Merge branch 'abseil:master' into patch-1

19 files changed, 183 insertions, 129 deletions

diff --git a/absl/base/internal/thread_annotations.h b/absl/base/internal/thread_annotations.h
index 4dab6a9c..8c5c67e0 100644
--- a/absl/base/internal/thread_annotations.h
+++ b/absl/base/internal/thread_annotations.h
@@ -38,6 +38,13 @@
 #ifndef ABSL_BASE_INTERNAL_THREAD_ANNOTATIONS_H_
 #define ABSL_BASE_INTERNAL_THREAD_ANNOTATIONS_H_
 
+// ABSL_LEGACY_THREAD_ANNOTATIONS is a *temporary* compatibility macro that can
+// be defined on the compile command-line to restore the legacy spellings of the
+// thread annotations macros/functions. The macros in this file are available
+// under ABSL_ prefixed spellings in absl/base/thread_annotations.h. This macro
+// and the legacy spellings will be removed in the future.
+#ifdef ABSL_LEGACY_THREAD_ANNOTATIONS
+
 #if defined(__clang__)
 #define THREAD_ANNOTATION_ATTRIBUTE__(x)   __attribute__((x))
 #else
@@ -268,4 +275,6 @@ inline T& ts_unchecked_read(T& v) NO_THREAD_SAFETY_ANALYSIS {
 
 }  // namespace thread_safety_analysis
 
+#endif  // defined(ABSL_LEGACY_THREAD_ANNOTATIONS)
+
 #endif  // ABSL_BASE_INTERNAL_THREAD_ANNOTATIONS_H_
diff --git a/absl/container/BUILD.bazel b/absl/container/BUILD.bazel
index 71afe9d2..15162f28 100644
--- a/absl/container/BUILD.bazel
+++ b/absl/container/BUILD.bazel
@@ -637,6 +637,8 @@ cc_test(
     ],
     deps = [
         ":container_memory",
+        ":flat_hash_map",
+        ":flat_hash_set",
         ":hash_function_defaults",
         ":hash_policy_testing",
         ":hashtable_debug",
@@ -646,6 +648,7 @@ cc_test(
         "//absl/base:core_headers",
         "//absl/base:prefetch",
         "//absl/base:raw_logging_internal",
+        "//absl/log",
         "//absl/strings",
         "@com_google_googletest//:gtest_main",
     ],
diff --git a/absl/container/CMakeLists.txt b/absl/container/CMakeLists.txt
index a3fdb969..6c2931b6 100644
--- a/absl/container/CMakeLists.txt
+++ b/absl/container/CMakeLists.txt
@@ -722,12 +722,15 @@ absl_cc_test(
     ${ABSL_TEST_COPTS}
   DEPS
     absl::container_memory
+    absl::flat_hash_map
+    absl::flat_hash_set
     absl::hash_function_defaults
     absl::hash_policy_testing
     absl::hashtable_debug
     absl::raw_hash_set
     absl::base
     absl::config
+    absl::log
     absl::core_headers
     absl::prefetch
     absl::raw_logging_internal
diff --git a/absl/container/internal/common_policy_traits.h b/absl/container/internal/common_policy_traits.h
index cc2e89ba..c99e68f4 100644
--- a/absl/container/internal/common_policy_traits.h
+++ b/absl/container/internal/common_policy_traits.h
@@ -16,6 +16,7 @@
 #define ABSL_CONTAINER_INTERNAL_COMMON_POLICY_TRAITS_H_
 
 #include <cstddef>
+#include <cstring>
 #include <memory>
 #include <new>
 #include <type_traits>
@@ -32,7 +33,8 @@ template <class Policy, class = void>
 struct common_policy_traits {
   // The actual object stored in the container.
   using slot_type = typename Policy::slot_type;
-
+  using reference = decltype(Policy::element(std::declval<slot_type*>()));
+  using value_type = typename std::remove_reference<reference>::type;
 
   // PRECONDITION: `slot` is UNINITIALIZED
   // POSTCONDITION: `slot` is INITIALIZED
@@ -89,6 +91,17 @@ struct common_policy_traits {
   template <class Alloc>
   static void transfer_impl(Alloc* alloc, slot_type* new_slot,
                             slot_type* old_slot, char) {
+#if defined(__cpp_lib_launder) && __cpp_lib_launder >= 201606
+    if (absl::is_trivially_relocatable<value_type>()) {
+      // TODO(b/247130232): remove cast after fixing class-memaccess warning.
+      std::memcpy(static_cast<void*>(
+                      std::launder(const_cast<std::remove_const_t<value_type>*>(
+                          &element(new_slot)))),
+                  &element(old_slot), sizeof(value_type));
+      return;
+    }
+#endif
+
     construct(alloc, new_slot, std::move(element(old_slot)));
     destroy(alloc, old_slot);
   }
diff --git a/absl/container/internal/common_policy_traits_test.cc b/absl/container/internal/common_policy_traits_test.cc
index 768d870e..5eaa4aae 100644
--- a/absl/container/internal/common_policy_traits_test.cc
+++ b/absl/container/internal/common_policy_traits_test.cc
@@ -27,7 +27,7 @@ namespace container_internal {
 namespace {
 
 using ::testing::MockFunction;
-using ::testing::Return;
+using ::testing::AnyNumber;
 using ::testing::ReturnRef;
 
 using Slot = int;
@@ -101,9 +101,10 @@ TEST_F(Test, element) {
 
 TEST_F(Test, without_transfer) {
   int b = 42;
-  EXPECT_CALL(element, Call(&b)).WillOnce(::testing::ReturnRef(b));
-  EXPECT_CALL(construct, Call(&alloc, &a, b));
-  EXPECT_CALL(destroy, Call(&alloc, &b));
+  EXPECT_CALL(element, Call(&a)).Times(AnyNumber()).WillOnce(ReturnRef(a));
+  EXPECT_CALL(element, Call(&b)).WillOnce(ReturnRef(b));
+  EXPECT_CALL(construct, Call(&alloc, &a, b)).Times(AnyNumber());
+  EXPECT_CALL(destroy, Call(&alloc, &b)).Times(AnyNumber());
   common_policy_traits<PolicyWithoutOptionalOps>::transfer(&alloc, &a, &b);
 }
 
diff --git a/absl/container/internal/container_memory.h b/absl/container/internal/container_memory.h
index 00e9f6d7..c29c533b 100644
--- a/absl/container/internal/container_memory.h
+++ b/absl/container/internal/container_memory.h
@@ -17,6 +17,7 @@
 
 #include <cassert>
 #include <cstddef>
+#include <cstring>
 #include <memory>
 #include <new>
 #include <tuple>
@@ -340,7 +341,8 @@ template <class K, class V>
 struct map_slot_policy {
   using slot_type = map_slot_type<K, V>;
   using value_type = std::pair<const K, V>;
-  using mutable_value_type = std::pair<K, V>;
+  using mutable_value_type =
+      std::pair<absl::remove_const_t<K>, absl::remove_const_t<V>>;
 
  private:
   static void emplace(slot_type* slot) {
@@ -424,6 +426,15 @@ struct map_slot_policy {
   static void transfer(Allocator* alloc, slot_type* new_slot,
                        slot_type* old_slot) {
     emplace(new_slot);
+#if defined(__cpp_lib_launder) && __cpp_lib_launder >= 201606
+    if (absl::is_trivially_relocatable<value_type>()) {
+      // TODO(b/247130232): remove cast after fixing class-memaccess warning.
+      std::memcpy(static_cast<void*>(std::launder(&new_slot->value)),
+                  &old_slot->value, sizeof(value_type));
+      return;
+    }
+#endif
+
     if (kMutableKeys::value) {
       absl::allocator_traits<Allocator>::construct(
           *alloc, &new_slot->mutable_value, std::move(old_slot->mutable_value));
diff --git a/absl/container/internal/raw_hash_set_test.cc b/absl/container/internal/raw_hash_set_test.cc
index f77ffbc1..eec9da43 100644
--- a/absl/container/internal/raw_hash_set_test.cc
+++ b/absl/container/internal/raw_hash_set_test.cc
@@ -14,17 +14,25 @@
 
 #include "absl/container/internal/raw_hash_set.h"
 
+#include <algorithm>
 #include <atomic>
 #include <cmath>
 #include <cstdint>
 #include <deque>
 #include <functional>
+#include <iterator>
+#include <list>
+#include <map>
 #include <memory>
 #include <numeric>
+#include <ostream>
 #include <random>
 #include <string>
+#include <type_traits>
 #include <unordered_map>
 #include <unordered_set>
+#include <utility>
+#include <vector>
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
@@ -33,10 +41,13 @@
 #include "absl/base/internal/cycleclock.h"
 #include "absl/base/internal/prefetch.h"
 #include "absl/base/internal/raw_logging.h"
+#include "absl/container/flat_hash_map.h"
+#include "absl/container/flat_hash_set.h"
 #include "absl/container/internal/container_memory.h"
 #include "absl/container/internal/hash_function_defaults.h"
 #include "absl/container/internal/hash_policy_testing.h"
 #include "absl/container/internal/hashtable_debug.h"
+#include "absl/log/log.h"
 #include "absl/strings/string_view.h"
 
 namespace absl {
@@ -339,7 +350,7 @@ class StringPolicy {
     struct ctor {};
 
     template <class... Ts>
-    slot_type(ctor, Ts&&... ts) : pair(std::forward<Ts>(ts)...) {}
+    explicit slot_type(ctor, Ts&&... ts) : pair(std::forward<Ts>(ts)...) {}
 
     std::pair<std::string, std::string> pair;
   };
@@ -411,7 +422,7 @@ struct CustomAlloc : std::allocator<T> {
   CustomAlloc() {}
 
   template <typename U>
-  CustomAlloc(const CustomAlloc<U>& other) {}
+  explicit CustomAlloc(const CustomAlloc<U>& /*other*/) {}
 
   template<class U> struct rebind {
     using other = CustomAlloc<U>;
@@ -1275,6 +1286,7 @@ TEST(Table, DISABLED_EnsureNonQuadraticTopNXorSeedByProbeSeqLength) {
   for (size_t size : sizes) {
     auto& stat = stats[size];
     VerifyStats(size, expected, stat);
+    LOG(INFO) << size << " " << stat;
   }
 }
 
@@ -1370,6 +1382,7 @@ TEST(Table, DISABLED_EnsureNonQuadraticTopNLinearTransformByProbeSeqLength) {
   for (size_t size : sizes) {
     auto& stat = stats[size];
     VerifyStats(size, expected, stat);
+    LOG(INFO) << size << " " << stat;
   }
 }
 
@@ -1504,7 +1517,7 @@ TEST(Table, RehashZeroForcesRehash) {
 TEST(Table, ConstructFromInitList) {
   using P = std::pair<std::string, std::string>;
   struct Q {
-    operator P() const { return {}; }
+    operator P() const { return {}; }  // NOLINT
   };
   StringTable t = {P(), Q(), {}, {{}, {}}};
 }
@@ -2027,7 +2040,7 @@ TEST(Table, UnstablePointers) {
 TEST(TableDeathTest, EraseOfEndAsserts) {
   // Use an assert with side-effects to figure out if they are actually enabled.
   bool assert_enabled = false;
-  assert([&]() {
+  assert([&]() {  // NOLINT
     assert_enabled = true;
     return true;
   }());
@@ -2047,7 +2060,7 @@ TEST(RawHashSamplerTest, Sample) {
 
   auto& sampler = GlobalHashtablezSampler();
   size_t start_size = 0;
-  std::unordered_set<const HashtablezInfo*> preexisting_info;
+  absl::flat_hash_set<const HashtablezInfo*> preexisting_info;
   start_size += sampler.Iterate([&](const HashtablezInfo& info) {
     preexisting_info.insert(&info);
     ++start_size;
@@ -2074,8 +2087,8 @@ TEST(RawHashSamplerTest, Sample) {
     }
   }
   size_t end_size = 0;
-  std::unordered_map<size_t, int> observed_checksums;
-  std::unordered_map<ssize_t, int> reservations;
+  absl::flat_hash_map<size_t, int> observed_checksums;
+  absl::flat_hash_map<ssize_t, int> reservations;
   end_size += sampler.Iterate([&](const HashtablezInfo& info) {
     if (preexisting_info.count(&info) == 0) {
       observed_checksums[info.hashes_bitwise_xor.load(
diff --git a/absl/hash/CMakeLists.txt b/absl/hash/CMakeLists.txt
index 46365790..15691254 100644
--- a/absl/hash/CMakeLists.txt
+++ b/absl/hash/CMakeLists.txt
@@ -82,6 +82,10 @@ absl_cc_test(
 )
 
 # Internal-only target, do not depend on directly.
+#
+# Note: Even though external code should not depend on this target
+# directly, it must be marked PUBLIC since it is a dependency of
+# hash_testing.
 absl_cc_library(
   NAME
     spy_hash_state
@@ -94,6 +98,7 @@ absl_cc_library(
     absl::strings
     absl::str_format
   TESTONLY
+  PUBLIC
 )
 
 # Internal-only target, do not depend on directly.
diff --git a/absl/log/internal/log_sink_set.cc b/absl/log/internal/log_sink_set.cc
index 4fe301c6..f9d030aa 100644
--- a/absl/log/internal/log_sink_set.cc
+++ b/absl/log/internal/log_sink_set.cc
@@ -69,6 +69,7 @@ bool& ThreadIsLoggingStatus() {
     }
     return true;
   }();
+  (void)unused;  // Fixes -wunused-variable warning
   bool* thread_is_logging_ptr =
       reinterpret_cast<bool*>(pthread_getspecific(thread_is_logging_key));
 
diff --git a/absl/log/log_entry.h b/absl/log/log_entry.h
index d90961fe..30114c33 100644
--- a/absl/log/log_entry.h
+++ b/absl/log/log_entry.h
@@ -58,8 +58,10 @@ class LogEntry final {
   static constexpr int kNoVerbosityLevel = -1;
   static constexpr int kNoVerboseLevel = -1;  // TO BE removed
 
-  LogEntry(const LogEntry&) = default;
-  LogEntry& operator=(const LogEntry&) = default;
+  // Pass `LogEntry` by reference, and do not store it as its state does not
+  // outlive the call to `LogSink::Send()`.
+  LogEntry(const LogEntry&) = delete;
+  LogEntry& operator=(const LogEntry&) = delete;
 
   // Source file and line where the log message occurred.  Taken from `__FILE__`
   // and `__LINE__` unless overridden by `LOG(...).AtLocation(...)`.
diff --git a/absl/strings/BUILD.bazel b/absl/strings/BUILD.bazel
index ba7ae835..5b12c010 100644
--- a/absl/strings/BUILD.bazel
+++ b/absl/strings/BUILD.bazel
@@ -747,13 +747,13 @@ cc_test(
         ":cordz_test_helpers",
         ":str_format",
         ":strings",
-        "//absl/base",
         "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:endian",
         "//absl/base:raw_logging_internal",
         "//absl/container:fixed_array",
         "//absl/hash",
+        "//absl/log",
         "//absl/random",
         "@com_google_googletest//:gtest_main",
     ],
@@ -963,8 +963,8 @@ cc_test(
     copts = ABSL_TEST_COPTS,
     visibility = ["//visibility:private"],
     deps = [
+        ":str_format",
         ":strings",
-        "//absl/base:core_headers",
         "@com_google_googletest//:gtest_main",
     ],
 )
@@ -1164,7 +1164,6 @@ cc_test(
         ":cord",
         ":str_format",
         ":strings",
-        "//absl/base:core_headers",
         "@com_google_googletest//:gtest_main",
     ],
 )
diff --git a/absl/strings/CMakeLists.txt b/absl/strings/CMakeLists.txt
index bb073301..01f86184 100644
--- a/absl/strings/CMakeLists.txt
+++ b/absl/strings/CMakeLists.txt
@@ -281,6 +281,7 @@ absl_cc_test(
     ${ABSL_TEST_COPTS}
   DEPS
     absl::strings
+    absl::str_format
     absl::core_headers
     GTest::gmock_main
 )
@@ -903,6 +904,7 @@ absl_cc_library(
     absl::cord_internal
     absl::strings
   TESTONLY
+  PUBLIC
 )
 
 # Internal-only target, do not depend on directly.
diff --git a/absl/strings/charconv.cc b/absl/strings/charconv.cc
index a961d16c..501297c8 100644
--- a/absl/strings/charconv.cc
+++ b/absl/strings/charconv.cc
@@ -229,6 +229,8 @@ struct FloatTraits<float> {
 //
 //   2**63 <= Power10Mantissa(n) < 2**64.
 //
+// See the "Table of powers of 10" comment below for a "1e60" example.
+//
 // Lookups into the power-of-10 table must first check the Power10Overflow() and
 // Power10Underflow() functions, to avoid out-of-bounds table access.
 //
@@ -236,7 +238,6 @@ struct FloatTraits<float> {
 // indexes range from kPower10TableMinInclusive to kPower10TableMaxExclusive.
 extern const uint64_t kPower10MantissaHighTable[];  // High 64 of 128 bits.
 extern const uint64_t kPower10MantissaLowTable[];   // Low  64 of 128 bits.
-extern const int16_t kPower10ExponentTable[];
 
 // The smallest (inclusive) allowed value for use with the Power10Mantissa()
 // and Power10Exponent() functions below.  (If a smaller exponent is needed in
@@ -253,7 +254,11 @@ uint64_t Power10Mantissa(int n) {
 }
 
 int Power10Exponent(int n) {
-  return kPower10ExponentTable[n - kPower10TableMinInclusive];
+  // The 217706 etc magic numbers encode the results as a formula instead of a
+  // table. Their equivalence (over the kPower10TableMinInclusive ..
+  // kPower10TableMaxExclusive range) is confirmed by
+  // https://github.com/google/wuffs/blob/315b2e52625ebd7b02d8fac13e3cd85ea374fb80/script/print-mpb-powers-of-10.go
+  return (217706 * n >> 16) - 63;
 }
 
 // Returns true if n is large enough that 10**n always results in an IEEE
@@ -698,9 +703,7 @@ bool EiselLemire(const strings_internal::ParsedFloat& input, bool negative,
   // (+) Normalization.
   int clz = countl_zero(man);
   man <<= static_cast<unsigned int>(clz);
-  // The 217706 etc magic numbers encode the kPower10ExponentTable as a formula
-  // instead of a table. Their equivalence is confirmed by
-  // https://github.com/google/wuffs/blob/315b2e52625ebd7b02d8fac13e3cd85ea374fb80/script/print-mpb-powers-of-10.go
+  // The 217706 etc magic numbers are from the Power10Exponent function.
   uint64_t ret_exp2 =
       static_cast<uint64_t>((217706 * exp10 >> 16) + 64 +
                             FloatTraits<FloatType>::kExponentBias - clz);
@@ -935,13 +938,33 @@ namespace {
 // kPower10MantissaHighTable[i - kPower10TableMinInclusive] stores the 64-bit
 // mantissa. The high bit is always on.
 //
-// kPower10ExponentTable[i - kPower10TableMinInclusive] stores the power-of-two
-// exponent.
+// kPower10MantissaLowTable extends that 64-bit mantissa to 128 bits.
 //
-// For a given number i, this gives the unique mantissa and exponent such that
-// (mantissa * 2**exponent) <= 10**i < ((mantissa + 1) * 2**exponent).
+// Power10Exponent(i) calculates the power-of-two exponent.
 //
-// kPower10MantissaLowTable extends that 64-bit mantissa to 128 bits.
+// For a number i, this gives the unique mantissaHigh and exponent such that
+// (mantissaHigh * 2**exponent) <= 10**i < ((mantissaHigh + 1) * 2**exponent).
+//
+// For example, Python can confirm that the exact hexadecimal value of 1e60 is:
+//    >>> a = 1000000000000000000000000000000000000000000000000000000000000
+//    >>> hex(a)
+//    '0x9f4f2726179a224501d762422c946590d91000000000000000'
+// Adding underscores at every 8th hex digit shows 50 hex digits:
+//    '0x9f4f2726_179a2245_01d76242_2c946590_d9100000_00000000_00'.
+// In this case, the high bit of the first hex digit, 9, is coincidentally set,
+// so we do not have to do further shifting to deduce the 128-bit mantissa:
+//   - kPower10MantissaHighTable[60 - kP10TMI] = 0x9f4f2726179a2245U
+//   - kPower10MantissaLowTable[ 60 - kP10TMI] = 0x01d762422c946590U
+// where kP10TMI is kPower10TableMinInclusive. The low 18 of those 50 hex
+// digits are truncated.
+//
+// 50 hex digits (with the high bit set) is 200 bits and mantissaHigh holds 64
+// bits, so Power10Exponent(60) = 200 - 64 = 136. Again, Python can confirm:
+//    >>> b = 0x9f4f2726179a2245
+//    >>> ((b+0)<<136) <= a
+//    True
+//    >>> ((b+1)<<136) <= a
+//    False
 //
 // The tables were generated by
 // https://github.com/google/wuffs/blob/315b2e52625ebd7b02d8fac13e3cd85ea374fb80/script/print-mpb-powers-of-10.go
@@ -1388,69 +1411,6 @@ const uint64_t kPower10MantissaLowTable[] = {
     0xe0133fe4adf8e952U, 0x58180fddd97723a6U, 0x570f09eaa7ea7648U,
 };
 
-const int16_t kPower10ExponentTable[] = {
-    -1200, -1196, -1193, -1190, -1186, -1183, -1180, -1176, -1173, -1170, -1166,
-    -1163, -1160, -1156, -1153, -1150, -1146, -1143, -1140, -1136, -1133, -1130,
-    -1127, -1123, -1120, -1117, -1113, -1110, -1107, -1103, -1100, -1097, -1093,
-    -1090, -1087, -1083, -1080, -1077, -1073, -1070, -1067, -1063, -1060, -1057,
-    -1053, -1050, -1047, -1043, -1040, -1037, -1034, -1030, -1027, -1024, -1020,
-    -1017, -1014, -1010, -1007, -1004, -1000, -997,  -994,  -990,  -987,  -984,
-    -980,  -977,  -974,  -970,  -967,  -964,  -960,  -957,  -954,  -950,  -947,
-    -944,  -940,  -937,  -934,  -931,  -927,  -924,  -921,  -917,  -914,  -911,
-    -907,  -904,  -901,  -897,  -894,  -891,  -887,  -884,  -881,  -877,  -874,
-    -871,  -867,  -864,  -861,  -857,  -854,  -851,  -847,  -844,  -841,  -838,
-    -834,  -831,  -828,  -824,  -821,  -818,  -814,  -811,  -808,  -804,  -801,
-    -798,  -794,  -791,  -788,  -784,  -781,  -778,  -774,  -771,  -768,  -764,
-    -761,  -758,  -754,  -751,  -748,  -744,  -741,  -738,  -735,  -731,  -728,
-    -725,  -721,  -718,  -715,  -711,  -708,  -705,  -701,  -698,  -695,  -691,
-    -688,  -685,  -681,  -678,  -675,  -671,  -668,  -665,  -661,  -658,  -655,
-    -651,  -648,  -645,  -642,  -638,  -635,  -632,  -628,  -625,  -622,  -618,
-    -615,  -612,  -608,  -605,  -602,  -598,  -595,  -592,  -588,  -585,  -582,
-    -578,  -575,  -572,  -568,  -565,  -562,  -558,  -555,  -552,  -549,  -545,
-    -542,  -539,  -535,  -532,  -529,  -525,  -522,  -519,  -515,  -512,  -509,
-    -505,  -502,  -499,  -495,  -492,  -489,  -485,  -482,  -479,  -475,  -472,
-    -469,  -465,  -462,  -459,  -455,  -452,  -449,  -446,  -442,  -439,  -436,
-    -432,  -429,  -426,  -422,  -419,  -416,  -412,  -409,  -406,  -402,  -399,
-    -396,  -392,  -389,  -386,  -382,  -379,  -376,  -372,  -369,  -366,  -362,
-    -359,  -356,  -353,  -349,  -346,  -343,  -339,  -336,  -333,  -329,  -326,
-    -323,  -319,  -316,  -313,  -309,  -306,  -303,  -299,  -296,  -293,  -289,
-    -286,  -283,  -279,  -276,  -273,  -269,  -266,  -263,  -259,  -256,  -253,
-    -250,  -246,  -243,  -240,  -236,  -233,  -230,  -226,  -223,  -220,  -216,
-    -213,  -210,  -206,  -203,  -200,  -196,  -193,  -190,  -186,  -183,  -180,
-    -176,  -173,  -170,  -166,  -163,  -160,  -157,  -153,  -150,  -147,  -143,
-    -140,  -137,  -133,  -130,  -127,  -123,  -120,  -117,  -113,  -110,  -107,
-    -103,  -100,  -97,   -93,   -90,   -87,   -83,   -80,   -77,   -73,   -70,
-    -67,   -63,   -60,   -57,   -54,   -50,   -47,   -44,   -40,   -37,   -34,
-    -30,   -27,   -24,   -20,   -17,   -14,   -10,   -7,    -4,    0,     3,
-    6,     10,    13,    16,    20,    23,    26,    30,    33,    36,    39,
-    43,    46,    49,    53,    56,    59,    63,    66,    69,    73,    76,
-    79,    83,    86,    89,    93,    96,    99,    103,   106,   109,   113,
-    116,   119,   123,   126,   129,   132,   136,   139,   142,   146,   149,
-    152,   156,   159,   162,   166,   169,   172,   176,   179,   182,   186,
-    189,   192,   196,   199,   202,   206,   209,   212,   216,   219,   222,
-    226,   229,   232,   235,   239,   242,   245,   249,   252,   255,   259,
-    262,   265,   269,   272,   275,   279,   282,   285,   289,   292,   295,
-    299,   302,   305,   309,   312,   315,   319,   322,   325,   328,   332,
-    335,   338,   342,   345,   348,   352,   355,   358,   362,   365,   368,
-    372,   375,   378,   382,   385,   388,   392,   395,   398,   402,   405,
-    408,   412,   415,   418,   422,   425,   428,   431,   435,   438,   441,
-    445,   448,   451,   455,   458,   461,   465,   468,   471,   475,   478,
-    481,   485,   488,   491,   495,   498,   501,   505,   508,   511,   515,
-    518,   521,   524,   528,   531,   534,   538,   541,   544,   548,   551,
-    554,   558,   561,   564,   568,   571,   574,   578,   581,   584,   588,
-    591,   594,   598,   601,   604,   608,   611,   614,   617,   621,   624,
-    627,   631,   634,   637,   641,   644,   647,   651,   654,   657,   661,
-    664,   667,   671,   674,   677,   681,   684,   687,   691,   694,   697,
-    701,   704,   707,   711,   714,   717,   720,   724,   727,   730,   734,
-    737,   740,   744,   747,   750,   754,   757,   760,   764,   767,   770,
-    774,   777,   780,   784,   787,   790,   794,   797,   800,   804,   807,
-    810,   813,   817,   820,   823,   827,   830,   833,   837,   840,   843,
-    847,   850,   853,   857,   860,   863,   867,   870,   873,   877,   880,
-    883,   887,   890,   893,   897,   900,   903,   907,   910,   913,   916,
-    920,   923,   926,   930,   933,   936,   940,   943,   946,   950,   953,
-    956,   960,
-};
-
 }  // namespace
 ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/cord_test.cc b/absl/strings/cord_test.cc
index d28ba113..1fc4be6e 100644
--- a/absl/strings/cord_test.cc
+++ b/absl/strings/cord_test.cc
@@ -28,7 +28,6 @@
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
-#include "absl/base/casts.h"
 #include "absl/base/config.h"
 #include "absl/base/internal/endian.h"
 #include "absl/base/internal/raw_logging.h"
diff --git a/absl/strings/str_cat.h b/absl/strings/str_cat.h
index 05728ab5..6ee88f14 100644
--- a/absl/strings/str_cat.h
+++ b/absl/strings/str_cat.h
@@ -85,6 +85,11 @@ class StringifySink {
 
   bool PutPaddedString(string_view v, int width, int precision, bool left);
 
+  // Support `absl::Format(&sink, format, args...)`.
+  friend void AbslFormatFlush(StringifySink* sink, absl::string_view v) {
+    sink->Append(v);
+  }
+
   template <typename T>
   friend string_view ExtractStringification(StringifySink& sink, const T& v);
 
diff --git a/absl/strings/str_cat_test.cc b/absl/strings/str_cat_test.cc
index 868b9bce..1b3b7ece 100644
--- a/absl/strings/str_cat_test.cc
+++ b/absl/strings/str_cat_test.cc
@@ -21,6 +21,7 @@
 #include <vector>
 
 #include "gtest/gtest.h"
+#include "absl/strings/str_format.h"
 #include "absl/strings/substitute.h"
 
 #ifdef __ANDROID__
@@ -632,4 +633,21 @@ TEST(StrCat, AbslStringifyExample) {
   EXPECT_EQ(absl::StrCat("a ", p, " z"), "a (10, 20) z");
 }
 
+struct PointStringifyUsingFormat {
+  template <typename FormatSink>
+  friend void AbslStringify(FormatSink& sink,
+                            const PointStringifyUsingFormat& p) {
+    absl::Format(&sink, "(%g, %g)", p.x, p.y);
+  }
+
+  double x = 10.0;
+  double y = 20.0;
+};
+
+TEST(StrCat, AbslStringifyExampleUsingFormat) {
+  PointStringifyUsingFormat p;
+  EXPECT_EQ(absl::StrCat(p), "(10, 20)");
+  EXPECT_EQ(absl::StrCat("a ", p, " z"), "a (10, 20) z");
+}
+
 }  // namespace
diff --git a/absl/strings/str_format.h b/absl/strings/str_format.h
index e6537ea0..ffbcb9af 100644
--- a/absl/strings/str_format.h
+++ b/absl/strings/str_format.h
@@ -789,6 +789,11 @@ class FormatSink {
     return sink_->PutPaddedString(v, width, precision, left);
   }
 
+  // Support `absl::Format(&sink, format, args...)`.
+  friend void AbslFormatFlush(FormatSink* sink, absl::string_view v) {
+    sink->Append(v);
+  }
+
  private:
   friend str_format_internal::FormatSinkImpl;
   explicit FormatSink(str_format_internal::FormatSinkImpl* s) : sink_(s) {}
diff --git a/absl/strings/str_format_test.cc b/absl/strings/str_format_test.cc
index 0c4f10c8..62ed262d 100644
--- a/absl/strings/str_format_test.cc
+++ b/absl/strings/str_format_test.cc
@@ -1118,6 +1118,23 @@ TEST_F(FormatExtensionTest, AbslStringifyExample) {
   PointStringify p;
   EXPECT_EQ(absl::StrFormat("a %v z", p), "a (10, 20) z");
 }
+
+struct PointStringifyUsingFormat {
+  template <typename FormatSink>
+  friend void AbslStringify(FormatSink& sink,
+                            const PointStringifyUsingFormat& p) {
+    absl::Format(&sink, "(%g, %g)", p.x, p.y);
+  }
+
+  double x = 10.0;
+  double y = 20.0;
+};
+
+TEST_F(FormatExtensionTest, AbslStringifyExampleUsingFormat) {
+  PointStringifyUsingFormat p;
+  EXPECT_EQ(absl::StrFormat("a %v z", p), "a (10, 20) z");
+}
+
 }  // namespace
 
 // Some codegen thunks that we can use to easily dump the generated assembly for
diff --git a/absl/types/internal/variant.h b/absl/types/internal/variant.h
index 9adea563..c82ded44 100644
--- a/absl/types/internal/variant.h
+++ b/absl/types/internal/variant.h
@@ -449,7 +449,7 @@ struct FlattenIndices;
 
 template <std::size_t HeadSize, std::size_t... TailSize>
 struct FlattenIndices<HeadSize, TailSize...> {
-  template<class... SizeType>
+  template <class... SizeType>
   static constexpr std::size_t Run(std::size_t head, SizeType... tail) {
     return head + HeadSize * FlattenIndices<TailSize...>::Run(tail...);
   }
@@ -498,8 +498,8 @@ struct VisitIndicesVariadicImpl<absl::index_sequence<N...>, EndIndices...> {
   };
 
   template <class Op, class... SizeType>
-  static VisitIndicesResultT<Op, decltype(EndIndices)...> Run(
-      Op&& op, SizeType... i) {
+  static VisitIndicesResultT<Op, decltype(EndIndices)...> Run(Op&& op,
+                                                              SizeType... i) {
     return VisitIndicesSwitch<NumCasesOfSwitch<EndIndices...>::value>::Run(
         FlattenedOp<Op>{absl::forward<Op>(op)},
         FlattenIndices<(EndIndices + std::size_t{1})...>::Run(
@@ -683,13 +683,13 @@ struct VariantCoreAccess {
         variant_internal::IndexOfConstructedType<Left, QualifiedNew>;
 
     void operator()(SizeT<NewIndex::value> /*old_i*/
-                    ) const {
+    ) const {
       Access<NewIndex::value>(*left) = absl::forward<QualifiedNew>(other);
     }
 
     template <std::size_t OldIndex>
     void operator()(SizeT<OldIndex> /*old_i*/
-                    ) const {
+    ) const {
       using New =
           typename absl::variant_alternative<NewIndex::value, Left>::type;
       if (std::is_nothrow_constructible<New, QualifiedNew>::value ||
@@ -868,18 +868,6 @@ struct IsNeitherSelfNorInPlace<Self, in_place_type_t<T>> : std::false_type {};
 template <class Self, std::size_t I>
 struct IsNeitherSelfNorInPlace<Self, in_place_index_t<I>> : std::false_type {};
 
-template <class Variant, class T, class = void>
-struct ConversionIsPossibleImpl : std::false_type {};
-
-template <class Variant, class T>
-struct ConversionIsPossibleImpl<
-    Variant, T,
-    void_t<decltype(ImaginaryFun<Variant>::Run(std::declval<T>(), {}))>>
-    : std::true_type {};
-
-template <class Variant, class T>
-struct ConversionIsPossible : ConversionIsPossibleImpl<Variant, T>::type {};
-
 template <class Variant, class T>
 struct IndexOfConstructedType<
     Variant, T,
@@ -1151,16 +1139,16 @@ struct VariantHelper<variant<Ts...>> {
   // Type metafunction which returns the element type selected if
   // OverloadSet::Overload() is well-formed when called with argument type U.
   template <typename U>
-  using BestMatch = decltype(
-      variant_internal::OverloadSet<Ts...>::Overload(std::declval<U>()));
+  using BestMatch = decltype(variant_internal::OverloadSet<Ts...>::Overload(
+      std::declval<U>()));
 
   // Type metafunction which returns true if OverloadSet::Overload() is
   // well-formed when called with argument type U.
   // CanAccept can't be just an alias because there is a MSVC bug on parameter
   // pack expansion involving decltype.
   template <typename U>
-  struct CanAccept :
-      std::integral_constant<bool, !std::is_void<BestMatch<U>>::value> {};
+  struct CanAccept
+      : std::integral_constant<bool, !std::is_void<BestMatch<U>>::value> {};
 
   // Type metafunction which returns true if Other is an instantiation of
   // variant, and variants's converting constructor from Other will be
@@ -1183,8 +1171,8 @@ struct TrivialMoveOnly {
 // A union's defaulted copy/move constructor is deleted if any variant member's
 // copy/move constructor is nontrivial.
 template <typename T>
-struct IsTriviallyMoveConstructible:
-  std::is_move_constructible<Union<T, TrivialMoveOnly>> {};
+struct IsTriviallyMoveConstructible
+    : std::is_move_constructible<Union<T, TrivialMoveOnly>> {};
 
 // To guarantee triviality of all special-member functions that can be trivial,
 // we use a chain of conditional bases for each one.
@@ -1419,14 +1407,14 @@ class VariantMoveAssignBaseNontrivial : protected VariantCopyBase<T...> {
   VariantMoveAssignBaseNontrivial& operator=(
       VariantMoveAssignBaseNontrivial const&) = default;
 
-    VariantMoveAssignBaseNontrivial&
-    operator=(VariantMoveAssignBaseNontrivial&& other) noexcept(
-        absl::conjunction<std::is_nothrow_move_constructible<T>...,
-                          std::is_nothrow_move_assignable<T>...>::value) {
-      VisitIndices<sizeof...(T)>::Run(
-          VariantCoreAccess::MakeMoveAssignVisitor(this, &other), other.index_);
-      return *this;
-    }
+  VariantMoveAssignBaseNontrivial&
+  operator=(VariantMoveAssignBaseNontrivial&& other) noexcept(
+      absl::conjunction<std::is_nothrow_move_constructible<T>...,
+                        std::is_nothrow_move_assignable<T>...>::value) {
+    VisitIndices<sizeof...(T)>::Run(
+        VariantCoreAccess::MakeMoveAssignVisitor(this, &other), other.index_);
+    return *this;
+  }
 
  protected:
   using Base::index_;
@@ -1450,12 +1438,12 @@ class VariantCopyAssignBaseNontrivial : protected VariantMoveAssignBase<T...> {
   VariantCopyAssignBaseNontrivial& operator=(
       VariantCopyAssignBaseNontrivial&&) = default;
 
-    VariantCopyAssignBaseNontrivial& operator=(
-        const VariantCopyAssignBaseNontrivial& other) {
-      VisitIndices<sizeof...(T)>::Run(
-          VariantCoreAccess::MakeCopyAssignVisitor(this, other), other.index_);
-      return *this;
-    }
+  VariantCopyAssignBaseNontrivial& operator=(
+      const VariantCopyAssignBaseNontrivial& other) {
+    VisitIndices<sizeof...(T)>::Run(
+        VariantCoreAccess::MakeCopyAssignVisitor(this, other), other.index_);
+    return *this;
+  }
 
  protected:
   using Base::index_;