Changes imported from Abseil "staging" branch:

  - 46a4bd582619bfc4799c1a907316e914ed0c0105 Fixes to mutex_nonprod.  Apparently this has never built.... by Greg Falcon <gfalcon@google.com>
  - 4bcf6f013aeee53057527d70100de8535aec9b93 Add some comments to copts.bzl by Tom Manshreck <shreck@google.com>
  - 54cf717b1c5dfb814721f92a8eb9df5587f5f758 Internal change by Abseil Team <absl-team@google.com>
  - d1f1c7e6e61358300963b7bd50c203740a49297d Eliminate kFast{UInt,Int}{32,64}ToBufferSize constants by Jorg Brown <jorg@google.com>

GitOrigin-RevId: 46a4bd582619bfc4799c1a907316e914ed0c0105
Change-Id: I129b6b3d27d9ae2c6eb21d6e44a52d10399ef8aa

absl/base/config.h

@@ -243,7 +243,7 @@
 //   Windows                           _WIN32
 //   NaCL                              __native_client__
 //   AsmJS                             __asmjs__
-//   Fuschia                           __Fuchsia__
+//   Fuchsia                           __Fuchsia__
 //
 // Note that since Android defines both __ANDROID__ and __linux__, one
 // may probe for either Linux or Android by simply testing for __linux__.

absl/copts.bzl

@@ -29,12 +29,18 @@ GCC_TEST_FLAGS = [
     "-Wno-unused-private-field",
 ]
 
+
+# Docs on single flags is preceded by a comment.
+# Docs on groups of flags is preceded by ###.
+
 LLVM_FLAGS = [
     "-Wall",
     "-Wextra",
     "-Weverything",
+    # Abseil does not support C++98
     "-Wno-c++98-compat-pedantic",
     "-Wno-comma",
+    # Turns off all implicit conversion warnings. Most are re-enabled below.
     "-Wno-conversion",
     "-Wno-covered-switch-default",
     "-Wno-deprecated",
@@ -47,6 +53,7 @@ LLVM_FLAGS = [
     "-Wno-float-conversion",
     "-Wno-float-equal",
     "-Wno-format-nonliteral",
+    # Too aggressive: warns on Clang extensions enclosed in Clang-only code paths.
     "-Wno-gcc-compat",
     "-Wno-global-constructors",
     "-Wno-nested-anon-types",
@@ -54,6 +61,7 @@ LLVM_FLAGS = [
     "-Wno-old-style-cast",
     "-Wno-packed",
     "-Wno-padded",
+    # Warns on preferred usage of non-POD types such as string_view
     "-Wno-range-loop-analysis",
     "-Wno-reserved-id-macro",
     "-Wno-shorten-64-to-32",
@@ -63,9 +71,12 @@ LLVM_FLAGS = [
     "-Wno-undef",
     "-Wno-unknown-warning-option",
     "-Wno-unreachable-code",
+    # Causes warnings on include guards
     "-Wno-unused-macros",
     "-Wno-weak-vtables",
-    # flags below are also controlled by -Wconversion which is disabled
+    ###
+    # Implicit conversion warnings turned off by -Wno-conversion
+    # which are re-enabled below.
     "-Wbitfield-enum-conversion",
     "-Wbool-conversion",
     "-Wconstant-conversion",
@@ -76,6 +87,7 @@ LLVM_FLAGS = [
     "-Wnull-conversion",
     "-Wobjc-literal-conversion",
     "-Wstring-conversion",
+    ###
 ]
 
 LLVM_TEST_FLAGS = [

absl/strings/internal/numbers_test_common.inc

@@ -17,16 +17,6 @@
 
 namespace {
 
-// Previously documented minimum buffer sizes for Fast*ToBuffer functions.
-// NOTE(edk): These should be deleted and uses replaced with kFastToBufferSize
-//            once existing code has been fixed to use kFastToBufferSize.
-enum {
-  kFastInt32ToBufferSize = 12,
-  kFastInt64ToBufferSize = 22,
-  kFastUInt32ToBufferSize = 12,
-  kFastUInt64ToBufferSize = 22
-};
-
 template <typename IntType>
 bool Itoa(IntType value, int base, std::string* destination) {
   destination->clear();

absl/strings/numbers_test.cc

@@ -28,11 +28,6 @@
 
 namespace {
 
-using absl::numbers_internal::FastInt32ToBuffer;
-using absl::numbers_internal::FastInt64ToBuffer;
-using absl::numbers_internal::FastUInt32ToBuffer;
-using absl::numbers_internal::FastUInt64ToBuffer;
-using absl::numbers_internal::kFastToBufferSize;
 using absl::numbers_internal::kSixDigitsToBufferSize;
 using absl::numbers_internal::safe_strto32_base;
 using absl::numbers_internal::safe_strto64_base;
@@ -116,22 +111,22 @@ TEST(ToString, PerfectDtoa) {
 }
 
 void CheckInt32(int32_t x) {
-  char buffer[kFastInt32ToBufferSize];
-  char* actual = FastInt32ToBuffer(x, buffer);
+  char buffer[absl::numbers_internal::kFastToBufferSize];
+  char* actual = absl::numbers_internal::FastInt32ToBuffer(x, buffer);
   std::string expected = std::to_string(x);
-  ASSERT_TRUE(expected == actual)
+  ASSERT_TRUE(expected == std::string(buffer, actual))
       << "Expected \"" << expected << "\", Actual \"" << actual << "\", Input "
       << x;
 }
 
 void CheckInt64(int64_t x) {
-  char buffer[kFastInt64ToBufferSize + 3];
+  char buffer[absl::numbers_internal::kFastToBufferSize + 3];
   buffer[0] = '*';
   buffer[23] = '*';
   buffer[24] = '*';
-  char* actual = FastInt64ToBuffer(x, &buffer[1]);
+  char* actual = absl::numbers_internal::FastInt64ToBuffer(x, &buffer[1]);
   std::string expected = std::to_string(x);
-  ASSERT_TRUE(expected == actual)
+  ASSERT_TRUE(expected == std::string(&buffer[1], actual))
       << "Expected \"" << expected << "\", Actual \"" << actual << "\", Input "
       << x;
   ASSERT_EQ(buffer[0], '*');
@@ -140,32 +135,32 @@ void CheckInt64(int64_t x) {
 }
 
 void CheckUInt32(uint32_t x) {
-  char buffer[kFastUInt64ToBufferSize];
-  char* actual = FastUInt32ToBuffer(x, buffer);
+  char buffer[absl::numbers_internal::kFastToBufferSize];
+  char* actual = absl::numbers_internal::FastUInt32ToBuffer(x, buffer);
   std::string expected = std::to_string(x);
-  ASSERT_TRUE(expected == actual)
+  ASSERT_TRUE(expected == std::string(buffer, actual))
       << "Expected \"" << expected << "\", Actual \"" << actual << "\", Input "
       << x;
 }
 
 void CheckUInt64(uint64_t x) {
-  char buffer[kFastUInt64ToBufferSize + 1];
-  char* actual = FastUInt64ToBuffer(x, &buffer[1]);
+  char buffer[absl::numbers_internal::kFastToBufferSize + 1];
+  char* actual = absl::numbers_internal::FastUInt64ToBuffer(x, &buffer[1]);
   std::string expected = std::to_string(x);
-  ASSERT_TRUE(expected == actual)
+  ASSERT_TRUE(expected == std::string(&buffer[1], actual))
       << "Expected \"" << expected << "\", Actual \"" << actual << "\", Input "
       << x;
 }
 
 void CheckHex64(uint64_t v) {
-  char expected[kFastUInt64ToBufferSize];
+  char expected[16 + 1];
   std::string actual = absl::StrCat(absl::Hex(v, absl::kZeroPad16));
   snprintf(expected, sizeof(expected), "%016" PRIx64, static_cast<uint64_t>(v));
   ASSERT_TRUE(expected == actual)
       << "Expected \"" << expected << "\", Actual \"" << actual << "\"";
 }
 
-void TestFastPrints() {
+TEST(Numbers, TestFastPrints) {
   for (int i = -100; i <= 100; i++) {
     CheckInt32(i);
     CheckInt64(i);
@@ -700,7 +695,7 @@ class SimpleDtoaTest : public testing::Test {
   }
 
   std::string ToNineDigits(double value) {
-    char buffer[kFastToBufferSize];  // more than enough for %.9g
+    char buffer[16];  // more than enough for %.9g
     snprintf(buffer, sizeof(buffer), "%.9g", value);
     return buffer;
   }

absl/synchronization/internal/mutex_nonprod.cc

@@ -231,6 +231,11 @@ bool Mutex::LockWhenWithTimeout(const Condition& cond, absl::Duration timeout) {
       cond, synchronization_internal::DeadlineFromTimeout(timeout));
 }
 
+void Mutex::ReaderLockWhen(const Condition& cond) {
+  ReaderLock();
+  Await(cond);
+}
+
 bool Mutex::ReaderLockWhenWithTimeout(const Condition& cond,
                                       absl::Duration timeout) {
   return LockWhenWithTimeout(cond, timeout);

absl/synchronization/internal/mutex_nonprod.inc

@@ -105,16 +105,16 @@ class MutexImpl {
 };
 
 // Do not use this implementation detail of CondVar and Mutex.  A storage
-// space for T that supports a base::LinkerInitialized constructor. T must
+// space for T that supports a LinkerInitialized constructor. T must
 // have a default constructor, which is called by the first call to
-// get(). T's destructor is never called if the base::LinkerInitialized
+// get(). T's destructor is never called if the LinkerInitialized
 // constructor is called.
 //
 // Objects constructed with the default constructor are constructed and
 // destructed like any other object, and should never be allocated in
 // static storage.
 //
-// Objects constructed with the base::LinkerInitialized constructor should
+// Objects constructed with the LinkerInitialized constructor should
 // always be in static storage. For such objects, calls to get() are always
 // valid, except from signal handlers.
 //
@@ -126,7 +126,7 @@ class MutexImpl {
 //
 // [basic.life] says an object has non-trivial initialization if it is of
 // class type and it is initialized by a constructor other than a trivial
-// default constructor.  (the base::LinkerInitialized constructor is
+// default constructor.  (the LinkerInitialized constructor is
 // non-trivial)
 //
 // [basic.life] says the lifetime of an object with a non-trivial
@@ -139,34 +139,34 @@ class MutexImpl {
 // members of an instance outside its
 // lifetime. (SynchronizationStorage::get() access non-static members)
 //
-// So, base::LinkerInitialized object of SynchronizationStorage uses a
+// So, LinkerInitialized object of SynchronizationStorage uses a
 // non-trivial constructor, which is called at some point during dynamic
 // initialization, and is therefore subject to order of dynamic
 // initialization bugs, where get() is called before the object's
 // constructor is, resulting in undefined behavior.
 //
-// Similarly, a base::LinkerInitialized SynchronizationStorage object has a
+// Similarly, a LinkerInitialized SynchronizationStorage object has a
 // non-trivial destructor, and so its lifetime ends at some point during
 // destruction of objects with static storage duration [basic.start.term]
 // p4. There is a window where other exit code could call get() after this
 // occurs, resulting in undefined behavior.
 //
-// Combined, these statements imply that base::LinkerInitialized instances
+// Combined, these statements imply that LinkerInitialized instances
 // of SynchronizationStorage<T> rely on undefined behavior.
 //
 // However, in practice, the implementation works on all supported
 // compilers. Specifically, we rely on:
 //
 // a) zero-initialization being sufficient to initialize
-// base::LinkerInitialized instances for the purposes of calling
+// LinkerInitialized instances for the purposes of calling
 // get(), regardless of when the constructor is called. This is
 // because the is_dynamic_ boolean is correctly zero-initialized to
 // false.
 //
-// b) the base::LinkerInitialized constructor is a NOP, and immaterial to
+// b) the LinkerInitialized constructor is a NOP, and immaterial to
 // even to concurrent calls to get().
 //
-// c) the destructor being a NOP for base::LinkerInitialized objects
+// c) the destructor being a NOP for LinkerInitialized objects
 // (guaranteed by a check for !is_dynamic_), and so any concurrent and
 // subsequent calls to get() functioning as if the destructor were not
 // called, by virtue of the instances' storage remaining valid after the
@@ -212,7 +212,7 @@ class SynchronizationStorage {
 
   // Instances allocated in static storage (not on the heap, not on the
   // stack) should use this constructor.
-  explicit SynchronizationStorage(base::LinkerInitialized) {}
+  explicit SynchronizationStorage(base_internal::LinkerInitialized) {}
 
   SynchronizationStorage(SynchronizationStorage&) = delete;
   SynchronizationStorage& operator=(SynchronizationStorage&) = delete;
@@ -227,7 +227,7 @@ class SynchronizationStorage {
   // incur the cost of absl::call_once().
   //
   // For instances in static storage constructed with the
-  // base::LinkerInitialized constructor, may be called at any time without
+  // LinkerInitialized constructor, may be called at any time without
   // regard for order of dynamic initialization or destruction of objects
   // in static storage. See the class comment for caveats.
   T* get() {
@@ -242,7 +242,7 @@ class SynchronizationStorage {
 
   // When true, T's destructor is run when this is destructed.
   //
-  // The base::LinkerInitialized constructor assumes this value will be set
+  // The LinkerInitialized constructor assumes this value will be set
   // false by static initialization.
   bool is_dynamic_;