting to wire format. Use `code` for error handling.
+  int raw_code() const;
+
+  // Returns the error message.  Note: prefer ToString() for debug logging.
+  // This message rarely describes the error code.  It is not unusual for the
+  // error message to be the empty std::string.
+  absl::string_view message() const;
+
+  friend bool operator==(const Status&, const Status&);
+  friend bool operator!=(const Status&, const Status&);
+
+  // Returns a combination of the error code name, the message and the payloads.
+  // You can expect the code name and the message to be substrings of the
+  // result, and the payloads to be printed by the registered printer extensions
+  // if they are recognized.
+  // WARNING: Do not depend on the exact format of the result of `ToString()`
+  // which is subject to change.
+  std::string ToString() const;
+
+  // Ignores any errors. This method does nothing except potentially suppress
+  // complaints from any tools that are checking that errors are not dropped on
+  // the floor.
+  void IgnoreError() const;
+
+  // Swap the contents of `a` with `b`
+  friend void swap(Status& a, Status& b);
+
+  // Payload management APIs
+
+  // Type URL should be unique and follow the naming convention below:
+  // The idea of type URL comes from `google.protobuf.Any`
+  // (https://developers.google.com/protocol-buffers/docs/proto3#any). The
+  // type URL should be globally unique and follow the format of URL
+  // (https://en.wikipedia.org/wiki/URL). The default type URL for a given
+  // protobuf message type is "type.googleapis.com/packagename.messagename". For
+  // other custom wire formats, users should define the format of type URL in a
+  // similar practice so as to minimize the chance of conflict between type
+  // URLs. Users should make sure that the type URL can be mapped to a concrete
+  // C++ type if they want to deserialize the payload and read it effectively.
+
+  // Gets the payload based for `type_url` key, if it is present.
+  absl::optional<absl::Cord> GetPayload(absl::string_view type_url) const;
+
+  // Sets the payload for `type_url` key for a non-ok status, overwriting any
+  // existing payload for `type_url`.
+  //
+  // NOTE: Does nothing if the Status is ok.
+  void SetPayload(absl::string_view type_url, absl::Cord payload);
+
+  // Erases the payload corresponding to the `type_url` key.  Returns true if
+  // the payload was present.
+  bool ErasePayload(absl::string_view type_url);
+
+  // Iterates over the stored payloads and calls `visitor(type_key, payload)`
+  // for each one.
+  //
+  // NOTE: The order of calls to `visitor` is not specified and may change at
+  // any time.
+  //
+  // NOTE: Any mutation on the same 'Status' object during visitation is
+  // forbidden and could result in undefined behavior.
+  void ForEachPayload(
+      const std::function<void(absl::string_view, const absl::Cord&)>& visitor)
+      const;
+
+ private:
+  friend Status CancelledError();
+
+  // Creates a status in the canonical error space with the specified
+  // code, and an empty error message.
+  explicit Status(absl::StatusCode code);
+
+  static void UnrefNonInlined(uintptr_t rep);
+  static void Ref(uintptr_t rep);
+  static void Unref(uintptr_t rep);
+
+  // REQUIRES: !ok()
+  // Ensures rep_ is not shared with any other Status.
+  void PrepareToModify();
+
+  const status_internal::Payloads* GetPayloads() const;
+  status_internal::Payloads* GetPayloads();
+
+  // Takes ownership of payload.
+  static uintptr_t NewRep(absl::StatusCode code, absl::string_view msg,
+                          std::unique_ptr<status_internal::Payloads> payload);
+  static bool EqualsSlow(const absl::Status& a, const absl::Status& b);
+
+  // MSVC 14.0 limitation requires the const.
+  static constexpr const char kMovedFromString[] =
+      "Status accessed after move.";
+
+  static const std::string* EmptyString();
+  static const std::string* MovedFromString();
+
+  // Returns whether rep contains an inlined representation.
+  // See rep_ for details.
+  static bool IsInlined(uintptr_t rep);
+
+  // Indicates whether this Status was the rhs of a move operation. See rep_
+  // for details.
+  static bool IsMovedFrom(uintptr_t rep);
+  static uintptr_t MovedFromRep();
+
+  // Convert between error::Code and the inlined uintptr_t representation used
+  // by rep_. See rep_ for details.
+  static uintptr_t CodeToInlinedRep(absl::StatusCode code);
+  static absl::StatusCode InlinedRepToCode(uintptr_t rep);
+
+  // Converts between StatusRep* and the external uintptr_t representation used
+  // by rep_. See rep_ for details.
+  static uintptr_t PointerToRep(status_internal::StatusRep* r);
+  static status_internal::StatusRep* RepToPointer(uintptr_t r);
+
+  // Returns std::string for non-ok Status.
+  std::string ToStringSlow() const;
+
+  // Status supports two different representations.
+  //  - When the low bit is off it is an inlined representation.
+  //    It uses the canonical error space, no message or payload.
+  //    The error code is (rep_ >> 2).
+  //    The (rep_ & 2) bit is the "moved from" indicator, used in IsMovedFrom().
+  //  - When the low bit is on it is an external representation.
+  //    In this case all the data comes from a heap allocated Rep object.
+  //    (rep_ - 1) is a status_internal::StatusRep* pointer to that structure.
+  uintptr_t rep_;
+};
+
+// Returns an OK status, equivalent to a default constructed instance.
+Status OkStatus();
+
+// Prints a human-readable representation of `x` to `os`.
+std::ostream& operator<<(std::ostream& os, const Status& x);
+
+// -----------------------------------------------------------------
+// Implementation details follow
+
+inline Status::Status() : rep_(CodeToInlinedRep(absl::StatusCode::kOk)) {}
+
+inline Status::Status(absl::StatusCode code) : rep_(CodeToInlinedRep(code)) {}
+
+inline Status::Status(const Status& x) : rep_(x.rep_) { Ref(rep_); }
+
+inline Status& Status::operator=(const Status& x) {
+  uintptr_t old_rep = rep_;
+  if (x.rep_ != old_rep) {
+    Ref(x.rep_);
+    rep_ = x.rep_;
+    Unref(old_rep);
+  }
+  return *this;
+}
+
+inline Status::Status(Status&& x) noexcept : rep_(x.rep_) {
+  x.rep_ = MovedFromRep();
+}
+
+inline Status& Status::operator=(Status&& x) {
+  uintptr_t old_rep = rep_;
+  rep_ = x.rep_;
+  x.rep_ = MovedFromRep();
+  Unref(old_rep);
+  return *this;
+}
+
+inline void Status::Update(const Status& new_status) {
+  if (ok()) {
+    *this = new_status;
+  }
+}
+
+inline void Status::Update(Status&& new_status) {
+  if (ok()) {
+    *this = std::move(new_status);
+  }
+}
+
+inline Status::~Status() { Unref(rep_); }
+
+inline bool Status::ok() const {
+  return rep_ == CodeToInlinedRep(absl::StatusCode::kOk);
+}
+
+inline absl::string_view Status::message() const {
+  return !IsInlined(rep_)
+             ? RepToPointer(rep_)->message
+             : (IsMovedFrom(rep_) ? absl::string_view(kMovedFromString)
+                                  : absl::string_view());
+}
+
+inline bool operator==(const Status& lhs, const Status& rhs) {
+  return lhs.rep_ == rhs.rep_ || Status::EqualsSlow(lhs, rhs);
+}
+
+inline bool operator!=(const Status& lhs, const Status& rhs) {
+  return !(lhs == rhs);
+}
+
+inline std::string Status::ToString() const {
+  return ok() ? "OK" : ToStringSlow();
+}
+
+inline void Status::IgnoreError() const {
+  // no-op
+}
+
+inline void swap(absl::Status& a, absl::Status& b) {
+  using std::swap;
+  swap(a.rep_, b.rep_);
+}
+
+inline const status_internal::Payloads* Status::GetPayloads() const {
+  return IsInlined(rep_) ? nullptr : RepToPointer(rep_)->payloads.get();
+}
+
+inline status_internal::Payloads* Status::GetPayloads() {
+  return IsInlined(rep_) ? nullptr : RepToPointer(rep_)->payloads.get();
+}
+
+inline bool Status::IsInlined(uintptr_t rep) { return (rep & 1) == 0; }
+
+inline bool Status::IsMovedFrom(uintptr_t rep) {
+  return IsInlined(rep) && (rep & 2) != 0;
+}
+
+inline uintptr_t Status::MovedFromRep() {
+  return CodeToInlinedRep(absl::StatusCode::kInternal) | 2;
+}
+
+inline uintptr_t Status::CodeToInlinedRep(absl::StatusCode code) {
+  return static_cast<uintptr_t>(code) << 2;
+}
+
+inline absl::StatusCode Status::InlinedRepToCode(uintptr_t rep) {
+  assert(IsInlined(rep));
+  return static_cast<absl::StatusCode>(rep >> 2);
+}
+
+inline status_internal::StatusRep* Status::RepToPointer(uintptr_t rep) {
+  assert(!IsInlined(rep));
+  return reinterpret_cast<status_internal::StatusRep*>(rep - 1);
+}
+
+inline uintptr_t Status::PointerToRep(status_internal::StatusRep* rep) {
+  return reinterpret_cast<uintptr_t>(rep) + 1;
+}
+
+inline void Status::Ref(uintptr_t rep) {
+  if (!IsInlined(rep)) {
+    RepToPointer(rep)->ref.fetch_add(1, std::memory_order_relaxed);
+  }
+}
+
+inline void Status::Unref(uintptr_t rep) {
+  if (!IsInlined(rep)) {
+    UnrefNonInlined(rep);
+  }
+}
+
+inline Status OkStatus() { return Status(); }
+
+// Each of the functions below creates a Status object with a particular error
+// code and the given message. The error code of the returned status object
+// matches the name of the function.
+Status AbortedError(absl::string_view message);
+Status AlreadyExistsError(absl::string_view message);
+Status CancelledError(absl::string_view message);
+Status DataLossError(absl::string_view message);
+Status DeadlineExceededError(absl::string_view message);
+Status FailedPreconditionError(absl::string_view message);
+Status InternalError(absl::string_view message);
+Status InvalidArgumentError(absl::string_view message);
+Status NotFoundError(absl::string_view message);
+Status OutOfRangeError(absl::string_view message);
+Status PermissionDeniedError(absl::string_view message);
+Status ResourceExhaustedError(absl::string_view message);
+Status UnauthenticatedError(absl::string_view message);
+Status UnavailableError(absl::string_view message);
+Status UnimplementedError(absl::string_view message);
+Status UnknownError(absl::string_view message);
+
+// Creates a `Status` object with the `absl::StatusCode::kCancelled` error code
+// and an empty message. It is provided only for efficiency, given that
+// message-less kCancelled errors are common in the infrastructure.
+inline Status CancelledError() { return Status(absl::StatusCode::kCancelled); }
+
+// Each of the functions below returns true if the given status matches the
+// error code implied by the function's name.
+ABSL_MUST_USE_RESULT bool IsAborted(const Status& status);
+ABSL_MUST_USE_RESULT bool IsAlreadyExists(const Status& status);
+ABSL_MUST_USE_RESULT bool IsCancelled(const Status& status);
+ABSL_MUST_USE_RESULT bool IsDataLoss(const Status& status);
+ABSL_MUST_USE_RESULT bool IsDeadlineExceeded(const Status& status);
+ABSL_MUST_USE_RESULT bool IsFailedPrecondition(const Status& status);
+ABSL_MUST_USE_RESULT bool IsInternal(const Status& status);
+ABSL_MUST_USE_RESULT bool IsInvalidArgument(const Status& status);
+ABSL_MUST_USE_RESULT bool IsNotFound(const Status& status);
+ABSL_MUST_USE_RESULT bool IsOutOfRange(const Status& status);
+ABSL_MUST_USE_RESULT bool IsPermissionDenied(const Status& status);
+ABSL_MUST_USE_RESULT bool IsResourceExhausted(const Status& status);
+ABSL_MUST_USE_RESULT bool IsUnauthenticated(const Status& status);
+ABSL_MUST_USE_RESULT bool IsUnavailable(const Status& status);
+ABSL_MUST_USE_RESULT bool IsUnimplemented(const Status& status);
+ABSL_MUST_USE_RESULT bool IsUnknown(const Status& status);
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STATUS_STATUS_H_
diff --git a/absl/status/status_payload_printer.cc b/absl/status/status_payload_printer.cc
new file mode 100644
index 00000000..ad96d76a
--- /dev/null
+++ b/absl/status/status_payload_printer.cc
@@ -0,0 +1,43 @@
+// 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.
+#include "absl/status/status_payload_printer.h"
+
+#include <atomic>
+
+#include "absl/base/attributes.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace status_internal {
+
+namespace {
+// Tried constant initialized global variable but it doesn't work with Lexan
+// (MSVC's `std::atomic` has trouble constant initializing).
+std::atomic<StatusPayloadPrinter>& GetStatusPayloadPrinterStorage() {
+  ABSL_CONST_INIT static std::atomic<StatusPayloadPrinter> instance{nullptr};
+  return instance;
+}
+}  // namespace
+
+void SetStatusPayloadPrinter(StatusPayloadPrinter printer) {
+  GetStatusPayloadPrinterStorage().store(printer, std::memory_order_relaxed);
+}
+
+StatusPayloadPrinter GetStatusPayloadPrinter() {
+  return GetStatusPayloadPrinterStorage().load(std::memory_order_relaxed);
+}
+
+}  // namespace status_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
diff --git a/absl/status/status_payload_printer.h b/absl/status/status_payload_printer.h
new file mode 100644
index 00000000..5e0937f6
--- /dev/null
+++ b/absl/status/status_payload_printer.h
@@ -0,0 +1,51 @@
+// 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_STATUS_PAYLOAD_PRINTER_H_
+#define ABSL_STATUS_STATUS_PAYLOAD_PRINTER_H_
+
+#include <string>
+
+#include "absl/strings/cord.h"
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace status_internal {
+
+// By default, `Status::ToString` and `operator<<(Status)` print a payload by
+// dumping the type URL and the raw bytes. To help debugging, we provide an
+// extension point, which is a global printer function that can be set by users
+// to specify how to print payloads. The function takes the type URL and the
+// payload as input, and should return a valid human-readable string on success
+// or `absl::nullopt` on failure (in which case it falls back to the default
+// approach of printing the raw bytes).
+// NOTE: This is an internal API and the design is subject to change in the
+// future in a non-backward-compatible way. Since it's only meant for debugging
+// purpose, you should not rely on it in any critical logic.
+using StatusPayloadPrinter = absl::optional<std::string> (*)(absl::string_view,
+                                                             const absl::Cord&);
+
+// Sets the global payload printer. Only one printer should be set per process.
+// If multiple printers are set, it's undefined which one will be used.
+void SetStatusPayloadPrinter(StatusPayloadPrinter);
+
+// Returns the global payload printer if previously set, otherwise `nullptr`.
+StatusPayloadPrinter GetStatusPayloadPrinter();
+
+}  // namespace status_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STATUS_STATUS_PAYLOAD_PRINTER_H_
diff --git a/absl/status/status_test.cc b/absl/status/status_test.cc
new file mode 100644
index 00000000..7cc65e45
--- /dev/null
+++ b/absl/status/status_test.cc
@@ -0,0 +1,401 @@
+// 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.
+
+#include "absl/status/status.h"
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/strings/str_cat.h"
+
+namespace {
+
+using ::testing::Eq;
+using ::testing::HasSubstr;
+using ::testing::Optional;
+using ::testing::UnorderedElementsAreArray;
+
+TEST(StatusCode, InsertionOperator) {
+  const absl::StatusCode code = absl::StatusCode::kUnknown;
+  std::ostringstream oss;
+  oss << code;
+  EXPECT_EQ(oss.str(), absl::StatusCodeToString(code));
+}
+
+// This structure holds the details for testing a single error code,
+// its creator, and its classifier.
+struct ErrorTest {
+  absl::StatusCode code;
+  using Creator = absl::Status (*)(absl::string_view);
+  using Classifier = bool (*)(const absl::Status&);
+  Creator creator;
+  Classifier classifier;
+};
+
+constexpr ErrorTest kErrorTests[]{
+    {absl::StatusCode::kCancelled, absl::CancelledError, absl::IsCancelled},
+    {absl::StatusCode::kUnknown, absl::UnknownError, absl::IsUnknown},
+    {absl::StatusCode::kInvalidArgument, absl::InvalidArgumentError,
+     absl::IsInvalidArgument},
+    {absl::StatusCode::kDeadlineExceeded, absl::DeadlineExceededError,
+     absl::IsDeadlineExceeded},
+    {absl::StatusCode::kNotFound, absl::NotFoundError, absl::IsNotFound},
+    {absl::StatusCode::kAlreadyExists, absl::AlreadyExistsError,
+     absl::IsAlreadyExists},
+    {absl::StatusCode::kPermissionDenied, absl::PermissionDeniedError,
+     absl::IsPermissionDenied},
+    {absl::StatusCode::kResourceExhausted, absl::ResourceExhaustedError,
+     absl::IsResourceExhausted},
+    {absl::StatusCode::kFailedPrecondition, absl::FailedPreconditionError,
+     absl::IsFailedPrecondition},
+    {absl::StatusCode::kAborted, absl::AbortedError, absl::IsAborted},
+    {absl::StatusCode::kOutOfRange, absl::OutOfRangeError, absl::IsOutOfRange},
+    {absl::StatusCode::kUnimplemented, absl::UnimplementedError,
+     absl::IsUnimplemented},
+    {absl::StatusCode::kInternal, absl::InternalError, absl::IsInternal},
+    {absl::StatusCode::kUnavailable, absl::UnavailableError,
+     absl::IsUnavailable},
+    {absl::StatusCode::kDataLoss, absl::DataLossError, absl::IsDataLoss},
+    {absl::StatusCode::kUnauthenticated, absl::UnauthenticatedError,
+     absl::IsUnauthenticated},
+};
+
+TEST(Status, CreateAndClassify) {
+  for (const auto& test : kErrorTests) {
+    SCOPED_TRACE(absl::StatusCodeToString(test.code));
+
+    // Ensure that the creator does, in fact, create status objects with the
+    // expected error code and message.
+    std::string message =
+        absl::StrCat("error code ", test.code, " test message");
+    absl::Status status = test.creator(message);
+    EXPECT_EQ(test.code, status.code());
+    EXPECT_EQ(message, status.message());
+
+    // Ensure that the classifier returns true for a status produced by the
+    // creator.
+    EXPECT_TRUE(test.classifier(status));
+
+    // Ensure that the classifier returns false for status with a different
+    // code.
+    for (const auto& other : kErrorTests) {
+      if (other.code != test.code) {
+        EXPECT_FALSE(test.classifier(absl::Status(other.code, "")))
+            << " other.code = " << other.code;
+      }
+    }
+  }
+}
+
+TEST(Status, DefaultConstructor) {
+  absl::Status status;
+  EXPECT_TRUE(status.ok());
+  EXPECT_EQ(absl::StatusCode::kOk, status.code());
+  EXPECT_EQ("", status.message());
+}
+
+TEST(Status, OkStatus) {
+  absl::Status status = absl::OkStatus();
+  EXPECT_TRUE(status.ok());
+  EXPECT_EQ(absl::StatusCode::kOk, status.code());
+  EXPECT_EQ("", status.message());
+}
+
+TEST(Status, ConstructorWithCodeMessage) {
+  {
+    absl::Status status(absl::StatusCode::kCancelled, "");
+    EXPECT_FALSE(status.ok());
+    EXPECT_EQ(absl::StatusCode::kCancelled, status.code());
+    EXPECT_EQ("", status.message());
+  }
+  {
+    absl::Status status(absl::StatusCode::kInternal, "message");
+    EXPECT_FALSE(status.ok());
+    EXPECT_EQ(absl::StatusCode::kInternal, status.code());
+    EXPECT_EQ("message", status.message());
+  }
+}
+
+TEST(Status, ConstructOutOfRangeCode) {
+  const int kRawCode = 9999;
+  absl::Status status(static_cast<absl::StatusCode>(kRawCode), "");
+  EXPECT_EQ(absl::StatusCode::kUnknown, status.code());
+  EXPECT_EQ(kRawCode, status.raw_code());
+}
+
+constexpr char kUrl1[] = "url.payload.1";
+constexpr char kUrl2[] = "url.payload.2";
+constexpr char kUrl3[] = "url.payload.3";
+constexpr char kUrl4[] = "url.payload.xx";
+
+constexpr char kPayload1[] = "aaaaa";
+constexpr char kPayload2[] = "bbbbb";
+constexpr char kPayload3[] = "ccccc";
+
+using PayloadsVec = std::vector<std::pair<std::string, absl::Cord>>;
+
+TEST(Status, TestGetSetPayload) {
+  absl::Status ok_status = absl::OkStatus();
+  ok_status.SetPayload(kUrl1, absl::Cord(kPayload1));
+  ok_status.SetPayload(kUrl2, absl::Cord(kPayload2));
+
+  EXPECT_FALSE(ok_status.GetPayload(kUrl1));
+  EXPECT_FALSE(ok_status.GetPayload(kUrl2));
+
+  absl::Status bad_status(absl::StatusCode::kInternal, "fail");
+  bad_status.SetPayload(kUrl1, absl::Cord(kPayload1));
+  bad_status.SetPayload(kUrl2, absl::Cord(kPayload2));
+
+  EXPECT_THAT(bad_status.GetPayload(kUrl1), Optional(Eq(kPayload1)));
+  EXPECT_THAT(bad_status.GetPayload(kUrl2), Optional(Eq(kPayload2)));
+
+  EXPECT_FALSE(bad_status.GetPayload(kUrl3));
+
+  bad_status.SetPayload(kUrl1, absl::Cord(kPayload3));
+  EXPECT_THAT(bad_status.GetPayload(kUrl1), Optional(Eq(kPayload3)));
+
+  // Testing dynamically generated type_url
+  bad_status.SetPayload(absl::StrCat(kUrl1, ".1"), absl::Cord(kPayload1));
+  EXPECT_THAT(bad_status.GetPayload(absl::StrCat(kUrl1, ".1")),
+              Optional(Eq(kPayload1)));
+}
+
+TEST(Status, TestErasePayload) {
+  absl::Status bad_status(absl::StatusCode::kInternal, "fail");
+  bad_status.SetPayload(kUrl1, absl::Cord(kPayload1));
+  bad_status.SetPayload(kUrl2, absl::Cord(kPayload2));
+  bad_status.SetPayload(kUrl3, absl::Cord(kPayload3));
+
+  EXPECT_FALSE(bad_status.ErasePayload(kUrl4));
+
+  EXPECT_TRUE(bad_status.GetPayload(kUrl2));
+  EXPECT_TRUE(bad_status.ErasePayload(kUrl2));
+  EXPECT_FALSE(bad_status.GetPayload(kUrl2));
+  EXPECT_FALSE(bad_status.ErasePayload(kUrl2));
+
+  EXPECT_TRUE(bad_status.ErasePayload(kUrl1));
+  EXPECT_TRUE(bad_status.ErasePayload(kUrl3));
+
+  bad_status.SetPayload(kUrl1, absl::Cord(kPayload1));
+  EXPECT_TRUE(bad_status.ErasePayload(kUrl1));
+}
+
+TEST(Status, TestComparePayloads) {
+  absl::Status bad_status1(absl::StatusCode::kInternal, "fail");
+  bad_status1.SetPayload(kUrl1, absl::Cord(kPayload1));
+  bad_status1.SetPayload(kUrl2, absl::Cord(kPayload2));
+  bad_status1.SetPayload(kUrl3, absl::Cord(kPayload3));
+
+  absl::Status bad_status2(absl::StatusCode::kInternal, "fail");
+  bad_status2.SetPayload(kUrl2, absl::Cord(kPayload2));
+  bad_status2.SetPayload(kUrl3, absl::Cord(kPayload3));
+  bad_status2.SetPayload(kUrl1, absl::Cord(kPayload1));
+
+  EXPECT_EQ(bad_status1, bad_status2);
+}
+
+PayloadsVec AllVisitedPayloads(const absl::Status& s) {
+  PayloadsVec result;
+
+  s.ForEachPayload([&](absl::string_view type_url, const absl::Cord& payload) {
+    result.push_back(std::make_pair(std::string(type_url), payload));
+  });
+
+  return result;
+}
+
+TEST(Status, TestForEachPayload) {
+  absl::Status bad_status(absl::StatusCode::kInternal, "fail");
+  bad_status.SetPayload(kUrl1, absl::Cord(kPayload1));
+  bad_status.SetPayload(kUrl2, absl::Cord(kPayload2));
+  bad_status.SetPayload(kUrl3, absl::Cord(kPayload3));
+
+  int count = 0;
+
+  bad_status.ForEachPayload(
+      [&count](absl::string_view, const absl::Cord&) { ++count; });
+
+  EXPECT_EQ(count, 3);
+
+  PayloadsVec expected_payloads = {{kUrl1, absl::Cord(kPayload1)},
+                                   {kUrl2, absl::Cord(kPayload2)},
+                                   {kUrl3, absl::Cord(kPayload3)}};
+
+  // Test that we visit all the payloads in the status.
+  PayloadsVec visited_payloads = AllVisitedPayloads(bad_status);
+  EXPECT_THAT(visited_payloads, UnorderedElementsAreArray(expected_payloads));
+
+  // Test that visitation order is not consistent between run.
+  std::vector<absl::Status> scratch;
+  while (true) {
+    scratch.emplace_back(absl::StatusCode::kInternal, "fail");
+
+    scratch.back().SetPayload(kUrl1, absl::Cord(kPayload1));
+    scratch.back().SetPayload(kUrl2, absl::Cord(kPayload2));
+    scratch.back().SetPayload(kUrl3, absl::Cord(kPayload3));
+
+    if (AllVisitedPayloads(scratch.back()) != visited_payloads) {
+      break;
+    }
+  }
+}
+
+TEST(Status, ToString) {
+  absl::Status s(absl::StatusCode::kInternal, "fail");
+  EXPECT_EQ("INTERNAL: fail", s.ToString());
+  s.SetPayload("foo", absl::Cord("bar"));
+  EXPECT_EQ("INTERNAL: fail [foo='bar']", s.ToString());
+  s.SetPayload("bar", absl::Cord("\377"));
+  EXPECT_THAT(s.ToString(),
+              AllOf(HasSubstr("INTERNAL: fail"), HasSubstr("[foo='bar']"),
+                    HasSubstr("[bar='\\xff']")));
+}
+
+TEST(Status, CopyConstructor) {
+  {
+    absl::Status status;
+    absl::Status copy(status);
+    EXPECT_EQ(copy, status);
+  }
+  {
+    absl::Status status(absl::StatusCode::kInvalidArgument, "message");
+    absl::Status copy(status);
+    EXPECT_EQ(copy, status);
+  }
+  {
+    absl::Status status(absl::StatusCode::kInvalidArgument, "message");
+    status.SetPayload(kUrl1, absl::Cord(kPayload1));
+    absl::Status copy(status);
+    EXPECT_EQ(copy, status);
+  }
+}
+
+TEST(Status, CopyAssignment) {
+  absl::Status assignee;
+  {
+    absl::Status status;
+    assignee = status;
+    EXPECT_EQ(assignee, status);
+  }
+  {
+    absl::Status status(absl::StatusCode::kInvalidArgument, "message");
+    assignee = status;
+    EXPECT_EQ(assignee, status);
+  }
+  {
+    absl::Status status(absl::StatusCode::kInvalidArgument, "message");
+    status.SetPayload(kUrl1, absl::Cord(kPayload1));
+    assignee = status;
+    EXPECT_EQ(assignee, status);
+  }
+}
+
+TEST(Status, MoveConstructor) {
+  {
+    absl::Status status;
+    absl::Status copy(absl::Status{});
+    EXPECT_EQ(copy, status);
+  }
+  {
+    absl::Status status(absl::StatusCode::kInvalidArgument, "message");
+    absl::Status copy(
+        absl::Status(absl::StatusCode::kInvalidArgument, "message"));
+    EXPECT_EQ(copy, status);
+  }
+  {
+    absl::Status status(absl::StatusCode::kInvalidArgument, "message");
+    status.SetPayload(kUrl1, absl::Cord(kPayload1));
+    absl::Status copy1(status);
+    absl::Status copy2(std::move(status));
+    EXPECT_EQ(copy1, copy2);
+  }
+}
+
+TEST(Status, MoveAssignment) {
+  absl::Status assignee;
+  {
+    absl::Status status;
+    assignee = absl::Status();
+    EXPECT_EQ(assignee, status);
+  }
+  {
+    absl::Status status(absl::StatusCode::kInvalidArgument, "message");
+    assignee = absl::Status(absl::StatusCode::kInvalidArgument, "message");
+    EXPECT_EQ(assignee, status);
+  }
+  {
+    absl::Status status(absl::StatusCode::kInvalidArgument, "message");
+    status.SetPayload(kUrl1, absl::Cord(kPayload1));
+    absl::Status copy(status);
+    assignee = std::move(status);
+    EXPECT_EQ(assignee, copy);
+  }
+}
+
+TEST(Status, Update) {
+  absl::Status s;
+  s.Update(absl::OkStatus());
+  EXPECT_TRUE(s.ok());
+  const absl::Status a(absl::StatusCode::kCancelled, "message");
+  s.Update(a);
+  EXPECT_EQ(s, a);
+  const absl::Status b(absl::StatusCode::kInternal, "other message");
+  s.Update(b);
+  EXPECT_EQ(s, a);
+  s.Update(absl::OkStatus());
+  EXPECT_EQ(s, a);
+  EXPECT_FALSE(s.ok());
+}
+
+TEST(Status, Equality) {
+  absl::Status ok;
+  absl::Status no_payload = absl::CancelledError("no payload");
+  absl::Status one_payload = absl::InvalidArgumentError("one payload");
+  one_payload.SetPayload(kUrl1, absl::Cord(kPayload1));
+  absl::Status two_payloads = one_payload;
+  two_payloads.SetPayload(kUrl2, absl::Cord(kPayload2));
+  const std::array<absl::Status, 4> status_arr = {ok, no_payload, one_payload,
+                                                  two_payloads};
+  for (int i = 0; i < status_arr.size(); i++) {
+    for (int j = 0; j < status_arr.size(); j++) {
+      if (i == j) {
+        EXPECT_TRUE(status_arr[i] == status_arr[j]);
+        EXPECT_FALSE(status_arr[i] != status_arr[j]);
+      } else {
+        EXPECT_TRUE(status_arr[i] != status_arr[j]);
+        EXPECT_FALSE(status_arr[i] == status_arr[j]);
+      }
+    }
+  }
+}
+
+TEST(Status, Swap) {
+  auto test_swap = [](const absl::Status& s1, const absl::Status& s2) {
+    absl::Status copy1 = s1, copy2 = s2;
+    swap(copy1, copy2);
+    EXPECT_EQ(copy1, s2);
+    EXPECT_EQ(copy2, s1);
+  };
+  const absl::Status ok;
+  const absl::Status no_payload(absl::StatusCode::kAlreadyExists, "no payload");
+  absl::Status with_payload(absl::StatusCode::kInternal, "with payload");
+  with_payload.SetPayload(kUrl1, absl::Cord(kPayload1));
+  test_swap(ok, no_payload);
+  test_swap(no_payload, ok);
+  test_swap(ok, with_payload);
+  test_swap(with_payload, ok);
+  test_swap(no_payload, with_payload);
+  test_swap(with_payload, no_payload);
+}
+
+}  // namespace
diff --git a/absl/strings/internal/str_format/arg_test.cc b/absl/strings/internal/str_format/arg_test.cc
index 04fa56cd..8d30d8b8 100644
--- a/absl/strings/internal/str_format/arg_test.cc
+++ b/absl/strings/internal/str_format/arg_test.cc
@@ -96,10 +96,10 @@ TEST_F(FormatArgImplTest, WorksWithCharArraysOfUnknownSize) {
   std::string s;
   FormatSinkImpl sink(&s);
   ConversionSpec conv;
-  conv.set_conv(ConversionChar::s);
-  conv.set_flags(Flags());
-  conv.set_width(-1);
-  conv.set_precision(-1);
+  FormatConversionSpecImplFriend::SetConversionChar(ConversionChar::s, &conv);
+  FormatConversionSpecImplFriend::SetFlags(Flags(), &conv);
+  FormatConversionSpecImplFriend::SetWidth(-1, &conv);
+  FormatConversionSpecImplFriend::SetPrecision(-1, &conv);
   EXPECT_TRUE(
       FormatArgImplFriend::Convert(FormatArgImpl(kMyArray), conv, &sink));
   sink.Flush();
diff --git a/absl/strings/internal/str_format/bind.cc b/absl/strings/internal/str_format/bind.cc
index 2d19b613..27522fdb 100644
--- a/absl/strings/internal/str_format/bind.cc
+++ b/absl/strings/internal/str_format/bind.cc
@@ -66,18 +66,22 @@ inline bool ArgContext::Bind(const UnboundConversion* unbound,
         return false;
     }
 
-    bound->set_width(width);
-    bound->set_precision(precision);
-    bound->set_flags(unbound->flags);
-    if (force_left)
-      bound->set_left(true);
+    FormatConversionSpecImplFriend::SetWidth(width, bound);
+    FormatConversionSpecImplFriend::SetPrecision(precision, bound);
+
+    if (force_left) {
+      Flags flags = unbound->flags;
+      flags.left = true;
+      FormatConversionSpecImplFriend::SetFlags(flags, bound);
+    } else {
+      FormatConversionSpecImplFriend::SetFlags(unbound->flags, bound);
+    }
   } else {
-    bound->set_flags(unbound->flags);
-    bound->set_width(-1);
-    bound->set_precision(-1);
+    FormatConversionSpecImplFriend::SetFlags(unbound->flags, bound);
+    FormatConversionSpecImplFriend::SetWidth(-1, bound);
+    FormatConversionSpecImplFriend::SetPrecision(-1, bound);
   }
-
-  bound->set_conv(unbound->conv);
+  FormatConversionSpecImplFriend::SetConversionChar(unbound->conv, bound);
   bound->set_arg(arg);
   return true;
 }
@@ -139,7 +143,8 @@ class SummarizingConverter {
     UntypedFormatSpecImpl spec("%d");
 
     std::ostringstream ss;
-    ss << "{" << Streamable(spec, {*bound.arg()}) << ":" << bound.flags();
+    ss << "{" << Streamable(spec, {*bound.arg()}) << ":"
+       << FormatConversionSpecImplFriend::FlagsToString(bound);
     if (bound.width() >= 0) ss << bound.width();
     if (bound.precision() >= 0) ss << "." << bound.precision();
     ss << bound.conv() << "}";
diff --git a/absl/strings/internal/str_format/extension.h b/absl/strings/internal/str_format/extension.h
index 1a863c20..16f6c0a4 100644
--- a/absl/strings/internal/str_format/extension.h
+++ b/absl/strings/internal/str_format/extension.h
@@ -260,9 +260,21 @@ inline std::ostream& operator<<(std::ostream& os, FormatConversionChar v) {
   return os << c;
 }
 
+struct FormatConversionSpecImplFriend;
+
 class ConversionSpec {
  public:
+  // Deprecated (use has_x_flag() instead).
   Flags flags() const { return flags_; }
+
+  // Width and precison are not specified, no flags are set.
+  bool is_basic() const { return flags_.basic; }
+  bool has_left_flag() const { return flags_.left; }
+  bool has_show_pos_flag() const { return flags_.show_pos; }
+  bool has_sign_col_flag() const { return flags_.sign_col; }
+  bool has_alt_flag() const { return flags_.alt; }
+  bool has_zero_flag() const { return flags_.zero; }
+
   FormatConversionChar conv() const {
     // Keep this field first in the struct . It generates better code when
     // accessing it when ConversionSpec is passed by value in registers.
@@ -277,19 +289,28 @@ class ConversionSpec {
   // negative value.
   int precision() const { return precision_; }
 
-  void set_flags(Flags f) { flags_ = f; }
-  void set_conv(FormatConversionChar c) { conv_ = c; }
-  void set_width(int w) { width_ = w; }
-  void set_precision(int p) { precision_ = p; }
-  void set_left(bool b) { flags_.left = b; }
-
  private:
+  friend struct str_format_internal::FormatConversionSpecImplFriend;
   FormatConversionChar conv_ = FormatConversionChar::kNone;
   Flags flags_;
   int width_;
   int precision_;
 };
 
+struct FormatConversionSpecImplFriend final {
+  static void SetFlags(Flags f, ConversionSpec* conv) { conv->flags_ = f; }
+  static void SetConversionChar(FormatConversionChar c, ConversionSpec* conv) {
+    conv->conv_ = c;
+  }
+  static void SetWidth(int w, ConversionSpec* conv) { conv->width_ = w; }
+  static void SetPrecision(int p, ConversionSpec* conv) {
+    conv->precision_ = p;
+  }
+  static std::string FlagsToString(const ConversionSpec& spec) {
+    return spec.flags_.ToString();
+  }
+};
+
 constexpr uint64_t FormatConversionCharToConvValue(char conv) {
   return
 #define CONV_SET_CASE(c)                                                     \
diff --git a/absl/strings/internal/str_format/float_conversion.cc b/absl/strings/internal/str_format/float_conversion.cc
index c98ed4ba..d4c647c3 100644
--- a/absl/strings/internal/str_format/float_conversion.cc
+++ b/absl/strings/internal/str_format/float_conversion.cc
@@ -28,7 +28,7 @@ bool FallbackToSnprintf(const Float v, const ConversionSpec &conv,
   {
     char *fp = fmt;
     *fp++ = '%';
-    fp = CopyStringTo(conv.flags().ToString(), fp);
+    fp = CopyStringTo(FormatConversionSpecImplFriend::FlagsToString(conv), fp);
     fp = CopyStringTo("*.*", fp);
     if (std::is_same<long double, Float>()) {
       *fp++ = 'L';