Export of internal Abseil changes

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cea62ebc5d31c62aabcb94c066d9be506f34baf6 by Abseil Team <absl-team@google.com>:

Fix typo in `Cord::EndsWith()` docs

PiperOrigin-RevId: 355023067

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f89225a55476478ec167be50dea543f5414836f9 by Abseil Team <absl-team@google.com>:

Add set_cordz_info() and get_cordz_info() methods to InlineData

This change has preparations for future (optional) integration of CordzInfo sampling data into Cord's InlineData for non inlined cords.

PiperOrigin-RevId: 354965340

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324057574aeb697bd3327cb905eb5bca16ade768 by Abseil Team <absl-team@google.com>:

Fix two comment typos.

PiperOrigin-RevId: 354952568

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5bb93ca3d57ead3633e1efde4aa28718987ef64f by CJ Johnson <johnsoncj@google.com>:

Clarify doc comment for absl::Cleanup by using absl::Status return type and clarify the engaged state by surfacing the initial value in the public header.

PiperOrigin-RevId: 354935253

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ec95424594b24a1aec9bf7972b2355f37285506a by Abseil Team <absl-team@google.com>:

Remove `preserve_most` attribute from CordRep::Destroy()

PiperOrigin-RevId: 354921927
GitOrigin-RevId: cea62ebc5d31c62aabcb94c066d9be506f34baf6
Change-Id: Ibe1d66197db7ce9554594e07b1c6e7c6dea3c9da

6 files changed, 64 insertions, 48 deletions

diff --git a/absl/cleanup/cleanup.h b/absl/cleanup/cleanup.h
index f606b3f..5a4bc54 100644
--- a/absl/cleanup/cleanup.h
+++ b/absl/cleanup/cleanup.h
@@ -16,35 +16,39 @@
 // File: cleanup.h
 // -----------------------------------------------------------------------------
 //
-// `absl::Cleanup` implements the scope guard idiom, invoking `operator()() &&`
-// on the callback it was constructed with, on scope exit.
+// `absl::Cleanup` implements the scope guard idiom, invoking the contained
+// callback's `operator()() &&` on scope exit.
 //
 // Example:
 //
 // ```
-//   void CopyGoodData(const char* input_path, const char* output_path) {
-//     FILE* in_file = fopen(input_path, "r");
-//     if (in_file == nullptr) return;
+//   absl::Status CopyGoodData(const char* source_path, const char* sink_path) {
+//     FILE* source_file = fopen(source_path, "r");
+//     if (source_file == nullptr) {
+//       return absl::NotFoundError("No source file");  // No cleanups execute
+//     }
 //
-//     // C++17 style using class template argument deduction
-//     absl::Cleanup in_closer = [in_file] { fclose(in_file); };
+//     // C++17 style cleanup using class template argument deduction
+//     absl::Cleanup source_closer = [source_file] { fclose(source_file); };
 //
-//     FILE* out_file = fopen(output_path, "w");
-//     if (out_file == nullptr) return;  // `in_closer` will run
+//     FILE* sink_file = fopen(sink_path, "w");
+//     if (sink_file == nullptr) {
+//       return absl::NotFoundError("No sink file");  // First cleanup executes
+//     }
 //
-//     // C++11 style using the factory function
-//     auto out_closer = absl::MakeCleanup([out_file] { fclose(out_file); });
+//     // C++11 style cleanup using the factory function
+//     auto sink_closer = absl::MakeCleanup([sink_file] { fclose(sink_file); });
 //
 //     Data data;
-//     while (ReadData(in_file, &data)) {
+//     while (ReadData(source_file, &data)) {
 //       if (data.IsBad()) {
-//         LOG(ERROR) << "Found bad data.";
-//         return;  // `in_closer` and `out_closer` will run
+//         absl::Status result = absl::FailedPreconditionError("Read bad data");
+//         return result;  // Both cleanups execute
 //       }
-//       SaveData(out_file, &data);
+//       SaveData(sink_file, &data);
 //     }
 //
-//     // `in_closer` and `out_closer` will run
+//     return absl::OkStatus();  // Both cleanups execute
 //   }
 // ```
 //
@@ -54,6 +58,12 @@
 //
 // `std::move(cleanup).Invoke()` will execute the callback early, before
 // destruction, and prevent the callback from executing in the destructor.
+//
+// Usage:
+//
+// `absl::Cleanup` is not an interface type. It is only intended to be used
+// within the body of a function. It is not a value type and instead models a
+// control flow construct. Check out `defer` in Golang for something similar.
 
 #ifndef ABSL_CLEANUP_CLEANUP_H_
 #define ABSL_CLEANUP_CLEANUP_H_
@@ -76,9 +86,10 @@ class ABSL_MUST_USE_RESULT Cleanup {
                 "Callbacks that return values are not supported.");
 
  public:
-  Cleanup(Callback callback) : storage_(std::move(callback)) {}  // NOLINT
+  Cleanup(Callback callback)  // NOLINT
+      : storage_(std::move(callback), /*engaged=*/true) {}
 
-  Cleanup(Cleanup&& other) : storage_(std::move(other.storage_)) {}
+  Cleanup(Cleanup&& other) = default;
 
   void Cancel() && {
     ABSL_HARDENING_ASSERT(storage_.IsCallbackEngaged());
@@ -103,7 +114,7 @@ class ABSL_MUST_USE_RESULT Cleanup {
 
 // `absl::Cleanup c = /* callback */;`
 //
-// C++17 type deduction API for creating an instance of `absl::Cleanup`.
+// C++17 type deduction API for creating an instance of `absl::Cleanup`
 #if defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
 template <typename Callback>
 Cleanup(Callback callback) -> Cleanup<cleanup_internal::Tag, Callback>;
@@ -111,7 +122,7 @@ Cleanup(Callback callback) -> Cleanup<cleanup_internal::Tag, Callback>;
 
 // `auto c = absl::MakeCleanup(/* callback */);`
 //
-// C++11 type deduction API for creating an instance of `absl::Cleanup`.
+// C++11 type deduction API for creating an instance of `absl::Cleanup`
 template <typename... Args, typename Callback>
 absl::Cleanup<cleanup_internal::Tag, Callback> MakeCleanup(Callback callback) {
   static_assert(cleanup_internal::WasDeduced<cleanup_internal::Tag, Args...>(),
diff --git a/absl/cleanup/internal/cleanup.h b/absl/cleanup/internal/cleanup.h
index 8fbca5b..b68e3dd 100644
--- a/absl/cleanup/internal/cleanup.h
+++ b/absl/cleanup/internal/cleanup.h
@@ -45,12 +45,12 @@ class Storage {
  public:
   Storage() = delete;
 
-  explicit Storage(Callback callback)
-      : engaged_(true), callback_(std::move(callback)) {}
+  Storage(Callback callback, bool engaged)
+      : callback_(std::move(callback)), engaged_(engaged) {}
 
   Storage(Storage&& other)
-      : engaged_(absl::exchange(other.engaged_, false)),
-        callback_(std::move(other.callback_)) {}
+      : callback_(std::move(other.callback_)),
+        engaged_(absl::exchange(other.engaged_, false)) {}
 
   Storage(const Storage& other) = delete;
 
@@ -67,8 +67,8 @@ class Storage {
   }
 
  private:
-  bool engaged_;
   Callback callback_;
+  bool engaged_;
 };
 
 }  // namespace cleanup_internal
diff --git a/absl/hash/internal/wyhash_test.cc b/absl/hash/internal/wyhash_test.cc
index 30dc9e3..9fb06d2 100644
--- a/absl/hash/internal/wyhash_test.cc
+++ b/absl/hash/internal/wyhash_test.cc
@@ -1,14 +1,14 @@
 // Copyright 2020 The Abseil Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in cokSaltliance with 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 ikSaltlied.
+// 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.
 
diff --git a/absl/strings/BUILD.bazel b/absl/strings/BUILD.bazel
index 794cf43..5efaf89 100644
--- a/absl/strings/BUILD.bazel
+++ b/absl/strings/BUILD.bazel
@@ -286,6 +286,7 @@ cc_library(
         "//absl/base:base_internal",
         "//absl/base:config",
         "//absl/base:core_headers",
+        "//absl/base:endian",
         "//absl/base:raw_logging_internal",
         "//absl/base:throw_delegate",
         "//absl/container:compressed_tuple",
diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index 17341bd..aefb5e5 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -289,7 +289,7 @@ class Cord {
   bool StartsWith(const Cord& rhs) const;
   bool StartsWith(absl::string_view rhs) const;
 
-  // Cord::EndsWidth()
+  // Cord::EndsWith()
   //
   // Determines whether the Cord ends with the passed string data `rhs`.
   bool EndsWith(absl::string_view rhs) const;
diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index 9650243..cda00a4 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -22,6 +22,7 @@
 #include <type_traits>
 
 #include "absl/base/config.h"
+#include "absl/base/internal/endian.h"
 #include "absl/base/internal/invoke.h"
 #include "absl/base/optimization.h"
 #include "absl/container/internal/compressed_tuple.h"
@@ -32,6 +33,8 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace cord_internal {
 
+class CordzInfo;
+
 // Default feature enable states for cord ring buffers
 enum CordFeatureDefaults {
   kCordEnableRingBufferDefault = false,
@@ -193,26 +196,7 @@ struct CordRep {
   // --------------------------------------------------------------------
   // Memory management
 
-  // This internal routine is called from the cold path of Unref below. Keeping
-  // it in a separate routine allows good inlining of Unref into many profitable
-  // call sites. However, the call to this function can be highly disruptive to
-  // the register pressure in those callers. To minimize the cost to callers, we
-  // use a special LLVM calling convention that preserves most registers. This
-  // allows the call to this routine in cold paths to not disrupt the caller's
-  // register pressure. This calling convention is not available on all
-  // platforms; we intentionally allow LLVM to ignore the attribute rather than
-  // attempting to hardcode the list of supported platforms.
-#if defined(__clang__) && !defined(__i386__)
-#if !(defined(ABSL_HAVE_MEMORY_SANITIZER) ||  \
-      defined(ABSL_HAVE_THREAD_SANITIZER) ||  \
-      defined(ABSL_HAVE_ADDRESS_SANITIZER) || \
-      defined(UNDEFINED_BEHAVIOR_SANITIZER))
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wattributes"
-  __attribute__((preserve_most))
-#pragma clang diagnostic pop
-#endif  // *_SANITIZER
-#endif
+  // Destroys the provided `rep`.
   static void Destroy(CordRep* rep);
 
   // Increments the reference count of `rep`.
@@ -383,6 +367,26 @@ class InlineData {
     return as_tree_.cordz_info != kNullCordzInfo;
   }
 
+  // Returns the cordz_info sampling instance for this instance, or nullptr
+  // if the current instance is not sampled and does not have CordzInfo data.
+  // Requires the current instance to hold a tree value.
+  CordzInfo* cordz_info() const {
+    assert(is_tree());
+    intptr_t info =
+        static_cast<intptr_t>(absl::big_endian::ToHost64(as_tree_.cordz_info));
+    assert(info & 1);
+    return reinterpret_cast<CordzInfo*>(info - 1);
+  }
+
+  // Sets the current cordz_info sampling instance for this instance, or nullptr
+  // if the current instance is not sampled and does not have CordzInfo data.
+  // Requires the current instance to hold a tree value.
+  void set_cordz_info(CordzInfo* cordz_info) {
+    assert(is_tree());
+    intptr_t info = reinterpret_cast<intptr_t>(cordz_info) | 1;
+    as_tree_.cordz_info = absl::big_endian::FromHost64(info);
+  }
+
   // Returns a read only pointer to the character data inside this instance.
   // Requires the current instance to hold inline data.
   const char* as_chars() const {