Export of internal Abseil changes.

--
5a5dba4252e764e6737070bf0a31074bf23a3b41 by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 244898913

--
3eb7d5b445ffbf08a104e39cd15aecf568417333 by Matt Calabrese <calabrese@google.com>:

Introduce absl::is_trivially_move_constructible and absl::is_trivially_move_assignable, and update the absl::is_trivially_copy_constructible and absl::is_trivially_copy_assignable traits to use similar techniques (should now be closer to the standard behavior).

PiperOrigin-RevId: 244859015

--
7da05a24fa786cab3985de0c39a186d73dcbcfb5 by Abseil Team <absl-team@google.com>:

Fix misspellings in comments in raw_hash_set.h.

PiperOrigin-RevId: 244754700

--
5c057be96048f21473d5ec45005ab4dcd8dd354f by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 244744239

--
592394e3c2e98f1238d3fb6fcb0d20c3e3739ba9 by Derek Mauro <dmauro@google.com>:

Limit the raw_hash_set prefetch test to x86-64.

PiperOrigin-RevId: 244737534

--
99ebe4e003633c8ff7838b035b31a827994879ef by Derek Mauro <dmauro@google.com>:

Workaround warning 4091 in an MSVC header.

PiperOrigin-RevId: 244701744

--
0aa23f09a32efe7985ee55b0217190f08da42477 by Abseil Team <absl-team@google.com>:

Fix comment typo.

PiperOrigin-RevId: 244659371

--
c6cdb87e9f28062c8daa29b3d8d68182ecc16383 by Derek Mauro <dmauro@google.com>:

Fix -Wundef warnings and support -Wundef.

PiperOrigin-RevId: 244244968

--
06b81245f7696b20c3c63b0618d33ac25e29cad6 by Abseil Team <absl-team@google.com>:

Fix a typo in inlined_vector.h.

PiperOrigin-RevId: 244230809

--
94877a2125d2cfe837384240e4d6551f39d737e4 by Greg Falcon <gfalcon@google.com>:

Fix sysinfo_test for emscripten.

PiperOrigin-RevId: 244198804

--
ec7783531ef7f9df2da37d341d61f7cb2bf843f0 by Shaindel Schwartz <shaindel@google.com>:

Import of CCTZ from GitHub.

Fixes #291.

PiperOrigin-RevId: 244184598

--
b652c14fa95ea206c217487ee713b11f5d1762b3 by Matt Calabrese <calabrese@google.com>:

Emulate the `in_place_index` and `in_place_type` variable templates such that they are syntactically usable in C++11 with `any` and `variant`. Also pull in the variable templates from namespace std when available.

The main observable differences here are:

1)
The types of `in_place_index_t<I>` and `in_place_type_t<T>` become function pointer types rather than structs when using the implementation that is not an alias of the std equivalents.

2)
The types of `in_place_index<I>` and `in_place_type<T>` are not directly `in_place_index_t<I>` and `in_place_type_t<T>`, but rather they become function types that decay to the corresponding function pointer types.

3)
The default constructor for `in_place_index_t` and `in_place_type_t` instantiations is no longer explicit, but for these templates I think that's less important than for something like `in_place_t` since the _type_t and _index_t versions basically never have their template parameter non-deduced when participating in overload resolution with conflicting candidates.

4) While idiomatic usage of `in_place_type_t` and `in_place_index_t` with std::variant and std::any should not be affected, there is the possibility that strange, non-idiomatic uses may be affected in the wild.

5) Default construction (rather than value-initialization) leads to a default-constructed pointer.

PiperOrigin-RevId: 244180003

--
b9ac5a96581837ffa24532117b7ea302a5569751 by Derek Mauro <dmauro@google.com>:

Fix MSVC debug assertion.

isprint is undefined for values not representable as unsigned char or
EOF.

PiperOrigin-RevId: 244083005

--
41758be6137c2f25e84b50f23938e49484be2903 by Shaindel Schwartz <shaindel@google.com>:

Update config settings for Apple platforms.

PiperOrigin-RevId: 244040587

--
c90df6a26db94b0305a0c954455a621542a89d91 by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 244024427

--
c71e9ceb89495354eca7d02bd905ffeaa9029aec by Derek Mauro <dmauro@google.com>:

Adds missing ABSL_DEFAULT_COPTS and ABSL_TEST_COPTS to CMakeLists.txt

Don't error on deprecated declarations in tests. It is completely
reasonable to test that code marked deprecated still works.

PiperOrigin-RevId: 244003941

--
e1326a96527a8ba9b8d120161545260da9c4562e by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 243990623

--
90b8e12934c7711e1bfcc0117d21288bf9220dee by Abseil Team <absl-team@google.com>:

Add variation of absl::Base64Escape/WebSafeBase64Escape that directly returns its result.

PiperOrigin-RevId: 243894308

--
317fef3344481ebc5c35712d42f5d8a0fa64dff4 by Abseil Team <absl-team@google.com>:

Enable raw logging in Emscripten builds.

PiperOrigin-RevId: 243893705
GitOrigin-RevId: 5a5dba4252e764e6737070bf0a31074bf23a3b41
Change-Id: I19293aab73cc98d9e9bf6a9fdc30819764adb9db

37 files changed, 694 insertions, 87 deletions

diff --git a/absl/BUILD.bazel b/absl/BUILD.bazel
index 8e3c1773..853330d4 100644
--- a/absl/BUILD.bazel
+++ b/absl/BUILD.bazel
@@ -25,13 +25,18 @@ create_llvm_config(
     visibility = [":__subpackages__"],
 )
 
-# following configs are based on mapping defined in: https://git.io/v5Ijz
+config_setting(
+    name = "osx",
+    constraint_values = [
+        "@bazel_tools//platforms:osx",
+    ],
+)
+
 config_setting(
     name = "ios",
-    values = {
-        "cpu": "darwin",
-    },
-    visibility = [":__subpackages__"],
+    constraint_values = [
+        "@bazel_tools//platforms:ios",
+    ],
 )
 
 config_setting(
diff --git a/absl/algorithm/CMakeLists.txt b/absl/algorithm/CMakeLists.txt
index c51eb10e..9fbe36f6 100644
--- a/absl/algorithm/CMakeLists.txt
+++ b/absl/algorithm/CMakeLists.txt
@@ -29,6 +29,8 @@ absl_cc_test(
     algorithm_test
   SRCS
     "algorithm_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::algorithm
     gmock_main
@@ -53,6 +55,8 @@ absl_cc_test(
     container_test
   SRCS
     "container_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::algorithm_container
     absl::base
diff --git a/absl/base/CMakeLists.txt b/absl/base/CMakeLists.txt
index 5042f156..b9f35bc0 100644
--- a/absl/base/CMakeLists.txt
+++ b/absl/base/CMakeLists.txt
@@ -26,6 +26,8 @@ absl_cc_library(
     "internal/spinlock_posix.inc"
     "internal/spinlock_wait.cc"
     "internal/spinlock_win32.inc"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
   DEPS
     absl::core_headers
 )
@@ -221,6 +223,8 @@ absl_cc_test(
     atomic_hook_test
   SRCS
     "internal/atomic_hook_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base
     absl::core_headers
@@ -232,6 +236,8 @@ absl_cc_test(
     bit_cast_test
   SRCS
     "bit_cast_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base
     absl::core_headers
@@ -243,6 +249,8 @@ absl_cc_test(
     throw_delegate_test
   SRCS
     "throw_delegate_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base
     absl::throw_delegate
@@ -257,6 +265,8 @@ absl_cc_test(
     "inline_variable_test.cc"
     "inline_variable_test_a.cc"
     "inline_variable_test_b.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base_internal
     gtest_main
@@ -267,6 +277,8 @@ absl_cc_test(
     invoke_test
   SRCS
     "invoke_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base_internal
     absl::memory
@@ -297,6 +309,8 @@ absl_cc_test(
     spinlock_test
   SRCS
     "spinlock_test_common.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base
     absl::core_headers
@@ -324,6 +338,8 @@ absl_cc_test(
     endian_test
   SRCS
     "internal/endian_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base
     absl::config
@@ -336,6 +352,8 @@ absl_cc_test(
     config_test
   SRCS
     "config_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::config
     absl::synchronization
@@ -347,6 +365,8 @@ absl_cc_test(
     call_once_test
   SRCS
     "call_once_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base
     absl::core_headers
@@ -359,6 +379,8 @@ absl_cc_test(
     raw_logging_test
   SRCS
     "raw_logging_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base
     absl::strings
@@ -370,6 +392,8 @@ absl_cc_test(
     sysinfo_test
   SRCS
     "internal/sysinfo_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base
     absl::synchronization
@@ -381,6 +405,8 @@ absl_cc_test(
     low_level_alloc_test
   SRCS
     "internal/low_level_alloc_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::malloc_internal
     Threads::Threads
@@ -391,6 +417,8 @@ absl_cc_test(
     thread_identity_test
   SRCS
     "internal/thread_identity_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base
     absl::core_headers
@@ -415,6 +443,8 @@ absl_cc_test(
     bits_test
   SRCS
     "internal/bits_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::bits
     gtest_main
@@ -438,6 +468,8 @@ absl_cc_test(
     scoped_set_env_test
   SRCS
     "internal/scoped_set_env_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::scoped_set_env
     gtest_main
@@ -448,6 +480,8 @@ absl_cc_test(
     cmake_thread_test
   SRCS
     "internal/cmake_thread_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::base
 )
diff --git a/absl/base/internal/raw_logging.cc b/absl/base/internal/raw_logging.cc
index b5a05e8c..878fe6c6 100644
--- a/absl/base/internal/raw_logging.cc
+++ b/absl/base/internal/raw_logging.cc
@@ -36,7 +36,8 @@
 // This preprocessor token is also defined in raw_io.cc.  If you need to copy
 // this, consider moving both to config.h instead.
 #if defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) || \
-    defined(__Fuchsia__) || defined(__native_client__)
+    defined(__Fuchsia__) || defined(__native_client__) || \
+    defined(__EMSCRIPTEN__)
 #include <unistd.h>
 
 
diff --git a/absl/base/internal/sysinfo_test.cc b/absl/base/internal/sysinfo_test.cc
index 247f3d88..82bbcc2b 100644
--- a/absl/base/internal/sysinfo_test.cc
+++ b/absl/base/internal/sysinfo_test.cc
@@ -37,12 +37,12 @@ TEST(SysinfoTest, NumCPUs) {
 }
 
 TEST(SysinfoTest, NominalCPUFrequency) {
-#if !(defined(__aarch64__) && defined(__linux__))
+#if !(defined(__aarch64__) && defined(__linux__)) && !defined(__EMSCRIPTEN__)
   EXPECT_GE(NominalCPUFrequency(), 1000.0)
       << "NominalCPUFrequency() did not return a reasonable value";
 #else
-  // TODO(absl-team): Aarch64 cannot read the CPU frequency from sysfs, so we
-  // get back 1.0. Fix once the value is available.
+  // Aarch64 cannot read the CPU frequency from sysfs, so we get back 1.0.
+  // Emscripten does not have a sysfs to read from at all.
   EXPECT_EQ(NominalCPUFrequency(), 1.0)
       << "CPU frequency detection was fixed! Please update unittest.";
 #endif
diff --git a/absl/base/internal/unscaledcycleclock.h b/absl/base/internal/unscaledcycleclock.h
index 58950cc2..2d361e96 100644
--- a/absl/base/internal/unscaledcycleclock.h
+++ b/absl/base/internal/unscaledcycleclock.h
@@ -59,7 +59,8 @@
 // CycleClock that runs at atleast 1 MHz. We've found some Android
 // ARM64 devices where this is not the case, so we disable it by
 // default on Android ARM64.
-#if defined(__native_client__) || TARGET_OS_IPHONE || \
+#if defined(__native_client__) ||                      \
+    (defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE) || \
     (defined(__ANDROID__) && defined(__aarch64__))
 #define ABSL_USE_UNSCALED_CYCLECLOCK_DEFAULT 0
 #else
diff --git a/absl/container/CMakeLists.txt b/absl/container/CMakeLists.txt
index 3c44bd0e..9531d7f9 100644
--- a/absl/container/CMakeLists.txt
+++ b/absl/container/CMakeLists.txt
@@ -27,7 +27,9 @@ absl_cc_library(
   NAME
     compressed_tuple
   HDRS
-   "internal/compressed_tuple.h"
+    "internal/compressed_tuple.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
   DEPS
     absl::utility
   PUBLIC
@@ -38,6 +40,8 @@ absl_cc_test(
     compressed_tuple_test
   SRCS
     "internal/compressed_tuple_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::compressed_tuple
     absl::memory
@@ -68,6 +72,7 @@ absl_cc_test(
   SRCS
     "fixed_array_test.cc"
   COPTS
+    ${ABSL_TEST_COPTS}
     ${ABSL_EXCEPTIONS_FLAG}
   LINKOPTS
     ${ABSL_EXCEPTIONS_FLAG_LINKOPTS}
@@ -84,6 +89,8 @@ absl_cc_test(
     fixed_array_test_noexceptions
   SRCS
     "fixed_array_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::fixed_array
     absl::exception_testing
@@ -98,6 +105,7 @@ absl_cc_test(
   SRCS
     "fixed_array_exception_safety_test.cc"
   COPTS
+    ${ABSL_TEST_COPTS}
     ${ABSL_EXCEPTIONS_FLAG}
   LINKOPTS
     ${ABSL_EXCEPTIONS_FLAG_LINKOPTS}
@@ -151,6 +159,7 @@ absl_cc_test(
   SRCS
     "inlined_vector_test.cc"
   COPTS
+    ${ABSL_TEST_COPTS}
     ${ABSL_EXCEPTIONS_FLAG}
   LINKOPTS
     ${ABSL_EXCEPTIONS_FLAG_LINKOPTS}
@@ -172,6 +181,8 @@ absl_cc_test(
     inlined_vector_test_noexceptions
   SRCS
     "inlined_vector_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::inlined_vector
     absl::test_instance_tracker
@@ -201,6 +212,8 @@ absl_cc_test(
     test_instance_tracker_test
   SRCS
     "internal/test_instance_tracker_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::test_instance_tracker
     gmock_main
@@ -227,6 +240,8 @@ absl_cc_test(
     flat_hash_map_test
   SRCS
     "flat_hash_map_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::flat_hash_map
     absl::hash_generator_testing
@@ -261,6 +276,7 @@ absl_cc_test(
   SRCS
     "flat_hash_set_test.cc"
   COPTS
+    ${ABSL_TEST_COPTS}
     "-DUNORDERED_SET_CXX17"
   DEPS
     absl::flat_hash_set
@@ -296,6 +312,8 @@ absl_cc_test(
     node_hash_map_test
   SRCS
     "node_hash_map_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::hash_generator_testing
     absl::node_hash_map
@@ -329,6 +347,7 @@ absl_cc_test(
   SRCS
     "node_hash_set_test.cc"
   COPTS
+    ${ABSL_TEST_COPTS}
     "-DUNORDERED_SET_CXX17"
   DEPS
     absl::hash_generator_testing
@@ -358,6 +377,8 @@ absl_cc_test(
     container_memory_test
   SRCS
     "internal/container_memory_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::container_memory
     absl::strings
@@ -383,6 +404,8 @@ absl_cc_test(
     hash_function_defaults_test
   SRCS
     "internal/hash_function_defaults_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::hash_function_defaults
     absl::hash
@@ -424,6 +447,8 @@ absl_cc_test(
     hash_policy_testing_test
   SRCS
     "internal/hash_policy_testing_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::hash_policy_testing
     gmock_main
@@ -446,6 +471,8 @@ absl_cc_test(
     hash_policy_traits_test
   SRCS
     "internal/hash_policy_traits_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::hash_policy_traits
     gmock_main
@@ -472,6 +499,8 @@ absl_cc_test(
     hashtablez_sampler_test
   SRCS
     "internal/hashtablez_sampler_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::hashtablez_sampler
     absl::have_sse
@@ -523,6 +552,8 @@ absl_cc_test(
     node_hash_policy_test
   SRCS
     "internal/node_hash_policy_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::hash_policy_traits
     absl::node_hash_policy
@@ -587,6 +618,8 @@ absl_cc_test(
     raw_hash_set_test
   SRCS
     "internal/raw_hash_set_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::container_memory
     absl::hash_function_defaults
@@ -604,6 +637,8 @@ absl_cc_test(
     raw_hash_set_allocator_test
   SRCS
     "internal/raw_hash_set_allocator_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::raw_hash_set
     absl::tracked
@@ -632,6 +667,8 @@ absl_cc_test(
     layout_test
   SRCS
     "internal/layout_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::layout
     absl::base
@@ -765,6 +802,8 @@ absl_cc_test(
     unordered_set_test
   SRCS
     "internal/unordered_set_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::unordered_set_constructor_test
     absl::unordered_set_lookup_test
@@ -778,6 +817,8 @@ absl_cc_test(
     unordered_map_test
   SRCS
     "internal/unordered_map_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::unordered_map_constructor_test
     absl::unordered_map_lookup_test
diff --git a/absl/container/inlined_vector.h b/absl/container/inlined_vector.h
index 978d5033..34e9aa0a 100644
--- a/absl/container/inlined_vector.h
+++ b/absl/container/inlined_vector.h
@@ -174,9 +174,9 @@ class InlinedVector {
   // Creates an inlined vector by moving in the contents of an `other` inlined
   // vector without performing any allocations. If `other` contains allocated
   // memory, the newly-created instance will take ownership of that memory
-  // (leaving `other` itself empty). However, if `other` does not contain any
-  // allocated memory, the new inlined vector will  will perform element-wise
-  // move construction of `other`s elements.
+  // (leaving `other` empty). However, if `other` does not contain allocated
+  // memory (i.e. is inlined), the new inlined vector will perform element-wise
+  // move construction of `other`'s elements.
   //
   // NOTE: since no allocation is performed for the inlined vector in either
   // case, the `noexcept(...)` specification depends on whether moving the
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index 9c926812..8ac0dda2 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -1437,15 +1437,15 @@ class raw_hash_set {
 
   void initialize_slots() {
     assert(capacity_);
-    // Folks with custom allocators often make unwaranted assumptions about the
+    // Folks with custom allocators often make unwarranted assumptions about the
     // behavior of their classes vis-a-vis trivial destructability and what
     // calls they will or wont make.  Avoid sampling for people with custom
-    // allocators to get us out of this mess.  This is not a hard guarntee but a
-    // workaround while we plan the exact guarantee we want to provide.
+    // allocators to get us out of this mess.  This is not a hard guarantee but
+    // a workaround while we plan the exact guarantee we want to provide.
     //
     // People are often sloppy with the exact type of their allocator (sometimes
     // it has an extra const or is missing the pair, but rebinds made it work
-    // anyway).  To avoid the ambiguitity, we work off SlotAlloc which we have
+    // anyway).  To avoid the ambiguity, we work off SlotAlloc which we have
     // bound more carefully.
     if (std::is_same<SlotAlloc, std::allocator<slot_type>>::value &&
         slots_ == nullptr) {
diff --git a/absl/container/internal/raw_hash_set_test.cc b/absl/container/internal/raw_hash_set_test.cc
index cb845121..ed4ca8c8 100644
--- a/absl/container/internal/raw_hash_set_test.cc
+++ b/absl/container/internal/raw_hash_set_test.cc
@@ -433,9 +433,10 @@ TEST(Table, Prefetch) {
 
   // Do not run in debug mode, when prefetch is not implemented, or when
   // sanitizers are enabled, or on WebAssembly.
-#if defined(NDEBUG) && defined(__GNUC__) && !defined(ADDRESS_SANITIZER) && \
-    !defined(MEMORY_SANITIZER) && !defined(THREAD_SANITIZER) &&            \
-    !defined(UNDEFINED_BEHAVIOR_SANITIZER) && !defined(__EMSCRIPTEN__)
+#if defined(NDEBUG) && defined(__GNUC__) && defined(__x86_64__) &&          \
+    !defined(ADDRESS_SANITIZER) && !defined(MEMORY_SANITIZER) &&            \
+    !defined(THREAD_SANITIZER) && !defined(UNDEFINED_BEHAVIOR_SANITIZER) && \
+    !defined(__EMSCRIPTEN__)
   const auto now = [] { return absl::base_internal::CycleClock::Now(); };
 
   // Make size enough to not fit in L2 cache (16.7 Mb)
@@ -1080,7 +1081,7 @@ ProbeStats CollectProbeStatsOnKeysXoredWithSeed(const std::vector<int64_t>& keys
 
 ExpectedStats XorSeedExpectedStats() {
   constexpr bool kRandomizesInserts =
-#if NDEBUG
+#ifdef NDEBUG
       false;
 #else   // NDEBUG
       true;
@@ -1174,7 +1175,7 @@ ProbeStats CollectProbeStatsOnLinearlyTransformedKeys(
 
 ExpectedStats LinearTransformExpectedStats() {
   constexpr bool kRandomizesInserts =
-#if NDEBUG
+#ifdef NDEBUG
       false;
 #else   // NDEBUG
       true;
diff --git a/absl/copts/GENERATED_AbseilCopts.cmake b/absl/copts/GENERATED_AbseilCopts.cmake
index 5543638c..27e6f5a0 100644
--- a/absl/copts/GENERATED_AbseilCopts.cmake
+++ b/absl/copts/GENERATED_AbseilCopts.cmake
@@ -37,7 +37,6 @@ list(APPEND ABSL_CLANG_CL_FLAGS
     "-Wno-shorten-64-to-32"
     "-Wno-switch-enum"
     "-Wno-thread-safety-negative"
-    "-Wno-undef"
     "-Wno-unknown-warning-option"
     "-Wno-unreachable-code"
     "-Wno-unused-macros"
@@ -62,6 +61,7 @@ list(APPEND ABSL_CLANG_CL_FLAGS
 
 list(APPEND ABSL_CLANG_CL_TEST_FLAGS
     "-Wno-c99-extensions"
+    "-Wno-deprecated-declarations"
     "-Wno-missing-noreturn"
     "-Wno-missing-prototypes"
     "-Wno-missing-variable-declarations"
@@ -103,6 +103,7 @@ list(APPEND ABSL_GCC_FLAGS
 
 list(APPEND ABSL_GCC_TEST_FLAGS
     "-Wno-conversion-null"
+    "-Wno-deprecated-declarations"
     "-Wno-missing-declarations"
     "-Wno-sign-compare"
     "-Wno-unused-function"
@@ -144,7 +145,6 @@ list(APPEND ABSL_LLVM_FLAGS
     "-Wno-shorten-64-to-32"
     "-Wno-switch-enum"
     "-Wno-thread-safety-negative"
-    "-Wno-undef"
     "-Wno-unknown-warning-option"
     "-Wno-unreachable-code"
     "-Wno-unused-macros"
@@ -164,6 +164,7 @@ list(APPEND ABSL_LLVM_FLAGS
 
 list(APPEND ABSL_LLVM_TEST_FLAGS
     "-Wno-c99-extensions"
+    "-Wno-deprecated-declarations"
     "-Wno-missing-noreturn"
     "-Wno-missing-prototypes"
     "-Wno-missing-variable-declarations"
@@ -211,5 +212,6 @@ list(APPEND ABSL_MSVC_TEST_FLAGS
     "/wd4018"
     "/wd4101"
     "/wd4503"
+    "/wd4996"
     "/DNOMINMAX"
 )
diff --git a/absl/copts/GENERATED_copts.bzl b/absl/copts/GENERATED_copts.bzl
index 10caa78a..0feb0f4b 100644
--- a/absl/copts/GENERATED_copts.bzl
+++ b/absl/copts/GENERATED_copts.bzl
@@ -38,7 +38,6 @@ ABSL_CLANG_CL_FLAGS = [
     "-Wno-shorten-64-to-32",
     "-Wno-switch-enum",
     "-Wno-thread-safety-negative",
-    "-Wno-undef",
     "-Wno-unknown-warning-option",
     "-Wno-unreachable-code",
     "-Wno-unused-macros",
@@ -63,6 +62,7 @@ ABSL_CLANG_CL_FLAGS = [
 
 ABSL_CLANG_CL_TEST_FLAGS = [
     "-Wno-c99-extensions",
+    "-Wno-deprecated-declarations",
     "-Wno-missing-noreturn",
     "-Wno-missing-prototypes",
     "-Wno-missing-variable-declarations",
@@ -104,6 +104,7 @@ ABSL_GCC_FLAGS = [
 
 ABSL_GCC_TEST_FLAGS = [
     "-Wno-conversion-null",
+    "-Wno-deprecated-declarations",
     "-Wno-missing-declarations",
     "-Wno-sign-compare",
     "-Wno-unused-function",
@@ -145,7 +146,6 @@ ABSL_LLVM_FLAGS = [
     "-Wno-shorten-64-to-32",
     "-Wno-switch-enum",
     "-Wno-thread-safety-negative",
-    "-Wno-undef",
     "-Wno-unknown-warning-option",
     "-Wno-unreachable-code",
     "-Wno-unused-macros",
@@ -165,6 +165,7 @@ ABSL_LLVM_FLAGS = [
 
 ABSL_LLVM_TEST_FLAGS = [
     "-Wno-c99-extensions",
+    "-Wno-deprecated-declarations",
     "-Wno-missing-noreturn",
     "-Wno-missing-prototypes",
     "-Wno-missing-variable-declarations",
@@ -212,5 +213,6 @@ ABSL_MSVC_TEST_FLAGS = [
     "/wd4018",
     "/wd4101",
     "/wd4503",
+    "/wd4996",
     "/DNOMINMAX",
 ]
diff --git a/absl/copts/copts.py b/absl/copts/copts.py
index cdcf61d6..154c0ce6 100644
--- a/absl/copts/copts.py
+++ b/absl/copts/copts.py
@@ -65,7 +65,6 @@ LLVM_DISABLE_WARNINGS_FLAGS = [
     "-Wno-shorten-64-to-32",
     "-Wno-switch-enum",
     "-Wno-thread-safety-negative",
-    "-Wno-undef",
     "-Wno-unknown-warning-option",
     "-Wno-unreachable-code",
     # Causes warnings on include guards
@@ -89,6 +88,7 @@ LLVM_DISABLE_WARNINGS_FLAGS = [
 
 LLVM_TEST_DISABLE_WARNINGS_FLAGS = [
     "-Wno-c99-extensions",
+    "-Wno-deprecated-declarations",
     "-Wno-missing-noreturn",
     "-Wno-missing-prototypes",
     "-Wno-missing-variable-declarations",
@@ -110,7 +110,9 @@ LLVM_TEST_DISABLE_WARNINGS_FLAGS = [
 ]
 
 MSVC_STYLE_EXCEPTIONS_FLAGS = [
-    "/U_HAS_EXCEPTIONS", "/D_HAS_EXCEPTIONS=1", "/EHsc"
+    "/U_HAS_EXCEPTIONS",
+    "/D_HAS_EXCEPTIONS=1",
+    "/EHsc"
 ]
 
 MSVC_DEFINES = [
@@ -148,6 +150,7 @@ COPT_VARS = {
     ],
     "ABSL_GCC_TEST_FLAGS": [
         "-Wno-conversion-null",
+        "-Wno-deprecated-declarations",
         "-Wno-missing-declarations",
         "-Wno-sign-compare",
         "-Wno-unused-function",
@@ -183,6 +186,7 @@ COPT_VARS = {
         "/wd4018",  # signed/unsigned mismatch
         "/wd4101",  # unreferenced local variable
         "/wd4503",  # decorated name length exceeded, name was truncated
+        "/wd4996",  # use of deprecated symbol
         "/DNOMINMAX",  # disable the min() and max() macros from <windows.h>
     ],
     "ABSL_MSVC_EXCEPTIONS_FLAGS":
diff --git a/absl/debugging/CMakeLists.txt b/absl/debugging/CMakeLists.txt
index dccd4a56..d813fede 100644
--- a/absl/debugging/CMakeLists.txt
+++ b/absl/debugging/CMakeLists.txt
@@ -43,6 +43,8 @@ absl_cc_library(
     "symbolize_win32.inc"
   COPTS
     ${ABSL_DEFAULT_COPTS}
+  LINKOPTS
+    ${ABSL_DEFAULT_LINKOPTS}
   DEPS
     absl::debugging_internal
     absl::demangle_internal
@@ -196,6 +198,8 @@ absl_cc_library(
     leak_check_disable
   SRCS
     "leak_check_disable.cc"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
   PUBLIC
 )
 
@@ -207,6 +211,7 @@ absl_cc_library(
   SRCS
     "leak_check.cc"
   COPTS
+    ${ABSL_DEFAULT_COPTS}
     $<$<BOOL:${ABSL_HAVE_LSAN}>:-DLEAK_SANITIZER>
   TESTONLY
 )
@@ -219,6 +224,7 @@ absl_cc_library(
   SRCS
     "leak_check.cc"
   COPTS
+    ${ABSL_DEFAULT_COPTS}
     "-ULEAK_SANITIZER"
   TESTONLY
 )
@@ -229,6 +235,7 @@ absl_cc_test(
   SRCS
     "leak_check_test.cc"
   COPTS
+    ${ABSL_DEFAULT_COPTS}
     "$<$<BOOL:${ABSL_HAVE_LSAN}>:-DABSL_EXPECT_LEAK_SANITIZER>"
   LINKOPTS
     "${ABSL_LSAN_LINKOPTS}"
@@ -244,6 +251,7 @@ absl_cc_test(
   SRCS
     "leak_check_test.cc"
   COPTS
+    ${ABSL_TEST_COPTS}
     "-UABSL_EXPECT_LEAK_SANITIZER"
   DEPS
     absl::leak_check_api_disabled_for_testing
@@ -256,6 +264,8 @@ absl_cc_test(
     disabled_leak_check_test
   SRCS
     "leak_check_fail_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   LINKOPTS
     "${ABSL_LSAN_LINKOPTS}"
   DEPS
@@ -298,6 +308,8 @@ absl_cc_test(
 absl_cc_library(
   NAME
     debugging
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
   DEPS
     absl::stacktrace
     absl::leak_check
diff --git a/absl/debugging/internal/demangle_test.cc b/absl/debugging/internal/demangle_test.cc
index 883b92db..a68ce324 100644
--- a/absl/debugging/internal/demangle_test.cc
+++ b/absl/debugging/internal/demangle_test.cc
@@ -81,8 +81,9 @@ TEST(Demangle, Clones) {
 // Tests that verify that Demangle footprint is within some limit.
 // They are not to be run under sanitizers as the sanitizers increase
 // stack consumption by about 4x.
-#if defined(ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION) && \
-    !ADDRESS_SANITIZER && !MEMORY_SANITIZER && !THREAD_SANITIZER
+#if defined(ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION) &&   \
+    !defined(ADDRESS_SANITIZER) && !defined(MEMORY_SANITIZER) && \
+    !defined(THREAD_SANITIZER)
 
 static const char *g_mangled;
 static char g_demangle_buffer[4096];
diff --git a/absl/debugging/symbolize_win32.inc b/absl/debugging/symbolize_win32.inc
index 17ea618a..7ed3bd3a 100644
--- a/absl/debugging/symbolize_win32.inc
+++ b/absl/debugging/symbolize_win32.inc
@@ -16,7 +16,13 @@
 // https://msdn.microsoft.com/en-us/library/windows/desktop/ms680578(v=vs.85).aspx
 
 #include <windows.h>
+
+// MSVC header DbgHelp.h has a warning for an ignored typedef.
+#pragma warning(push)
+#pragma warning(disable:4091)
 #include <DbgHelp.h>
+#pragma warning(pop)
+
 #pragma comment(lib, "DbgHelp")
 
 #include <algorithm>
diff --git a/absl/hash/CMakeLists.txt b/absl/hash/CMakeLists.txt
index 4cafc133..febc551f 100644
--- a/absl/hash/CMakeLists.txt
+++ b/absl/hash/CMakeLists.txt
@@ -43,6 +43,8 @@ absl_cc_library(
     hash_testing
   HDRS
     "hash_testing.h"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::spy_hash_state
     absl::meta
@@ -56,7 +58,9 @@ absl_cc_test(
   NAME
     hash_test
   SRCS
-   "hash_test.cc"
+    "hash_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   DEPS
     absl::hash
     absl::hash_testing
diff --git a/absl/hash/internal/hash.h b/absl/hash/internal/hash.h
index 9ab98901..18665173 100644
--- a/absl/hash/internal/hash.h
+++ b/absl/hash/internal/hash.h
@@ -615,7 +615,7 @@ struct HashSelect {
 
  public:
   // Probe each implementation in order.
-  // disjunction provides short circuting wrt instantiation.
+  // disjunction provides short circuiting wrt instantiation.
   template <typename T>
   using Apply = absl::disjunction<         //
       Probe<UniquelyRepresentedProbe, T>,  //
diff --git a/absl/memory/memory_test.cc b/absl/memory/memory_test.cc
index 8905433c..c47820e5 100644
--- a/absl/memory/memory_test.cc
+++ b/absl/memory/memory_test.cc
@@ -620,7 +620,7 @@ TEST(AllocatorTraits, FunctionsFull) {
 }
 
 TEST(AllocatorNoThrowTest, DefaultAllocator) {
-#if ABSL_ALLOCATOR_NOTHROW
+#if defined(ABSL_ALLOCATOR_NOTHROW) && ABSL_ALLOCATOR_NOTHROW
   EXPECT_TRUE(absl::default_allocator_is_nothrow::value);
 #else
   EXPECT_FALSE(absl::default_allocator_is_nothrow::value);
@@ -628,7 +628,7 @@ TEST(AllocatorNoThrowTest, DefaultAllocator) {
 }
 
 TEST(AllocatorNoThrowTest, StdAllocator) {
-#if ABSL_ALLOCATOR_NOTHROW
+#if defined(ABSL_ALLOCATOR_NOTHROW) && ABSL_ALLOCATOR_NOTHROW
   EXPECT_TRUE(absl::allocator_is_nothrow<std::allocator<int>>::value);
 #else
   EXPECT_FALSE(absl::allocator_is_nothrow<std::allocator<int>>::value);
diff --git a/absl/meta/CMakeLists.txt b/absl/meta/CMakeLists.txt
index f866e54e..672ead2f 100644
--- a/absl/meta/CMakeLists.txt
+++ b/absl/meta/CMakeLists.txt
@@ -42,6 +42,8 @@ absl_cc_test(
 absl_cc_library(
   NAME
     meta
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
   DEPS
     absl::type_traits
   PUBLIC
diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h
index a8068e31..c08e3754 100644
--- a/absl/meta/type_traits.h
+++ b/absl/meta/type_traits.h
@@ -43,8 +43,39 @@
 
 namespace absl {
 
+// Defined and documented later on in this file.
+template <typename T>
+struct is_trivially_move_assignable;
+
 namespace type_traits_internal {
 
+// Silence MSVC warnings about the destructor being defined as deleted.
+#if defined(_MSC_VER) && !defined(__GNUC__)
+#pragma warning(push)
+#pragma warning(disable : 4624)
+#endif  // defined(_MSC_VER) && !defined(__GNUC__)
+
+template <class T>
+union SingleMemberUnion {
+  T t;
+};
+
+// Restore the state of the destructor warning that was silenced above.
+#if defined(_MSC_VER) && !defined(__GNUC__)
+#pragma warning(pop)
+#endif  // defined(_MSC_VER) && !defined(__GNUC__)
+
+template <class T>
+struct IsTriviallyMoveAssignableReference : std::false_type {};
+
+template <class T>
+struct IsTriviallyMoveAssignableReference<T&>
+    : absl::is_trivially_move_assignable<T>::type {};
+
+template <class T>
+struct IsTriviallyMoveAssignableReference<T&&>
+    : absl::is_trivially_move_assignable<T>::type {};
+
 template <typename... Ts>
 struct VoidTImpl {
   using type = void;
@@ -275,6 +306,40 @@ struct is_trivially_default_constructible
 #endif  // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE
 };
 
+// is_trivially_move_constructible()
+//
+// Determines whether the passed type `T` is trivially move constructible.
+//
+// This metafunction is designed to be a drop-in replacement for the C++11
+// `std::is_trivially_move_constructible()` metafunction for platforms that have
+// incomplete C++11 support (such as libstdc++ 4.x). On any platforms that do
+// fully support C++11, we check whether this yields the same result as the std
+// implementation.
+//
+// NOTE: `T obj(declval<T>());` needs to be well-formed and not call any
+// nontrivial operation.  Nontrivially destructible types will cause the
+// expression to be nontrivial.
+template <typename T>
+struct is_trivially_move_constructible
+    : std::conditional<
+          std::is_object<T>::value && !std::is_array<T>::value,
+          std::is_move_constructible<
+              type_traits_internal::SingleMemberUnion<T>>,
+          std::is_reference<T>>::type::type {
+#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE
+ private:
+  static constexpr bool compliant =
+      std::is_trivially_move_constructible<T>::value ==
+      is_trivially_move_constructible::value;
+  static_assert(compliant || std::is_trivially_move_constructible<T>::value,
+                "Not compliant with std::is_trivially_move_constructible; "
+                "Standard: false, Implementation: true");
+  static_assert(compliant || !std::is_trivially_move_constructible<T>::value,
+                "Not compliant with std::is_trivially_move_constructible; "
+                "Standard: true, Implementation: false");
+#endif  // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE
+};
+
 // is_trivially_copy_constructible()
 //
 // Determines whether the passed type `T` is trivially copy constructible.
@@ -290,9 +355,11 @@ struct is_trivially_default_constructible
 // expression to be nontrivial.
 template <typename T>
 struct is_trivially_copy_constructible
-    : std::integral_constant<bool, __has_trivial_copy(T) &&
-                                   std::is_copy_constructible<T>::value &&
-                                   is_trivially_destructible<T>::value> {
+    : std::conditional<
+          std::is_object<T>::value && !std::is_array<T>::value,
+          std::is_copy_constructible<
+              type_traits_internal::SingleMemberUnion<T>>,
+          std::is_lvalue_reference<T>>::type::type {
 #ifdef ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE
  private:
   static constexpr bool compliant =
@@ -307,6 +374,42 @@ struct is_trivially_copy_constructible
 #endif  // ABSL_HAVE_STD_IS_TRIVIALLY_CONSTRUCTIBLE
 };
 
+// is_trivially_move_assignable()
+//
+// Determines whether the passed type `T` is trivially move assignable.
+//
+// This metafunction is designed to be a drop-in replacement for the C++11
+// `std::is_trivially_move_assignable()` metafunction for platforms that have
+// incomplete C++11 support (such as libstdc++ 4.x). On any platforms that do
+// fully support C++11, we check whether this yields the same result as the std
+// implementation.
+//
+// NOTE: `is_assignable<T, U>::value` is `true` if the expression
+// `declval<T>() = declval<U>()` is well-formed when treated as an unevaluated
+// operand. `is_trivially_assignable<T, U>` requires the assignment to call no
+// operation that is not trivial. `is_trivially_copy_assignable<T>` is simply
+// `is_trivially_assignable<T&, T>`.
+template <typename T>
+struct is_trivially_move_assignable
+    : std::conditional<
+          std::is_object<T>::value && !std::is_array<T>::value,
+          std::is_move_assignable<type_traits_internal::SingleMemberUnion<T>>,
+          type_traits_internal::IsTriviallyMoveAssignableReference<T>>::type::
+          type {
+#ifdef ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE
+ private:
+  static constexpr bool compliant =
+      std::is_trivially_move_assignable<T>::value ==
+      is_trivially_move_assignable::value;
+  static_assert(compliant || std::is_trivially_move_assignable<T>::value,
+                "Not compliant with std::is_trivially_move_assignable; "
+                "Standard: false, Implementation: true");
+  static_assert(compliant || !std::is_trivially_move_assignable<T>::value,
+                "Not compliant with std::is_trivially_move_assignable; "
+                "Standard: true, Implementation: false");
+#endif  // ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE
+};
+
 // is_trivially_copy_assignable()
 //
 // Determines whether the passed type `T` is trivially copy assignable.
diff --git a/absl/meta/type_traits_test.cc b/absl/meta/type_traits_test.cc
index d3ead6d0..82b1be51 100644
--- a/absl/meta/type_traits_test.cc
+++ b/absl/meta/type_traits_test.cc
@@ -214,6 +214,29 @@ class DeletedDefaultCtor {
   int n_;
 };
 
+class TrivialMoveCtor {
+ public:
+  explicit TrivialMoveCtor(int n) : n_(n) {}
+  TrivialMoveCtor(TrivialMoveCtor&&) = default;
+  TrivialMoveCtor& operator=(const TrivialMoveCtor& t) {
+    n_ = t.n_;
+    return *this;
+  }
+
+ private:
+  int n_;
+};
+
+class NontrivialMoveCtor {
+ public:
+  explicit NontrivialMoveCtor(int n) : n_(n) {}
+  NontrivialMoveCtor(NontrivialMoveCtor&& t) noexcept : n_(t.n_) {}
+  NontrivialMoveCtor& operator=(const NontrivialMoveCtor&) = default;
+
+ private:
+  int n_;
+};
+
 class TrivialCopyCtor {
  public:
   explicit TrivialCopyCtor(int n) : n_(n) {}
@@ -247,6 +270,29 @@ class DeletedCopyCtor {
   int n_;
 };
 
+class TrivialMoveAssign {
+ public:
+  explicit TrivialMoveAssign(int n) : n_(n) {}
+  TrivialMoveAssign(const TrivialMoveAssign& t) : n_(t.n_) {}
+  TrivialMoveAssign& operator=(TrivialMoveAssign&&) = default;
+  ~TrivialMoveAssign() {}  // can have nontrivial destructor
+ private:
+  int n_;
+};
+
+class NontrivialMoveAssign {
+ public:
+  explicit NontrivialMoveAssign(int n) : n_(n) {}
+  NontrivialMoveAssign(const NontrivialMoveAssign&) = default;
+  NontrivialMoveAssign& operator=(NontrivialMoveAssign&& t) noexcept {
+    n_ = t.n_;
+    return *this;
+  }
+
+ private:
+  int n_;
+};
+
 class TrivialCopyAssign {
  public:
   explicit TrivialCopyAssign(int n) : n_(n) {}
@@ -484,6 +530,79 @@ TEST(TypeTraitsTest, TestTrivialDefaultCtor) {
 #endif
 }
 
+TEST(TypeTraitsTest, TestTrivialMoveCtor) {
+  // Verify that arithmetic types and pointers have trivial move
+  // constructors.
+  EXPECT_TRUE(absl::is_trivially_move_constructible<bool>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<char>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<unsigned char>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<signed char>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<wchar_t>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<int>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<unsigned int>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<int16_t>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<uint16_t>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<int64_t>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<uint64_t>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<float>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<double>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<long double>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<std::string*>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<Trivial*>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<const std::string*>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<const Trivial*>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<std::string**>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<Trivial**>::value);
+
+  // Reference types
+  EXPECT_TRUE(absl::is_trivially_move_constructible<int&>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<int&&>::value);
+
+  // types with compiler generated move ctors
+  EXPECT_TRUE(absl::is_trivially_move_constructible<Trivial>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<TrivialMoveCtor>::value);
+
+  // Verify that types without them (i.e. nontrivial or deleted) are not.
+  EXPECT_FALSE(
+      absl::is_trivially_move_constructible<NontrivialCopyCtor>::value);
+  EXPECT_FALSE(absl::is_trivially_move_constructible<DeletedCopyCtor>::value);
+  EXPECT_FALSE(
+      absl::is_trivially_move_constructible<NonCopyableOrMovable>::value);
+
+#ifdef ABSL_TRIVIALLY_CONSTRUCTIBLE_VERIFY_TRIVIALLY_DESTRUCTIBLE
+  // type with nontrivial destructor are nontrivial move construbtible
+  EXPECT_FALSE(
+      absl::is_trivially_move_constructible<NontrivialDestructor>::value);
+#endif
+
+  // types with vtables
+  EXPECT_FALSE(absl::is_trivially_move_constructible<Base>::value);
+
+  // Verify that simple_pair of such types is trivially move constructible
+  EXPECT_TRUE(
+      (absl::is_trivially_move_constructible<simple_pair<int, char*>>::value));
+  EXPECT_TRUE((
+      absl::is_trivially_move_constructible<simple_pair<int, Trivial>>::value));
+  EXPECT_TRUE((absl::is_trivially_move_constructible<
+               simple_pair<int, TrivialMoveCtor>>::value));
+
+  // Verify that types without trivial move constructors are
+  // correctly marked as such.
+  EXPECT_FALSE(absl::is_trivially_move_constructible<std::string>::value);
+  EXPECT_FALSE(absl::is_trivially_move_constructible<std::vector<int>>::value);
+
+  // Verify that simple_pairs of types without trivial move constructors
+  // are not marked as trivial.
+  EXPECT_FALSE((absl::is_trivially_move_constructible<
+                simple_pair<int, std::string>>::value));
+  EXPECT_FALSE((absl::is_trivially_move_constructible<
+                simple_pair<std::string, int>>::value));
+
+  // Verify that arrays are not
+  using int10 = int[10];
+  EXPECT_FALSE(absl::is_trivially_move_constructible<int10>::value);
+}
+
 TEST(TypeTraitsTest, TestTrivialCopyCtor) {
   // Verify that arithmetic types and pointers have trivial copy
   // constructors.
@@ -508,6 +627,10 @@ TEST(TypeTraitsTest, TestTrivialCopyCtor) {
   EXPECT_TRUE(absl::is_trivially_copy_constructible<std::string**>::value);
   EXPECT_TRUE(absl::is_trivially_copy_constructible<Trivial**>::value);
 
+  // Reference types
+  EXPECT_TRUE(absl::is_trivially_copy_constructible<int&>::value);
+  EXPECT_FALSE(absl::is_trivially_copy_constructible<int&&>::value);
+
   // types with compiler generated copy ctors
   EXPECT_TRUE(absl::is_trivially_copy_constructible<Trivial>::value);
   EXPECT_TRUE(absl::is_trivially_copy_constructible<TrivialCopyCtor>::value);
@@ -555,6 +678,74 @@ TEST(TypeTraitsTest, TestTrivialCopyCtor) {
   EXPECT_FALSE(absl::is_trivially_copy_constructible<int10>::value);
 }
 
+TEST(TypeTraitsTest, TestTrivialMoveAssign) {
+  // Verify that arithmetic types and pointers have trivial move
+  // assignment operators.
+  EXPECT_TRUE(absl::is_trivially_move_assignable<bool>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<char>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<unsigned char>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<signed char>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<wchar_t>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<int>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<unsigned int>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<int16_t>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<uint16_t>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<int64_t>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<uint64_t>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<float>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<double>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<long double>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<std::string*>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<Trivial*>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<const std::string*>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<const Trivial*>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<std::string**>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<Trivial**>::value);
+
+  // const qualified types are not assignable
+  EXPECT_FALSE(absl::is_trivially_move_assignable<const int>::value);
+
+  // types with compiler generated move assignment
+  EXPECT_TRUE(absl::is_trivially_move_assignable<Trivial>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<TrivialMoveAssign>::value);
+
+  // Verify that types without them (i.e. nontrivial or deleted) are not.
+  EXPECT_FALSE(absl::is_trivially_move_assignable<NontrivialCopyAssign>::value);
+  EXPECT_FALSE(absl::is_trivially_move_assignable<DeletedCopyAssign>::value);
+  EXPECT_FALSE(absl::is_trivially_move_assignable<NonCopyableOrMovable>::value);
+
+  // types with vtables
+  EXPECT_FALSE(absl::is_trivially_move_assignable<Base>::value);
+
+  // Verify that simple_pair is trivially assignable
+  EXPECT_TRUE(
+      (absl::is_trivially_move_assignable<simple_pair<int, char*>>::value));
+  EXPECT_TRUE(
+      (absl::is_trivially_move_assignable<simple_pair<int, Trivial>>::value));
+  EXPECT_TRUE((absl::is_trivially_move_assignable<
+               simple_pair<int, TrivialMoveAssign>>::value));
+
+  // Verify that types not trivially move assignable are
+  // correctly marked as such.
+  EXPECT_FALSE(absl::is_trivially_move_assignable<std::string>::value);
+  EXPECT_FALSE(absl::is_trivially_move_assignable<std::vector<int>>::value);
+
+  // Verify that simple_pairs of types not trivially move assignable
+  // are not marked as trivial.
+  EXPECT_FALSE((absl::is_trivially_move_assignable<
+                simple_pair<int, std::string>>::value));
+  EXPECT_FALSE((absl::is_trivially_move_assignable<
+                simple_pair<std::string, int>>::value));
+
+  // Verify that arrays are not trivially move assignable
+  using int10 = int[10];
+  EXPECT_FALSE(absl::is_trivially_move_assignable<int10>::value);
+
+  // Verify that references are handled correctly
+  EXPECT_TRUE(absl::is_trivially_move_assignable<Trivial&&>::value);
+  EXPECT_TRUE(absl::is_trivially_move_assignable<Trivial&>::value);
+}
+
 TEST(TypeTraitsTest, TestTrivialCopyAssign) {
   // Verify that arithmetic types and pointers have trivial copy
   // assignment operators.
diff --git a/absl/numeric/CMakeLists.txt b/absl/numeric/CMakeLists.txt
index d26141c7..242889f0 100644
--- a/absl/numeric/CMakeLists.txt
+++ b/absl/numeric/CMakeLists.txt
@@ -52,6 +52,8 @@ absl_cc_test(
 absl_cc_library(
   NAME
     numeric
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
   DEPS
     absl::int128
   PUBLIC
diff --git a/absl/strings/CMakeLists.txt b/absl/strings/CMakeLists.txt
index d3393a39..8515ec2b 100644
--- a/absl/strings/CMakeLists.txt
+++ b/absl/strings/CMakeLists.txt
@@ -501,6 +501,8 @@ absl_cc_library(
     "internal/pow10_helper.h"
   SRCS
     "internal/pow10_helper.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
   TESTONLY
 )
 
diff --git a/absl/strings/escaping.cc b/absl/strings/escaping.cc
index bc8307e1..0d336e3f 100644
--- a/absl/strings/escaping.cc
+++ b/absl/strings/escaping.cc
@@ -1055,10 +1055,10 @@ std::string Utf8SafeCHexEscape(absl::string_view src) {
 }
 
 // ----------------------------------------------------------------------
-// ptrdiff_t Base64Unescape() - base64 decoder
-// ptrdiff_t Base64Escape() - base64 encoder
-// ptrdiff_t WebSafeBase64Unescape() - Google's variation of base64 decoder
-// ptrdiff_t WebSafeBase64Escape() - Google's variation of base64 encoder
+// Base64Unescape() - base64 decoder
+// Base64Escape() - base64 encoder
+// WebSafeBase64Unescape() - Google's variation of base64 decoder
+// WebSafeBase64Escape() - Google's variation of base64 encoder
 //
 // Check out
 // http://tools.ietf.org/html/rfc2045 for formal description, but what we
@@ -1096,6 +1096,20 @@ void WebSafeBase64Escape(absl::string_view src, std::string* dest) {
                        src.size(), dest, false, kWebSafeBase64Chars);
 }
 
+std::string Base64Escape(absl::string_view src) {
+  std::string dest;
+  Base64EscapeInternal(reinterpret_cast<const unsigned char*>(src.data()),
+                       src.size(), &dest, true, kBase64Chars);
+  return dest;
+}
+
+std::string WebSafeBase64Escape(absl::string_view src) {
+  std::string dest;
+  Base64EscapeInternal(reinterpret_cast<const unsigned char*>(src.data()),
+                       src.size(), &dest, false, kWebSafeBase64Chars);
+  return dest;
+}
+
 std::string HexStringToBytes(absl::string_view from) {
   std::string result;
   const auto num = from.size() / 2;
diff --git a/absl/strings/escaping.h b/absl/strings/escaping.h
index fd9be786..198b9348 100644
--- a/absl/strings/escaping.h
+++ b/absl/strings/escaping.h
@@ -132,16 +132,18 @@ bool WebSafeBase64Unescape(absl::string_view src, std::string* dest);
 
 // Base64Escape()
 //
-// Encodes a `src` string into a `dest` buffer using base64 encoding, with
-// padding characters. This function conforms with RFC 4648 section 4 (base64).
+// Encodes a `src` string into a base64-encoded string, with padding characters.
+// This function conforms with RFC 4648 section 4 (base64).
 void Base64Escape(absl::string_view src, std::string* dest);
+std::string Base64Escape(absl::string_view src);
 
 // WebSafeBase64Escape()
 //
-// Encodes a `src` string into a `dest` buffer using '-' instead of '+' and
-// '_' instead of '/', and without padding. This function conforms with RFC 4648
-// section 5 (base64url).
+// Encodes a `src` string into a base64-like string, using '-' instead of '+'
+// and '_' instead of '/', and without padding. This function conforms with RFC
+// 4648 section 5 (base64url).
 void WebSafeBase64Escape(absl::string_view src, std::string* dest);
+std::string WebSafeBase64Escape(absl::string_view src);
 
 // HexStringToBytes()
 //
diff --git a/absl/strings/escaping_test.cc b/absl/strings/escaping_test.cc
index d433b4c5..6a633cdc 100644
--- a/absl/strings/escaping_test.cc
+++ b/absl/strings/escaping_test.cc
@@ -556,6 +556,7 @@ void TestEscapeAndUnescape() {
     StringType encoded("this junk should be ignored");
     absl::Base64Escape(tc.plaintext, &encoded);
     EXPECT_EQ(encoded, tc.cyphertext);
+    EXPECT_EQ(absl::Base64Escape(tc.plaintext), tc.cyphertext);
 
     StringType decoded("this junk should be ignored");
     EXPECT_TRUE(absl::Base64Unescape(encoded, &decoded));
@@ -574,6 +575,7 @@ void TestEscapeAndUnescape() {
     encoded = "this junk should be ignored";
     absl::WebSafeBase64Escape(tc.plaintext, &encoded);
     EXPECT_EQ(encoded, websafe);
+    EXPECT_EQ(absl::WebSafeBase64Escape(tc.plaintext), websafe);
 
     // Let's try the std::string version of the decoder
     decoded = "this junk should be ignored";
@@ -586,6 +588,7 @@ void TestEscapeAndUnescape() {
     StringType buffer;
     absl::WebSafeBase64Escape(tc.plaintext, &buffer);
     EXPECT_EQ(tc.cyphertext, buffer);
+    EXPECT_EQ(absl::WebSafeBase64Escape(tc.plaintext), tc.cyphertext);
   }
 
   // Verify the behavior when decoding bad data
diff --git a/absl/strings/internal/str_format/convert_test.cc b/absl/strings/internal/str_format/convert_test.cc
index 99cc0afe..3b4d4b0c 100644
--- a/absl/strings/internal/str_format/convert_test.cc
+++ b/absl/strings/internal/str_format/convert_test.cc
@@ -1,6 +1,7 @@
 #include <errno.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <cctype>
 #include <cmath>
 #include <string>
 
@@ -32,7 +33,9 @@ std::string LengthModFor(long long) { return "ll"; }           // NOLINT
 std::string LengthModFor(unsigned long long) { return "ll"; }  // NOLINT
 
 std::string EscCharImpl(int v) {
-  if (isprint(v)) return std::string(1, static_cast<char>(v));
+  if (std::isprint(static_cast<unsigned char>(v))) {
+    return std::string(1, static_cast<char>(v));
+  }
   char buf[64];
   int n = snprintf(buf, sizeof(buf), "\\%#.2x",
                    static_cast<unsigned>(v & 0xff));
@@ -155,7 +158,7 @@ TEST_F(FormatConvertTest, StringPrecision) {
 }
 
 TEST_F(FormatConvertTest, Pointer) {
-#if _MSC_VER
+#ifdef _MSC_VER
   // MSVC's printf implementation prints pointers differently. We can't easily
   // compare our implementation to theirs.
   return;
@@ -390,7 +393,7 @@ TEST_F(FormatConvertTest, Uint128) {
 }
 
 TEST_F(FormatConvertTest, Float) {
-#if _MSC_VER
+#ifdef _MSC_VER
   // MSVC has a different rounding policy than us so we can't test our
   // implementation against the native one there.
   return;
diff --git a/absl/synchronization/CMakeLists.txt b/absl/synchronization/CMakeLists.txt
index 9156f5ad..6fdbcb28 100644
--- a/absl/synchronization/CMakeLists.txt
+++ b/absl/synchronization/CMakeLists.txt
@@ -113,6 +113,8 @@ absl_cc_library(
     thread_pool
   HDRS
     "internal/thread_pool.h"
+  COPTS
+    ${ABSL_DEFAULT_COPTS}
   DEPS
     absl::synchronization
     absl::core_headers
diff --git a/absl/time/internal/cctz/BUILD.bazel b/absl/time/internal/cctz/BUILD.bazel
index 05f56bca..b05c2347 100644
--- a/absl/time/internal/cctz/BUILD.bazel
+++ b/absl/time/internal/cctz/BUILD.bazel
@@ -16,6 +16,20 @@ package(features = ["-parse_headers"])
 
 licenses(["notice"])  # Apache License
 
+config_setting(
+    name = "osx",
+    constraint_values = [
+        "@bazel_tools//platforms:osx",
+    ],
+)
+
+config_setting(
+    name = "ios",
+    constraint_values = [
+        "@bazel_tools//platforms:ios",
+    ],
+)
+
 ### libraries
 
 cc_library(
@@ -62,6 +76,15 @@ cc_library(
         "include/cctz/time_zone.h",
         "include/cctz/zone_info_source.h",
     ],
+    linkopts = select({
+        ":osx": [
+            "-framework Foundation",
+        ],
+        ":ios": [
+            "-framework Foundation",
+        ],
+        "//conditions:default": [],
+    }),
     visibility = ["//visibility:public"],
     deps = [":civil_time"],
 )
diff --git a/absl/time/internal/cctz/include/cctz/civil_time_detail.h b/absl/time/internal/cctz/include/cctz/civil_time_detail.h
index a5923f13..bb191b3f 100644
--- a/absl/time/internal/cctz/include/cctz/civil_time_detail.h
+++ b/absl/time/internal/cctz/include/cctz/civil_time_detail.h
@@ -21,7 +21,7 @@
 #include <type_traits>
 
 // Disable constexpr support unless we are in C++14 mode.
-#if __cpp_constexpr >= 201304 || _MSC_VER >= 1910
+#if __cpp_constexpr >= 201304 || (defined(_MSC_VER) && _MSC_VER >= 1910)
 #define CONSTEXPR_D constexpr  // data
 #define CONSTEXPR_F constexpr  // function
 #define CONSTEXPR_M constexpr  // member
diff --git a/absl/time/internal/cctz/src/civil_time_test.cc b/absl/time/internal/cctz/src/civil_time_test.cc
index e590ee30..dc7e5a1d 100644
--- a/absl/time/internal/cctz/src/civil_time_test.cc
+++ b/absl/time/internal/cctz/src/civil_time_test.cc
@@ -37,7 +37,7 @@ std::string Format(const T& t) {
 
 }  // namespace
 
-#if __cpp_constexpr >= 201304 || _MSC_VER >= 1910
+#if __cpp_constexpr >= 201304 || (defined(_MSC_VER) && _MSC_VER >= 1910)
 // Construction constexpr tests
 
 TEST(CivilTime, Normal) {
@@ -319,7 +319,7 @@ TEST(CivilTime, YearDay) {
   constexpr int yd = get_yearday(cd);
   static_assert(yd == 28, "YearDay");
 }
-#endif  // __cpp_constexpr >= 201304 || _MSC_VER >= 1910
+#endif  // __cpp_constexpr >= 201304 || (defined(_MSC_VER) && _MSC_VER >= 1910)
 
 // The remaining tests do not use constexpr.
 
diff --git a/absl/time/internal/cctz/src/time_zone_lookup.cc b/absl/time/internal/cctz/src/time_zone_lookup.cc
index a27bfc13..3c53dd1a 100644
--- a/absl/time/internal/cctz/src/time_zone_lookup.cc
+++ b/absl/time/internal/cctz/src/time_zone_lookup.cc
@@ -16,7 +16,7 @@
 
 #if defined(__ANDROID__)
 #include <sys/system_properties.h>
-#if __ANDROID_API__ >= 21
+#if defined(__ANDROID_API__) && __ANDROID_API__ >= 21
 #include <dlfcn.h>
 #endif
 #endif
@@ -37,7 +37,7 @@ namespace absl {
 namespace time_internal {
 namespace cctz {
 
-#if defined(__ANDROID__) && __ANDROID_API__ >= 21
+#if defined(__ANDROID__) && defined(__ANDROID_API__) && __ANDROID_API__ >= 21
 namespace {
 // Android 'L' removes __system_property_get() from the NDK, however
 // it is still a hidden symbol in libc so we use dlsym() to access it.
diff --git a/absl/time/time_test.cc b/absl/time/time_test.cc
index 74148d58..4d791f4d 100644
--- a/absl/time/time_test.cc
+++ b/absl/time/time_test.cc
@@ -28,7 +28,7 @@
 
 namespace {
 
-#if GTEST_USES_SIMPLE_RE
+#if defined(GTEST_USES_SIMPLE_RE) && GTEST_USES_SIMPLE_RE
 const char kZoneAbbrRE[] = ".*";  // just punt
 #else
 const char kZoneAbbrRE[] = "[A-Za-z]{3,4}|[-+][0-9]{2}([0-9]{2})?";
diff --git a/absl/types/any_test.cc b/absl/types/any_test.cc
index a6351bf9..87104721 100644
--- a/absl/types/any_test.cc
+++ b/absl/types/any_test.cc
@@ -154,6 +154,14 @@ TEST(AnyTest, InPlaceConstruction) {
   EXPECT_EQ(5, v.value);
 }
 
+TEST(AnyTest, InPlaceConstructionVariableTemplate) {
+  const CopyOnly copy_only{};
+  absl::any o(absl::in_place_type<IntMoveOnlyCopyOnly>, 5, MoveOnly(),
+              copy_only);
+  auto& v = absl::any_cast<IntMoveOnlyCopyOnly&>(o);
+  EXPECT_EQ(5, v.value);
+}
+
 TEST(AnyTest, InPlaceConstructionWithCV) {
   const CopyOnly copy_only{};
   absl::any o(absl::in_place_type_t<const volatile IntMoveOnlyCopyOnly>(), 5,
@@ -162,12 +170,26 @@ TEST(AnyTest, InPlaceConstructionWithCV) {
   EXPECT_EQ(5, v.value);
 }
 
+TEST(AnyTest, InPlaceConstructionWithCVVariableTemplate) {
+  const CopyOnly copy_only{};
+  absl::any o(absl::in_place_type<const volatile IntMoveOnlyCopyOnly>, 5,
+              MoveOnly(), copy_only);
+  auto& v = absl::any_cast<IntMoveOnlyCopyOnly&>(o);
+  EXPECT_EQ(5, v.value);
+}
+
 TEST(AnyTest, InPlaceConstructionWithFunction) {
   absl::any o(absl::in_place_type_t<FunctionType>(), FunctionToEmplace);
   FunctionType*& construction_result = absl::any_cast<FunctionType*&>(o);
   EXPECT_EQ(&FunctionToEmplace, construction_result);
 }
 
+TEST(AnyTest, InPlaceConstructionWithFunctionVariableTemplate) {
+  absl::any o(absl::in_place_type<FunctionType>, FunctionToEmplace);
+  auto& construction_result = absl::any_cast<FunctionType*&>(o);
+  EXPECT_EQ(&FunctionToEmplace, construction_result);
+}
+
 TEST(AnyTest, InPlaceConstructionWithArray) {
   ArrayType ar = {5, 42};
   absl::any o(absl::in_place_type_t<ArrayType>(), ar);
@@ -175,6 +197,13 @@ TEST(AnyTest, InPlaceConstructionWithArray) {
   EXPECT_EQ(&ar[0], construction_result);
 }
 
+TEST(AnyTest, InPlaceConstructionWithArrayVariableTemplate) {
+  ArrayType ar = {5, 42};
+  absl::any o(absl::in_place_type<ArrayType>, ar);
+  auto& construction_result = absl::any_cast<DecayedArray&>(o);
+  EXPECT_EQ(&ar[0], construction_result);
+}
+
 TEST(AnyTest, InPlaceConstructionIlist) {
   const CopyOnly copy_only{};
   absl::any o(absl::in_place_type_t<ListMoveOnlyCopyOnly>(), {1, 2, 3, 4},
@@ -184,6 +213,15 @@ TEST(AnyTest, InPlaceConstructionIlist) {
   EXPECT_EQ(expected_values, v.values);
 }
 
+TEST(AnyTest, InPlaceConstructionIlistVariableTemplate) {
+  const CopyOnly copy_only{};
+  absl::any o(absl::in_place_type<ListMoveOnlyCopyOnly>, {1, 2, 3, 4},
+              MoveOnly(), copy_only);
+  auto& v = absl::any_cast<ListMoveOnlyCopyOnly&>(o);
+  std::vector<int> expected_values = {1, 2, 3, 4};
+  EXPECT_EQ(expected_values, v.values);
+}
+
 TEST(AnyTest, InPlaceConstructionIlistWithCV) {
   const CopyOnly copy_only{};
   absl::any o(absl::in_place_type_t<const volatile ListMoveOnlyCopyOnly>(),
@@ -193,11 +231,25 @@ TEST(AnyTest, InPlaceConstructionIlistWithCV) {
   EXPECT_EQ(expected_values, v.values);
 }
 
+TEST(AnyTest, InPlaceConstructionIlistWithCVVariableTemplate) {
+  const CopyOnly copy_only{};
+  absl::any o(absl::in_place_type<const volatile ListMoveOnlyCopyOnly>,
+              {1, 2, 3, 4}, MoveOnly(), copy_only);
+  auto& v = absl::any_cast<ListMoveOnlyCopyOnly&>(o);
+  std::vector<int> expected_values = {1, 2, 3, 4};
+  EXPECT_EQ(expected_values, v.values);
+}
+
 TEST(AnyTest, InPlaceNoArgs) {
   absl::any o(absl::in_place_type_t<int>{});
   EXPECT_EQ(0, absl::any_cast<int&>(o));
 }
 
+TEST(AnyTest, InPlaceNoArgsVariableTemplate) {
+  absl::any o(absl::in_place_type<int>);
+  EXPECT_EQ(0, absl::any_cast<int&>(o));
+}
+
 template <typename Enabler, typename T, typename... Args>
 struct CanEmplaceAnyImpl : std::false_type {};
 
@@ -501,7 +553,7 @@ TEST(AnyTest, Copy) {
   InstanceTracker tracker_raii;
 
   {
-    absl::any o(absl::in_place_type_t<CopyableOnlyInstance>{}, 123);
+    absl::any o(absl::in_place_type<CopyableOnlyInstance>, 123);
     CopyableOnlyInstance* f1 = absl::any_cast<CopyableOnlyInstance>(&o);
 
     absl::any o2(o);
@@ -622,7 +674,7 @@ TEST(AnyTest, ThrowBadAlloc) {
   }
 
   {
-    absl::any a(absl::in_place_type_t<int>{});
+    absl::any a(absl::in_place_type<int>);
     ABSL_ANY_TEST_EXPECT_BAD_ANY_CAST(absl::any_cast<float&>(a));
     ABSL_ANY_TEST_EXPECT_BAD_ANY_CAST(absl::any_cast<const float&>(a));
     ABSL_ANY_TEST_EXPECT_BAD_ANY_CAST(absl::any_cast<float&&>(absl::any{}));
@@ -665,7 +717,7 @@ TEST(AnyTest, FailedCopy) {
   }
 
   {
-    absl::any src(absl::in_place_type_t<BadCopyable>{});
+    absl::any src(absl::in_place_type<BadCopyable>);
     ABSL_ANY_TEST_EXPECT_BAD_COPY(absl::any{src});
   }
 
@@ -677,21 +729,21 @@ TEST(AnyTest, FailedCopy) {
 
   {
     BadCopyable bad;
-    absl::any target(absl::in_place_type_t<BadCopyable>{});
+    absl::any target(absl::in_place_type<BadCopyable>);
     ABSL_ANY_TEST_EXPECT_BAD_COPY(target = bad);
     EXPECT_TRUE(target.has_value());
   }
 
   {
-    absl::any src(absl::in_place_type_t<BadCopyable>{});
+    absl::any src(absl::in_place_type<BadCopyable>);
     absl::any target;
     ABSL_ANY_TEST_EXPECT_BAD_COPY(target = src);
     EXPECT_FALSE(target.has_value());
   }
 
   {
-    absl::any src(absl::in_place_type_t<BadCopyable>{});
-    absl::any target(absl::in_place_type_t<BadCopyable>{});
+    absl::any src(absl::in_place_type<BadCopyable>);
+    absl::any target(absl::in_place_type<BadCopyable>);
     ABSL_ANY_TEST_EXPECT_BAD_COPY(target = src);
     EXPECT_TRUE(target.has_value());
   }
@@ -707,7 +759,7 @@ TEST(AnyTest, FailedEmplace) {
 
   {
     BadCopyable bad;
-    absl::any target(absl::in_place_type_t<int>{});
+    absl::any target(absl::in_place_type<int>);
     ABSL_ANY_TEST_EXPECT_BAD_COPY(target.emplace<BadCopyable>(bad));
 #if defined(ABSL_HAVE_STD_ANY) && defined(__GLIBCXX__)
     // libstdc++ std::any::emplace() implementation (as of 7.2) has a bug: if an
diff --git a/absl/types/variant_test.cc b/absl/types/variant_test.cc
index ab40ed2a..b9c98118 100644
--- a/absl/types/variant_test.cc
+++ b/absl/types/variant_test.cc
@@ -384,7 +384,7 @@ struct MoveOnly {
 TEST(VariantTest, TestMoveConstruct) {
   using V = variant<MoveOnly<class A>, MoveOnly<class B>, MoveOnly<class C>>;
 
-  V v(in_place_index_t<1>{}, 10);
+  V v(in_place_index<1>, 10);
   V v2 = absl::move(v);
   EXPECT_EQ(10, absl::get<1>(v2).value);
 }
@@ -483,6 +483,29 @@ TEST(VariantTest, InPlaceType) {
   EXPECT_THAT(absl::get<std::vector<int>>(v5), ::testing::ElementsAre(1, 2, 3));
 }
 
+TEST(VariantTest, InPlaceTypeVariableTemplate) {
+  using Var = variant<int, std::string, NonCopyable, std::vector<int>>;
+
+  Var v1(in_place_type<int>, 7);
+  ASSERT_TRUE(absl::holds_alternative<int>(v1));
+  EXPECT_EQ(7, absl::get<int>(v1));
+
+  Var v2(in_place_type<std::string>, "ABC");
+  ASSERT_TRUE(absl::holds_alternative<std::string>(v2));
+  EXPECT_EQ("ABC", absl::get<std::string>(v2));
+
+  Var v3(in_place_type<std::string>, "ABC", 2);
+  ASSERT_TRUE(absl::holds_alternative<std::string>(v3));
+  EXPECT_EQ("AB", absl::get<std::string>(v3));
+
+  Var v4(in_place_type<NonCopyable>);
+  ASSERT_TRUE(absl::holds_alternative<NonCopyable>(v4));
+
+  Var v5(in_place_type<std::vector<int>>, {1, 2, 3});
+  ASSERT_TRUE(absl::holds_alternative<std::vector<int>>(v5));
+  EXPECT_THAT(absl::get<std::vector<int>>(v5), ::testing::ElementsAre(1, 2, 3));
+}
+
 TEST(VariantTest, InPlaceTypeInitializerList) {
   using Var =
       variant<int, std::string, NonCopyable, MoveOnlyWithListConstructor>;
@@ -492,6 +515,15 @@ TEST(VariantTest, InPlaceTypeInitializerList) {
   EXPECT_EQ(6, absl::get<MoveOnlyWithListConstructor>(v1).value);
 }
 
+TEST(VariantTest, InPlaceTypeInitializerListVariabletemplate) {
+  using Var =
+      variant<int, std::string, NonCopyable, MoveOnlyWithListConstructor>;
+
+  Var v1(in_place_type<MoveOnlyWithListConstructor>, {1, 2, 3, 4, 5}, 6);
+  ASSERT_TRUE(absl::holds_alternative<MoveOnlyWithListConstructor>(v1));
+  EXPECT_EQ(6, absl::get<MoveOnlyWithListConstructor>(v1).value);
+}
+
 TEST(VariantTest, InPlaceIndex) {
   using Var = variant<int, std::string, NonCopyable, std::vector<int>>;
 
@@ -519,6 +551,33 @@ TEST(VariantTest, InPlaceIndex) {
   EXPECT_THAT(absl::get<std::vector<int>>(v5), ::testing::ElementsAre(1, 2, 3));
 }
 
+TEST(VariantTest, InPlaceIndexVariableTemplate) {
+  using Var = variant<int, std::string, NonCopyable, std::vector<int>>;
+
+  Var v1(in_place_index<0>, 7);
+  ASSERT_TRUE(absl::holds_alternative<int>(v1));
+  EXPECT_EQ(7, absl::get<int>(v1));
+
+  Var v2(in_place_index<1>, "ABC");
+  ASSERT_TRUE(absl::holds_alternative<std::string>(v2));
+  EXPECT_EQ("ABC", absl::get<std::string>(v2));
+
+  Var v3(in_place_index<1>, "ABC", 2);
+  ASSERT_TRUE(absl::holds_alternative<std::string>(v3));
+  EXPECT_EQ("AB", absl::get<std::string>(v3));
+
+  Var v4(in_place_index<2>);
+  EXPECT_TRUE(absl::holds_alternative<NonCopyable>(v4));
+
+  // Verify that a variant with only non-copyables can still be constructed.
+  EXPECT_TRUE(absl::holds_alternative<NonCopyable>(
+      variant<NonCopyable>(in_place_index<0>)));
+
+  Var v5(in_place_index<3>, {1, 2, 3});
+  ASSERT_TRUE(absl::holds_alternative<std::vector<int>>(v5));
+  EXPECT_THAT(absl::get<std::vector<int>>(v5), ::testing::ElementsAre(1, 2, 3));
+}
+
 TEST(VariantTest, InPlaceIndexInitializerList) {
   using Var =
       variant<int, std::string, NonCopyable, MoveOnlyWithListConstructor>;
@@ -528,6 +587,15 @@ TEST(VariantTest, InPlaceIndexInitializerList) {
   EXPECT_EQ(6, absl::get<MoveOnlyWithListConstructor>(v1).value);
 }
 
+TEST(VariantTest, InPlaceIndexInitializerListVariableTemplate) {
+  using Var =
+      variant<int, std::string, NonCopyable, MoveOnlyWithListConstructor>;
+
+  Var v1(in_place_index<3>, {1, 2, 3, 4, 5}, 6);
+  ASSERT_TRUE(absl::holds_alternative<MoveOnlyWithListConstructor>(v1));
+  EXPECT_EQ(6, absl::get<MoveOnlyWithListConstructor>(v1).value);
+}
+
 ////////////////////
 // [variant.dtor] //
 ////////////////////
@@ -576,7 +644,7 @@ TEST(VariantTest, TestDtorValuelessByException)
   {
     using Variant = VariantFactory<IncrementInDtor>::Type;
 
-    Variant v(in_place_index_t<0>(), counter_adjuster);
+    Variant v(in_place_index<0>, counter_adjuster);
     EXPECT_EQ(0, counter);
 
     ToValuelessByException(v);
@@ -810,7 +878,7 @@ TEST(VariantTest, TestBackupAssign) {
 TEST(VariantTest, TestEmplaceBasic) {
   using Variant = variant<int, char>;
 
-  Variant v(absl::in_place_index_t<0>{}, 0);
+  Variant v(absl::in_place_index<0>, 0);
 
   {
     char& emplace_result = v.emplace<char>();
@@ -837,7 +905,7 @@ TEST(VariantTest, TestEmplaceInitializerList) {
   using Var =
       variant<int, std::string, NonCopyable, MoveOnlyWithListConstructor>;
 
-  Var v1(absl::in_place_index_t<0>{}, 555);
+  Var v1(absl::in_place_index<0>, 555);
   MoveOnlyWithListConstructor& emplace_result =
       v1.emplace<MoveOnlyWithListConstructor>({1, 2, 3, 4, 5}, 6);
   ASSERT_TRUE(absl::holds_alternative<MoveOnlyWithListConstructor>(v1));
@@ -848,7 +916,7 @@ TEST(VariantTest, TestEmplaceInitializerList) {
 TEST(VariantTest, TestEmplaceIndex) {
   using Variant = variant<int, char>;
 
-  Variant v(absl::in_place_index_t<0>{}, 555);
+  Variant v(absl::in_place_index<0>, 555);
 
   {
     char& emplace_result = v.emplace<1>();
@@ -875,7 +943,7 @@ TEST(VariantTest, TestEmplaceIndexInitializerList) {
   using Var =
       variant<int, std::string, NonCopyable, MoveOnlyWithListConstructor>;
 
-  Var v1(absl::in_place_index_t<0>{}, 555);
+  Var v1(absl::in_place_index<0>, 555);
   MoveOnlyWithListConstructor& emplace_result =
       v1.emplace<3>({1, 2, 3, 4, 5}, 6);
   ASSERT_TRUE(absl::holds_alternative<MoveOnlyWithListConstructor>(v1));
@@ -924,7 +992,7 @@ TEST(VariantTest, NotValuelessByException) {
 TEST(VariantTest, IndexValuelessByException) {
   using Var = variant<MoveCanThrow, std::string, double>;
 
-  Var v(absl::in_place_index_t<0>{});
+  Var v(absl::in_place_index<0>);
   EXPECT_EQ(0, v.index());
   ToValuelessByException(v);
   EXPECT_EQ(absl::variant_npos, v.index());
@@ -935,7 +1003,7 @@ TEST(VariantTest, IndexValuelessByException) {
 TEST(VariantTest, ValuelessByException) {
   using Var = variant<MoveCanThrow, std::string, double>;
 
-  Var v(absl::in_place_index_t<0>{});
+  Var v(absl::in_place_index<0>);
   EXPECT_FALSE(v.valueless_by_exception());
   ToValuelessByException(v);
   EXPECT_TRUE(v.valueless_by_exception());
@@ -966,7 +1034,7 @@ TEST(VariantTest, MemberSwap) {
   using V = variant<MoveCanThrow, std::string, int>;
   int i = 33;
   std::string s = "abc";
-  V valueless(in_place_index_t<0>{});
+  V valueless(in_place_index<0>);
   ToValuelessByException(valueless);
   {
     // lhs and rhs holds different alternative
@@ -1127,7 +1195,7 @@ TEST(VariantTest, GetIndex) {
   using Var = variant<int, std::string, double, int>;
 
   {
-    Var v(absl::in_place_index_t<0>{}, 0);
+    Var v(absl::in_place_index<0>, 0);
 
     using LValueGetType = decltype(absl::get<0>(v));
     using RValueGetType = decltype(absl::get<0>(absl::move(v)));
@@ -1187,7 +1255,7 @@ TEST(VariantTest, GetIndex) {
   }
 
   {
-    Var v(absl::in_place_index_t<0>{}, 0);
+    Var v(absl::in_place_index<0>, 0);
     v.emplace<3>(1);
 
     using LValueGetType = decltype(absl::get<3>(v));
@@ -1334,7 +1402,7 @@ TEST(VariantTest, GetIfIndex) {
   using Var = variant<int, std::string, double, int>;
 
   {
-    Var v(absl::in_place_index_t<0>{}, 0);
+    Var v(absl::in_place_index<0>, 0);
     EXPECT_TRUE(noexcept(absl::get_if<0>(&v)));
 
     {
@@ -1492,7 +1560,7 @@ TEST(VariantTest, GetIfIndex) {
   }
 
   {
-    Var v(absl::in_place_index_t<0>{}, 0);
+    Var v(absl::in_place_index<0>, 0);
     v.emplace<3>(1);
     EXPECT_TRUE(noexcept(absl::get_if<3>(&v)));
 
@@ -1638,8 +1706,8 @@ TEST(VariantTest, OperatorRelational) {
 
 TEST(VariantTest, ValuelessOperatorEquals) {
   variant<MoveCanThrow, std::string> int_v(1), string_v("Hello"),
-      valueless(absl::in_place_index_t<0>{}),
-      other_valueless(absl::in_place_index_t<0>{});
+      valueless(absl::in_place_index<0>),
+      other_valueless(absl::in_place_index<0>);
   ToValuelessByException(valueless);
   ToValuelessByException(other_valueless);
 
@@ -1660,8 +1728,8 @@ TEST(VariantTest, ValuelessOperatorEquals) {
 
 TEST(VariantTest, ValuelessOperatorRelational) {
   variant<MoveCanThrow, std::string> int_v(1), string_v("Hello"),
-      valueless(absl::in_place_index_t<0>{}),
-      other_valueless(absl::in_place_index_t<0>{});
+      valueless(absl::in_place_index<0>),
+      other_valueless(absl::in_place_index<0>);
   ToValuelessByException(valueless);
   ToValuelessByException(other_valueless);
 
@@ -2008,8 +2076,8 @@ TEST(VariantTest, Hash) {
 #if !(defined(_MSC_VER) && defined(ABSL_HAVE_STD_VARIANT))
   {
     // same value as different alternative
-    variant<int, int> v0(in_place_index_t<0>{}, 42);
-    variant<int, int> v1(in_place_index_t<1>{}, 42);
+    variant<int, int> v0(in_place_index<0>, 42);
+    variant<int, int> v1(in_place_index<1>, 42);
     std::hash<variant<int, int>> hash;
     EXPECT_NE(hash(v0), hash(v1));
   }
@@ -2605,7 +2673,7 @@ TEST(VariantTest, MoveCtorBug) {
   };
   {
     using V = absl::variant<TrivialCopyNontrivialMove, int>;
-    V v1(absl::in_place_index_t<0>{});
+    V v1(absl::in_place_index<0>);
     // this should invoke the move ctor, rather than the trivial copy ctor.
     V v2(std::move(v1));
     EXPECT_TRUE(absl::get<0>(v2).called);
@@ -2613,7 +2681,7 @@ TEST(VariantTest, MoveCtorBug) {
   {
     // this case failed to compile before our fix due to a GCC bug.
     using V = absl::variant<int, TrivialCopyNontrivialMove>;
-    V v1(absl::in_place_index_t<1>{});
+    V v1(absl::in_place_index<1>);
     // this should invoke the move ctor, rather than the trivial copy ctor.
     V v2(std::move(v1));
     EXPECT_TRUE(absl::get<1>(v2).called);
diff --git a/absl/utility/utility.h b/absl/utility/utility.h
index 853c1fb8..7686db12 100644
--- a/absl/utility/utility.h
+++ b/absl/utility/utility.h
@@ -113,6 +113,20 @@ struct Gen<T, 0> {
   using type = integer_sequence<T>;
 };
 
+template <typename T>
+struct InPlaceTypeTag {
+  explicit InPlaceTypeTag() = delete;
+  InPlaceTypeTag(const InPlaceTypeTag&) = delete;
+  InPlaceTypeTag& operator=(const InPlaceTypeTag&) = delete;
+};
+
+template <size_t I>
+struct InPlaceIndexTag {
+  explicit InPlaceIndexTag() = delete;
+  InPlaceIndexTag(const InPlaceIndexTag&) = delete;
+  InPlaceIndexTag& operator=(const InPlaceIndexTag&) = delete;
+};
+
 }  // namespace utility_internal
 
 // Compile-time sequences of integers
@@ -162,6 +176,7 @@ ABSL_INTERNAL_INLINE_CONSTEXPR(in_place_t, in_place, {});
 #endif  // ABSL_HAVE_STD_OPTIONAL
 
 #if defined(ABSL_HAVE_STD_ANY) || defined(ABSL_HAVE_STD_VARIANT)
+using std::in_place_type;
 using std::in_place_type_t;
 #else
 
@@ -171,10 +186,14 @@ using std::in_place_type_t;
 // be specified, such as with `absl::any`, designed to be a drop-in replacement
 // for C++17's `std::in_place_type_t`.
 template <typename T>
-struct in_place_type_t {};
+using in_place_type_t = void (*)(utility_internal::InPlaceTypeTag<T>);
+
+template <typename T>
+void in_place_type(utility_internal::InPlaceTypeTag<T>) {}
 #endif  // ABSL_HAVE_STD_ANY || ABSL_HAVE_STD_VARIANT
 
 #ifdef ABSL_HAVE_STD_VARIANT
+using std::in_place_index;
 using std::in_place_index_t;
 #else
 
@@ -184,7 +203,10 @@ using std::in_place_index_t;
 // be specified, such as with `absl::any`, designed to be a drop-in replacement
 // for C++17's `std::in_place_index_t`.
 template <size_t I>
-struct in_place_index_t {};
+using in_place_index_t = void (*)(utility_internal::InPlaceIndexTag<I>);
+
+template <size_t I>
+void in_place_index(utility_internal::InPlaceIndexTag<I>) {}
 #endif  // ABSL_HAVE_STD_VARIANT
 
 // Constexpr move and forward