From 389ec3f906f018661a5308458d623d01f96d7b23 Mon Sep 17 00:00:00 2001
From: Abseil Team <absl-team@google.com>
Date: Thu, 13 Dec 2018 10:30:03 -0800
Subject: Export of internal Abseil changes. --
 636137f6f0de910691a3950387fefacfa4909fb8 by Abseil Team
 <absl-team@google.com>:

Add move semantics to absl::container_internal::CompressedTuple

PiperOrigin-RevId: 225394165

--
43da91e4f95a196b2e6b76f1c2f4158817b0ebb0 by Greg Falcon <gfalcon@google.com>:

Add a constructor to allow for global absl::Mutex instances.

This adds a new constexpr constructor to absl::Mutex, invoked with the absl::kConstInit tag value, which is intended to be used to construct Mutex instances with static storage duration.

What's tricky about is absl::Mutex (like std::mutex) is not a trivially destructible class, so by the letter of the law, accessing a global Mutex instance after it is destroyed results in undefined behavior.  Despite this, we take care in the destructor to not invalidate the memory layout of the Mutex.  Using a kConstInit-constructed global Mutex after it is destroyed happens to work on the toolchains we use.  Google relies heavily on this behavior internally.

Code sanitizers that detect undefined behavior are able to notice use-after-free of globals, and might complain about this pattern.

PiperOrigin-RevId: 225389447

--
7b553a54bc6460cc7008b028552e66799475ca64 by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 225373389

--
fd0c722d217b3b509102274765ccb1a0b596cf46 by Abseil Team <absl-team@google.com>:

Update absl/time/CMakeLists.txt to use new functions
i.e. absl_cc_(library|test)

PiperOrigin-RevId: 225246853

--
9f8f3ba3b67a6d1ac4ecdc529c8b8eb0f02576d9 by Abseil Team <absl-team@google.com>:

Update absl/synchronisation/CMakeLists.txt to use new functions
i.e. absl_cc_(library|test)

PiperOrigin-RevId: 225237980

--
a3fdd67dad2e596f804f5e100c8d3a74d8064faa by Abseil Team <absl-team@google.com>:

Internal cleanup

PiperOrigin-RevId: 225226813

--
48fab23fb8cdca45e95da14fce0de56614d09c25 by Jon Cohen <cohenjon@google.com>:

Use a shim #define for wchar_t in msvc in int128.

On ancient versions of msvc and with some compatibility flags on wchar_t is a typedef for unsigned short, whereas on standards-conforming versions wchar_t is a typedef for __wchar_t.  The first situation causes int128 to not compile as you can't define both `operator wchar_t()` and `operator unsigned short()` because they are the same type.

This CL introduces a wrapper #define in order to abstract over the different typedefs for wchar_t.  We do a define instead of a typedef so that we can #undef at the end and not leak the symbol, since we need it in a header.

https://docs.microsoft.com/en-us/previous-versions/dh8che7s(v=vs.140) has more detail about the underlying problem.

PiperOrigin-RevId: 225223756
GitOrigin-RevId: 636137f6f0de910691a3950387fefacfa4909fb8
Change-Id: Iad94e52e9484c5acec115a2f09ef2d5ec22c2074
---
 absl/synchronization/internal/mutex_nonprod.inc | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'absl/synchronization/internal/mutex_nonprod.inc')

diff --git a/absl/synchronization/internal/mutex_nonprod.inc b/absl/synchronization/internal/mutex_nonprod.inc
index 0aab3d13..b8d5af79 100644
--- a/absl/synchronization/internal/mutex_nonprod.inc
+++ b/absl/synchronization/internal/mutex_nonprod.inc
@@ -214,6 +214,9 @@ class SynchronizationStorage {
   // stack) should use this constructor.
   explicit SynchronizationStorage(base_internal::LinkerInitialized) {}
 
+  constexpr explicit SynchronizationStorage(absl::ConstInitType)
+      : is_dynamic_(false), once_(), space_{{0}} {}
+
   SynchronizationStorage(SynchronizationStorage&) = delete;
   SynchronizationStorage& operator=(SynchronizationStorage&) = delete;
 
-- 
cgit v1.2.3


From 12bc53e0318d80569270a5b26ccbc62b52022b89 Mon Sep 17 00:00:00 2001
From: Abseil Team <absl-team@google.com>
Date: Thu, 12 Dec 2019 10:36:03 -0800
Subject: Export of internal Abseil changes

--
c99f979ad34f155fbeeea69b88bdc7458d89a21c by Derek Mauro <dmauro@google.com>:

Remove a floating point division by zero test.

This isn't testing behavior related to the library, and MSVC warns
about it in opt mode.

PiperOrigin-RevId: 285220804

--
68b015491f0dbf1ab547994673281abd1f34cd4b by Gennadiy Rozental <rogeeff@google.com>:

This CL introduces following changes to the class FlagImpl:
* We eliminate the CommandLineFlagLocks struct. Instead callback guard and callback function are combined into a single CallbackData struct, while primary data lock is stored separately.
* CallbackData member of class FlagImpl is initially set to be nullptr and is only allocated and initialized when a flag's callback is being set. For most flags we do not pay for the extra space and extra absl::Mutex now.
* Primary data guard is stored in data_guard_ data member. This is a properly aligned character buffer of necessary size. During initialization of the flag we construct absl::Mutex in this space using placement new call.
* We now avoid extra value copy after successful attempt to parse value out of string. Instead we swap flag's current value with tentative value we just produced.

PiperOrigin-RevId: 285132636

--
ed45d118fb818969eb13094cf7827c885dfc562c by Tom Manshreck <shreck@google.com>:

Change null-term* (and nul-term*) to NUL-term* in comments

PiperOrigin-RevId: 285036610

--
729619017944db895ce8d6d29c1995aa2e5628a5 by Derek Mauro <dmauro@google.com>:

Use the Posix implementation of thread identity on MinGW.
Some versions of MinGW suffer from thread_local bugs.

PiperOrigin-RevId: 285022920

--
39a25493503c76885bc3254c28f66a251c5b5bb0 by Greg Falcon <gfalcon@google.com>:

Implementation detail change.

Add further ABSL_NAMESPACE_BEGIN and _END annotation macros to files in Abseil.

PiperOrigin-RevId: 285012012
GitOrigin-RevId: c99f979ad34f155fbeeea69b88bdc7458d89a21c
Change-Id: I4c85d3704e45d11a9ac50d562f39640a6adbedc1
---
 absl/algorithm/BUILD.bazel                         |   1 +
 absl/algorithm/CMakeLists.txt                      |   2 +
 absl/algorithm/algorithm.h                         |   4 +
 absl/algorithm/container.h                         |   2 +
 absl/base/internal/raw_logging.h                   |   2 +-
 absl/base/internal/thread_identity.h               |   2 +-
 absl/container/BUILD.bazel                         |   8 ++
 absl/container/CMakeLists.txt                      |   8 ++
 absl/container/btree_map.h                         |   2 +
 absl/container/btree_set.h                         |   2 +
 absl/container/btree_test.cc                       |   2 +
 absl/container/btree_test.h                        |   2 +
 absl/container/fixed_array.h                       |   2 +
 .../container/fixed_array_exception_safety_test.cc |   2 +
 absl/container/flat_hash_map.h                     |   2 +
 absl/container/flat_hash_map_test.cc               |   2 +
 absl/container/flat_hash_set.h                     |   2 +
 absl/container/flat_hash_set_test.cc               |   2 +
 absl/container/inlined_vector.h                    |   2 +
 absl/container/internal/btree.h                    |   2 +
 absl/container/internal/btree_container.h          |   2 +
 absl/container/internal/common.h                   |   2 +
 absl/container/internal/compressed_tuple.h         |   2 +
 absl/container/internal/compressed_tuple_test.cc   |   2 +
 absl/container/internal/container_memory.h         |   2 +
 absl/container/internal/container_memory_test.cc   |   2 +
 absl/container/internal/counting_allocator.h       |   4 +
 absl/container/internal/hash_function_defaults.h   |   2 +
 .../internal/hash_function_defaults_test.cc        |   4 +
 absl/container/internal/hash_generator_testing.cc  |   2 +
 absl/container/internal/hash_generator_testing.h   |   2 +
 absl/container/internal/hash_policy_testing.h      |   2 +
 .../container/internal/hash_policy_testing_test.cc |   2 +
 absl/container/internal/hash_policy_traits.h       |   2 +
 absl/container/internal/hash_policy_traits_test.cc |   2 +
 absl/container/internal/hashtable_debug.h          |   2 +
 absl/container/internal/hashtable_debug_hooks.h    |   4 +
 absl/container/internal/hashtablez_sampler.cc      |   2 +
 absl/container/internal/hashtablez_sampler.h       |   2 +
 .../hashtablez_sampler_force_weak_definition.cc    |   2 +
 absl/container/internal/hashtablez_sampler_test.cc |   2 +
 absl/container/internal/inlined_vector.h           |   2 +
 absl/container/internal/layout.h                   |   2 +
 absl/container/internal/layout_test.cc             |   2 +
 absl/container/internal/node_hash_policy.h         |   4 +
 absl/container/internal/node_hash_policy_test.cc   |   2 +
 absl/container/internal/raw_hash_map.h             |   2 +
 absl/container/internal/raw_hash_set.cc            |   2 +
 absl/container/internal/raw_hash_set.h             |   2 +
 .../internal/raw_hash_set_allocator_test.cc        |   2 +
 absl/container/internal/raw_hash_set_test.cc       |   2 +
 absl/container/internal/test_instance_tracker.cc   |   2 +
 absl/container/internal/test_instance_tracker.h    |   2 +
 absl/container/internal/tracked.h                  |   5 +
 .../internal/unordered_map_constructor_test.h      |   2 +
 .../container/internal/unordered_map_lookup_test.h |   2 +
 .../internal/unordered_map_members_test.h          |   2 +
 .../internal/unordered_map_modifiers_test.h        |   2 +
 absl/container/internal/unordered_map_test.cc      |   2 +
 .../internal/unordered_set_constructor_test.h      |   2 +
 .../container/internal/unordered_set_lookup_test.h |   2 +
 .../internal/unordered_set_members_test.h          |   2 +
 .../internal/unordered_set_modifiers_test.h        |   2 +
 absl/container/internal/unordered_set_test.cc      |   2 +
 absl/container/node_hash_map.h                     |   2 +
 absl/container/node_hash_map_test.cc               |   2 +
 absl/container/node_hash_set.h                     |   2 +
 absl/container/node_hash_set_test.cc               |   2 +
 absl/debugging/BUILD.bazel                         |  18 +++-
 absl/debugging/CMakeLists.txt                      |   6 ++
 absl/debugging/failure_signal_handler.cc           |   2 +
 absl/debugging/failure_signal_handler.h            |   4 +
 absl/debugging/internal/address_is_readable.cc     |   4 +
 absl/debugging/internal/address_is_readable.h      |   4 +
 absl/debugging/internal/demangle.cc                |   2 +
 absl/debugging/internal/demangle.h                 |   4 +
 absl/debugging/internal/demangle_test.cc           |   2 +
 absl/debugging/internal/elf_mem_image.cc           |   2 +
 absl/debugging/internal/elf_mem_image.h            |   4 +
 absl/debugging/internal/examine_stack.cc           |   2 +
 absl/debugging/internal/examine_stack.h            |   4 +
 absl/debugging/internal/stack_consumption.cc       |   2 +
 absl/debugging/internal/stack_consumption.h        |   4 +
 absl/debugging/internal/stack_consumption_test.cc  |   2 +
 absl/debugging/internal/stacktrace_aarch64-inl.inc |   2 +
 absl/debugging/internal/stacktrace_arm-inl.inc     |   2 +
 absl/debugging/internal/stacktrace_generic-inl.inc |   2 +
 absl/debugging/internal/stacktrace_powerpc-inl.inc |   2 +
 .../internal/stacktrace_unimplemented-inl.inc      |   2 +
 absl/debugging/internal/stacktrace_win32-inl.inc   |   2 +
 absl/debugging/internal/stacktrace_x86-inl.inc     |   2 +
 absl/debugging/internal/symbolize.h                |   6 ++
 absl/debugging/internal/vdso_support.cc            |   2 +
 absl/debugging/internal/vdso_support.h             |   2 +
 absl/debugging/leak_check.cc                       |   4 +
 absl/debugging/leak_check.h                        |   4 +
 absl/debugging/stacktrace.cc                       |   2 +
 absl/debugging/stacktrace.h                        |   4 +
 absl/debugging/symbolize.h                         |   2 +
 absl/debugging/symbolize_elf.inc                   |   2 +
 absl/debugging/symbolize_unimplemented.inc         |   2 +
 absl/debugging/symbolize_win32.inc                 |   2 +
 absl/flags/declare.h                               |   2 +
 absl/flags/flag.cc                                 |   2 +
 absl/flags/flag.h                                  |   2 +
 absl/flags/flag_test_defs.cc                       |   2 +
 absl/flags/internal/commandlineflag.cc             |   2 +
 absl/flags/internal/commandlineflag.h              |   4 +-
 absl/flags/internal/flag.cc                        | 113 ++++++++++++++-------
 absl/flags/internal/flag.h                         |  54 +++++-----
 absl/flags/internal/parse.h                        |   2 +
 absl/flags/internal/path_util.h                    |   2 +
 absl/flags/internal/program_name.cc                |   2 +
 absl/flags/internal/program_name.h                 |   2 +
 absl/flags/internal/registry.cc                    |   4 +-
 absl/flags/internal/registry.h                     |   2 +
 absl/flags/internal/type_erased.cc                 |   2 +
 absl/flags/internal/type_erased.h                  |   2 +
 absl/flags/internal/usage.cc                       |   2 +
 absl/flags/internal/usage.h                        |   2 +
 absl/flags/marshalling.cc                          |   2 +
 absl/flags/marshalling.h                           |   2 +
 absl/flags/parse.cc                                |   4 +
 absl/flags/parse.h                                 |   2 +
 absl/flags/usage.cc                                |   2 +
 absl/flags/usage.h                                 |   2 +
 absl/flags/usage_config.cc                         |   2 +
 absl/flags/usage_config.h                          |   2 +
 absl/functional/function_ref.h                     |   2 +
 absl/functional/function_ref_benchmark.cc          |   2 +
 absl/functional/function_ref_test.cc               |   2 +
 absl/functional/internal/function_ref.h            |   2 +
 absl/hash/hash.h                                   |   2 +
 absl/hash/hash_test.cc                             |   2 +
 absl/hash/hash_testing.h                           |   2 +
 absl/hash/internal/city.cc                         |   2 +
 absl/hash/internal/city.h                          |   5 +
 absl/hash/internal/city_test.cc                    |   2 +
 absl/hash/internal/hash.cc                         |   2 +
 absl/hash/internal/hash.h                          |   2 +
 absl/hash/internal/spy_hash_state.h                |   2 +
 absl/memory/memory.h                               |   2 +
 absl/memory/memory_exception_safety_test.cc        |   2 +
 absl/meta/type_traits.h                            |   2 +
 absl/numeric/int128.cc                             |   2 +
 absl/numeric/int128.h                              |   6 ++
 absl/random/CMakeLists.txt                         |  14 +++
 absl/random/bernoulli_distribution.h               |   2 +
 absl/random/beta_distribution.h                    |   2 +
 absl/random/bit_gen_ref.h                          |   2 +
 absl/random/bit_gen_ref_test.cc                    |   2 +
 absl/random/discrete_distribution.cc               |   2 +
 absl/random/discrete_distribution.h                |   2 +
 absl/random/distribution_format_traits.h           |   2 +
 absl/random/distributions.h                        |   2 +
 absl/random/exponential_distribution.h             |   2 +
 absl/random/gaussian_distribution.cc               |   2 +
 absl/random/gaussian_distribution.h                |   2 +
 absl/random/internal/BUILD.bazel                   |   9 ++
 absl/random/internal/chi_square.cc                 |   2 +
 absl/random/internal/chi_square.h                  |   4 +
 absl/random/internal/distribution_caller.h         |   4 +
 absl/random/internal/distribution_test_util.cc     |   2 +
 absl/random/internal/distribution_test_util.h      |   2 +
 absl/random/internal/distributions.h               |   2 +
 absl/random/internal/explicit_seed_seq.h           |   4 +
 absl/random/internal/fast_uniform_bits.h           |   4 +
 absl/random/internal/fast_uniform_bits_test.cc     |   2 +
 absl/random/internal/fastmath.h                    |   2 +
 .../internal/gaussian_distribution_gentables.cc    |   2 +
 absl/random/internal/generate_real.h               |   2 +
 absl/random/internal/iostream_state_saver.h        |   2 +
 absl/random/internal/mock_overload_set.h           |   2 +
 absl/random/internal/mocking_bit_gen_base.h        |   2 +
 absl/random/internal/nanobenchmark.cc              |   2 +
 absl/random/internal/nanobenchmark.h               |   4 +
 absl/random/internal/nanobenchmark_test.cc         |   2 +
 absl/random/internal/nonsecure_base.h              |   2 +
 absl/random/internal/pcg_engine.h                  |   2 +
 absl/random/internal/pool_urbg.cc                  |   2 +
 absl/random/internal/pool_urbg.h                   |   2 +
 absl/random/internal/randen.cc                     |   2 +
 absl/random/internal/randen.h                      |   2 +
 absl/random/internal/randen_detect.cc              |   2 +
 absl/random/internal/randen_detect.h               |   4 +
 absl/random/internal/randen_engine.h               |   2 +
 absl/random/internal/randen_hwaes.cc               |   4 +
 absl/random/internal/randen_hwaes.h                |   4 +
 absl/random/internal/randen_slow.cc                |   2 +
 absl/random/internal/randen_slow.h                 |   4 +
 absl/random/internal/randen_traits.h               |   4 +
 absl/random/internal/salted_seed_seq.h             |   2 +
 absl/random/internal/seed_material.cc              |   2 +
 absl/random/internal/seed_material.h               |   2 +
 absl/random/internal/sequence_urbg.h               |   4 +
 absl/random/internal/traits.h                      |   2 +
 absl/random/internal/uniform_helper.h              |   2 +
 absl/random/internal/wide_multiply.h               |   2 +
 absl/random/log_uniform_int_distribution.h         |   2 +
 absl/random/mock_distributions.h                   |   2 +
 absl/random/mocking_bit_gen.cc                     |   2 +
 absl/random/mocking_bit_gen.h                      |   2 +
 absl/random/poisson_distribution.h                 |   2 +
 absl/random/random.h                               |   2 +
 absl/random/seed_gen_exception.cc                  |   2 +
 absl/random/seed_gen_exception.h                   |   4 +
 absl/random/seed_sequences.cc                      |   2 +
 absl/random/seed_sequences.h                       |   2 +
 absl/random/uniform_int_distribution.h             |   2 +
 absl/random/uniform_real_distribution.h            |   2 +
 absl/random/zipf_distribution.h                    |   2 +
 absl/strings/BUILD.bazel                           |   5 +
 absl/strings/CMakeLists.txt                        |   6 ++
 absl/strings/ascii.cc                              |   2 +
 absl/strings/ascii.h                               |   2 +
 absl/strings/charconv.cc                           |   2 +
 absl/strings/charconv.h                            |   4 +
 absl/strings/escaping.cc                           |   2 +
 absl/strings/escaping.h                            |   2 +
 absl/strings/internal/char_map.h                   |   2 +
 absl/strings/internal/charconv_bigint.cc           |   2 +
 absl/strings/internal/charconv_bigint.h            |   2 +
 absl/strings/internal/charconv_bigint_test.cc      |   2 +
 absl/strings/internal/charconv_parse.cc            |   2 +
 absl/strings/internal/charconv_parse.h             |   3 +
 absl/strings/internal/escaping_test_common.h       |   2 +
 absl/strings/internal/memutil.cc                   |   2 +
 absl/strings/internal/memutil.h                    |   2 +
 absl/strings/internal/numbers_test_common.h        |   4 +
 absl/strings/internal/ostringstream.cc             |   2 +
 absl/strings/internal/ostringstream.h              |   2 +
 absl/strings/internal/pow10_helper.cc              |   2 +
 absl/strings/internal/pow10_helper.h               |   4 +
 absl/strings/internal/pow10_helper_test.cc         |   2 +
 absl/strings/internal/resize_uninitialized.h       |   2 +
 absl/strings/internal/stl_type_traits.h            |   2 +
 absl/strings/internal/str_format/arg.cc            |   2 +
 absl/strings/internal/str_format/arg.h             |   2 +
 absl/strings/internal/str_format/arg_test.cc       |   2 +
 absl/strings/internal/str_format/bind.cc           |   2 +
 absl/strings/internal/str_format/bind.h            |   2 +
 absl/strings/internal/str_format/bind_test.cc      |   2 +
 absl/strings/internal/str_format/checker.h         |   2 +
 absl/strings/internal/str_format/checker_test.cc   |   2 +
 absl/strings/internal/str_format/convert_test.cc   |   2 +
 absl/strings/internal/str_format/extension.cc      |   2 +
 absl/strings/internal/str_format/extension.h       |   2 +
 .../internal/str_format/float_conversion.cc        |   2 +
 .../strings/internal/str_format/float_conversion.h |   2 +
 absl/strings/internal/str_format/output.cc         |   2 +
 absl/strings/internal/str_format/output.h          |   2 +
 absl/strings/internal/str_format/output_test.cc    |   2 +
 absl/strings/internal/str_format/parser.cc         |   2 +
 absl/strings/internal/str_format/parser.h          |   2 +
 absl/strings/internal/str_format/parser_test.cc    |   2 +
 absl/strings/internal/str_join_internal.h          |   2 +
 absl/strings/internal/str_split_internal.h         |   2 +
 absl/strings/internal/utf8.cc                      |   2 +
 absl/strings/internal/utf8.h                       |   4 +
 absl/strings/match.cc                              |   2 +
 absl/strings/match.h                               |   4 +-
 absl/strings/numbers.cc                            |   2 +
 absl/strings/numbers.h                             |   4 +
 absl/strings/str_cat.cc                            |   2 +
 absl/strings/str_cat.h                             |   2 +
 absl/strings/str_format.h                          |   2 +
 absl/strings/str_format_test.cc                    |   2 +
 absl/strings/str_join.h                            |   2 +
 absl/strings/str_replace.cc                        |   2 +
 absl/strings/str_replace.h                         |   2 +
 absl/strings/str_split.cc                          |   2 +
 absl/strings/str_split.h                           |   2 +
 absl/strings/string_view.cc                        |   2 +
 absl/strings/string_view.h                         |  20 ++--
 absl/strings/strip.h                               |   2 +
 absl/strings/substitute.cc                         |   2 +
 absl/strings/substitute.h                          |   2 +
 absl/synchronization/BUILD.bazel                   |   1 +
 absl/synchronization/CMakeLists.txt                |   1 +
 absl/synchronization/barrier.cc                    |   2 +
 absl/synchronization/barrier.h                     |   2 +
 absl/synchronization/blocking_counter.cc           |   2 +
 absl/synchronization/blocking_counter.h            |   2 +
 absl/synchronization/blocking_counter_test.cc      |   2 +
 .../internal/create_thread_identity.cc             |   2 +
 .../internal/create_thread_identity.h              |   2 +
 absl/synchronization/internal/graphcycles.cc       |   2 +
 absl/synchronization/internal/graphcycles.h        |   4 +
 absl/synchronization/internal/graphcycles_test.cc  |   2 +
 absl/synchronization/internal/kernel_timeout.h     |   2 +
 absl/synchronization/internal/mutex_nonprod.cc     |   2 +
 absl/synchronization/internal/mutex_nonprod.inc    |   2 +
 absl/synchronization/internal/per_thread_sem.cc    |   2 +
 absl/synchronization/internal/per_thread_sem.h     |   2 +
 .../internal/per_thread_sem_test.cc                |   2 +
 absl/synchronization/internal/thread_pool.h        |   2 +
 absl/synchronization/internal/waiter.cc            |   2 +
 absl/synchronization/internal/waiter.h             |   2 +
 absl/synchronization/mutex.cc                      |   4 +-
 absl/synchronization/mutex.h                       |   4 +-
 absl/synchronization/notification.cc               |   2 +
 absl/synchronization/notification.h                |   2 +
 absl/synchronization/notification_test.cc          |   2 +
 absl/time/civil_time.cc                            |   2 +
 absl/time/civil_time.h                             |   2 +
 absl/time/clock.cc                                 |   8 ++
 absl/time/clock.h                                  |   2 +
 absl/time/duration.cc                              |   2 +
 absl/time/duration_test.cc                         |   5 -
 absl/time/format.cc                                |   2 +
 absl/time/internal/get_current_time_chrono.inc     |   2 +
 absl/time/internal/get_current_time_posix.inc      |   2 +
 absl/time/internal/test_util.cc                    |   4 +
 absl/time/internal/test_util.h                     |   2 +
 absl/time/time.cc                                  |   2 +
 absl/time/time.h                                   |   2 +
 absl/types/any.h                                   |   4 +
 absl/types/bad_any_cast.cc                         |   2 +
 absl/types/bad_any_cast.h                          |   4 +
 absl/types/bad_optional_access.cc                  |   2 +
 absl/types/bad_optional_access.h                   |   4 +
 absl/types/bad_variant_access.cc                   |   2 +
 absl/types/bad_variant_access.h                    |   4 +
 absl/types/compare.h                               |   2 +
 absl/types/compare_test.cc                         |   2 +
 absl/types/internal/conformance_aliases.h          |   2 +
 absl/types/internal/conformance_archetype.h        |   2 +
 absl/types/internal/conformance_profile.h          |   2 +
 absl/types/internal/optional.h                     |   2 +
 absl/types/internal/span.h                         |   2 +
 absl/types/internal/variant.h                      |   2 +
 absl/types/optional.h                              |   4 +
 absl/types/optional_exception_safety_test.cc       |   2 +
 absl/types/span.h                                  |   2 +
 absl/types/variant.h                               |   6 ++
 absl/types/variant_benchmark.cc                    |   2 +
 absl/types/variant_exception_safety_test.cc        |   2 +
 absl/types/variant_test.cc                         |   2 +
 absl/utility/utility.h                             |   2 +
 339 files changed, 949 insertions(+), 83 deletions(-)

(limited to 'absl/synchronization/internal/mutex_nonprod.inc')

diff --git a/absl/algorithm/BUILD.bazel b/absl/algorithm/BUILD.bazel
index 2ee8c09e..6a96420b 100644
--- a/absl/algorithm/BUILD.bazel
+++ b/absl/algorithm/BUILD.bazel
@@ -31,6 +31,7 @@ cc_library(
     hdrs = ["algorithm.h"],
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = ["//absl/base:config"],
 )
 
 cc_test(
diff --git a/absl/algorithm/CMakeLists.txt b/absl/algorithm/CMakeLists.txt
index 9fbe36f6..56cd0fb8 100644
--- a/absl/algorithm/CMakeLists.txt
+++ b/absl/algorithm/CMakeLists.txt
@@ -21,6 +21,8 @@ absl_cc_library(
     "algorithm.h"
   COPTS
     ${ABSL_DEFAULT_COPTS}
+  DEPS
+    absl::config
   PUBLIC
 )
 
diff --git a/absl/algorithm/algorithm.h b/absl/algorithm/algorithm.h
index 771228a0..e9b47338 100644
--- a/absl/algorithm/algorithm.h
+++ b/absl/algorithm/algorithm.h
@@ -26,7 +26,10 @@
 #include <iterator>
 #include <type_traits>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace algorithm_internal {
 
@@ -150,6 +153,7 @@ ForwardIterator rotate(ForwardIterator first, ForwardIterator middle,
                    ForwardIterator>());
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_ALGORITHM_ALGORITHM_H_
diff --git a/absl/algorithm/container.h b/absl/algorithm/container.h
index 5dae9fd6..d72532de 100644
--- a/absl/algorithm/container.h
+++ b/absl/algorithm/container.h
@@ -55,6 +55,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_algorithm_internal {
 
 // NOTE: it is important to defer to ADL lookup for building with C++ modules,
@@ -1720,6 +1721,7 @@ OutputIt c_partial_sum(const InputSequence& input, OutputIt output_first,
                           output_first, std::forward<BinaryOp>(op));
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_ALGORITHM_CONTAINER_H_
diff --git a/absl/base/internal/raw_logging.h b/absl/base/internal/raw_logging.h
index 12145c48..cff45058 100644
--- a/absl/base/internal/raw_logging.h
+++ b/absl/base/internal/raw_logging.h
@@ -154,7 +154,7 @@ using LogPrefixHook = bool (*)(absl::LogSeverity severity, const char* file,
 //
 // 'file' and 'line' are the file and line number where the ABSL_RAW_LOG macro
 // was located.
-// The null-terminated logged message lives in the buffer between 'buf_start'
+// The NUL-terminated logged message lives in the buffer between 'buf_start'
 // and 'buf_end'.  'prefix_end' points to the first non-prefix character of the
 // buffer (as written by the LogPrefixHook.)
 using AbortHook = void (*)(const char* file, int line, const char* buf_start,
diff --git a/absl/base/internal/thread_identity.h b/absl/base/internal/thread_identity.h
index a1aa45ff..5dfd0715 100644
--- a/absl/base/internal/thread_identity.h
+++ b/absl/base/internal/thread_identity.h
@@ -209,7 +209,7 @@ void ClearCurrentThreadIdentity();
 #error ABSL_THREAD_IDENTITY_MODE cannot be direcly set
 #elif defined(ABSL_FORCE_THREAD_IDENTITY_MODE)
 #define ABSL_THREAD_IDENTITY_MODE ABSL_FORCE_THREAD_IDENTITY_MODE
-#elif defined(_WIN32)
+#elif defined(_WIN32) && !defined(__MINGW32__)
 #define ABSL_THREAD_IDENTITY_MODE ABSL_THREAD_IDENTITY_MODE_USE_CPP11
 #elif ABSL_PER_THREAD_TLS && defined(__GOOGLE_GRTE_VERSION__) && \
     (__GOOGLE_GRTE_VERSION__ >= 20140228L)
diff --git a/absl/container/BUILD.bazel b/absl/container/BUILD.bazel
index e60979b2..1f7abe07 100644
--- a/absl/container/BUILD.bazel
+++ b/absl/container/BUILD.bazel
@@ -141,6 +141,7 @@ cc_library(
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
     visibility = ["//visibility:private"],
+    deps = ["//absl/base:config"],
 )
 
 cc_test(
@@ -478,6 +479,9 @@ cc_library(
     hdrs = ["internal/hashtable_debug_hooks.h"],
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        "//absl/base:config",
+    ],
 )
 
 cc_library(
@@ -521,6 +525,7 @@ cc_library(
     hdrs = ["internal/node_hash_policy.h"],
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = ["//absl/base:config"],
 )
 
 cc_test(
@@ -662,6 +667,9 @@ cc_library(
     hdrs = ["internal/tracked.h"],
     copts = ABSL_TEST_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = [
+        "//absl/base:config",
+    ],
 )
 
 cc_library(
diff --git a/absl/container/CMakeLists.txt b/absl/container/CMakeLists.txt
index aa33659b..a931f334 100644
--- a/absl/container/CMakeLists.txt
+++ b/absl/container/CMakeLists.txt
@@ -204,6 +204,8 @@ absl_cc_library(
     "internal/counting_allocator.h"
   COPTS
     ${ABSL_DEFAULT_COPTS}
+  DEPS
+    absl::config
 )
 
 absl_cc_test(
@@ -574,6 +576,8 @@ absl_cc_library(
     "internal/hashtable_debug_hooks.h"
   COPTS
     ${ABSL_DEFAULT_COPTS}
+  DEPS
+    absl::config
   PUBLIC
 )
 
@@ -593,6 +597,8 @@ absl_cc_library(
     "internal/node_hash_policy.h"
   COPTS
     ${ABSL_DEFAULT_COPTS}
+  DEPS
+    absl::config
   PUBLIC
 )
 
@@ -735,6 +741,8 @@ absl_cc_library(
     "internal/tracked.h"
   COPTS
     ${ABSL_TEST_COPTS}
+  DEPS
+    absl::config
   TESTONLY
 )
 
diff --git a/absl/container/btree_map.h b/absl/container/btree_map.h
index 9f35f639..470e3197 100644
--- a/absl/container/btree_map.h
+++ b/absl/container/btree_map.h
@@ -51,6 +51,7 @@
 #include "absl/container/internal/btree_container.h"  // IWYU pragma: export
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::btree_map<>
 //
@@ -700,6 +701,7 @@ void swap(btree_multimap<K, V, C, A> &x, btree_multimap<K, V, C, A> &y) {
   return x.swap(y);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_BTREE_MAP_H_
diff --git a/absl/container/btree_set.h b/absl/container/btree_set.h
index 6e47b4aa..2a4d0ace 100644
--- a/absl/container/btree_set.h
+++ b/absl/container/btree_set.h
@@ -51,6 +51,7 @@
 #include "absl/container/internal/btree_container.h"  // IWYU pragma: export
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::btree_set<>
 //
@@ -648,6 +649,7 @@ void swap(btree_multiset<K, C, A> &x, btree_multiset<K, C, A> &y) {
   return x.swap(y);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_BTREE_SET_H_
diff --git a/absl/container/btree_test.cc b/absl/container/btree_test.cc
index ea73f032..f8aadd62 100644
--- a/absl/container/btree_test.cc
+++ b/absl/container/btree_test.cc
@@ -42,6 +42,7 @@
 ABSL_FLAG(int, test_values, 10000, "The number of values to use for tests");
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -2304,4 +2305,5 @@ TEST(Btree, EmptyTree) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/btree_test.h b/absl/container/btree_test.h
index 5ecf43ce..218ba41d 100644
--- a/absl/container/btree_test.h
+++ b/absl/container/btree_test.h
@@ -28,6 +28,7 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // Like remove_const but propagates the removal through std::pair.
@@ -148,6 +149,7 @@ std::vector<V> GenerateValuesWithSeed(int n, int maxval, int seed) {
 }
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_BTREE_TEST_H_
diff --git a/absl/container/fixed_array.h b/absl/container/fixed_array.h
index 70e94ad5..a9ce99ba 100644
--- a/absl/container/fixed_array.h
+++ b/absl/container/fixed_array.h
@@ -50,6 +50,7 @@
 #include "absl/memory/memory.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 constexpr static auto kFixedArrayUseDefault = static_cast<size_t>(-1);
 
@@ -508,6 +509,7 @@ void FixedArray<T, N, A>::NonEmptyInlinedStorage::AnnotateDestruct(
 #endif                   // ADDRESS_SANITIZER
   static_cast<void>(n);  // Mark used when not in asan mode
 }
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_FIXED_ARRAY_H_
diff --git a/absl/container/fixed_array_exception_safety_test.cc b/absl/container/fixed_array_exception_safety_test.cc
index 5ebeac05..a5bb009d 100644
--- a/absl/container/fixed_array_exception_safety_test.cc
+++ b/absl/container/fixed_array_exception_safety_test.cc
@@ -23,6 +23,7 @@
 #include "absl/base/internal/exception_safety_testing.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace {
 
@@ -195,6 +196,7 @@ TEST(FixedArrayExceptionSafety, FillWithAlloc) {
 
 }  // namespace
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HAVE_EXCEPTIONS
diff --git a/absl/container/flat_hash_map.h b/absl/container/flat_hash_map.h
index 283f2439..fb570cd4 100644
--- a/absl/container/flat_hash_map.h
+++ b/absl/container/flat_hash_map.h
@@ -42,6 +42,7 @@
 #include "absl/memory/memory.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 template <class K, class V>
 struct FlatHashMapPolicy;
@@ -584,6 +585,7 @@ struct IsUnorderedContainer<
 
 }  // namespace container_algorithm_internal
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_FLAT_HASH_MAP_H_
diff --git a/absl/container/flat_hash_map_test.cc b/absl/container/flat_hash_map_test.cc
index 02d1f879..dae8e003 100644
--- a/absl/container/flat_hash_map_test.cc
+++ b/absl/container/flat_hash_map_test.cc
@@ -24,6 +24,7 @@
 #include "absl/types/any.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 using ::absl::container_internal::hash_internal::Enum;
@@ -251,4 +252,5 @@ TEST(FlatHashMap, Any) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/flat_hash_set.h b/absl/container/flat_hash_set.h
index 2a51c341..930107ea 100644
--- a/absl/container/flat_hash_set.h
+++ b/absl/container/flat_hash_set.h
@@ -40,6 +40,7 @@
 #include "absl/memory/memory.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 template <typename T>
 struct FlatHashSetPolicy;
@@ -488,6 +489,7 @@ struct IsUnorderedContainer<absl::flat_hash_set<Key, Hash, KeyEqual, Allocator>>
 
 }  // namespace container_algorithm_internal
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_FLAT_HASH_SET_H_
diff --git a/absl/container/flat_hash_set_test.cc b/absl/container/flat_hash_set_test.cc
index b55be59b..6eacb1bb 100644
--- a/absl/container/flat_hash_set_test.cc
+++ b/absl/container/flat_hash_set_test.cc
@@ -25,6 +25,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -125,4 +126,5 @@ TEST(FlatHashSet, MergeExtractInsert) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/inlined_vector.h b/absl/container/inlined_vector.h
index d5c67db5..2388d471 100644
--- a/absl/container/inlined_vector.h
+++ b/absl/container/inlined_vector.h
@@ -54,6 +54,7 @@
 #include "absl/memory/memory.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 // -----------------------------------------------------------------------------
 // InlinedVector
 // -----------------------------------------------------------------------------
@@ -841,6 +842,7 @@ H AbslHashValue(H h, const absl::InlinedVector<T, N, A>& a) {
   return H::combine(H::combine_contiguous(std::move(h), a.data(), size), size);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INLINED_VECTOR_H_
diff --git a/absl/container/internal/btree.h b/absl/container/internal/btree.h
index 40217dd5..aef861dc 100644
--- a/absl/container/internal/btree.h
+++ b/absl/container/internal/btree.h
@@ -70,6 +70,7 @@
 #include "absl/utility/utility.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // A helper class that indicates if the Compare parameter is a key-compare-to
@@ -2606,6 +2607,7 @@ int btree<P>::internal_verify(
 }
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_BTREE_H_
diff --git a/absl/container/internal/btree_container.h b/absl/container/internal/btree_container.h
index 774412d9..04795c2e 100644
--- a/absl/container/internal/btree_container.h
+++ b/absl/container/internal/btree_container.h
@@ -26,6 +26,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // A common base class for btree_set, btree_map, btree_multiset, and
@@ -602,6 +603,7 @@ class btree_multimap_container : public btree_multiset_container<Tree> {
 };
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_BTREE_CONTAINER_H_
diff --git a/absl/container/internal/common.h b/absl/container/internal/common.h
index cc7633dc..853a5b21 100644
--- a/absl/container/internal/common.h
+++ b/absl/container/internal/common.h
@@ -22,6 +22,7 @@
 #include "absl/types/optional.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class, class = void>
@@ -196,6 +197,7 @@ struct InsertReturnType {
 };
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_CONTAINER_H_
diff --git a/absl/container/internal/compressed_tuple.h b/absl/container/internal/compressed_tuple.h
index 7d08e370..4bfe92fd 100644
--- a/absl/container/internal/compressed_tuple.h
+++ b/absl/container/internal/compressed_tuple.h
@@ -48,6 +48,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <typename... Ts>
@@ -256,6 +257,7 @@ template <>
 class ABSL_INTERNAL_COMPRESSED_TUPLE_DECLSPEC CompressedTuple<> {};
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #undef ABSL_INTERNAL_COMPRESSED_TUPLE_DECLSPEC
diff --git a/absl/container/internal/compressed_tuple_test.cc b/absl/container/internal/compressed_tuple_test.cc
index 19af8f10..76bc9213 100644
--- a/absl/container/internal/compressed_tuple_test.cc
+++ b/absl/container/internal/compressed_tuple_test.cc
@@ -48,6 +48,7 @@ struct TwoValues {
 
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -408,4 +409,5 @@ TEST(CompressedTupleTest, EmptyFinalClass) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/container_memory.h b/absl/container/internal/container_memory.h
index e5bb9773..d24b0f84 100644
--- a/absl/container/internal/container_memory.h
+++ b/absl/container/internal/container_memory.h
@@ -34,6 +34,7 @@
 #include "absl/utility/utility.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // Allocates at least n bytes aligned to the specified alignment.
@@ -433,6 +434,7 @@ struct map_slot_policy {
 };
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_CONTAINER_MEMORY_H_
diff --git a/absl/container/internal/container_memory_test.cc b/absl/container/internal/container_memory_test.cc
index d6b0495f..7942c7be 100644
--- a/absl/container/internal/container_memory_test.cc
+++ b/absl/container/internal/container_memory_test.cc
@@ -23,6 +23,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -185,4 +186,5 @@ TEST(DecomposePair, NotDecomposable) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/counting_allocator.h b/absl/container/internal/counting_allocator.h
index 4e717bef..9efdc662 100644
--- a/absl/container/internal/counting_allocator.h
+++ b/absl/container/internal/counting_allocator.h
@@ -19,7 +19,10 @@
 #include <cstdint>
 #include <memory>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // This is a stateful allocator, but the state lives outside of the
@@ -74,6 +77,7 @@ class CountingAllocator : public std::allocator<T> {
 };
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_COUNTING_ALLOCATOR_H_
diff --git a/absl/container/internal/hash_function_defaults.h b/absl/container/internal/hash_function_defaults.h
index cb8f03c8..401ddf4d 100644
--- a/absl/container/internal/hash_function_defaults.h
+++ b/absl/container/internal/hash_function_defaults.h
@@ -56,6 +56,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // The hash of an object of type T is computed by using absl::Hash.
@@ -139,6 +140,7 @@ template <class T>
 using hash_default_eq = typename container_internal::HashEq<T>::Eq;
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_HASH_FUNCTION_DEFAULTS_H_
diff --git a/absl/container/internal/hash_function_defaults_test.cc b/absl/container/internal/hash_function_defaults_test.cc
index 82708dbe..2eefc7e0 100644
--- a/absl/container/internal/hash_function_defaults_test.cc
+++ b/absl/container/internal/hash_function_defaults_test.cc
@@ -22,6 +22,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -248,6 +249,7 @@ TYPED_TEST_SUITE(StringLikeTest, StringTypesCartesianProduct);
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 enum Hash : size_t {
@@ -278,6 +280,7 @@ struct hash<Hashable<H>> {
 }  // namespace std
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -292,4 +295,5 @@ TEST(Delegate, HashDispatch) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/hash_generator_testing.cc b/absl/container/internal/hash_generator_testing.cc
index 37a23d60..75c4db6c 100644
--- a/absl/container/internal/hash_generator_testing.cc
+++ b/absl/container/internal/hash_generator_testing.cc
@@ -17,6 +17,7 @@
 #include <deque>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace hash_internal {
 namespace {
@@ -69,4 +70,5 @@ absl::string_view Generator<absl::string_view>::operator()() const {
 
 }  // namespace hash_internal
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/hash_generator_testing.h b/absl/container/internal/hash_generator_testing.h
index 477215cd..6869fe45 100644
--- a/absl/container/internal/hash_generator_testing.h
+++ b/absl/container/internal/hash_generator_testing.h
@@ -33,6 +33,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace hash_internal {
 namespace generator_internal {
@@ -154,6 +155,7 @@ using GeneratedType = decltype(
 
 }  // namespace hash_internal
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_HASH_GENERATOR_TESTING_H_
diff --git a/absl/container/internal/hash_policy_testing.h b/absl/container/internal/hash_policy_testing.h
index c57407a0..01c40d2e 100644
--- a/absl/container/internal/hash_policy_testing.h
+++ b/absl/container/internal/hash_policy_testing.h
@@ -30,6 +30,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace hash_testing_internal {
 
@@ -162,6 +163,7 @@ auto keys(const Set& s)
 }
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // ABSL_UNORDERED_SUPPORTS_ALLOC_CTORS is false for glibcxx versions
diff --git a/absl/container/internal/hash_policy_testing_test.cc b/absl/container/internal/hash_policy_testing_test.cc
index 0c95eb5e..f0b20fe3 100644
--- a/absl/container/internal/hash_policy_testing_test.cc
+++ b/absl/container/internal/hash_policy_testing_test.cc
@@ -17,6 +17,7 @@
 #include "gtest/gtest.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -40,4 +41,5 @@ TEST(_, Hash) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/hash_policy_traits.h b/absl/container/internal/hash_policy_traits.h
index fd007de7..3e1209c6 100644
--- a/absl/container/internal/hash_policy_traits.h
+++ b/absl/container/internal/hash_policy_traits.h
@@ -23,6 +23,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // Defines how slots are initialized/destroyed/moved.
@@ -184,6 +185,7 @@ struct hash_policy_traits {
 };
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_HASH_POLICY_TRAITS_H_
diff --git a/absl/container/internal/hash_policy_traits_test.cc b/absl/container/internal/hash_policy_traits_test.cc
index e643d189..6ef8b9e0 100644
--- a/absl/container/internal/hash_policy_traits_test.cc
+++ b/absl/container/internal/hash_policy_traits_test.cc
@@ -22,6 +22,7 @@
 #include "gtest/gtest.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -139,4 +140,5 @@ TEST_F(Test, with_transfer) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/hashtable_debug.h b/absl/container/internal/hashtable_debug.h
index 71930004..19d52121 100644
--- a/absl/container/internal/hashtable_debug.h
+++ b/absl/container/internal/hashtable_debug.h
@@ -38,6 +38,7 @@
 #include "absl/container/internal/hashtable_debug_hooks.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // Returns the number of probes required to lookup `key`.  Returns 0 for a
@@ -103,6 +104,7 @@ size_t LowerBoundAllocatedByteSize(size_t num_elements) {
 }
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_HASHTABLE_DEBUG_H_
diff --git a/absl/container/internal/hashtable_debug_hooks.h b/absl/container/internal/hashtable_debug_hooks.h
index 371ce81f..3e9ea595 100644
--- a/absl/container/internal/hashtable_debug_hooks.h
+++ b/absl/container/internal/hashtable_debug_hooks.h
@@ -23,7 +23,10 @@
 #include <type_traits>
 #include <vector>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace hashtable_debug_internal {
 
@@ -76,6 +79,7 @@ struct HashtableDebugAccess {
 
 }  // namespace hashtable_debug_internal
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_HASHTABLE_DEBUG_HOOKS_H_
diff --git a/absl/container/internal/hashtablez_sampler.cc b/absl/container/internal/hashtablez_sampler.cc
index 6deeca44..e15f4444 100644
--- a/absl/container/internal/hashtablez_sampler.cc
+++ b/absl/container/internal/hashtablez_sampler.cc
@@ -28,6 +28,7 @@
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 constexpr int HashtablezInfo::kMaxStackDepth;
 
@@ -265,4 +266,5 @@ void SetHashtablezMaxSamples(int32_t max) {
 }
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/hashtablez_sampler.h b/absl/container/internal/hashtablez_sampler.h
index c694df05..c4f9629f 100644
--- a/absl/container/internal/hashtablez_sampler.h
+++ b/absl/container/internal/hashtablez_sampler.h
@@ -51,6 +51,7 @@
 #include "absl/utility/utility.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // Stores information about a sampled hashtable.  All mutations to this *must*
@@ -281,6 +282,7 @@ void SetHashtablezMaxSamples(int32_t max);
 extern "C" bool AbslContainerInternalSampleEverything();
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_HASHTABLEZ_SAMPLER_H_
diff --git a/absl/container/internal/hashtablez_sampler_force_weak_definition.cc b/absl/container/internal/hashtablez_sampler_force_weak_definition.cc
index 984dce5d..78b9d362 100644
--- a/absl/container/internal/hashtablez_sampler_force_weak_definition.cc
+++ b/absl/container/internal/hashtablez_sampler_force_weak_definition.cc
@@ -17,6 +17,7 @@
 #include "absl/base/attributes.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // See hashtablez_sampler.h for details.
@@ -25,4 +26,5 @@ extern "C" ABSL_ATTRIBUTE_WEAK bool AbslContainerInternalSampleEverything() {
 }
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/hashtablez_sampler_test.cc b/absl/container/internal/hashtablez_sampler_test.cc
index af4b5ee1..102b2375 100644
--- a/absl/container/internal/hashtablez_sampler_test.cc
+++ b/absl/container/internal/hashtablez_sampler_test.cc
@@ -36,6 +36,7 @@ constexpr int kProbeLength = 8;
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 class HashtablezInfoHandlePeer {
  public:
@@ -354,4 +355,5 @@ TEST(HashtablezSamplerTest, Callback) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/inlined_vector.h b/absl/container/internal/inlined_vector.h
index 84aa785a..4d80b727 100644
--- a/absl/container/internal/inlined_vector.h
+++ b/absl/container/internal/inlined_vector.h
@@ -30,6 +30,7 @@
 #include "absl/types/span.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace inlined_vector_internal {
 
 template <typename Iterator>
@@ -885,6 +886,7 @@ auto Storage<T, N, A>::Swap(Storage* other_storage_ptr) -> void {
 }
 
 }  // namespace inlined_vector_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_INLINED_VECTOR_INTERNAL_H_
diff --git a/absl/container/internal/layout.h b/absl/container/internal/layout.h
index bbdde507..69cc85dd 100644
--- a/absl/container/internal/layout.h
+++ b/absl/container/internal/layout.h
@@ -188,6 +188,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // A type wrapper that instructs `Layout` to use the specific alignment for the
@@ -734,6 +735,7 @@ class Layout : public internal_layout::LayoutType<sizeof...(Ts), Ts...> {
 };
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_LAYOUT_H_
diff --git a/absl/container/internal/layout_test.cc b/absl/container/internal/layout_test.cc
index 33b72bd3..8f3628a1 100644
--- a/absl/container/internal/layout_test.cc
+++ b/absl/container/internal/layout_test.cc
@@ -28,6 +28,7 @@
 #include "absl/types/span.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -1562,4 +1563,5 @@ TEST(CompactString, Works) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/node_hash_policy.h b/absl/container/internal/node_hash_policy.h
index 19b4fc09..4617162f 100644
--- a/absl/container/internal/node_hash_policy.h
+++ b/absl/container/internal/node_hash_policy.h
@@ -39,7 +39,10 @@
 #include <type_traits>
 #include <utility>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class Reference, class Policy>
@@ -83,6 +86,7 @@ struct node_hash_policy {
 };
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_NODE_HASH_POLICY_H_
diff --git a/absl/container/internal/node_hash_policy_test.cc b/absl/container/internal/node_hash_policy_test.cc
index f1d3ec30..84aabba9 100644
--- a/absl/container/internal/node_hash_policy_test.cc
+++ b/absl/container/internal/node_hash_policy_test.cc
@@ -21,6 +21,7 @@
 #include "absl/container/internal/hash_policy_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -64,4 +65,5 @@ TEST_F(NodeTest, transfer) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/raw_hash_map.h b/absl/container/internal/raw_hash_map.h
index 7dad120a..0a02757d 100644
--- a/absl/container/internal/raw_hash_map.h
+++ b/absl/container/internal/raw_hash_map.h
@@ -24,6 +24,7 @@
 #include "absl/container/internal/raw_hash_set.h"  // IWYU pragma: export
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class Policy, class Hash, class Eq, class Alloc>
@@ -190,6 +191,7 @@ class raw_hash_map : public raw_hash_set<Policy, Hash, Eq, Alloc> {
 };
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_RAW_HASH_MAP_H_
diff --git a/absl/container/internal/raw_hash_set.cc b/absl/container/internal/raw_hash_set.cc
index ac2d10a7..919ac074 100644
--- a/absl/container/internal/raw_hash_set.cc
+++ b/absl/container/internal/raw_hash_set.cc
@@ -20,6 +20,7 @@
 #include "absl/base/config.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 constexpr size_t Group::kWidth;
@@ -43,4 +44,5 @@ bool ShouldInsertBackwards(size_t hash, ctrl_t* ctrl) {
 }
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index 469226fe..4103e02a 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -118,6 +118,7 @@
 #include "absl/utility/utility.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <size_t Width>
@@ -1861,6 +1862,7 @@ struct HashtableDebugAccess<Set, absl::void_t<typename Set::raw_hash_set>> {
 
 }  // namespace hashtable_debug_internal
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_RAW_HASH_SET_H_
diff --git a/absl/container/internal/raw_hash_set_allocator_test.cc b/absl/container/internal/raw_hash_set_allocator_test.cc
index a5eff0b3..7ac4b9f7 100644
--- a/absl/container/internal/raw_hash_set_allocator_test.cc
+++ b/absl/container/internal/raw_hash_set_allocator_test.cc
@@ -20,6 +20,7 @@
 #include "absl/container/internal/tracked.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -425,4 +426,5 @@ TEST_F(PropagateOnAll, Swap) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/raw_hash_set_test.cc b/absl/container/internal/raw_hash_set_test.cc
index ec8f9231..38e5e0e8 100644
--- a/absl/container/internal/raw_hash_set_test.cc
+++ b/absl/container/internal/raw_hash_set_test.cc
@@ -35,6 +35,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 struct RawHashSetTestOnlyAccess {
@@ -1913,4 +1914,5 @@ TEST(Sanitizer, PoisoningOnErase) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/test_instance_tracker.cc b/absl/container/internal/test_instance_tracker.cc
index 5a66cb4d..f9947f04 100644
--- a/absl/container/internal/test_instance_tracker.cc
+++ b/absl/container/internal/test_instance_tracker.cc
@@ -15,6 +15,7 @@
 #include "absl/container/internal/test_instance_tracker.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace test_internal {
 int BaseCountedInstance::num_instances_ = 0;
 int BaseCountedInstance::num_live_instances_ = 0;
@@ -24,4 +25,5 @@ int BaseCountedInstance::num_swaps_ = 0;
 int BaseCountedInstance::num_comparisons_ = 0;
 
 }  // namespace test_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/test_instance_tracker.h b/absl/container/internal/test_instance_tracker.h
index c4731dbe..5ff6fd71 100644
--- a/absl/container/internal/test_instance_tracker.h
+++ b/absl/container/internal/test_instance_tracker.h
@@ -21,6 +21,7 @@
 #include "absl/types/compare.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace test_internal {
 
 // A type that counts number of occurrences of the type, the live occurrences of
@@ -267,6 +268,7 @@ class MovableOnlyInstance : public BaseCountedInstance {
 };
 
 }  // namespace test_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_TEST_INSTANCE_TRACKER_H_
diff --git a/absl/container/internal/tracked.h b/absl/container/internal/tracked.h
index 75173ab0..29f5829f 100644
--- a/absl/container/internal/tracked.h
+++ b/absl/container/internal/tracked.h
@@ -16,10 +16,14 @@
 #define ABSL_CONTAINER_INTERNAL_TRACKED_H_
 
 #include <stddef.h>
+
 #include <memory>
 #include <utility>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 // A class that tracks its copies and moves so that it can be queried in tests.
@@ -73,6 +77,7 @@ class Tracked {
 };
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_TRACKED_H_
diff --git a/absl/container/internal/unordered_map_constructor_test.h b/absl/container/internal/unordered_map_constructor_test.h
index 68817e4e..76ee95e6 100644
--- a/absl/container/internal/unordered_map_constructor_test.h
+++ b/absl/container/internal/unordered_map_constructor_test.h
@@ -24,6 +24,7 @@
 #include "absl/container/internal/hash_policy_testing.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class UnordMap>
@@ -482,6 +483,7 @@ REGISTER_TYPED_TEST_CASE_P(
     AssignmentFromInitializerListOverwritesExisting, AssignmentOnSelf);
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_UNORDERED_MAP_CONSTRUCTOR_TEST_H_
diff --git a/absl/container/internal/unordered_map_lookup_test.h b/absl/container/internal/unordered_map_lookup_test.h
index ebd3612b..e76421e5 100644
--- a/absl/container/internal/unordered_map_lookup_test.h
+++ b/absl/container/internal/unordered_map_lookup_test.h
@@ -21,6 +21,7 @@
 #include "absl/container/internal/hash_policy_testing.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class UnordMap>
@@ -110,6 +111,7 @@ REGISTER_TYPED_TEST_CASE_P(LookupTest, At, OperatorBracket, Count, Find,
                            EqualRange);
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_UNORDERED_MAP_LOOKUP_TEST_H_
diff --git a/absl/container/internal/unordered_map_members_test.h b/absl/container/internal/unordered_map_members_test.h
index 1bf31ab4..7d48cdb8 100644
--- a/absl/container/internal/unordered_map_members_test.h
+++ b/absl/container/internal/unordered_map_members_test.h
@@ -21,6 +21,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class UnordMap>
@@ -80,6 +81,7 @@ TYPED_TEST_P(MembersTest, BeginEnd) {
 REGISTER_TYPED_TEST_SUITE_P(MembersTest, Typedefs, SimpleFunctions, BeginEnd);
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_UNORDERED_MAP_MEMBERS_TEST_H_
diff --git a/absl/container/internal/unordered_map_modifiers_test.h b/absl/container/internal/unordered_map_modifiers_test.h
index f6aff542..b8c513f1 100644
--- a/absl/container/internal/unordered_map_modifiers_test.h
+++ b/absl/container/internal/unordered_map_modifiers_test.h
@@ -23,6 +23,7 @@
 #include "absl/container/internal/hash_policy_testing.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class UnordMap>
@@ -309,6 +310,7 @@ TYPED_TEST_P(UniquePtrModifiersTest, TryEmplace) {
 REGISTER_TYPED_TEST_SUITE_P(UniquePtrModifiersTest, TryEmplace);
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_UNORDERED_MAP_MODIFIERS_TEST_H_
diff --git a/absl/container/internal/unordered_map_test.cc b/absl/container/internal/unordered_map_test.cc
index 114b342d..9cbf512f 100644
--- a/absl/container/internal/unordered_map_test.cc
+++ b/absl/container/internal/unordered_map_test.cc
@@ -21,6 +21,7 @@
 #include "absl/container/internal/unordered_map_modifiers_test.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -45,4 +46,5 @@ INSTANTIATE_TYPED_TEST_SUITE_P(UnorderedMap, UniquePtrModifiersTest,
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/internal/unordered_set_constructor_test.h b/absl/container/internal/unordered_set_constructor_test.h
index f4844683..41165b05 100644
--- a/absl/container/internal/unordered_set_constructor_test.h
+++ b/absl/container/internal/unordered_set_constructor_test.h
@@ -26,6 +26,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class UnordMap>
@@ -489,6 +490,7 @@ REGISTER_TYPED_TEST_CASE_P(
     AssignmentFromInitializerListOverwritesExisting, AssignmentOnSelf);
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_UNORDERED_SET_CONSTRUCTOR_TEST_H_
diff --git a/absl/container/internal/unordered_set_lookup_test.h b/absl/container/internal/unordered_set_lookup_test.h
index 05b32b5d..8f2f4b20 100644
--- a/absl/container/internal/unordered_set_lookup_test.h
+++ b/absl/container/internal/unordered_set_lookup_test.h
@@ -21,6 +21,7 @@
 #include "absl/container/internal/hash_policy_testing.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class UnordSet>
@@ -84,6 +85,7 @@ TYPED_TEST_P(LookupTest, EqualRange) {
 REGISTER_TYPED_TEST_CASE_P(LookupTest, Count, Find, EqualRange);
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_UNORDERED_SET_LOOKUP_TEST_H_
diff --git a/absl/container/internal/unordered_set_members_test.h b/absl/container/internal/unordered_set_members_test.h
index b96c945a..4c5e104a 100644
--- a/absl/container/internal/unordered_set_members_test.h
+++ b/absl/container/internal/unordered_set_members_test.h
@@ -21,6 +21,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class UnordSet>
@@ -79,6 +80,7 @@ TYPED_TEST_P(MembersTest, BeginEnd) {
 REGISTER_TYPED_TEST_SUITE_P(MembersTest, Typedefs, SimpleFunctions, BeginEnd);
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_UNORDERED_SET_MEMBERS_TEST_H_
diff --git a/absl/container/internal/unordered_set_modifiers_test.h b/absl/container/internal/unordered_set_modifiers_test.h
index 79a8d422..26be58d9 100644
--- a/absl/container/internal/unordered_set_modifiers_test.h
+++ b/absl/container/internal/unordered_set_modifiers_test.h
@@ -21,6 +21,7 @@
 #include "absl/container/internal/hash_policy_testing.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
 template <class UnordSet>
@@ -183,6 +184,7 @@ REGISTER_TYPED_TEST_CASE_P(ModifiersTest, Clear, Insert, InsertHint,
                            EraseKey, Swap);
 
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INTERNAL_UNORDERED_SET_MODIFIERS_TEST_H_
diff --git a/absl/container/internal/unordered_set_test.cc b/absl/container/internal/unordered_set_test.cc
index 6478fac1..a134b539 100644
--- a/absl/container/internal/unordered_set_test.cc
+++ b/absl/container/internal/unordered_set_test.cc
@@ -20,6 +20,7 @@
 #include "absl/container/internal/unordered_set_modifiers_test.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -36,4 +37,5 @@ INSTANTIATE_TYPED_TEST_SUITE_P(UnorderedSet, ModifiersTest, SetTypes);
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/node_hash_map.h b/absl/container/node_hash_map.h
index a718842b..e8065a98 100644
--- a/absl/container/node_hash_map.h
+++ b/absl/container/node_hash_map.h
@@ -48,6 +48,7 @@
 #include "absl/memory/memory.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 template <class Key, class Value>
 class NodeHashMapPolicy;
@@ -581,6 +582,7 @@ struct IsUnorderedContainer<
 
 }  // namespace container_algorithm_internal
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_NODE_HASH_MAP_H_
diff --git a/absl/container/node_hash_map_test.cc b/absl/container/node_hash_map_test.cc
index 0f2714a7..f923e915 100644
--- a/absl/container/node_hash_map_test.cc
+++ b/absl/container/node_hash_map_test.cc
@@ -21,6 +21,7 @@
 #include "absl/container/internal/unordered_map_modifiers_test.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 
@@ -217,4 +218,5 @@ TEST(NodeHashMap, MergeExtractInsert) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/container/node_hash_set.h b/absl/container/node_hash_set.h
index 0cd1fe57..43ada3f9 100644
--- a/absl/container/node_hash_set.h
+++ b/absl/container/node_hash_set.h
@@ -44,6 +44,7 @@
 #include "absl/memory/memory.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 template <typename T>
 struct NodeHashSetPolicy;
@@ -483,6 +484,7 @@ struct IsUnorderedContainer<absl::node_hash_set<Key, Hash, KeyEqual, Allocator>>
     : std::true_type {};
 
 }  // namespace container_algorithm_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_NODE_HASH_SET_H_
diff --git a/absl/container/node_hash_set_test.cc b/absl/container/node_hash_set_test.cc
index 0ea76e7c..e1d544ff 100644
--- a/absl/container/node_hash_set_test.cc
+++ b/absl/container/node_hash_set_test.cc
@@ -20,6 +20,7 @@
 #include "absl/container/internal/unordered_set_modifiers_test.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 namespace {
 using ::absl::container_internal::hash_internal::Enum;
@@ -102,4 +103,5 @@ TEST(NodeHashSet, MergeExtractInsert) {
 
 }  // namespace
 }  // namespace container_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/debugging/BUILD.bazel b/absl/debugging/BUILD.bazel
index 2601090b..32cacefd 100644
--- a/absl/debugging/BUILD.bazel
+++ b/absl/debugging/BUILD.bazel
@@ -38,6 +38,7 @@ cc_library(
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":debugging_internal",
+        "//absl/base:config",
         "//absl/base:core_headers",
     ],
 )
@@ -63,6 +64,7 @@ cc_library(
         ":debugging_internal",
         ":demangle_internal",
         "//absl/base",
+        "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:dynamic_annotations",
         "//absl/base:malloc_internal",
@@ -106,6 +108,7 @@ cc_library(
     deps = [
         ":stacktrace",
         ":symbolize",
+        "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:raw_logging_internal",
     ],
@@ -168,6 +171,7 @@ cc_library(
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
+        "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:dynamic_annotations",
         "//absl/base:raw_logging_internal",
@@ -181,6 +185,7 @@ cc_library(
     copts = ABSL_DEFAULT_COPTS,
     deps = [
         "//absl/base",
+        "//absl/base:config",
         "//absl/base:core_headers",
     ],
 )
@@ -205,7 +210,10 @@ cc_library(
     srcs = ["leak_check.cc"],
     hdrs = ["leak_check.h"],
     linkopts = ABSL_DEFAULT_LINKOPTS,
-    deps = ["//absl/base:core_headers"],
+    deps = [
+        "//absl/base:config",
+        "//absl/base:core_headers",
+    ],
 )
 
 # Adding a dependency to leak_check_disable will disable
@@ -216,6 +224,7 @@ cc_library(
     srcs = ["leak_check_disable.cc"],
     linkopts = ABSL_DEFAULT_LINKOPTS,
     linkstatic = 1,
+    deps = ["//absl/base:config"],
     alwayslink = 1,
 )
 
@@ -237,6 +246,9 @@ cc_library(
     }),
     linkopts = ABSL_DEFAULT_LINKOPTS,
     visibility = ["//visibility:private"],
+    deps = [
+        "//absl/base:config",
+    ],
 )
 
 cc_library(
@@ -247,6 +259,9 @@ cc_library(
     copts = ["-ULEAK_SANITIZER"],
     linkopts = ABSL_DEFAULT_LINKOPTS,
     visibility = ["//visibility:private"],
+    deps = [
+        "//absl/base:config",
+    ],
 )
 
 cc_test(
@@ -304,6 +319,7 @@ cc_library(
     linkopts = ABSL_DEFAULT_LINKOPTS,
     visibility = ["//visibility:private"],
     deps = [
+        "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:raw_logging_internal",
     ],
diff --git a/absl/debugging/CMakeLists.txt b/absl/debugging/CMakeLists.txt
index eff504b4..ef9e71fc 100644
--- a/absl/debugging/CMakeLists.txt
+++ b/absl/debugging/CMakeLists.txt
@@ -25,6 +25,7 @@ absl_cc_library(
     ${ABSL_DEFAULT_COPTS}
   DEPS
     absl::debugging_internal
+    absl::config
     absl::core_headers
   PUBLIC
 )
@@ -49,6 +50,7 @@ absl_cc_library(
     absl::debugging_internal
     absl::demangle_internal
     absl::base
+    absl::config
     absl::core_headers
     absl::dynamic_annotations
     absl::malloc_internal
@@ -88,6 +90,7 @@ absl_cc_library(
   DEPS
     absl::stacktrace
     absl::symbolize
+    absl::config
     absl::core_headers
     absl::raw_logging_internal
 )
@@ -151,6 +154,7 @@ absl_cc_library(
     ${ABSL_DEFAULT_COPTS}
   DEPS
     absl::core_headers
+    absl::config
     absl::dynamic_annotations
     absl::raw_logging_internal
 )
@@ -196,6 +200,7 @@ absl_cc_library(
   COPTS
     ${ABSL_DEFAULT_COPTS}
   DEPS
+    absl::config
     absl::core_headers
   PUBLIC
 )
@@ -293,6 +298,7 @@ absl_cc_library(
   COPTS
     ${ABSL_DEFAULT_COPTS}
   DEPS
+    absl::config
     absl::core_headers
     absl::raw_logging_internal
   TESTONLY
diff --git a/absl/debugging/failure_signal_handler.cc b/absl/debugging/failure_signal_handler.cc
index c6a4d962..470d6768 100644
--- a/absl/debugging/failure_signal_handler.cc
+++ b/absl/debugging/failure_signal_handler.cc
@@ -47,6 +47,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 ABSL_CONST_INIT static FailureSignalHandlerOptions fsh_options;
 
@@ -356,4 +357,5 @@ void InstallFailureSignalHandler(const FailureSignalHandlerOptions& options) {
   }
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/debugging/failure_signal_handler.h b/absl/debugging/failure_signal_handler.h
index 1beb78b9..f5a83962 100644
--- a/absl/debugging/failure_signal_handler.h
+++ b/absl/debugging/failure_signal_handler.h
@@ -44,7 +44,10 @@
 #ifndef ABSL_DEBUGGING_FAILURE_SIGNAL_HANDLER_H_
 #define ABSL_DEBUGGING_FAILURE_SIGNAL_HANDLER_H_
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // FailureSignalHandlerOptions
 //
@@ -112,6 +115,7 @@ namespace debugging_internal {
 const char* FailureSignalToString(int signo);
 }  // namespace debugging_internal
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_FAILURE_SIGNAL_HANDLER_H_
diff --git a/absl/debugging/internal/address_is_readable.cc b/absl/debugging/internal/address_is_readable.cc
index 99c4c64b..f45e59b3 100644
--- a/absl/debugging/internal/address_is_readable.cc
+++ b/absl/debugging/internal/address_is_readable.cc
@@ -20,12 +20,14 @@
 #if !defined(__linux__) || defined(__ANDROID__)
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 // On platforms other than Linux, just return true.
 bool AddressIsReadable(const void* /* addr */) { return true; }
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #else
@@ -40,6 +42,7 @@ bool AddressIsReadable(const void* /* addr */) { return true; }
 #include "absl/base/internal/raw_logging.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 // Pack a pid and two file descriptors into a 64-bit word,
@@ -128,6 +131,7 @@ bool AddressIsReadable(const void *addr) {
 }
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif
diff --git a/absl/debugging/internal/address_is_readable.h b/absl/debugging/internal/address_is_readable.h
index ca8003e6..4bbaf4d6 100644
--- a/absl/debugging/internal/address_is_readable.h
+++ b/absl/debugging/internal/address_is_readable.h
@@ -15,7 +15,10 @@
 #ifndef ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_
 #define ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 // Return whether the byte at *addr is readable, without faulting.
@@ -23,6 +26,7 @@ namespace debugging_internal {
 bool AddressIsReadable(const void *addr);
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_ADDRESS_IS_READABLE_H_
diff --git a/absl/debugging/internal/demangle.cc b/absl/debugging/internal/demangle.cc
index 3809e496..fc615c3f 100644
--- a/absl/debugging/internal/demangle.cc
+++ b/absl/debugging/internal/demangle.cc
@@ -24,6 +24,7 @@
 #include <limits>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 typedef struct {
@@ -1890,4 +1891,5 @@ bool Demangle(const char *mangled, char *out, int out_size) {
 }
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/debugging/internal/demangle.h b/absl/debugging/internal/demangle.h
index 81bb0dfd..c314d9bc 100644
--- a/absl/debugging/internal/demangle.h
+++ b/absl/debugging/internal/demangle.h
@@ -53,7 +53,10 @@
 #ifndef ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_
 #define ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 // Demangle `mangled`.  On success, return true and write the
@@ -62,6 +65,7 @@ namespace debugging_internal {
 bool Demangle(const char *mangled, char *out, int out_size);
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_DEMANGLE_H_
diff --git a/absl/debugging/internal/demangle_test.cc b/absl/debugging/internal/demangle_test.cc
index a68ce324..c6f1ce18 100644
--- a/absl/debugging/internal/demangle_test.cc
+++ b/absl/debugging/internal/demangle_test.cc
@@ -23,6 +23,7 @@
 #include "absl/memory/memory.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 namespace {
 
@@ -190,4 +191,5 @@ TEST(DemangleRegression, DeeplyNestedArrayType) {
 
 }  // namespace
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/debugging/internal/elf_mem_image.cc b/absl/debugging/internal/elf_mem_image.cc
index e7408bca..24cc0130 100644
--- a/absl/debugging/internal/elf_mem_image.cc
+++ b/absl/debugging/internal/elf_mem_image.cc
@@ -38,6 +38,7 @@
 #define VERSYM_VERSION 0x7fff
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 namespace {
@@ -375,6 +376,7 @@ void ElfMemImage::SymbolIterator::Update(int increment) {
 }
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HAVE_ELF_MEM_IMAGE
diff --git a/absl/debugging/internal/elf_mem_image.h b/absl/debugging/internal/elf_mem_image.h
index d84200db..46bfade3 100644
--- a/absl/debugging/internal/elf_mem_image.h
+++ b/absl/debugging/internal/elf_mem_image.h
@@ -23,6 +23,8 @@
 // used.
 #include <climits>
 
+#include "absl/base/config.h"
+
 // Maybe one day we can rewrite this file not to require the elf
 // symbol extensions in glibc, but for right now we need them.
 #ifdef ABSL_HAVE_ELF_MEM_IMAGE
@@ -39,6 +41,7 @@
 #include <link.h>  // for ElfW
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 // An in-memory ELF image (may not exist on disk).
@@ -123,6 +126,7 @@ class ElfMemImage {
 };
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HAVE_ELF_MEM_IMAGE
diff --git a/absl/debugging/internal/examine_stack.cc b/absl/debugging/internal/examine_stack.cc
index 1ebc788f..22f41b46 100644
--- a/absl/debugging/internal/examine_stack.cc
+++ b/absl/debugging/internal/examine_stack.cc
@@ -30,6 +30,7 @@
 #include "absl/debugging/symbolize.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 // Returns the program counter from signal context, nullptr if
@@ -150,4 +151,5 @@ void DumpPCAndFrameSizesAndStackTrace(
 }
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/debugging/internal/examine_stack.h b/absl/debugging/internal/examine_stack.h
index 56c9763e..39336913 100644
--- a/absl/debugging/internal/examine_stack.h
+++ b/absl/debugging/internal/examine_stack.h
@@ -17,7 +17,10 @@
 #ifndef ABSL_DEBUGGING_INTERNAL_EXAMINE_STACK_H_
 #define ABSL_DEBUGGING_INTERNAL_EXAMINE_STACK_H_
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 // Returns the program counter from signal context, or nullptr if
@@ -33,6 +36,7 @@ void DumpPCAndFrameSizesAndStackTrace(
     void (*writerfn)(const char*, void*), void* writerfn_arg);
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_EXAMINE_STACK_H_
diff --git a/absl/debugging/internal/stack_consumption.cc b/absl/debugging/internal/stack_consumption.cc
index d4703264..875ca6d9 100644
--- a/absl/debugging/internal/stack_consumption.cc
+++ b/absl/debugging/internal/stack_consumption.cc
@@ -27,6 +27,7 @@
 #include "absl/base/internal/raw_logging.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 namespace {
 
@@ -177,6 +178,7 @@ int GetSignalHandlerStackConsumption(void (*signal_handler)(int)) {
 }
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
diff --git a/absl/debugging/internal/stack_consumption.h b/absl/debugging/internal/stack_consumption.h
index b860a3c1..5e60ec42 100644
--- a/absl/debugging/internal/stack_consumption.h
+++ b/absl/debugging/internal/stack_consumption.h
@@ -18,6 +18,8 @@
 #ifndef ABSL_DEBUGGING_INTERNAL_STACK_CONSUMPTION_H_
 #define ABSL_DEBUGGING_INTERNAL_STACK_CONSUMPTION_H_
 
+#include "absl/base/config.h"
+
 // The code in this module is not portable.
 // Use this feature test macro to detect its availability.
 #ifdef ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
@@ -27,6 +29,7 @@
 #define ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION 1
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 // Returns the stack consumption in bytes for the code exercised by
@@ -38,6 +41,7 @@ namespace debugging_internal {
 int GetSignalHandlerStackConsumption(void (*signal_handler)(int));
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
diff --git a/absl/debugging/internal/stack_consumption_test.cc b/absl/debugging/internal/stack_consumption_test.cc
index 68bfa126..80445bf4 100644
--- a/absl/debugging/internal/stack_consumption_test.cc
+++ b/absl/debugging/internal/stack_consumption_test.cc
@@ -23,6 +23,7 @@
 #include "absl/base/internal/raw_logging.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 namespace {
 
@@ -43,6 +44,7 @@ TEST(SignalHandlerStackConsumptionTest, MeasuresStackConsumption) {
 
 }  // namespace
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
diff --git a/absl/debugging/internal/stacktrace_aarch64-inl.inc b/absl/debugging/internal/stacktrace_aarch64-inl.inc
index 7ed6b3eb..411ea308 100644
--- a/absl/debugging/internal/stacktrace_aarch64-inl.inc
+++ b/absl/debugging/internal/stacktrace_aarch64-inl.inc
@@ -180,11 +180,13 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
 }
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 bool StackTraceWorksForTest() {
   return true;
 }
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_AARCH64_INL_H_
diff --git a/absl/debugging/internal/stacktrace_arm-inl.inc b/absl/debugging/internal/stacktrace_arm-inl.inc
index c8408337..fffda968 100644
--- a/absl/debugging/internal/stacktrace_arm-inl.inc
+++ b/absl/debugging/internal/stacktrace_arm-inl.inc
@@ -113,11 +113,13 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
 }
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 bool StackTraceWorksForTest() {
   return false;
 }
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_ARM_INL_H_
diff --git a/absl/debugging/internal/stacktrace_generic-inl.inc b/absl/debugging/internal/stacktrace_generic-inl.inc
index 81a49ef2..ac034c9f 100644
--- a/absl/debugging/internal/stacktrace_generic-inl.inc
+++ b/absl/debugging/internal/stacktrace_generic-inl.inc
@@ -87,11 +87,13 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
 }
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 bool StackTraceWorksForTest() {
   return true;
 }
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_GENERIC_INL_H_
diff --git a/absl/debugging/internal/stacktrace_powerpc-inl.inc b/absl/debugging/internal/stacktrace_powerpc-inl.inc
index 3a070ee4..2e7c2f40 100644
--- a/absl/debugging/internal/stacktrace_powerpc-inl.inc
+++ b/absl/debugging/internal/stacktrace_powerpc-inl.inc
@@ -236,11 +236,13 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
 }
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 bool StackTraceWorksForTest() {
   return true;
 }
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_POWERPC_INL_H_
diff --git a/absl/debugging/internal/stacktrace_unimplemented-inl.inc b/absl/debugging/internal/stacktrace_unimplemented-inl.inc
index e256fdd4..5b8fb191 100644
--- a/absl/debugging/internal/stacktrace_unimplemented-inl.inc
+++ b/absl/debugging/internal/stacktrace_unimplemented-inl.inc
@@ -12,11 +12,13 @@ static int UnwindImpl(void** /* result */, int* /* sizes */,
 }
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 bool StackTraceWorksForTest() {
   return false;
 }
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_UNIMPLEMENTED_INL_H_
diff --git a/absl/debugging/internal/stacktrace_win32-inl.inc b/absl/debugging/internal/stacktrace_win32-inl.inc
index 247e7428..9c2c5580 100644
--- a/absl/debugging/internal/stacktrace_win32-inl.inc
+++ b/absl/debugging/internal/stacktrace_win32-inl.inc
@@ -73,11 +73,13 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
 }
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 bool StackTraceWorksForTest() {
   return false;
 }
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
diff --git a/absl/debugging/internal/stacktrace_x86-inl.inc b/absl/debugging/internal/stacktrace_x86-inl.inc
index 9494441e..972febdd 100644
--- a/absl/debugging/internal/stacktrace_x86-inl.inc
+++ b/absl/debugging/internal/stacktrace_x86-inl.inc
@@ -330,11 +330,13 @@ static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
 }
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 bool StackTraceWorksForTest() {
   return true;
 }
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_STACKTRACE_X86_INL_INC_
diff --git a/absl/debugging/internal/symbolize.h b/absl/debugging/internal/symbolize.h
index 3e537893..5d0858b5 100644
--- a/absl/debugging/internal/symbolize.h
+++ b/absl/debugging/internal/symbolize.h
@@ -21,6 +21,8 @@
 #include <cstddef>
 #include <cstdint>
 
+#include "absl/base/config.h"
+
 #ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
 #error ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE cannot be directly set
 #elif defined(__ELF__) && defined(__GLIBC__) && !defined(__native_client__) && \
@@ -33,6 +35,7 @@
 #include <string>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 // Iterates over all sections, invoking callback on each with the section name
@@ -51,11 +54,13 @@ bool GetSectionHeaderByName(int fd, const char *name, size_t name_len,
                             ElfW(Shdr) *out);
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 struct SymbolDecoratorArgs {
@@ -117,6 +122,7 @@ bool GetFileMappingHint(const void** start,
                         const char** filename);
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_INTERNAL_SYMBOLIZE_H_
diff --git a/absl/debugging/internal/vdso_support.cc b/absl/debugging/internal/vdso_support.cc
index d13ef25d..1e8a78ac 100644
--- a/absl/debugging/internal/vdso_support.cc
+++ b/absl/debugging/internal/vdso_support.cc
@@ -38,6 +38,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 ABSL_CONST_INIT
@@ -187,6 +188,7 @@ static class VDSOInitHelper {
 } vdso_init_helper;
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HAVE_VDSO_SUPPORT
diff --git a/absl/debugging/internal/vdso_support.h b/absl/debugging/internal/vdso_support.h
index 9895b48d..6562c6c2 100644
--- a/absl/debugging/internal/vdso_support.h
+++ b/absl/debugging/internal/vdso_support.h
@@ -53,6 +53,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
 
 // NOTE: this class may be used from within tcmalloc, and can not
@@ -149,6 +150,7 @@ class VDSOSupport {
 int GetCPU();
 
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HAVE_ELF_MEM_IMAGE
diff --git a/absl/debugging/leak_check.cc b/absl/debugging/leak_check.cc
index ffe3d1bd..ff904955 100644
--- a/absl/debugging/leak_check.cc
+++ b/absl/debugging/leak_check.cc
@@ -21,12 +21,14 @@
 #ifndef LEAK_SANITIZER
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 bool HaveLeakSanitizer() { return false; }
 void DoIgnoreLeak(const void*) { }
 void RegisterLivePointers(const void*, size_t) { }
 void UnRegisterLivePointers(const void*, size_t) { }
 LeakCheckDisabler::LeakCheckDisabler() { }
 LeakCheckDisabler::~LeakCheckDisabler() { }
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #else
@@ -34,6 +36,7 @@ LeakCheckDisabler::~LeakCheckDisabler() { }
 #include <sanitizer/lsan_interface.h>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 bool HaveLeakSanitizer() { return true; }
 void DoIgnoreLeak(const void* ptr) { __lsan_ignore_object(ptr); }
 void RegisterLivePointers(const void* ptr, size_t size) {
@@ -44,6 +47,7 @@ void UnRegisterLivePointers(const void* ptr, size_t size) {
 }
 LeakCheckDisabler::LeakCheckDisabler() { __lsan_disable(); }
 LeakCheckDisabler::~LeakCheckDisabler() { __lsan_enable(); }
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // LEAK_SANITIZER
diff --git a/absl/debugging/leak_check.h b/absl/debugging/leak_check.h
index 4d489c58..7a5a22dd 100644
--- a/absl/debugging/leak_check.h
+++ b/absl/debugging/leak_check.h
@@ -32,7 +32,10 @@
 
 #include <cstddef>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // HaveLeakSanitizer()
 //
@@ -104,6 +107,7 @@ void RegisterLivePointers(const void* ptr, size_t size);
 // `RegisterLivePointers()`, enabling leak checking of those pointers.
 void UnRegisterLivePointers(const void* ptr, size_t size);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_LEAK_CHECK_H_
diff --git a/absl/debugging/stacktrace.cc b/absl/debugging/stacktrace.cc
index 9de8782f..1f7c7d82 100644
--- a/absl/debugging/stacktrace.cc
+++ b/absl/debugging/stacktrace.cc
@@ -57,6 +57,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 typedef int (*Unwinder)(void**, int*, int, int, const void*, int*);
@@ -135,4 +136,5 @@ int DefaultStackUnwinder(void** pcs, int* sizes, int depth, int skip,
   return n;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/debugging/stacktrace.h b/absl/debugging/stacktrace.h
index cd8fae76..0ec0ffda 100644
--- a/absl/debugging/stacktrace.h
+++ b/absl/debugging/stacktrace.h
@@ -31,7 +31,10 @@
 #ifndef ABSL_DEBUGGING_STACKTRACE_H_
 #define ABSL_DEBUGGING_STACKTRACE_H_
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // GetStackFrames()
 //
@@ -222,6 +225,7 @@ namespace debugging_internal {
 // working.
 extern bool StackTraceWorksForTest();
 }  // namespace debugging_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_STACKTRACE_H_
diff --git a/absl/debugging/symbolize.h b/absl/debugging/symbolize.h
index a73dbd9e..a8ff3740 100644
--- a/absl/debugging/symbolize.h
+++ b/absl/debugging/symbolize.h
@@ -55,6 +55,7 @@
 #include "absl/debugging/internal/symbolize.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // InitializeSymbolizer()
 //
@@ -92,6 +93,7 @@ void InitializeSymbolizer(const char* argv0);
 //  }
 bool Symbolize(const void *pc, char *out, int out_size);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_DEBUGGING_SYMBOLIZE_H_
diff --git a/absl/debugging/symbolize_elf.inc b/absl/debugging/symbolize_elf.inc
index 14f0c972..c371635f 100644
--- a/absl/debugging/symbolize_elf.inc
+++ b/absl/debugging/symbolize_elf.inc
@@ -76,6 +76,7 @@
 #include "absl/debugging/internal/vdso_support.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Value of argv[0]. Used by MaybeInitializeObjFile().
 static char *argv0_value = nullptr;
@@ -1475,4 +1476,5 @@ bool Symbolize(const void *pc, char *out, int out_size) {
   return ok;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/debugging/symbolize_unimplemented.inc b/absl/debugging/symbolize_unimplemented.inc
index 7c580fe4..db24456b 100644
--- a/absl/debugging/symbolize_unimplemented.inc
+++ b/absl/debugging/symbolize_unimplemented.inc
@@ -17,6 +17,7 @@
 #include "absl/base/internal/raw_logging.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace debugging_internal {
 
@@ -35,4 +36,5 @@ bool GetFileMappingHint(const void **, const void **, uint64_t *, const char **)
 void InitializeSymbolizer(const char*) {}
 bool Symbolize(const void *, char *, int) { return false; }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/debugging/symbolize_win32.inc b/absl/debugging/symbolize_win32.inc
index bd6fbd5e..c3df46f6 100644
--- a/absl/debugging/symbolize_win32.inc
+++ b/absl/debugging/symbolize_win32.inc
@@ -31,6 +31,7 @@
 #include "absl/base/internal/raw_logging.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 static HANDLE process = NULL;
 
@@ -76,4 +77,5 @@ bool Symbolize(const void* pc, char* out, int out_size) {
   return true;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/declare.h b/absl/flags/declare.h
index 4926a09e..f7509ce7 100644
--- a/absl/flags/declare.h
+++ b/absl/flags/declare.h
@@ -28,6 +28,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 // absl::Flag<T> represents a flag of type 'T' created by ABSL_FLAG.
@@ -47,6 +48,7 @@ template <typename T>
 using Flag = flags_internal::Flag<T>;
 #endif
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // ABSL_DECLARE_FLAG()
diff --git a/absl/flags/flag.cc b/absl/flags/flag.cc
index 37bbce23..7faa7ade 100644
--- a/absl/flags/flag.cc
+++ b/absl/flags/flag.cc
@@ -18,6 +18,7 @@
 #include <cstring>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // We want to validate the type mismatch between type definition and
 // declaration. The lock-free implementation does not allow us to do it,
@@ -55,4 +56,5 @@ absl::Mutex* GetGlobalConstructionGuard() { return &construction_guard; }
 
 #endif
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/flag.h b/absl/flags/flag.h
index 52c3cede..b6fbd116 100644
--- a/absl/flags/flag.h
+++ b/absl/flags/flag.h
@@ -38,6 +38,7 @@
 #include "absl/flags/marshalling.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Flag
 //
@@ -219,6 +220,7 @@ void SetFlag(absl::Flag<T>* flag, const V& v) {
   flag->Set(value);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 
diff --git a/absl/flags/flag_test_defs.cc b/absl/flags/flag_test_defs.cc
index 3366c580..49f91dee 100644
--- a/absl/flags/flag_test_defs.cc
+++ b/absl/flags/flag_test_defs.cc
@@ -20,3 +20,5 @@
 
 ABSL_FLAG(int, mistyped_int_flag, 0, "");
 ABSL_FLAG(std::string, mistyped_string_flag, "", "");
+ABSL_RETIRED_FLAG(bool, old_bool_flag, true,
+                  "repetition of retired flag definition");
diff --git a/absl/flags/internal/commandlineflag.cc b/absl/flags/internal/commandlineflag.cc
index 88f91e16..09249274 100644
--- a/absl/flags/internal/commandlineflag.cc
+++ b/absl/flags/internal/commandlineflag.cc
@@ -18,6 +18,7 @@
 #include "absl/flags/usage_config.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 // The help message indicating that the commandline flag has been
@@ -57,4 +58,5 @@ std::string CommandLineFlag::Filename() const {
 }
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/internal/commandlineflag.h b/absl/flags/internal/commandlineflag.h
index 7964f1bf..49e13d1e 100644
--- a/absl/flags/internal/commandlineflag.h
+++ b/absl/flags/internal/commandlineflag.h
@@ -23,6 +23,7 @@
 #include "absl/types/optional.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 // Type-specific operations, eg., parsing, copying, etc. are provided
@@ -158,7 +159,7 @@ class CommandLineFlag {
       : name_(name), filename_(filename) {}
 
   // Virtual destructor
-  virtual void Destroy() const = 0;
+  virtual void Destroy() = 0;
 
   // Not copyable/assignable.
   CommandLineFlag(const CommandLineFlag&) = delete;
@@ -280,6 +281,7 @@ class CommandLineFlag {
   A(float)
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
diff --git a/absl/flags/internal/flag.cc b/absl/flags/internal/flag.cc
index 435cc362..599bd7a4 100644
--- a/absl/flags/internal/flag.cc
+++ b/absl/flags/internal/flag.cc
@@ -19,6 +19,7 @@
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 namespace {
 
@@ -34,20 +35,40 @@ bool ShouldValidateFlagValue(const CommandLineFlag& flag) {
   return true;
 }
 
+// RAII helper used to temporarily unlock and relock `absl::Mutex`.
+// This is used when we need to ensure that locks are released while
+// invoking user supplied callbacks and then reacquired, since callbacks may
+// need to acquire these locks themselves.
+class MutexRelock {
+ public:
+  explicit MutexRelock(absl::Mutex* mu) : mu_(mu) { mu_->Unlock(); }
+  ~MutexRelock() { mu_->Lock(); }
+
+  MutexRelock(const MutexRelock&) = delete;
+  MutexRelock& operator=(const MutexRelock&) = delete;
+
+ private:
+  absl::Mutex* mu_;
+};
+
+// This global lock guards the initialization and destruction of data_guard_,
+// which is used to guard the other Flag data.
+ABSL_CONST_INIT static absl::Mutex flag_mutex_lifetime_guard(absl::kConstInit);
+
 }  // namespace
 
 void FlagImpl::Init() {
-  ABSL_CONST_INIT static absl::Mutex init_lock(absl::kConstInit);
-
   {
-    absl::MutexLock lock(&init_lock);
+    absl::MutexLock lock(&flag_mutex_lifetime_guard);
 
-    if (locks_ == nullptr) {  // Must initialize Mutexes for this flag.
-      locks_ = new FlagImpl::CommandLineFlagLocks;
+    // Must initialize data guard for this flag.
+    if (!is_data_guard_inited_) {
+      new (&data_guard_) absl::Mutex;
+      is_data_guard_inited_ = true;
     }
   }
 
-  absl::MutexLock lock(&locks_->primary_mu);
+  absl::MutexLock lock(reinterpret_cast<absl::Mutex*>(&data_guard_));
 
   if (cur_ != nullptr) {
     inited_.store(true, std::memory_order_release);
@@ -67,21 +88,29 @@ absl::Mutex* FlagImpl::DataGuard() const {
     const_cast<FlagImpl*>(this)->Init();
   }
 
-  // All fields initialized; locks_ is therefore safe to read.
-  return &locks_->primary_mu;
+  // data_guard_ is initialized.
+  return reinterpret_cast<absl::Mutex*>(&data_guard_);
 }
 
-void FlagImpl::Destroy() const {
+void FlagImpl::Destroy() {
   {
     absl::MutexLock l(DataGuard());
 
     // Values are heap allocated for Abseil Flags.
     if (cur_) Delete(op_, cur_);
-    if (def_kind_ == FlagDefaultSrcKind::kDynamicValue)
+
+    // Release the dynamically allocated default value if any.
+    if (def_kind_ == FlagDefaultSrcKind::kDynamicValue) {
       Delete(op_, default_src_.dynamic_value);
+    }
+
+    // If this flag has an assigned callback, release callback data.
+    if (callback_data_) delete callback_data_;
   }
 
-  delete locks_;
+  absl::MutexLock l(&flag_mutex_lifetime_guard);
+  DataGuard()->~Mutex();
+  is_data_guard_inited_ = false;
 }
 
 std::unique_ptr<void, DynValueDeleter> FlagImpl::MakeInitValue() const {
@@ -126,13 +155,20 @@ void FlagImpl::SetCallback(
     const flags_internal::FlagCallback mutation_callback) {
   absl::MutexLock l(DataGuard());
 
-  callback_ = mutation_callback;
+  if (callback_data_ == nullptr) {
+    callback_data_ = new CallbackData;
+  }
+  callback_data_->func = mutation_callback;
 
   InvokeCallback();
 }
 
 void FlagImpl::InvokeCallback() const {
-  if (!callback_) return;
+  if (!callback_data_) return;
+
+  // Make a copy of the C-style function pointer that we are about to invoke
+  // before we release the lock guarding it.
+  FlagCallback cb = callback_data_->func;
 
   // If the flag has a mutation callback this function invokes it. While the
   // callback is being invoked the primary flag's mutex is unlocked and it is
@@ -145,14 +181,9 @@ void FlagImpl::InvokeCallback() const {
   // and it also can be different by the time the callback invocation is
   // completed. Requires that *primary_lock be held in exclusive mode; it may be
   // released and reacquired by the implementation.
-  DataGuard()->Unlock();
-
-  {
-    absl::MutexLock lock(&locks_->callback_mu);
-    callback_();
-  }
-
-  DataGuard()->Lock();
+  MutexRelock relock(DataGuard());
+  absl::MutexLock lock(&callback_data_->guard);
+  cb();
 }
 
 bool FlagImpl::RestoreState(const CommandLineFlag& flag, const void* value,
@@ -177,12 +208,13 @@ bool FlagImpl::RestoreState(const CommandLineFlag& flag, const void* value,
 }
 
 // Attempts to parse supplied `value` string using parsing routine in the `flag`
-// argument. If parsing successful, this function stores the parsed value in
-// 'dst' assuming it is a pointer to the flag's value type. In case if any error
-// is encountered in either step, the error message is stored in 'err'
-bool FlagImpl::TryParse(const CommandLineFlag& flag, void* dst,
+// argument. If parsing successful, this function replaces the dst with newly
+// parsed value. In case if any error is encountered in either step, the error
+// message is stored in 'err'
+bool FlagImpl::TryParse(const CommandLineFlag& flag, void** dst,
                         absl::string_view value, std::string* err) const {
   auto tentative_value = MakeInitValue();
+
   std::string parse_err;
   if (!Parse(marshalling_op_, value, tentative_value.get(), &parse_err)) {
     auto type_name = flag.Typename();
@@ -194,7 +226,10 @@ bool FlagImpl::TryParse(const CommandLineFlag& flag, void* dst,
     return false;
   }
 
-  Copy(op_, tentative_value.get(), dst);
+  void* old_val = *dst;
+  *dst = tentative_value.release();
+  tentative_value.reset(old_val);
+
   return true;
 }
 
@@ -274,7 +309,7 @@ bool FlagImpl::SetFromString(const CommandLineFlag& flag,
   switch (set_mode) {
     case SET_FLAGS_VALUE: {
       // set or modify the flag's value
-      if (!TryParse(flag, cur_, value, err)) return false;
+      if (!TryParse(flag, &cur_, value, err)) return false;
       modified_ = true;
       counter_++;
       StoreAtomic();
@@ -288,7 +323,7 @@ bool FlagImpl::SetFromString(const CommandLineFlag& flag,
     case SET_FLAG_IF_DEFAULT: {
       // set the flag's value, but only if it hasn't been set by someone else
       if (!modified_) {
-        if (!TryParse(flag, cur_, value, err)) return false;
+        if (!TryParse(flag, &cur_, value, err)) return false;
         modified_ = true;
         counter_++;
         StoreAtomic();
@@ -305,18 +340,19 @@ bool FlagImpl::SetFromString(const CommandLineFlag& flag,
       break;
     }
     case SET_FLAGS_DEFAULT: {
-      // Flag's new default-value.
-      auto new_default_value = MakeInitValue();
-
-      if (!TryParse(flag, new_default_value.get(), value, err)) return false;
-
       if (def_kind_ == FlagDefaultSrcKind::kDynamicValue) {
-        // Release old default value.
-        Delete(op_, default_src_.dynamic_value);
-      }
+        if (!TryParse(flag, &default_src_.dynamic_value, value, err)) {
+          return false;
+        }
+      } else {
+        void* new_default_val = nullptr;
+        if (!TryParse(flag, &new_default_val, value, err)) {
+          return false;
+        }
 
-      default_src_.dynamic_value = new_default_value.release();
-      def_kind_ = FlagDefaultSrcKind::kDynamicValue;
+        default_src_.dynamic_value = new_default_val;
+        def_kind_ = FlagDefaultSrcKind::kDynamicValue;
+      }
 
       if (!modified_) {
         // Need to set both default value *and* current, in this case
@@ -361,4 +397,5 @@ bool FlagImpl::ValidateInputValue(absl::string_view value) const {
 }
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index 947a8cad..20de406f 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -27,6 +27,7 @@
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 constexpr int64_t AtomicInit() { return 0xababababababababll; }
@@ -156,10 +157,11 @@ class FlagImpl {
         help_(help.source),
         help_source_kind_(help.kind),
         def_kind_(flags_internal::FlagDefaultSrcKind::kGenFunc),
-        default_src_(default_value_gen) {}
+        default_src_(default_value_gen),
+        data_guard_{} {}
 
   // Forces destruction of the Flag's data.
-  void Destroy() const;
+  void Destroy();
 
   // Constant access methods
   std::string Help() const;
@@ -170,9 +172,10 @@ class FlagImpl {
   void Read(const CommandLineFlag& flag, void* dst,
             const flags_internal::FlagOpFn dst_op) const
       ABSL_LOCKS_EXCLUDED(*DataGuard());
-  // Attempts to parse supplied `value` std::string.
-  bool TryParse(const CommandLineFlag& flag, void* dst, absl::string_view value,
-                std::string* err) const
+  // Attempts to parse supplied `value` std::string. If parsing is successful, then
+  // it replaces `dst` with the new value.
+  bool TryParse(const CommandLineFlag& flag, void** dst,
+                absl::string_view value, std::string* err) const
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
   template <typename T>
   bool AtomicGet(T* v) const {
@@ -226,8 +229,7 @@ class FlagImpl {
   void Init();
   // Ensures that the lazily initialized data is initialized,
   // and returns pointer to the mutex guarding flags data.
-  absl::Mutex* DataGuard() const ABSL_LOCK_RETURNED(locks_->primary_mu);
-
+  absl::Mutex* DataGuard() const ABSL_LOCK_RETURNED((absl::Mutex*)&data_guard_);
   // Returns heap allocated value of type T initialized with default value.
   std::unique_ptr<void, DynValueDeleter> MakeInitValue() const
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
@@ -239,9 +241,12 @@ class FlagImpl {
   // Indicates if help message was supplied as literal or generator func.
   const FlagHelpSrcKind help_source_kind_;
 
-  // Mutable Flag's data. (guarded by DataGuard()).
-  // Indicates that locks_ and cur_ fields have been lazily initialized.
+  // Indicates that the Flag state is initialized.
   std::atomic<bool> inited_{false};
+  // Mutable Flag state (guarded by data_guard_).
+  // Additional bool to protect against multiple concurrent constructions
+  // of `data_guard_`.
+  bool is_data_guard_inited_ = false;
   // Has flag value been modified?
   bool modified_ ABSL_GUARDED_BY(*DataGuard()) = false;
   // Specified on command line.
@@ -261,22 +266,20 @@ class FlagImpl {
   // For some types, a copy of the current value is kept in an atomically
   // accessible field.
   std::atomic<int64_t> atomic_{flags_internal::AtomicInit()};
-  // Mutation callback
-  FlagCallback callback_ = nullptr;
-
-  // Lazily initialized mutexes for this flag value.  We cannot inline a
-  // SpinLock or Mutex here because those have non-constexpr constructors and
-  // so would prevent constant initialization of this type.
-  // TODO(rogeeff): fix it once Mutex has constexpr constructor
-  // The following struct contains the locks in a CommandLineFlag struct.
-  // They are in a separate struct that is lazily allocated to avoid problems
-  // with static initialization and to avoid multiple allocations.
-  struct CommandLineFlagLocks {
-    absl::Mutex primary_mu;   // protects several fields in CommandLineFlag
-    absl::Mutex callback_mu;  // used to serialize callbacks
-  };
 
-  CommandLineFlagLocks* locks_ = nullptr;  // locks, laziliy allocated.
+  struct CallbackData {
+    FlagCallback func;
+    absl::Mutex guard;  // Guard for concurrent callback invocations.
+  };
+  CallbackData* callback_data_ ABSL_GUARDED_BY(*DataGuard()) = nullptr;
+  // This is reserved space for an absl::Mutex to guard flag data. It will be
+  // initialized in FlagImpl::Init via placement new.
+  // We can't use "absl::Mutex data_guard_", since this class is not literal.
+  // We do not want to use "absl::Mutex* data_guard_", since this would require
+  // heap allocation during initialization, which is both slows program startup
+  // and can fail. Using reserved space + placement new allows us to avoid both
+  // problems.
+  alignas(absl::Mutex) mutable char data_guard_[sizeof(absl::Mutex)];
 };
 
 // This is "unspecified" implementation of absl::Flag<T> type.
@@ -354,7 +357,7 @@ class Flag final : public flags_internal::CommandLineFlag {
  private:
   friend class FlagState<T>;
 
-  void Destroy() const override { impl_.Destroy(); }
+  void Destroy() override { impl_.Destroy(); }
 
   void Read(void* dst) const override {
     impl_.Read(*this, dst, &flags_internal::FlagOps<T>);
@@ -414,6 +417,7 @@ T* MakeFromDefaultValue(EmptyBraces) {
 }
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FLAGS_INTERNAL_FLAG_H_
diff --git a/absl/flags/internal/parse.h b/absl/flags/internal/parse.h
index fd3aca61..e534635b 100644
--- a/absl/flags/internal/parse.h
+++ b/absl/flags/internal/parse.h
@@ -27,6 +27,7 @@ ABSL_DECLARE_FLAG(std::vector<std::string>, tryfromenv);
 ABSL_DECLARE_FLAG(std::vector<std::string>, undefok);
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 enum class ArgvListAction { kRemoveParsedArgs, kKeepParsedArgs };
@@ -43,6 +44,7 @@ std::vector<char*> ParseCommandLineImpl(int argc, char* argv[],
                                         OnUndefinedFlag on_undef_flag);
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FLAGS_INTERNAL_PARSE_H_
diff --git a/absl/flags/internal/path_util.h b/absl/flags/internal/path_util.h
index 5615c0e6..41696377 100644
--- a/absl/flags/internal/path_util.h
+++ b/absl/flags/internal/path_util.h
@@ -20,6 +20,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 // A portable interface that returns the basename of the filename passed as an
@@ -55,6 +56,7 @@ inline absl::string_view Package(absl::string_view filename) {
 }
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FLAGS_INTERNAL_PATH_UTIL_H_
diff --git a/absl/flags/internal/program_name.cc b/absl/flags/internal/program_name.cc
index f0811f14..df0c3309 100644
--- a/absl/flags/internal/program_name.cc
+++ b/absl/flags/internal/program_name.cc
@@ -21,6 +21,7 @@
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 ABSL_CONST_INIT static absl::Mutex program_name_guard(absl::kConstInit);
@@ -50,4 +51,5 @@ void SetProgramInvocationName(absl::string_view prog_name_str) {
 }
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/internal/program_name.h b/absl/flags/internal/program_name.h
index 326f24bb..317a7c5c 100644
--- a/absl/flags/internal/program_name.h
+++ b/absl/flags/internal/program_name.h
@@ -24,6 +24,7 @@
 // Program name
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 // Returns program invocation name or "UNKNOWN" if `SetProgramInvocationName()`
@@ -42,6 +43,7 @@ std::string ShortProgramInvocationName();
 void SetProgramInvocationName(absl::string_view prog_name_str);
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FLAGS_INTERNAL_PROGRAM_NAME_H_
diff --git a/absl/flags/internal/registry.cc b/absl/flags/internal/registry.cc
index 52d9f3c7..5eae933c 100644
--- a/absl/flags/internal/registry.cc
+++ b/absl/flags/internal/registry.cc
@@ -30,6 +30,7 @@
 //    set it.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 // --------------------------------------------------------------------
@@ -281,7 +282,7 @@ class RetiredFlagObj final : public flags_internal::CommandLineFlag {
         op_(ops) {}
 
  private:
-  void Destroy() const override {
+  void Destroy() override {
     // Values are heap allocated for Retired Flags.
     delete this;
   }
@@ -336,4 +337,5 @@ bool IsRetiredFlag(absl::string_view name, bool* type_is_bool) {
 }
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/internal/registry.h b/absl/flags/internal/registry.h
index 1889f3a0..d2145a8a 100644
--- a/absl/flags/internal/registry.h
+++ b/absl/flags/internal/registry.h
@@ -27,6 +27,7 @@
 // Global flags registry API.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 CommandLineFlag* FindCommandLineFlag(absl::string_view name);
@@ -115,6 +116,7 @@ class FlagSaver {
 };
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FLAGS_INTERNAL_REGISTRY_H_
diff --git a/absl/flags/internal/type_erased.cc b/absl/flags/internal/type_erased.cc
index a1650fcf..7910db8f 100644
--- a/absl/flags/internal/type_erased.cc
+++ b/absl/flags/internal/type_erased.cc
@@ -21,6 +21,7 @@
 #include "absl/strings/str_cat.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 bool GetCommandLineOption(absl::string_view name, std::string* value) {
@@ -79,4 +80,5 @@ bool SpecifiedOnCommandLine(absl::string_view name) {
 }
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/internal/type_erased.h b/absl/flags/internal/type_erased.h
index a9551166..6cbd84cd 100644
--- a/absl/flags/internal/type_erased.h
+++ b/absl/flags/internal/type_erased.h
@@ -25,6 +25,7 @@
 // Registry interfaces operating on type erased handles.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 // If a flag named "name" exists, store its current value in *OUTPUT
@@ -81,6 +82,7 @@ inline bool GetByName(absl::string_view name, T* dst) {
 }
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FLAGS_INTERNAL_TYPE_ERASED_H_
diff --git a/absl/flags/internal/usage.cc b/absl/flags/internal/usage.cc
index dc12e32f..4602c019 100644
--- a/absl/flags/internal/usage.cc
+++ b/absl/flags/internal/usage.cc
@@ -44,6 +44,7 @@ ABSL_FLAG(std::string, helpmatch, "",
           "show help on modules whose name contains the specified substr");
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 namespace {
 
@@ -404,4 +405,5 @@ int HandleUsageFlags(std::ostream& out,
 }
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/internal/usage.h b/absl/flags/internal/usage.h
index 76075b08..5e8ca6a1 100644
--- a/absl/flags/internal/usage.h
+++ b/absl/flags/internal/usage.h
@@ -27,6 +27,7 @@
 // Usage reporting interfaces
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 // The format to report the help messages in.
@@ -64,6 +65,7 @@ int HandleUsageFlags(std::ostream& out,
                      absl::string_view program_usage_message);
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 ABSL_DECLARE_FLAG(bool, help);
diff --git a/absl/flags/marshalling.cc b/absl/flags/marshalling.cc
index f4ebe0e3..87020a27 100644
--- a/absl/flags/marshalling.cc
+++ b/absl/flags/marshalling.cc
@@ -27,6 +27,7 @@
 #include "absl/strings/str_split.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 // --------------------------------------------------------------------
@@ -226,4 +227,5 @@ std::string AbslUnparseFlag(absl::LogSeverity v) {
   return absl::UnparseFlag(static_cast<int>(v));
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/marshalling.h b/absl/flags/marshalling.h
index 6d391804..b9fca752 100644
--- a/absl/flags/marshalling.h
+++ b/absl/flags/marshalling.h
@@ -168,6 +168,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 // Overloads of `AbslParseFlag()` and `AbslUnparseFlag()` for fundamental types.
@@ -256,6 +257,7 @@ enum class LogSeverity : int;
 bool AbslParseFlag(absl::string_view, absl::LogSeverity*, std::string*);
 std::string AbslUnparseFlag(absl::LogSeverity);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FLAGS_MARSHALLING_H_
diff --git a/absl/flags/parse.cc b/absl/flags/parse.cc
index 16c4d68f..5a56a356 100644
--- a/absl/flags/parse.cc
+++ b/absl/flags/parse.cc
@@ -38,6 +38,7 @@
 // --------------------------------------------------------------------
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 namespace {
 
@@ -52,6 +53,7 @@ ABSL_CONST_INIT bool tryfromenv_needs_processing
 
 }  // namespace
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 ABSL_FLAG(std::vector<std::string>, flagfile, {},
@@ -109,6 +111,7 @@ ABSL_FLAG(std::vector<std::string>, undefok, {},
           "with that name");
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 namespace {
@@ -748,4 +751,5 @@ std::vector<char*> ParseCommandLine(int argc, char* argv[]) {
       flags_internal::OnUndefinedFlag::kAbortIfUndefined);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/parse.h b/absl/flags/parse.h
index dbb75101..871fc993 100644
--- a/absl/flags/parse.h
+++ b/absl/flags/parse.h
@@ -29,6 +29,7 @@
 #include "absl/flags/internal/parse.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // ParseCommandLine()
 //
@@ -53,6 +54,7 @@ namespace absl {
 // help messages and then exits the program.
 std::vector<char*> ParseCommandLine(int argc, char* argv[]);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FLAGS_PARSE_H_
diff --git a/absl/flags/usage.cc b/absl/flags/usage.cc
index dff7a3da..60459bc2 100644
--- a/absl/flags/usage.cc
+++ b/absl/flags/usage.cc
@@ -20,6 +20,7 @@
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 namespace {
 ABSL_CONST_INIT absl::Mutex usage_message_guard(absl::kConstInit);
@@ -53,4 +54,5 @@ absl::string_view ProgramUsageMessage() {
              : "Warning: SetProgramUsageMessage() never called";
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/usage.h b/absl/flags/usage.h
index 3a121071..299e5c34 100644
--- a/absl/flags/usage.h
+++ b/absl/flags/usage.h
@@ -22,6 +22,7 @@
 // Usage reporting interfaces
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Sets the "usage" message to be used by help reporting routines.
 // For example:
@@ -35,6 +36,7 @@ void SetProgramUsageMessage(absl::string_view new_usage_message);
 // Returns the usage message set by SetProgramUsageMessage().
 absl::string_view ProgramUsageMessage();
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FLAGS_USAGE_H_
diff --git a/absl/flags/usage_config.cc b/absl/flags/usage_config.cc
index f97bf300..21a2dd01 100644
--- a/absl/flags/usage_config.cc
+++ b/absl/flags/usage_config.cc
@@ -34,6 +34,7 @@ ABSL_ATTRIBUTE_WEAK void AbslInternalReportFatalUsageError(absl::string_view) {}
 }  // extern "C"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
 namespace {
@@ -149,4 +150,5 @@ void SetFlagsUsageConfig(FlagsUsageConfig usage_config) {
     flags_internal::custom_usage_config = new FlagsUsageConfig(usage_config);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/usage_config.h b/absl/flags/usage_config.h
index bfd0eedb..e6428e0a 100644
--- a/absl/flags/usage_config.h
+++ b/absl/flags/usage_config.h
@@ -54,6 +54,7 @@
 //     Shows help on modules whose name contains the specified substring
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace flags_internal {
 using FlagKindFilter = std::function<bool (absl::string_view)>;
@@ -118,6 +119,7 @@ FlagsUsageConfig GetUsageConfig();
 void ReportUsageError(absl::string_view msg, bool is_fatal);
 
 }  // namespace flags_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 extern "C" {
diff --git a/absl/functional/function_ref.h b/absl/functional/function_ref.h
index 42d9f16f..370acc55 100644
--- a/absl/functional/function_ref.h
+++ b/absl/functional/function_ref.h
@@ -54,6 +54,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // FunctionRef
 //
@@ -132,6 +133,7 @@ class FunctionRef<R(Args...)> {
   absl::functional_internal::Invoker<R, Args...> invoker_;
 };
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FUNCTIONAL_FUNCTION_REF_H_
diff --git a/absl/functional/function_ref_benchmark.cc b/absl/functional/function_ref_benchmark.cc
index f6dfcabf..045305bf 100644
--- a/absl/functional/function_ref_benchmark.cc
+++ b/absl/functional/function_ref_benchmark.cc
@@ -20,6 +20,7 @@
 #include "absl/base/attributes.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 int dummy = 0;
@@ -137,4 +138,5 @@ void BM_NonTrivialArgsFunctionRef(benchmark::State& state) {
 BENCHMARK(BM_NonTrivialArgsFunctionRef);
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/functional/function_ref_test.cc b/absl/functional/function_ref_test.cc
index 90829db0..3aa59745 100644
--- a/absl/functional/function_ref_test.cc
+++ b/absl/functional/function_ref_test.cc
@@ -22,6 +22,7 @@
 #include "absl/memory/memory.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 void RunFun(FunctionRef<void()> f) { f(); }
@@ -252,4 +253,5 @@ TEST(FunctionRef, PassByValueTypes) {
 }
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/functional/internal/function_ref.h b/absl/functional/internal/function_ref.h
index fcb0496c..d1575054 100644
--- a/absl/functional/internal/function_ref.h
+++ b/absl/functional/internal/function_ref.h
@@ -23,6 +23,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace functional_internal {
 
 // Like a void* that can handle function pointers as well. The standard does not
@@ -99,6 +100,7 @@ template <bool C>
 using EnableIf = typename ::std::enable_if<C, int>::type;
 
 }  // namespace functional_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_FUNCTIONAL_INTERNAL_FUNCTION_REF_H_
diff --git a/absl/hash/hash.h b/absl/hash/hash.h
index 297dc9cb..23a65ea8 100644
--- a/absl/hash/hash.h
+++ b/absl/hash/hash.h
@@ -73,6 +73,7 @@
 #include "absl/hash/internal/hash.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // `absl::Hash`
@@ -317,6 +318,7 @@ class HashState : public hash_internal::HashStateBase<HashState> {
   void (*combine_contiguous_)(void*, const unsigned char*, size_t);
 };
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HASH_HASH_H_
diff --git a/absl/hash/hash_test.cc b/absl/hash/hash_test.cc
index 42c0c3d8..7a9d57f7 100644
--- a/absl/hash/hash_test.cc
+++ b/absl/hash/hash_test.cc
@@ -681,6 +681,7 @@ H AbslHashValue(H state, CustomHashType<Tags...> t) {
 }  // namespace
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace hash_internal {
 template <InvokeTag... Tags>
 struct is_uniquely_represented<
@@ -688,6 +689,7 @@ struct is_uniquely_represented<
     typename EnableIfContained<InvokeTag::kUniquelyRepresented, Tags...>::type>
     : std::true_type {};
 }  // namespace hash_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #if ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
diff --git a/absl/hash/hash_testing.h b/absl/hash/hash_testing.h
index c45bc154..1e1c5741 100644
--- a/absl/hash/hash_testing.h
+++ b/absl/hash/hash_testing.h
@@ -28,6 +28,7 @@
 #include "absl/types/variant.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Run the absl::Hash algorithm over all the elements passed in and verify that
 // their hash expansion is congruent with their `==` operator.
@@ -371,6 +372,7 @@ VerifyTypeImplementsAbslHashCorrectly(std::initializer_list<T> values,
       equals);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HASH_HASH_TESTING_H_
diff --git a/absl/hash/internal/city.cc b/absl/hash/internal/city.cc
index dc7650a7..e122c184 100644
--- a/absl/hash/internal/city.cc
+++ b/absl/hash/internal/city.cc
@@ -30,6 +30,7 @@
 #include "absl/base/optimization.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace hash_internal {
 
 #ifdef ABSL_IS_BIG_ENDIAN
@@ -341,4 +342,5 @@ uint64_t CityHash64WithSeeds(const char *s, size_t len, uint64_t seed0,
 }
 
 }  // namespace hash_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/hash/internal/city.h b/absl/hash/internal/city.h
index b43d3407..161c7748 100644
--- a/absl/hash/internal/city.h
+++ b/absl/hash/internal/city.h
@@ -47,9 +47,13 @@
 
 #include <stdint.h>
 #include <stdlib.h>  // for size_t.
+
 #include <utility>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace hash_internal {
 
 typedef std::pair<uint64_t, uint64_t> uint128;
@@ -86,6 +90,7 @@ inline uint64_t Hash128to64(const uint128 &x) {
 }
 
 }  // namespace hash_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HASH_INTERNAL_CITY_H_
diff --git a/absl/hash/internal/city_test.cc b/absl/hash/internal/city_test.cc
index 71b4ecce..251d381d 100644
--- a/absl/hash/internal/city_test.cc
+++ b/absl/hash/internal/city_test.cc
@@ -20,6 +20,7 @@
 #include "gtest/gtest.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace hash_internal {
 
 static const uint64_t k0 = 0xc3a5c85c97cb3127ULL;
@@ -590,4 +591,5 @@ TEST(CityHashTest, Unchanging) {
 }
 
 }  // namespace hash_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/hash/internal/hash.cc b/absl/hash/internal/hash.cc
index c17f3be1..b44ecb3a 100644
--- a/absl/hash/internal/hash.cc
+++ b/absl/hash/internal/hash.cc
@@ -15,6 +15,7 @@
 #include "absl/hash/internal/hash.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace hash_internal {
 
 uint64_t CityHashState::CombineLargeContiguousImpl32(uint64_t state,
@@ -50,4 +51,5 @@ uint64_t CityHashState::CombineLargeContiguousImpl64(uint64_t state,
 ABSL_CONST_INIT const void* const CityHashState::kSeed = &kSeed;
 
 }  // namespace hash_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/hash/internal/hash.h b/absl/hash/internal/hash.h
index 7d44f57d..2564978a 100644
--- a/absl/hash/internal/hash.h
+++ b/absl/hash/internal/hash.h
@@ -50,6 +50,7 @@
 #include "absl/hash/internal/city.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace hash_internal {
 
 class PiecewiseCombiner;
@@ -980,6 +981,7 @@ H PiecewiseCombiner::finalize(H state) {
 }
 
 }  // namespace hash_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HASH_INTERNAL_HASH_H_
diff --git a/absl/hash/internal/spy_hash_state.h b/absl/hash/internal/spy_hash_state.h
index 05c7cafe..c0831208 100644
--- a/absl/hash/internal/spy_hash_state.h
+++ b/absl/hash/internal/spy_hash_state.h
@@ -25,6 +25,7 @@
 #include "absl/strings/str_join.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace hash_internal {
 
 // SpyHashState is an implementation of the HashState API that simply
@@ -224,6 +225,7 @@ void AbslHashValue(SpyHashStateImpl<T>, const U&);
 using SpyHashState = SpyHashStateImpl<void>;
 
 }  // namespace hash_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HASH_INTERNAL_SPY_HASH_STATE_H_
diff --git a/absl/memory/memory.h b/absl/memory/memory.h
index 243a5dda..513f7103 100644
--- a/absl/memory/memory.h
+++ b/absl/memory/memory.h
@@ -34,6 +34,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // Function Template: WrapUnique()
@@ -688,6 +689,7 @@ void CopyRange(Allocator& alloc, Iterator destination, InputIterator first,
   }
 }
 }  // namespace memory_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_MEMORY_MEMORY_H_
diff --git a/absl/memory/memory_exception_safety_test.cc b/absl/memory/memory_exception_safety_test.cc
index 729507e9..c0910dc7 100644
--- a/absl/memory/memory_exception_safety_test.cc
+++ b/absl/memory/memory_exception_safety_test.cc
@@ -22,6 +22,7 @@
 #include "absl/base/internal/exception_safety_testing.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 constexpr int kLength = 50;
@@ -53,6 +54,7 @@ TEST(MakeUnique, CheckForLeaks) {
 }
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_HAVE_EXCEPTIONS
diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h
index 8cd5f043..ba87d2f0 100644
--- a/absl/meta/type_traits.h
+++ b/absl/meta/type_traits.h
@@ -48,6 +48,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Defined and documented later on in this file.
 template <typename T>
@@ -752,6 +753,7 @@ using swap_internal::Swap;
 using swap_internal::StdSwapIsUnconstrained;
 
 }  // namespace type_traits_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_META_TYPE_TRAITS_H_
diff --git a/absl/numeric/int128.cc b/absl/numeric/int128.cc
index 1eba09de..a20a77e7 100644
--- a/absl/numeric/int128.cc
+++ b/absl/numeric/int128.cc
@@ -23,6 +23,7 @@
 #include <type_traits>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 const uint128 kuint128max = MakeUint128(std::numeric_limits<uint64_t>::max(),
                                         std::numeric_limits<uint64_t>::max());
@@ -349,6 +350,7 @@ std::ostream& operator<<(std::ostream& os, int128 v) {
   return os << rep;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 namespace std {
diff --git a/absl/numeric/int128.h b/absl/numeric/int128.h
index 50617612..718f70b1 100644
--- a/absl/numeric/int128.h
+++ b/absl/numeric/int128.h
@@ -49,6 +49,7 @@
 #endif  // defined(_MSC_VER)
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 class int128;
 
@@ -245,6 +246,7 @@ constexpr uint128 Uint128Max() {
                  (std::numeric_limits<uint64_t>::max)());
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // Specialized numeric_limits for uint128.
@@ -293,6 +295,7 @@ class numeric_limits<absl::uint128> {
 }  // namespace std
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // int128
 //
@@ -478,6 +481,7 @@ constexpr int128 Int128Min() {
   return int128((std::numeric_limits<int64_t>::min)(), 0);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // Specialized numeric_limits for int128.
@@ -529,6 +533,7 @@ class numeric_limits<absl::int128> {
 //                      Implementation details follow
 // --------------------------------------------------------------------------
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 constexpr uint128 MakeUint128(uint64_t high, uint64_t low) {
   return uint128(high, low);
@@ -1078,6 +1083,7 @@ constexpr int64_t BitCastToSigned(uint64_t v) {
 #include "absl/numeric/int128_no_intrinsic.inc"  // IWYU pragma: export
 #endif  // ABSL_HAVE_INTRINSIC_INT128
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #undef ABSL_INTERNAL_WCHAR_T
diff --git a/absl/random/CMakeLists.txt b/absl/random/CMakeLists.txt
index 13e96357..46dbc3ef 100644
--- a/absl/random/CMakeLists.txt
+++ b/absl/random/CMakeLists.txt
@@ -526,6 +526,8 @@ absl_cc_library(
     ${ABSL_DEFAULT_COPTS}
   LINKOPTS
     ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
 )
 
 # Internal-only target, do not depend on directly.
@@ -559,6 +561,8 @@ absl_cc_library(
     ${ABSL_DEFAULT_COPTS}
   LINKOPTS
     ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
 )
 
 # Internal-only target, do not depend on directly.
@@ -618,6 +622,8 @@ absl_cc_library(
     ${ABSL_DEFAULT_COPTS}
   LINKOPTS
     ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
   TESTONLY
 )
 
@@ -631,6 +637,8 @@ absl_cc_library(
     ${ABSL_DEFAULT_COPTS}
   LINKOPTS
     ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
   TESTONLY
 )
 
@@ -782,6 +790,8 @@ absl_cc_library(
     ${ABSL_DEFAULT_COPTS}
   LINKOPTS
     ${ABSL_DEFAULT_LINKOPTS}
+  DEPS
+    absl::config
 )
 
 # Internal-only target, do not depend on directly.
@@ -816,6 +826,7 @@ absl_cc_library(
     ${ABSL_DEFAULT_LINKOPTS}
   DEPS
     absl::random_internal_platform
+    absl::config
 )
 
 # Internal-only target, do not depend on directly.
@@ -835,6 +846,7 @@ absl_cc_library(
   DEPS
     absl::random_internal_platform
     absl::random_internal_randen_hwaes_impl
+    absl::config
 )
 
 # Internal-only target, do not depend on directly.
@@ -851,6 +863,7 @@ absl_cc_library(
     ${ABSL_DEFAULT_LINKOPTS}
   DEPS
     absl::random_internal_platform
+    absl::config
 )
 
 # Internal-only target, do not depend on directly.
@@ -868,6 +881,7 @@ absl_cc_library(
   LINKOPTS
     ${ABSL_DEFAULT_LINKOPTS}
   DEPS
+    absl::config
     absl::core_headers
     absl::raw_logging_internal
     absl::strings
diff --git a/absl/random/bernoulli_distribution.h b/absl/random/bernoulli_distribution.h
index 326fcb6e..25bd0d5c 100644
--- a/absl/random/bernoulli_distribution.h
+++ b/absl/random/bernoulli_distribution.h
@@ -24,6 +24,7 @@
 #include "absl/random/internal/iostream_state_saver.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::bernoulli_distribution is a drop in replacement for
 // std::bernoulli_distribution. It guarantees that (given a perfect
@@ -193,6 +194,7 @@ bool bernoulli_distribution::Generate(double p,
   }
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_BERNOULLI_DISTRIBUTION_H_
diff --git a/absl/random/beta_distribution.h b/absl/random/beta_distribution.h
index b09b02f0..c154066f 100644
--- a/absl/random/beta_distribution.h
+++ b/absl/random/beta_distribution.h
@@ -29,6 +29,7 @@
 #include "absl/random/internal/iostream_state_saver.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::beta_distribution:
 // Generate a floating-point variate conforming to a Beta distribution:
@@ -420,6 +421,7 @@ std::basic_istream<CharT, Traits>& operator>>(
   return is;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_BETA_DISTRIBUTION_H_
diff --git a/absl/random/bit_gen_ref.h b/absl/random/bit_gen_ref.h
index 00e904f8..e8771162 100644
--- a/absl/random/bit_gen_ref.h
+++ b/absl/random/bit_gen_ref.h
@@ -31,6 +31,7 @@
 #include "absl/random/internal/mocking_bit_gen_base.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 template <typename URBG, typename = void, typename = void, typename = void>
@@ -146,6 +147,7 @@ struct DistributionCaller<absl::BitGenRef> {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_BIT_GEN_REF_H_
diff --git a/absl/random/bit_gen_ref_test.cc b/absl/random/bit_gen_ref_test.cc
index bc02ca5c..ca0e4d70 100644
--- a/absl/random/bit_gen_ref_test.cc
+++ b/absl/random/bit_gen_ref_test.cc
@@ -21,6 +21,7 @@
 #include "absl/random/random.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 class ConstBitGen : public absl::random_internal::MockingBitGenBase {
   bool CallImpl(const std::type_info&, void*, void* result) override {
@@ -96,4 +97,5 @@ TEST(BitGenRefTest, MockingBitGenBaseOverrides) {
   EXPECT_EQ(FnTest(gen_ref), 42);  // Copy
 }
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/discrete_distribution.cc b/absl/random/discrete_distribution.cc
index e6c09c51..081accee 100644
--- a/absl/random/discrete_distribution.cc
+++ b/absl/random/discrete_distribution.cc
@@ -15,6 +15,7 @@
 #include "absl/random/discrete_distribution.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // Initializes the distribution table for Walker's Aliasing algorithm, described
@@ -93,4 +94,5 @@ std::vector<std::pair<double, size_t>> InitDiscreteDistribution(
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/discrete_distribution.h b/absl/random/discrete_distribution.h
index 1560f03c..171aa11a 100644
--- a/absl/random/discrete_distribution.h
+++ b/absl/random/discrete_distribution.h
@@ -29,6 +29,7 @@
 #include "absl/random/uniform_int_distribution.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::discrete_distribution
 //
@@ -240,6 +241,7 @@ std::basic_istream<CharT, Traits>& operator>>(
   return is;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_DISCRETE_DISTRIBUTION_H_
diff --git a/absl/random/distribution_format_traits.h b/absl/random/distribution_format_traits.h
index f9f07058..22b358cc 100644
--- a/absl/random/distribution_format_traits.h
+++ b/absl/random/distribution_format_traits.h
@@ -36,6 +36,7 @@
 #include "absl/types/span.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 struct IntervalClosedClosedTag;
 struct IntervalClosedOpenTag;
@@ -271,6 +272,7 @@ struct DistributionFormatTraits<UniformDistributionWrapper<NumType>> {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_DISTRIBUTION_FORMAT_TRAITS_H_
diff --git a/absl/random/distributions.h b/absl/random/distributions.h
index 6ced6061..c1fb6650 100644
--- a/absl/random/distributions.h
+++ b/absl/random/distributions.h
@@ -67,6 +67,7 @@
 #include "absl/random/zipf_distribution.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 ABSL_INTERNAL_INLINE_CONSTEXPR(IntervalClosedClosedTag, IntervalClosedClosed,
                                {});
@@ -458,6 +459,7 @@ IntType Zipf(URBG&& urbg,  // NOLINT(runtime/references)
       distribution_t, format_t>(&urbg, hi, q, v);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_DISTRIBUTIONS_H_
diff --git a/absl/random/exponential_distribution.h b/absl/random/exponential_distribution.h
index 24abf57e..b5caf8a1 100644
--- a/absl/random/exponential_distribution.h
+++ b/absl/random/exponential_distribution.h
@@ -27,6 +27,7 @@
 #include "absl/random/internal/iostream_state_saver.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::exponential_distribution:
 // Generates a number conforming to an exponential distribution and is
@@ -158,6 +159,7 @@ std::basic_istream<CharT, Traits>& operator>>(
   return is;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_EXPONENTIAL_DISTRIBUTION_H_
diff --git a/absl/random/gaussian_distribution.cc b/absl/random/gaussian_distribution.cc
index 5dd84619..c7a72cb2 100644
--- a/absl/random/gaussian_distribution.cc
+++ b/absl/random/gaussian_distribution.cc
@@ -4,6 +4,7 @@
 #include "absl/random/gaussian_distribution.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 const gaussian_distribution_base::Tables
@@ -96,6 +97,7 @@ const gaussian_distribution_base::Tables
      0.9362826816850632339, 0.9635996931270905952, 1}};
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // clang-format on
diff --git a/absl/random/gaussian_distribution.h b/absl/random/gaussian_distribution.h
index c299e944..c1427b06 100644
--- a/absl/random/gaussian_distribution.h
+++ b/absl/random/gaussian_distribution.h
@@ -33,6 +33,7 @@
 #include "absl/random/internal/iostream_state_saver.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // absl::gaussian_distribution_base implements the underlying ziggurat algorithm
@@ -267,6 +268,7 @@ inline double gaussian_distribution_base::zignor(
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_GAUSSIAN_DISTRIBUTION_H_
diff --git a/absl/random/internal/BUILD.bazel b/absl/random/internal/BUILD.bazel
index 952929ea..d7ad4efe 100644
--- a/absl/random/internal/BUILD.bazel
+++ b/absl/random/internal/BUILD.bazel
@@ -51,6 +51,7 @@ cc_library(
     visibility = [
         "//absl/random:__pkg__",
     ],
+    deps = ["//absl/base:config"],
 )
 
 cc_library(
@@ -78,6 +79,7 @@ cc_library(
     visibility = [
         "//absl/random:__pkg__",
     ],
+    deps = ["//absl/base:config"],
 )
 
 cc_library(
@@ -138,6 +140,7 @@ cc_library(
     ],
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = ["//absl/base:config"],
 )
 
 cc_library(
@@ -148,6 +151,7 @@ cc_library(
     ],
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
+    deps = ["//absl/base:config"],
 )
 
 cc_library(
@@ -269,6 +273,7 @@ cc_library(
         "randen-keys.inc",
         "platform.h",
     ],
+    deps = ["//absl/base:config"],
 )
 
 cc_library(
@@ -297,6 +302,7 @@ cc_library(
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":platform",
+        "//absl/base:config",
         "//absl/base:core_headers",
     ],
 )
@@ -317,6 +323,7 @@ cc_library(
     deps = [
         ":platform",
         ":randen_hwaes_impl",
+        "//absl/base:config",
     ],
 )
 
@@ -338,6 +345,7 @@ cc_library(
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":platform",
+        "//absl/base:config",
         "//absl/base:core_headers",
     ],
 )
@@ -368,6 +376,7 @@ cc_library(
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
+        "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:raw_logging_internal",
         "//absl/strings",
diff --git a/absl/random/internal/chi_square.cc b/absl/random/internal/chi_square.cc
index c0acc947..640d48ce 100644
--- a/absl/random/internal/chi_square.cc
+++ b/absl/random/internal/chi_square.cc
@@ -19,6 +19,7 @@
 #include "absl/random/internal/distribution_test_util.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 namespace {
 
@@ -227,4 +228,5 @@ double ChiSquarePValue(double chi_square, int dof) {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/internal/chi_square.h b/absl/random/internal/chi_square.h
index fa8646f2..07f4fbe5 100644
--- a/absl/random/internal/chi_square.h
+++ b/absl/random/internal/chi_square.h
@@ -26,7 +26,10 @@
 
 #include <cassert>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 constexpr const char kChiSquared[] = "chi-squared";
@@ -80,6 +83,7 @@ double ChiSquareValue(int dof, double p);
 double ChiSquarePValue(double chi_square, int dof);
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_CHI_SQUARE_H_
diff --git a/absl/random/internal/distribution_caller.h b/absl/random/internal/distribution_caller.h
index 0318e1f8..02603cf8 100644
--- a/absl/random/internal/distribution_caller.h
+++ b/absl/random/internal/distribution_caller.h
@@ -19,7 +19,10 @@
 
 #include <utility>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // DistributionCaller provides an opportunity to overload the general
@@ -51,6 +54,7 @@ struct DistributionCaller {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_DISTRIBUTION_CALLER_H_
diff --git a/absl/random/internal/distribution_test_util.cc b/absl/random/internal/distribution_test_util.cc
index 85c8d596..e9005658 100644
--- a/absl/random/internal/distribution_test_util.cc
+++ b/absl/random/internal/distribution_test_util.cc
@@ -25,6 +25,7 @@
 #include "absl/strings/str_format.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 namespace {
 
@@ -413,4 +414,5 @@ double MaxErrorTolerance(double acceptance_probability) {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/internal/distribution_test_util.h b/absl/random/internal/distribution_test_util.h
index b5ba49fa..6d94cf6c 100644
--- a/absl/random/internal/distribution_test_util.h
+++ b/absl/random/internal/distribution_test_util.h
@@ -26,6 +26,7 @@
 // non-test code.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // http://webspace.ship.edu/pgmarr/Geo441/Lectures/Lec%205%20-%20Normality%20Testing.pdf
@@ -106,6 +107,7 @@ double BetaIncomplete(double x, double p, double q);
 double BetaIncompleteInv(double p, double q, double alpha);
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_DISTRIBUTION_TEST_UTIL_H_
diff --git a/absl/random/internal/distributions.h b/absl/random/internal/distributions.h
index c8cec02b..d7e3c016 100644
--- a/absl/random/internal/distributions.h
+++ b/absl/random/internal/distributions.h
@@ -23,6 +23,7 @@
 #include "absl/random/internal/uniform_helper.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // In the absence of an explicitly provided return-type, the template
@@ -45,6 +46,7 @@ using uniform_inferred_return_t =
                           is_widening_convertible<A, B>::value, B, A>::type>;
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_DISTRIBUTIONS_H_
diff --git a/absl/random/internal/explicit_seed_seq.h b/absl/random/internal/explicit_seed_seq.h
index b660ece5..6a743eaf 100644
--- a/absl/random/internal/explicit_seed_seq.h
+++ b/absl/random/internal/explicit_seed_seq.h
@@ -22,7 +22,10 @@
 #include <iterator>
 #include <vector>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // This class conforms to the C++ Standard "Seed Sequence" concept
@@ -82,6 +85,7 @@ class ExplicitSeedSeq {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_EXPLICIT_SEED_SEQ_H_
diff --git a/absl/random/internal/fast_uniform_bits.h b/absl/random/internal/fast_uniform_bits.h
index e8df92f3..f13c8729 100644
--- a/absl/random/internal/fast_uniform_bits.h
+++ b/absl/random/internal/fast_uniform_bits.h
@@ -20,7 +20,10 @@
 #include <limits>
 #include <type_traits>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 // Returns true if the input value is zero or a power of two. Useful for
 // determining if the range of output values in a URBG
@@ -255,6 +258,7 @@ FastUniformBits<UIntType>::Generate(URBG& g,  // NOLINT(runtime/references)
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_FAST_UNIFORM_BITS_H_
diff --git a/absl/random/internal/fast_uniform_bits_test.cc b/absl/random/internal/fast_uniform_bits_test.cc
index 9f2e8268..f5b837e5 100644
--- a/absl/random/internal/fast_uniform_bits_test.cc
+++ b/absl/random/internal/fast_uniform_bits_test.cc
@@ -19,6 +19,7 @@
 #include "gtest/gtest.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 namespace {
 
@@ -269,4 +270,5 @@ TEST(FastUniformBitsTest, URBG32bitRegression) {
 
 }  // namespace
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/internal/fastmath.h b/absl/random/internal/fastmath.h
index 4bd18410..6baeb5a7 100644
--- a/absl/random/internal/fastmath.h
+++ b/absl/random/internal/fastmath.h
@@ -25,6 +25,7 @@
 #include "absl/base/internal/bits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // Returns the position of the first bit set.
@@ -67,6 +68,7 @@ inline constexpr uint64_t rotr(uint64_t value, uint8_t bits) {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_FASTMATH_H_
diff --git a/absl/random/internal/gaussian_distribution_gentables.cc b/absl/random/internal/gaussian_distribution_gentables.cc
index 16a23cb2..a2bf0394 100644
--- a/absl/random/internal/gaussian_distribution_gentables.cc
+++ b/absl/random/internal/gaussian_distribution_gentables.cc
@@ -27,6 +27,7 @@
 #include "absl/base/macros.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 namespace {
 
@@ -135,6 +136,7 @@ void TableGenerator::Print(std::ostream* os) {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 int main(int, char**) {
diff --git a/absl/random/internal/generate_real.h b/absl/random/internal/generate_real.h
index 246d863e..20f6d208 100644
--- a/absl/random/internal/generate_real.h
+++ b/absl/random/internal/generate_real.h
@@ -29,6 +29,7 @@
 #include "absl/random/internal/traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // Tristate tag types controlling the output of GenerateRealFromBits.
@@ -139,6 +140,7 @@ inline RealType GenerateRealFromBits(uint64_t bits, int exp_bias = 0) {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_GENERATE_REAL_H_
diff --git a/absl/random/internal/iostream_state_saver.h b/absl/random/internal/iostream_state_saver.h
index df88fa76..7378829a 100644
--- a/absl/random/internal/iostream_state_saver.h
+++ b/absl/random/internal/iostream_state_saver.h
@@ -24,6 +24,7 @@
 #include "absl/numeric/int128.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // The null_state_saver does nothing.
@@ -238,6 +239,7 @@ inline FloatType read_floating_point(IStream& is) {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_IOSTREAM_STATE_SAVER_H_
diff --git a/absl/random/internal/mock_overload_set.h b/absl/random/internal/mock_overload_set.h
index 539313d7..c2a30d89 100644
--- a/absl/random/internal/mock_overload_set.h
+++ b/absl/random/internal/mock_overload_set.h
@@ -23,6 +23,7 @@
 #include "absl/random/mocking_bit_gen.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 template <typename DistrT, typename Fn>
@@ -85,5 +86,6 @@ struct MockOverloadSet<DistrT, FirstSig, Rest...>
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 #endif  // ABSL_RANDOM_INTERNAL_MOCK_OVERLOAD_SET_H_
diff --git a/absl/random/internal/mocking_bit_gen_base.h b/absl/random/internal/mocking_bit_gen_base.h
index aff2ba6d..eeeae9d2 100644
--- a/absl/random/internal/mocking_bit_gen_base.h
+++ b/absl/random/internal/mocking_bit_gen_base.h
@@ -25,6 +25,7 @@
 #include "absl/strings/str_cat.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // MockingBitGenExpectationFormatter is invoked to format unsatisfied mocks
@@ -113,6 +114,7 @@ class MockingBitGenBase {
 };  // namespace random_internal
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_MOCKING_BIT_GEN_BASE_H_
diff --git a/absl/random/internal/nanobenchmark.cc b/absl/random/internal/nanobenchmark.cc
index feb81c85..8fee77fc 100644
--- a/absl/random/internal/nanobenchmark.cc
+++ b/absl/random/internal/nanobenchmark.cc
@@ -70,6 +70,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal_nanobenchmark {
 namespace {
 
@@ -799,4 +800,5 @@ size_t Measure(const Func func, const void* arg, const FuncInput* inputs,
 }
 
 }  // namespace random_internal_nanobenchmark
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/internal/nanobenchmark.h b/absl/random/internal/nanobenchmark.h
index c2b650d1..a5097ba2 100644
--- a/absl/random/internal/nanobenchmark.h
+++ b/absl/random/internal/nanobenchmark.h
@@ -50,7 +50,10 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal_nanobenchmark {
 
 // Input influencing the function being measured (e.g. number of bytes to copy).
@@ -163,6 +166,7 @@ static inline size_t MeasureClosure(const Closure& closure,
 }
 
 }  // namespace random_internal_nanobenchmark
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_NANOBENCHMARK_H_
diff --git a/absl/random/internal/nanobenchmark_test.cc b/absl/random/internal/nanobenchmark_test.cc
index 383345a8..ab824ef5 100644
--- a/absl/random/internal/nanobenchmark_test.cc
+++ b/absl/random/internal/nanobenchmark_test.cc
@@ -18,6 +18,7 @@
 #include "absl/strings/numbers.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal_nanobenchmark {
 namespace {
 
@@ -67,6 +68,7 @@ void RunAll(const int argc, char* argv[]) {
 
 }  // namespace
 }  // namespace random_internal_nanobenchmark
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 int main(int argc, char* argv[]) {
diff --git a/absl/random/internal/nonsecure_base.h b/absl/random/internal/nonsecure_base.h
index 8847e74b..730fa2ea 100644
--- a/absl/random/internal/nonsecure_base.h
+++ b/absl/random/internal/nonsecure_base.h
@@ -33,6 +33,7 @@
 #include "absl/types/span.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // Each instance of NonsecureURBGBase<URBG> will be seeded by variates produced
@@ -143,6 +144,7 @@ class NonsecureURBGBase {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_NONSECURE_BASE_H_
diff --git a/absl/random/internal/pcg_engine.h b/absl/random/internal/pcg_engine.h
index b5df4eaf..53c23fe1 100644
--- a/absl/random/internal/pcg_engine.h
+++ b/absl/random/internal/pcg_engine.h
@@ -24,6 +24,7 @@
 #include "absl/random/internal/iostream_state_saver.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // pcg_engine is a simplified implementation of Melissa O'Neil's PCG engine in
@@ -300,6 +301,7 @@ using pcg32_2018_engine = pcg_engine<
     random_internal::pcg_xsh_rr_64_32>;
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_PCG_ENGINE_H_
diff --git a/absl/random/internal/pool_urbg.cc b/absl/random/internal/pool_urbg.cc
index f2e1c1f6..5bee5307 100644
--- a/absl/random/internal/pool_urbg.cc
+++ b/absl/random/internal/pool_urbg.cc
@@ -37,6 +37,7 @@ using absl::base_internal::SpinLock;
 using absl::base_internal::SpinLockHolder;
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 namespace {
 
@@ -249,4 +250,5 @@ template class RandenPool<uint32_t>;
 template class RandenPool<uint64_t>;
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/internal/pool_urbg.h b/absl/random/internal/pool_urbg.h
index 9b2dd4bf..05721929 100644
--- a/absl/random/internal/pool_urbg.h
+++ b/absl/random/internal/pool_urbg.h
@@ -22,6 +22,7 @@
 #include "absl/types/span.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // RandenPool is a thread-safe random number generator [random.req.urbg] that
@@ -124,6 +125,7 @@ class PoolURBG {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_POOL_URBG_H_
diff --git a/absl/random/internal/randen.cc b/absl/random/internal/randen.cc
index bab8075a..78a1e00c 100644
--- a/absl/random/internal/randen.cc
+++ b/absl/random/internal/randen.cc
@@ -41,6 +41,7 @@
 // structured/low-entropy counters to digits of Pi.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 namespace {
 
@@ -86,4 +87,5 @@ Randen::Randen() {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/internal/randen.h b/absl/random/internal/randen.h
index a4ff2545..c2834aaf 100644
--- a/absl/random/internal/randen.h
+++ b/absl/random/internal/randen.h
@@ -23,6 +23,7 @@
 #include "absl/random/internal/randen_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // RANDen = RANDom generator or beetroots in Swiss German.
@@ -95,6 +96,7 @@ class Randen {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_RANDEN_H_
diff --git a/absl/random/internal/randen_detect.cc b/absl/random/internal/randen_detect.cc
index d5946b21..d63230c2 100644
--- a/absl/random/internal/randen_detect.cc
+++ b/absl/random/internal/randen_detect.cc
@@ -95,6 +95,7 @@ static uint32_t GetAuxval(uint32_t hwcap_type) {
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // The default return at the end of the function might be unreachable depending
@@ -216,4 +217,5 @@ bool CPUSupportsRandenHwAes() {
 #endif
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/internal/randen_detect.h b/absl/random/internal/randen_detect.h
index 44c5c667..f283f432 100644
--- a/absl/random/internal/randen_detect.h
+++ b/absl/random/internal/randen_detect.h
@@ -15,7 +15,10 @@
 #ifndef ABSL_RANDOM_INTERNAL_RANDEN_DETECT_H_
 #define ABSL_RANDOM_INTERNAL_RANDEN_DETECT_H_
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // Returns whether the current CPU supports RandenHwAes implementation.
@@ -24,6 +27,7 @@ namespace random_internal {
 bool CPUSupportsRandenHwAes();
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_RANDEN_DETECT_H_
diff --git a/absl/random/internal/randen_engine.h b/absl/random/internal/randen_engine.h
index 02212a13..6b337313 100644
--- a/absl/random/internal/randen_engine.h
+++ b/absl/random/internal/randen_engine.h
@@ -28,6 +28,7 @@
 #include "absl/random/internal/randen.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // Deterministic pseudorandom byte generator with backtracking resistance
@@ -223,6 +224,7 @@ class alignas(16) randen_engine {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_RANDEN_ENGINE_H_
diff --git a/absl/random/internal/randen_hwaes.cc b/absl/random/internal/randen_hwaes.cc
index 6cc36fd3..e23844f1 100644
--- a/absl/random/internal/randen_hwaes.cc
+++ b/absl/random/internal/randen_hwaes.cc
@@ -75,6 +75,7 @@
 #include <cstdlib>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // No accelerated implementation.
@@ -106,6 +107,7 @@ void RandenHwAes::Generate(const void*, void*) {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #else  // defined(ABSL_RANDEN_HWAES_IMPL)
@@ -518,6 +520,7 @@ inline ABSL_TARGET_CRYPTO void Permute(
 }  // namespace
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 bool HasRandenHwAesImplementation() { return true; }
@@ -629,6 +632,7 @@ void ABSL_TARGET_CRYPTO RandenHwAes::Generate(const void* keys,
 #endif
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // (ABSL_RANDEN_HWAES_IMPL)
diff --git a/absl/random/internal/randen_hwaes.h b/absl/random/internal/randen_hwaes.h
index d8e6055f..bce36b52 100644
--- a/absl/random/internal/randen_hwaes.h
+++ b/absl/random/internal/randen_hwaes.h
@@ -15,12 +15,15 @@
 #ifndef ABSL_RANDOM_INTERNAL_RANDEN_HWAES_H_
 #define ABSL_RANDOM_INTERNAL_RANDEN_HWAES_H_
 
+#include "absl/base/config.h"
+
 // HERMETIC NOTE: The randen_hwaes target must not introduce duplicate
 // symbols from arbitrary system and other headers, since it may be built
 // with different flags from other targets, using different levels of
 // optimization, potentially introducing ODR violations.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // RANDen = RANDom generator or beetroots in Swiss German.
@@ -41,6 +44,7 @@ class RandenHwAes {
 bool HasRandenHwAesImplementation();
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_RANDEN_HWAES_H_
diff --git a/absl/random/internal/randen_slow.cc b/absl/random/internal/randen_slow.cc
index e7959c7e..8d074582 100644
--- a/absl/random/internal/randen_slow.cc
+++ b/absl/random/internal/randen_slow.cc
@@ -462,6 +462,7 @@ inline ABSL_RANDOM_INTERNAL_ATTRIBUTE_ALWAYS_INLINE void Permute(
 }  // namespace
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 const void* RandenSlow::GetKeys() {
@@ -501,4 +502,5 @@ void RandenSlow::Generate(const void* keys, void* state_void) {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/internal/randen_slow.h b/absl/random/internal/randen_slow.h
index 30586130..72f92b54 100644
--- a/absl/random/internal/randen_slow.h
+++ b/absl/random/internal/randen_slow.h
@@ -17,7 +17,10 @@
 
 #include <cstddef>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // RANDen = RANDom generator or beetroots in Swiss German.
@@ -38,6 +41,7 @@ class RandenSlow {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_RANDEN_SLOW_H_
diff --git a/absl/random/internal/randen_traits.h b/absl/random/internal/randen_traits.h
index 4f1f408d..2b8bbe73 100644
--- a/absl/random/internal/randen_traits.h
+++ b/absl/random/internal/randen_traits.h
@@ -22,7 +22,10 @@
 
 #include <cstddef>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // RANDen = RANDom generator or beetroots in Swiss German.
@@ -54,6 +57,7 @@ struct RandenTraits {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_RANDEN_TRAITS_H_
diff --git a/absl/random/internal/salted_seed_seq.h b/absl/random/internal/salted_seed_seq.h
index 86487006..5953a090 100644
--- a/absl/random/internal/salted_seed_seq.h
+++ b/absl/random/internal/salted_seed_seq.h
@@ -30,6 +30,7 @@
 #include "absl/types/span.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // This class conforms to the C++ Standard "Seed Sequence" concept
@@ -160,6 +161,7 @@ SaltedSeedSeq<typename std::decay<SSeq>::type> MakeSaltedSeedSeq(SSeq&& seq) {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_SALTED_SEED_SEQ_H_
diff --git a/absl/random/internal/seed_material.cc b/absl/random/internal/seed_material.cc
index ab4dd0c2..4d38a574 100644
--- a/absl/random/internal/seed_material.cc
+++ b/absl/random/internal/seed_material.cc
@@ -61,6 +61,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 namespace {
 
@@ -214,4 +215,5 @@ absl::optional<uint32_t> GetSaltMaterial() {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/internal/seed_material.h b/absl/random/internal/seed_material.h
index 57de8a24..4be10e92 100644
--- a/absl/random/internal/seed_material.h
+++ b/absl/random/internal/seed_material.h
@@ -27,6 +27,7 @@
 #include "absl/types/span.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // Returns the number of 32-bit blocks needed to contain the given number of
@@ -97,6 +98,7 @@ void MixIntoSeedMaterial(absl::Span<const uint32_t> sequence,
 absl::optional<uint32_t> GetSaltMaterial();
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_SEED_MATERIAL_H_
diff --git a/absl/random/internal/sequence_urbg.h b/absl/random/internal/sequence_urbg.h
index 9a9b5773..bc96a12c 100644
--- a/absl/random/internal/sequence_urbg.h
+++ b/absl/random/internal/sequence_urbg.h
@@ -21,7 +21,10 @@
 #include <type_traits>
 #include <vector>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // `sequence_urbg` is a simple random number generator which meets the
@@ -51,6 +54,7 @@ class sequence_urbg {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_SEQUENCE_URBG_H_
diff --git a/absl/random/internal/traits.h b/absl/random/internal/traits.h
index 40eb011f..75772bd9 100644
--- a/absl/random/internal/traits.h
+++ b/absl/random/internal/traits.h
@@ -22,6 +22,7 @@
 #include "absl/base/config.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // random_internal::is_widening_convertible<A, B>
@@ -94,6 +95,7 @@ struct make_unsigned_bits {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_TRAITS_H_
diff --git a/absl/random/internal/uniform_helper.h b/absl/random/internal/uniform_helper.h
index f68b1823..663107cb 100644
--- a/absl/random/internal/uniform_helper.h
+++ b/absl/random/internal/uniform_helper.h
@@ -22,6 +22,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 template <typename IntType>
 class uniform_int_distribution;
 
@@ -173,6 +174,7 @@ struct UniformDistributionWrapper : public UniformDistribution<NumType> {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_UNIFORM_HELPER_H_
diff --git a/absl/random/internal/wide_multiply.h b/absl/random/internal/wide_multiply.h
index ebbfa1f2..6e4cf1be 100644
--- a/absl/random/internal/wide_multiply.h
+++ b/absl/random/internal/wide_multiply.h
@@ -31,6 +31,7 @@
 #include "absl/random/internal/traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace random_internal {
 
 // Helper object to multiply two 64-bit values to a 128-bit value.
@@ -104,6 +105,7 @@ struct wide_multiply<uint64_t> {
 #endif
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_INTERNAL_WIDE_MULTIPLY_H_
diff --git a/absl/random/log_uniform_int_distribution.h b/absl/random/log_uniform_int_distribution.h
index de58bdbe..960816e2 100644
--- a/absl/random/log_uniform_int_distribution.h
+++ b/absl/random/log_uniform_int_distribution.h
@@ -30,6 +30,7 @@
 #include "absl/random/uniform_int_distribution.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // log_uniform_int_distribution:
 //
@@ -247,6 +248,7 @@ std::basic_istream<CharT, Traits>& operator>>(
   return is;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_LOG_UNIFORM_INT_DISTRIBUTION_H_
diff --git a/absl/random/mock_distributions.h b/absl/random/mock_distributions.h
index 1af98a24..d36d5ba0 100644
--- a/absl/random/mock_distributions.h
+++ b/absl/random/mock_distributions.h
@@ -53,6 +53,7 @@
 #include "absl/random/mocking_bit_gen.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // absl::MockUniform
@@ -254,6 +255,7 @@ using MockZipf =
                                      IntType(MockingBitGen&, IntType, double,
                                              double)>;
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_MOCK_DISTRIBUTIONS_H_
diff --git a/absl/random/mocking_bit_gen.cc b/absl/random/mocking_bit_gen.cc
index 73144528..6bb1e414 100644
--- a/absl/random/mocking_bit_gen.cc
+++ b/absl/random/mocking_bit_gen.cc
@@ -18,6 +18,7 @@
 #include <string>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 MockingBitGen::~MockingBitGen() {
 
   for (const auto& del : deleters_) {
@@ -25,4 +26,5 @@ MockingBitGen::~MockingBitGen() {
   }
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/mocking_bit_gen.h b/absl/random/mocking_bit_gen.h
index d1b524a9..36cef911 100644
--- a/absl/random/mocking_bit_gen.h
+++ b/absl/random/mocking_bit_gen.h
@@ -51,6 +51,7 @@
 #include "absl/utility/utility.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace random_internal {
 
@@ -189,6 +190,7 @@ struct DistributionCaller<absl::MockingBitGen> {
 };
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_MOCKING_BIT_GEN_H_
diff --git a/absl/random/poisson_distribution.h b/absl/random/poisson_distribution.h
index 23a953ff..cb5f5d5d 100644
--- a/absl/random/poisson_distribution.h
+++ b/absl/random/poisson_distribution.h
@@ -28,6 +28,7 @@
 #include "absl/random/internal/iostream_state_saver.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::poisson_distribution:
 // Generates discrete variates conforming to a Poisson distribution.
@@ -251,6 +252,7 @@ std::basic_istream<CharT, Traits>& operator>>(
   return is;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_POISSON_DISTRIBUTION_H_
diff --git a/absl/random/random.h b/absl/random/random.h
index dc6852f4..c8f326e6 100644
--- a/absl/random/random.h
+++ b/absl/random/random.h
@@ -41,6 +41,7 @@
 #include "absl/random/seed_sequences.h"  // IWYU pragma: export
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // absl::BitGen
@@ -182,6 +183,7 @@ using InsecureBitGen =
 // discards the intermediate results.
 // ---------------------------------------------------------------------------
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_RANDOM_H_
diff --git a/absl/random/seed_gen_exception.cc b/absl/random/seed_gen_exception.cc
index e4271baa..fdcb54a8 100644
--- a/absl/random/seed_gen_exception.cc
+++ b/absl/random/seed_gen_exception.cc
@@ -19,6 +19,7 @@
 #include "absl/base/config.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 static constexpr const char kExceptionMessage[] =
     "Failed generating seed-material for URBG.";
@@ -41,4 +42,5 @@ void ThrowSeedGenException() {
 }
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/seed_gen_exception.h b/absl/random/seed_gen_exception.h
index b464d52f..53539005 100644
--- a/absl/random/seed_gen_exception.h
+++ b/absl/random/seed_gen_exception.h
@@ -28,7 +28,10 @@
 
 #include <exception>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 //------------------------------------------------------------------------------
 // SeedGenException
@@ -46,6 +49,7 @@ namespace random_internal {
 [[noreturn]] void ThrowSeedGenException();
 
 }  // namespace random_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_SEED_GEN_EXCEPTION_H_
diff --git a/absl/random/seed_sequences.cc b/absl/random/seed_sequences.cc
index 9f319615..426eafd3 100644
--- a/absl/random/seed_sequences.cc
+++ b/absl/random/seed_sequences.cc
@@ -17,6 +17,7 @@
 #include "absl/random/internal/pool_urbg.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 SeedSeq MakeSeedSeq() {
   SeedSeq::result_type seed_material[8];
@@ -24,4 +25,5 @@ SeedSeq MakeSeedSeq() {
   return SeedSeq(std::begin(seed_material), std::end(seed_material));
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/random/seed_sequences.h b/absl/random/seed_sequences.h
index 631d1ecd..ff1340cc 100644
--- a/absl/random/seed_sequences.h
+++ b/absl/random/seed_sequences.h
@@ -34,6 +34,7 @@
 #include "absl/types/span.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // absl::SeedSeq
@@ -103,6 +104,7 @@ SeedSeq CreateSeedSeqFrom(URBG* urbg) {
 //
 SeedSeq MakeSeedSeq();
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_SEED_SEQUENCES_H_
diff --git a/absl/random/uniform_int_distribution.h b/absl/random/uniform_int_distribution.h
index dc8ba8c1..da66564a 100644
--- a/absl/random/uniform_int_distribution.h
+++ b/absl/random/uniform_int_distribution.h
@@ -40,6 +40,7 @@
 #include "absl/random/internal/wide_multiply.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::uniform_int_distribution<T>
 //
@@ -268,6 +269,7 @@ uniform_int_distribution<IntType>::Generate(
   return helper::hi(product);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_UNIFORM_INT_DISTRIBUTION_H_
diff --git a/absl/random/uniform_real_distribution.h b/absl/random/uniform_real_distribution.h
index bf2ed2c5..5ba17b23 100644
--- a/absl/random/uniform_real_distribution.h
+++ b/absl/random/uniform_real_distribution.h
@@ -45,6 +45,7 @@
 #include "absl/random/internal/iostream_state_saver.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::uniform_real_distribution<T>
 //
@@ -195,6 +196,7 @@ std::basic_istream<CharT, Traits>& operator>>(
   }
   return is;
 }
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_UNIFORM_REAL_DISTRIBUTION_H_
diff --git a/absl/random/zipf_distribution.h b/absl/random/zipf_distribution.h
index d7b4ac38..22ebc756 100644
--- a/absl/random/zipf_distribution.h
+++ b/absl/random/zipf_distribution.h
@@ -26,6 +26,7 @@
 #include "absl/random/uniform_real_distribution.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::zipf_distribution produces random integer-values in the range [0, k],
 // distributed according to the discrete probability function:
@@ -264,6 +265,7 @@ std::basic_istream<CharT, Traits>& operator>>(
   return is;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_RANDOM_ZIPF_DISTRIBUTION_H_
diff --git a/absl/strings/BUILD.bazel b/absl/strings/BUILD.bazel
index e38c8ad6..8d0a6b6d 100644
--- a/absl/strings/BUILD.bazel
+++ b/absl/strings/BUILD.bazel
@@ -94,6 +94,7 @@ cc_library(
     ],
     copts = ABSL_DEFAULT_COPTS,
     deps = [
+        "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:endian",
         "//absl/meta:type_traits",
@@ -413,6 +414,7 @@ cc_test(
     deps = [
         ":pow10_helper",
         ":strings",
+        "//absl/base:config",
         "//absl/base:raw_logging_internal",
         "//absl/random",
         "//absl/random:distributions",
@@ -489,6 +491,7 @@ cc_test(
     copts = ABSL_TEST_COPTS,
     deps = [
         ":strings",
+        "//absl/base:config",
         "//absl/base:raw_logging_internal",
         "@com_google_googletest//:gtest_main",
     ],
@@ -504,6 +507,7 @@ cc_test(
     copts = ABSL_TEST_COPTS,
     deps = [
         ":strings",
+        "//absl/base:config",
         "@com_google_googletest//:gtest_main",
     ],
 )
@@ -668,6 +672,7 @@ cc_library(
     srcs = ["internal/pow10_helper.cc"],
     hdrs = ["internal/pow10_helper.h"],
     visibility = ["//visibility:private"],
+    deps = ["//absl/base:config"],
 )
 
 cc_test(
diff --git a/absl/strings/CMakeLists.txt b/absl/strings/CMakeLists.txt
index cd52a472..98101573 100644
--- a/absl/strings/CMakeLists.txt
+++ b/absl/strings/CMakeLists.txt
@@ -81,6 +81,7 @@ absl_cc_library(
   COPTS
     ${ABSL_DEFAULT_COPTS}
   DEPS
+    absl::config
     absl::core_headers
     absl::endian
     absl::type_traits
@@ -276,6 +277,7 @@ absl_cc_test(
     absl::strings
     absl::core_headers
     absl::pow10_helper
+    absl::config
     absl::raw_logging_internal
     absl::random_random
     absl::random_distributions
@@ -331,6 +333,7 @@ absl_cc_test(
     ${ABSL_TEST_COPTS}
   DEPS
     absl::strings
+    absl::config
     absl::raw_logging_internal
     gmock_main
 )
@@ -346,6 +349,7 @@ absl_cc_test(
     ${ABSL_TEST_COPTS}
   DEPS
     absl::strings
+    absl::config
     gmock_main
 )
 
@@ -502,6 +506,8 @@ absl_cc_library(
     "internal/pow10_helper.cc"
   COPTS
     ${ABSL_TEST_COPTS}
+  DEPS
+    absl::config
   TESTONLY
 )
 
diff --git a/absl/strings/ascii.cc b/absl/strings/ascii.cc
index 3f7c581f..abea3e4f 100644
--- a/absl/strings/ascii.cc
+++ b/absl/strings/ascii.cc
@@ -15,6 +15,7 @@
 #include "absl/strings/ascii.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace ascii_internal {
 
 // # Table generated by this Python code (bit 0x02 is currently unused):
@@ -195,4 +196,5 @@ void RemoveExtraAsciiWhitespace(std::string* str) {
   str->erase(output_it - &(*str)[0]);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/ascii.h b/absl/strings/ascii.h
index f9e4fd1d..792aabe5 100644
--- a/absl/strings/ascii.h
+++ b/absl/strings/ascii.h
@@ -59,6 +59,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace ascii_internal {
 
 // Declaration for an array of bitfields holding character information.
@@ -234,6 +235,7 @@ inline void StripAsciiWhitespace(std::string* str) {
 // Removes leading, trailing, and consecutive internal whitespace.
 void RemoveExtraAsciiWhitespace(std::string*);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_ASCII_H_
diff --git a/absl/strings/charconv.cc b/absl/strings/charconv.cc
index bc07e7ab..d9bc2dd2 100644
--- a/absl/strings/charconv.cc
+++ b/absl/strings/charconv.cc
@@ -57,6 +57,7 @@
 // narrower mantissas.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 template <typename FloatType>
@@ -980,4 +981,5 @@ const int16_t kPower10ExponentTable[] = {
 };
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/charconv.h b/absl/strings/charconv.h
index 3f5891ba..e04be32f 100644
--- a/absl/strings/charconv.h
+++ b/absl/strings/charconv.h
@@ -17,7 +17,10 @@
 
 #include <system_error>  // NOLINT(build/c++11)
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Workalike compatibilty version of std::chars_format from C++17.
 //
@@ -110,6 +113,7 @@ inline chars_format& operator^=(chars_format& lhs, chars_format rhs) {
   return lhs;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_CHARCONV_H_
diff --git a/absl/strings/escaping.cc b/absl/strings/escaping.cc
index 18b746e3..d2fcd9c1 100644
--- a/absl/strings/escaping.cc
+++ b/absl/strings/escaping.cc
@@ -33,6 +33,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 // These are used for the leave_nulls_escaped argument to CUnescapeInternal().
@@ -1106,4 +1107,5 @@ std::string BytesToHexString(absl::string_view from) {
   return result;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/escaping.h b/absl/strings/escaping.h
index 198b9348..f5ca26c5 100644
--- a/absl/strings/escaping.h
+++ b/absl/strings/escaping.h
@@ -33,6 +33,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // CUnescape()
 //
@@ -157,6 +158,7 @@ std::string HexStringToBytes(absl::string_view from);
 // `2*from.size()`.
 std::string BytesToHexString(absl::string_view from);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_ESCAPING_H_
diff --git a/absl/strings/internal/char_map.h b/absl/strings/internal/char_map.h
index b9108b8c..a76e6036 100644
--- a/absl/strings/internal/char_map.h
+++ b/absl/strings/internal/char_map.h
@@ -28,6 +28,7 @@
 #include "absl/base/port.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 class Charmap {
@@ -149,6 +150,7 @@ constexpr Charmap GraphCharmap() { return PrintCharmap() & ~SpaceCharmap(); }
 constexpr Charmap PunctCharmap() { return GraphCharmap() & ~AlnumCharmap(); }
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_CHAR_MAP_H_
diff --git a/absl/strings/internal/charconv_bigint.cc b/absl/strings/internal/charconv_bigint.cc
index 95d471d9..860c27b2 100644
--- a/absl/strings/internal/charconv_bigint.cc
+++ b/absl/strings/internal/charconv_bigint.cc
@@ -19,6 +19,7 @@
 #include <string>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 namespace {
@@ -354,4 +355,5 @@ template class BigUnsigned<4>;
 template class BigUnsigned<84>;
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/charconv_bigint.h b/absl/strings/internal/charconv_bigint.h
index 7da9a7e7..108e1eb2 100644
--- a/absl/strings/internal/charconv_bigint.h
+++ b/absl/strings/internal/charconv_bigint.h
@@ -25,6 +25,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 // The largest power that 5 that can be raised to, and still fit in a uint32_t.
@@ -414,6 +415,7 @@ extern template class BigUnsigned<4>;
 extern template class BigUnsigned<84>;
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_CHARCONV_BIGINT_H_
diff --git a/absl/strings/internal/charconv_bigint_test.cc b/absl/strings/internal/charconv_bigint_test.cc
index 745714ac..363bcb03 100644
--- a/absl/strings/internal/charconv_bigint_test.cc
+++ b/absl/strings/internal/charconv_bigint_test.cc
@@ -19,6 +19,7 @@
 #include "gtest/gtest.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 TEST(BigUnsigned, ShiftLeft) {
@@ -200,4 +201,5 @@ TEST(BigUnsigned, TenToTheNth) {
 
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/charconv_parse.cc b/absl/strings/internal/charconv_parse.cc
index fa9a8965..d9a57a78 100644
--- a/absl/strings/internal/charconv_parse.cc
+++ b/absl/strings/internal/charconv_parse.cc
@@ -22,6 +22,7 @@
 #include "absl/strings/internal/memutil.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 // ParseFloat<10> will read the first 19 significant digits of the mantissa.
@@ -499,4 +500,5 @@ template ParsedFloat ParseFloat<16>(const char* begin, const char* end,
                                     chars_format format_flags);
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/charconv_parse.h b/absl/strings/internal/charconv_parse.h
index 44d06b2e..505998b5 100644
--- a/absl/strings/internal/charconv_parse.h
+++ b/absl/strings/internal/charconv_parse.h
@@ -17,9 +17,11 @@
 
 #include <cstdint>
 
+#include "absl/base/config.h"
 #include "absl/strings/charconv.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 // Enum indicating whether a parsed float is a number or special value.
@@ -92,5 +94,6 @@ extern template ParsedFloat ParseFloat<16>(const char* begin, const char* end,
                                            absl::chars_format format_flags);
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 #endif  // ABSL_STRINGS_INTERNAL_CHARCONV_PARSE_H_
diff --git a/absl/strings/internal/escaping_test_common.h b/absl/strings/internal/escaping_test_common.h
index bd803031..7b18017a 100644
--- a/absl/strings/internal/escaping_test_common.h
+++ b/absl/strings/internal/escaping_test_common.h
@@ -22,6 +22,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 struct base64_testcase {
@@ -126,6 +127,7 @@ inline const std::array<base64_testcase, 5>& base64_strings() {
 }
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_ESCAPING_TEST_COMMON_H_
diff --git a/absl/strings/internal/memutil.cc b/absl/strings/internal/memutil.cc
index 77aa63c2..2519c688 100644
--- a/absl/strings/internal/memutil.cc
+++ b/absl/strings/internal/memutil.cc
@@ -17,6 +17,7 @@
 #include <cstdlib>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 int memcasecmp(const char* s1, const char* s2, size_t len) {
@@ -107,4 +108,5 @@ const char* memmatch(const char* phaystack, size_t haylen, const char* pneedle,
 }
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/memutil.h b/absl/strings/internal/memutil.h
index 7c071a82..9ad05358 100644
--- a/absl/strings/internal/memutil.h
+++ b/absl/strings/internal/memutil.h
@@ -69,6 +69,7 @@
 #include "absl/strings/ascii.h"  // for absl::ascii_tolower
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 inline char* memcat(char* dest, size_t destlen, const char* src,
@@ -141,6 +142,7 @@ const char* memmatch(const char* phaystack, size_t haylen, const char* pneedle,
                      size_t neelen);
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_MEMUTIL_H_
diff --git a/absl/strings/internal/numbers_test_common.h b/absl/strings/internal/numbers_test_common.h
index a263219e..1a1e50c4 100644
--- a/absl/strings/internal/numbers_test_common.h
+++ b/absl/strings/internal/numbers_test_common.h
@@ -23,7 +23,10 @@
 #include <limits>
 #include <string>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 template <typename IntType>
@@ -175,6 +178,7 @@ inline const std::array<uint64_test_case, 34>& strtouint64_test_cases() {
 }
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_NUMBERS_TEST_COMMON_H_
diff --git a/absl/strings/internal/ostringstream.cc b/absl/strings/internal/ostringstream.cc
index d0f0f84b..05324c78 100644
--- a/absl/strings/internal/ostringstream.cc
+++ b/absl/strings/internal/ostringstream.cc
@@ -15,6 +15,7 @@
 #include "absl/strings/internal/ostringstream.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 OStringStream::Buf::int_type OStringStream::overflow(int c) {
@@ -31,4 +32,5 @@ std::streamsize OStringStream::xsputn(const char* s, std::streamsize n) {
 }
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/ostringstream.h b/absl/strings/internal/ostringstream.h
index 20792015..d25d6047 100644
--- a/absl/strings/internal/ostringstream.h
+++ b/absl/strings/internal/ostringstream.h
@@ -23,6 +23,7 @@
 #include "absl/base/port.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 // The same as std::ostringstream but appends to a user-specified std::string,
@@ -82,6 +83,7 @@ class OStringStream : private std::basic_streambuf<char>, public std::ostream {
 };
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_OSTRINGSTREAM_H_
diff --git a/absl/strings/internal/pow10_helper.cc b/absl/strings/internal/pow10_helper.cc
index 03ed8d07..42e96c34 100644
--- a/absl/strings/internal/pow10_helper.cc
+++ b/absl/strings/internal/pow10_helper.cc
@@ -17,6 +17,7 @@
 #include <cmath>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 namespace {
@@ -117,4 +118,5 @@ double Pow10(int exp) {
 }
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/pow10_helper.h b/absl/strings/internal/pow10_helper.h
index 9d1aa710..c37c2c3f 100644
--- a/absl/strings/internal/pow10_helper.h
+++ b/absl/strings/internal/pow10_helper.h
@@ -22,7 +22,10 @@
 
 #include <vector>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 // Computes the precise value of 10^exp. (I.e. the nearest representable
@@ -31,6 +34,7 @@ namespace strings_internal {
 double Pow10(int exp);
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_POW10_HELPER_H_
diff --git a/absl/strings/internal/pow10_helper_test.cc b/absl/strings/internal/pow10_helper_test.cc
index a4a68b5d..a4ff76d3 100644
--- a/absl/strings/internal/pow10_helper_test.cc
+++ b/absl/strings/internal/pow10_helper_test.cc
@@ -20,6 +20,7 @@
 #include "absl/strings/str_format.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 namespace {
@@ -117,4 +118,5 @@ TEST(Pow10HelperTest, Works) {
 
 }  // namespace
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/resize_uninitialized.h b/absl/strings/internal/resize_uninitialized.h
index 0f5e964d..e42628e3 100644
--- a/absl/strings/internal/resize_uninitialized.h
+++ b/absl/strings/internal/resize_uninitialized.h
@@ -25,6 +25,7 @@
 #include "absl/meta/type_traits.h"  //  for void_t
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 // Is a subclass of true_type or false_type, depending on whether or not
@@ -66,6 +67,7 @@ inline void STLStringResizeUninitialized(string_type* s, size_t new_size) {
 }
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_RESIZE_UNINITIALIZED_H_
diff --git a/absl/strings/internal/stl_type_traits.h b/absl/strings/internal/stl_type_traits.h
index 202ab374..6035ca45 100644
--- a/absl/strings/internal/stl_type_traits.h
+++ b/absl/strings/internal/stl_type_traits.h
@@ -40,6 +40,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 template <typename C, template <typename...> class T>
@@ -242,5 +243,6 @@ struct IsStrictlyBaseOfAndConvertibleToSTLContainer
                         IsConvertibleToSTLContainer<C>> {};
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 #endif  // ABSL_STRINGS_INTERNAL_STL_TYPE_TRAITS_H_
diff --git a/absl/strings/internal/str_format/arg.cc b/absl/strings/internal/str_format/arg.cc
index b567a5c5..875bd99c 100644
--- a/absl/strings/internal/str_format/arg.cc
+++ b/absl/strings/internal/str_format/arg.cc
@@ -14,6 +14,7 @@
 #include "absl/strings/internal/str_format/float_conversion.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 namespace {
 
@@ -386,4 +387,5 @@ ABSL_INTERNAL_FORMAT_DISPATCH_OVERLOADS_EXPAND_();
 
 }  // namespace str_format_internal
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_format/arg.h b/absl/strings/internal/str_format/arg.h
index a209a927..b672a229 100644
--- a/absl/strings/internal/str_format/arg.h
+++ b/absl/strings/internal/str_format/arg.h
@@ -19,6 +19,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 class Cord;
 class FormatCountCapture;
@@ -426,6 +427,7 @@ ABSL_INTERNAL_FORMAT_DISPATCH_OVERLOADS_EXPAND_(extern);
 
 
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_STR_FORMAT_ARG_H_
diff --git a/absl/strings/internal/str_format/arg_test.cc b/absl/strings/internal/str_format/arg_test.cc
index 3421fac1..96c9cfd3 100644
--- a/absl/strings/internal/str_format/arg_test.cc
+++ b/absl/strings/internal/str_format/arg_test.cc
@@ -14,6 +14,7 @@
 #include "absl/strings/str_format.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 namespace {
 
@@ -108,4 +109,5 @@ const char kMyArray[] = "ABCDE";
 
 }  // namespace
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_format/bind.cc b/absl/strings/internal/str_format/bind.cc
index 45e335a3..1ee281af 100644
--- a/absl/strings/internal/str_format/bind.cc
+++ b/absl/strings/internal/str_format/bind.cc
@@ -6,6 +6,7 @@
 #include <string>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 
 namespace {
@@ -236,4 +237,5 @@ int SnprintF(char* output, size_t size, const UntypedFormatSpecImpl format,
 }
 
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_format/bind.h b/absl/strings/internal/str_format/bind.h
index dafcd610..2bf0c085 100644
--- a/absl/strings/internal/str_format/bind.h
+++ b/absl/strings/internal/str_format/bind.h
@@ -13,6 +13,7 @@
 #include "absl/types/span.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 class UntypedFormatSpec;
 
@@ -202,6 +203,7 @@ class StreamedWrapper {
 };
 
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_STR_FORMAT_BIND_H_
diff --git a/absl/strings/internal/str_format/bind_test.cc b/absl/strings/internal/str_format/bind_test.cc
index 2574801a..f6817419 100644
--- a/absl/strings/internal/str_format/bind_test.cc
+++ b/absl/strings/internal/str_format/bind_test.cc
@@ -6,6 +6,7 @@
 #include "gtest/gtest.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 namespace {
 
@@ -138,4 +139,5 @@ TEST_F(FormatBindTest, FormatPack) {
 
 }  // namespace
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_format/checker.h b/absl/strings/internal/str_format/checker.h
index 04a88827..8993a79b 100644
--- a/absl/strings/internal/str_format/checker.h
+++ b/absl/strings/internal/str_format/checker.h
@@ -14,6 +14,7 @@
 #endif  // ABSL_INTERNAL_ENABLE_FORMAT_CHECKER
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 
 constexpr bool AllOf() { return true; }
@@ -319,6 +320,7 @@ constexpr bool ValidFormatImpl(string_view format) {
 #endif  // ABSL_INTERNAL_ENABLE_FORMAT_CHECKER
 
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_STR_FORMAT_CHECKER_H_
diff --git a/absl/strings/internal/str_format/checker_test.cc b/absl/strings/internal/str_format/checker_test.cc
index 7aa194a7..c309e203 100644
--- a/absl/strings/internal/str_format/checker_test.cc
+++ b/absl/strings/internal/str_format/checker_test.cc
@@ -5,6 +5,7 @@
 #include "absl/strings/str_format.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 namespace {
 
@@ -147,4 +148,5 @@ TEST(StrFormatChecker, LongFormat) {
 
 }  // namespace
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_format/convert_test.cc b/absl/strings/internal/str_format/convert_test.cc
index 5f198059..ca994346 100644
--- a/absl/strings/internal/str_format/convert_test.cc
+++ b/absl/strings/internal/str_format/convert_test.cc
@@ -11,6 +11,7 @@
 #include "absl/strings/internal/str_format/bind.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 namespace {
 
@@ -646,4 +647,5 @@ TEST_F(FormatConvertTest, ExpectedFailures) {
 
 }  // namespace
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_format/extension.cc b/absl/strings/internal/str_format/extension.cc
index d7f58159..559011bf 100644
--- a/absl/strings/internal/str_format/extension.cc
+++ b/absl/strings/internal/str_format/extension.cc
@@ -20,6 +20,7 @@
 #include <string>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 namespace {
 // clang-format off
@@ -81,4 +82,5 @@ bool FormatSinkImpl::PutPaddedString(string_view v, int w, int p, bool l) {
 }
 
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_format/extension.h b/absl/strings/internal/str_format/extension.h
index 3f4788c9..5726ea5c 100644
--- a/absl/strings/internal/str_format/extension.h
+++ b/absl/strings/internal/str_format/extension.h
@@ -26,6 +26,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 class Cord;
 
@@ -406,6 +407,7 @@ inline size_t Excess(size_t used, size_t capacity) {
 
 }  // namespace str_format_internal
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_STR_FORMAT_EXTENSION_H_
diff --git a/absl/strings/internal/str_format/float_conversion.cc b/absl/strings/internal/str_format/float_conversion.cc
index 9236acdc..ebe4da5b 100644
--- a/absl/strings/internal/str_format/float_conversion.cc
+++ b/absl/strings/internal/str_format/float_conversion.cc
@@ -9,6 +9,7 @@
 #include "absl/base/config.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 
 namespace {
@@ -482,4 +483,5 @@ bool ConvertFloatImpl(double v, const ConversionSpec &conv,
 }
 
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_format/float_conversion.h b/absl/strings/internal/str_format/float_conversion.h
index 8ba5566d..49a6a636 100644
--- a/absl/strings/internal/str_format/float_conversion.h
+++ b/absl/strings/internal/str_format/float_conversion.h
@@ -4,6 +4,7 @@
 #include "absl/strings/internal/str_format/extension.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 
 bool ConvertFloatImpl(float v, const ConversionSpec &conv,
@@ -16,6 +17,7 @@ bool ConvertFloatImpl(long double v, const ConversionSpec &conv,
                       FormatSinkImpl *sink);
 
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_STR_FORMAT_FLOAT_CONVERSION_H_
diff --git a/absl/strings/internal/str_format/output.cc b/absl/strings/internal/str_format/output.cc
index 38987b63..c4b24706 100644
--- a/absl/strings/internal/str_format/output.cc
+++ b/absl/strings/internal/str_format/output.cc
@@ -18,6 +18,7 @@
 #include <cstring>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 
 namespace {
@@ -67,4 +68,5 @@ void FILERawSink::Write(string_view v) {
 }
 
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_format/output.h b/absl/strings/internal/str_format/output.h
index 6dc2f3f7..28b288b7 100644
--- a/absl/strings/internal/str_format/output.h
+++ b/absl/strings/internal/str_format/output.h
@@ -29,6 +29,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 class Cord;
 
@@ -97,6 +98,7 @@ auto InvokeFlush(T* out, string_view s)
 }
 
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_STR_FORMAT_OUTPUT_H_
diff --git a/absl/strings/internal/str_format/output_test.cc b/absl/strings/internal/str_format/output_test.cc
index 6e04abef..e54e6f70 100644
--- a/absl/strings/internal/str_format/output_test.cc
+++ b/absl/strings/internal/str_format/output_test.cc
@@ -21,6 +21,7 @@
 #include "gtest/gtest.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 TEST(InvokeFlush, String) {
@@ -67,5 +68,6 @@ TEST(BufferRawSink, Limits) {
 }
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
 
diff --git a/absl/strings/internal/str_format/parser.cc b/absl/strings/internal/str_format/parser.cc
index 9ef5615c..eff68f35 100644
--- a/absl/strings/internal/str_format/parser.cc
+++ b/absl/strings/internal/str_format/parser.cc
@@ -14,6 +14,7 @@
 #include <unordered_set>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 
 using CC = ConversionChar::Id;
@@ -300,4 +301,5 @@ bool ParsedFormatBase::MatchesConversions(
 }
 
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_format/parser.h b/absl/strings/internal/str_format/parser.h
index 4b441f71..116dda06 100644
--- a/absl/strings/internal/str_format/parser.h
+++ b/absl/strings/internal/str_format/parser.h
@@ -16,6 +16,7 @@
 #include "absl/strings/internal/str_format/extension.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 
 // The analyzed properties of a single specified conversion.
@@ -317,6 +318,7 @@ class ExtendedParsedFormat : public str_format_internal::ParsedFormatBase {
       : ParsedFormatBase(s, allow_ignored, {C...}) {}
 };
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_STR_FORMAT_PARSER_H_
diff --git a/absl/strings/internal/str_format/parser_test.cc b/absl/strings/internal/str_format/parser_test.cc
index 6d356093..33ed8f09 100644
--- a/absl/strings/internal/str_format/parser_test.cc
+++ b/absl/strings/internal/str_format/parser_test.cc
@@ -7,6 +7,7 @@
 #include "absl/base/macros.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 
 namespace {
@@ -389,4 +390,5 @@ TEST_F(ParsedFormatTest, ParsingFlagOrder) {
 
 }  // namespace
 }  // namespace str_format_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/str_join_internal.h b/absl/strings/internal/str_join_internal.h
index 7c35f4de..31dbf672 100644
--- a/absl/strings/internal/str_join_internal.h
+++ b/absl/strings/internal/str_join_internal.h
@@ -43,6 +43,7 @@
 #include "absl/strings/str_cat.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 //
@@ -307,6 +308,7 @@ std::string JoinRange(const Range& range, absl::string_view separator) {
 }
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_STR_JOIN_INTERNAL_H_
diff --git a/absl/strings/internal/str_split_internal.h b/absl/strings/internal/str_split_internal.h
index 52f62226..b54f6ebe 100644
--- a/absl/strings/internal/str_split_internal.h
+++ b/absl/strings/internal/str_split_internal.h
@@ -47,6 +47,7 @@
 #endif  // _GLIBCXX_DEBUG
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 // This class is implicitly constructible from everything that absl::string_view
@@ -448,6 +449,7 @@ class Splitter {
 };
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_STR_SPLIT_INTERNAL_H_
diff --git a/absl/strings/internal/utf8.cc b/absl/strings/internal/utf8.cc
index 82d36c24..8fd8edc1 100644
--- a/absl/strings/internal/utf8.cc
+++ b/absl/strings/internal/utf8.cc
@@ -17,6 +17,7 @@
 #include "absl/strings/internal/utf8.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 size_t EncodeUTF8Char(char *buffer, char32_t utf8_char) {
@@ -48,4 +49,5 @@ size_t EncodeUTF8Char(char *buffer, char32_t utf8_char) {
 }
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/internal/utf8.h b/absl/strings/internal/utf8.h
index 04236304..32fb1093 100644
--- a/absl/strings/internal/utf8.h
+++ b/absl/strings/internal/utf8.h
@@ -20,7 +20,10 @@
 #include <cstddef>
 #include <cstdint>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 // For Unicode code points 0 through 0x10FFFF, EncodeUTF8Char writes
@@ -41,6 +44,7 @@ enum { kMaxEncodedUTF8Size = 4 };
 size_t EncodeUTF8Char(char *buffer, char32_t utf8_char);
 
 }  // namespace strings_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_INTERNAL_UTF8_H_
diff --git a/absl/strings/match.cc b/absl/strings/match.cc
index 7b24241a..8127cb0c 100644
--- a/absl/strings/match.cc
+++ b/absl/strings/match.cc
@@ -17,6 +17,7 @@
 #include "absl/strings/internal/memutil.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 bool EqualsIgnoreCase(absl::string_view piece1, absl::string_view piece2) {
   return (piece1.size() == piece2.size() &&
@@ -35,4 +36,5 @@ bool EndsWithIgnoreCase(absl::string_view text, absl::string_view suffix) {
          EqualsIgnoreCase(text.substr(text.size() - suffix.size()), suffix);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/match.h b/absl/strings/match.h
index 762f359f..90fca98a 100644
--- a/absl/strings/match.h
+++ b/absl/strings/match.h
@@ -20,7 +20,7 @@
 // This file contains simple utilities for performing string matching checks.
 // All of these function parameters are specified as `absl::string_view`,
 // meaning that these functions can accept `std::string`, `absl::string_view` or
-// nul-terminated C-style strings.
+// NUL-terminated C-style strings.
 //
 // Examples:
 //   std::string s = "foo";
@@ -38,6 +38,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // StrContains()
 //
@@ -83,6 +84,7 @@ bool StartsWithIgnoreCase(absl::string_view text, absl::string_view prefix);
 // case in the comparison.
 bool EndsWithIgnoreCase(absl::string_view text, absl::string_view suffix);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_MATCH_H_
diff --git a/absl/strings/numbers.cc b/absl/strings/numbers.cc
index 4890bd54..caab4631 100644
--- a/absl/strings/numbers.cc
+++ b/absl/strings/numbers.cc
@@ -40,6 +40,7 @@
 #include "absl/strings/str_cat.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 bool SimpleAtof(absl::string_view str, float* out) {
   *out = 0.0;
@@ -911,4 +912,5 @@ bool safe_strtou128_base(absl::string_view text, uint128* value, int base) {
 }
 
 }  // namespace numbers_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/numbers.h b/absl/strings/numbers.h
index 7a0d6f50..61204683 100644
--- a/absl/strings/numbers.h
+++ b/absl/strings/numbers.h
@@ -51,6 +51,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // SimpleAtoi()
 //
@@ -95,11 +96,13 @@ ABSL_MUST_USE_RESULT bool SimpleAtod(absl::string_view str, double* out);
 // unspecified state.
 ABSL_MUST_USE_RESULT bool SimpleAtob(absl::string_view str, bool* out);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // End of public API.  Implementation details follow.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace numbers_internal {
 
 // Digit conversion.
@@ -254,6 +257,7 @@ ABSL_MUST_USE_RESULT inline bool SimpleAtoi(absl::string_view str,
   return numbers_internal::safe_strtou128_base(str, out, 10);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_NUMBERS_H_
diff --git a/absl/strings/str_cat.cc b/absl/strings/str_cat.cc
index 4bd56f5f..d9afe2f3 100644
--- a/absl/strings/str_cat.cc
+++ b/absl/strings/str_cat.cc
@@ -25,6 +25,7 @@
 #include "absl/strings/numbers.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 AlphaNum::AlphaNum(Hex hex) {
   static_assert(numbers_internal::kFastToBufferSize >= 32,
@@ -241,4 +242,5 @@ void StrAppend(std::string* dest, const AlphaNum& a, const AlphaNum& b,
   assert(out == begin + dest->size());
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/str_cat.h b/absl/strings/str_cat.h
index 663a1945..292fa235 100644
--- a/absl/strings/str_cat.h
+++ b/absl/strings/str_cat.h
@@ -64,6 +64,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace strings_internal {
 // AlphaNumBuffer allows a way to pass a string to StrCat without having to do
@@ -401,6 +402,7 @@ SixDigits(double d) {
   return result;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_STR_CAT_H_
diff --git a/absl/strings/str_format.h b/absl/strings/str_format.h
index c11c93a2..fbbfe43d 100644
--- a/absl/strings/str_format.h
+++ b/absl/strings/str_format.h
@@ -82,6 +82,7 @@
 #include "absl/strings/internal/str_format/parser.h"  // IWYU pragma: export
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // UntypedFormatSpec
 //
@@ -530,6 +531,7 @@ ABSL_MUST_USE_RESULT inline bool FormatUntyped(
       str_format_internal::UntypedFormatSpecImpl::Extract(format), args);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_STR_FORMAT_H_
diff --git a/absl/strings/str_format_test.cc b/absl/strings/str_format_test.cc
index cfd81bb3..d33bcaa2 100644
--- a/absl/strings/str_format_test.cc
+++ b/absl/strings/str_format_test.cc
@@ -10,6 +10,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 using str_format_internal::FormatArgImpl;
 
@@ -622,6 +623,7 @@ TEST_F(FormatWrapperTest, ParsedFormat) {
 }
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // Some codegen thunks that we can use to easily dump the generated assembly for
diff --git a/absl/strings/str_join.h b/absl/strings/str_join.h
index 4772f5d1..ae5731a4 100644
--- a/absl/strings/str_join.h
+++ b/absl/strings/str_join.h
@@ -60,6 +60,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // Concept: Formatter
@@ -286,6 +287,7 @@ std::string StrJoin(const std::tuple<T...>& value,
   return strings_internal::JoinAlgorithm(value, separator, AlphaNumFormatter());
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_STR_JOIN_H_
diff --git a/absl/strings/str_replace.cc b/absl/strings/str_replace.cc
index 280f63d3..2bd5fa98 100644
--- a/absl/strings/str_replace.cc
+++ b/absl/strings/str_replace.cc
@@ -17,6 +17,7 @@
 #include "absl/strings/str_cat.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace strings_internal {
 
 using FixedMapping =
@@ -77,4 +78,5 @@ int StrReplaceAll(strings_internal::FixedMapping replacements,
   return StrReplaceAll<strings_internal::FixedMapping>(replacements, target);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/str_replace.h b/absl/strings/str_replace.h
index 30540d02..273c7077 100644
--- a/absl/strings/str_replace.h
+++ b/absl/strings/str_replace.h
@@ -46,6 +46,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // StrReplaceAll()
 //
@@ -212,6 +213,7 @@ int StrReplaceAll(const StrToStrMapping& replacements, std::string* target) {
   return substitutions;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_STR_REPLACE_H_
diff --git a/absl/strings/str_split.cc b/absl/strings/str_split.cc
index 25931307..d0f86669 100644
--- a/absl/strings/str_split.cc
+++ b/absl/strings/str_split.cc
@@ -27,6 +27,7 @@
 #include "absl/strings/ascii.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace {
 
@@ -134,4 +135,5 @@ absl::string_view ByLength::Find(absl::string_view text,
   return absl::string_view(substr.data() + length_, 0);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/str_split.h b/absl/strings/str_split.h
index 73330789..a79cd4a0 100644
--- a/absl/strings/str_split.h
+++ b/absl/strings/str_split.h
@@ -49,6 +49,7 @@
 #include "absl/strings/strip.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 //------------------------------------------------------------------------------
 // Delimiters
@@ -506,6 +507,7 @@ StrSplit(strings_internal::ConvertibleToStringView text, Delimiter d,
       std::move(text), DelimiterType(d), std::move(p));
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_STR_SPLIT_H_
diff --git a/absl/strings/string_view.cc b/absl/strings/string_view.cc
index d5e1a3de..c5f5de93 100644
--- a/absl/strings/string_view.cc
+++ b/absl/strings/string_view.cc
@@ -24,6 +24,7 @@
 #include "absl/strings/internal/memutil.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace {
 void WritePadding(std::ostream& o, size_t pad) {
@@ -228,6 +229,7 @@ constexpr string_view::size_type string_view::npos;
 ABSL_STRING_VIEW_SELECTANY
 constexpr string_view::size_type string_view::kMaxSize;
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_USES_STD_STRING_VIEW
diff --git a/absl/strings/string_view.h b/absl/strings/string_view.h
index 6a650874..4b34e563 100644
--- a/absl/strings/string_view.h
+++ b/absl/strings/string_view.h
@@ -35,7 +35,9 @@
 #include <string_view>  // IWYU pragma: export
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 using std::string_view;
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #else  // ABSL_USES_STD_STRING_VIEW
@@ -61,6 +63,7 @@ using std::string_view;
 #include "absl/base/port.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // absl::string_view
 //
@@ -109,10 +112,10 @@ namespace absl {
 // example, when splitting a string, `std::vector<absl::string_view>` is a
 // natural data type for the output.
 //
-// When constructed from a source which is nul-terminated, the `string_view`
-// itself will not include the nul-terminator unless a specific size (including
-// the nul) is passed to the constructor. As a result, common idioms that work
-// on nul-terminated strings do not work on `string_view` objects. If you write
+// When constructed from a source which is NUL-terminated, the `string_view`
+// itself will not include the NUL-terminator unless a specific size (including
+// the NUL) is passed to the constructor. As a result, common idioms that work
+// on NUL-terminated strings do not work on `string_view` objects. If you write
 // code that scans a `string_view`, you must check its length rather than test
 // for nul, for example. Note, however, that nuls may still be embedded within
 // a `string_view` explicitly.
@@ -179,7 +182,7 @@ class string_view {
       // doesn't need to be reevaluated after `ptr_` is set.
       : string_view(str.data(), str.size()) {}
 
-  // Implicit constructor of a `string_view` from nul-terminated `str`. When
+  // Implicit constructor of a `string_view` from NUL-terminated `str`. When
   // accepting possibly null strings, use `absl::NullSafeStringView(str)`
   // instead (see below).
   constexpr string_view(const char* str)  // NOLINT(runtime/explicit)
@@ -309,8 +312,8 @@ class string_view {
   //
   // Returns a pointer to the underlying character array (which is of course
   // stored elsewhere). Note that `string_view::data()` may contain embedded nul
-  // characters, but the returned buffer may or may not be nul-terminated;
-  // therefore, do not pass `data()` to a routine that expects a nul-terminated
+  // characters, but the returned buffer may or may not be NUL-terminated;
+  // therefore, do not pass `data()` to a routine that expects a NUL-terminated
   // std::string.
   constexpr const_pointer data() const noexcept { return ptr_; }
 
@@ -577,6 +580,7 @@ constexpr bool operator>=(string_view x, string_view y) noexcept {
 // IO Insertion Operator
 std::ostream& operator<<(std::ostream& o, string_view piece);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #undef ABSL_INTERNAL_STRING_VIEW_MEMCMP
@@ -584,6 +588,7 @@ std::ostream& operator<<(std::ostream& o, string_view piece);
 #endif  // ABSL_USES_STD_STRING_VIEW
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // ClippedSubstr()
 //
@@ -604,6 +609,7 @@ inline string_view NullSafeStringView(const char* p) {
   return p ? string_view(p) : string_view();
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_STRING_VIEW_H_
diff --git a/absl/strings/strip.h b/absl/strings/strip.h
index e1341e08..111872ca 100644
--- a/absl/strings/strip.h
+++ b/absl/strings/strip.h
@@ -30,6 +30,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // ConsumePrefix()
 //
@@ -84,6 +85,7 @@ ABSL_MUST_USE_RESULT inline absl::string_view StripSuffix(
   return str;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_STRIP_H_
diff --git a/absl/strings/substitute.cc b/absl/strings/substitute.cc
index 5d28c528..5b69a3ef 100644
--- a/absl/strings/substitute.cc
+++ b/absl/strings/substitute.cc
@@ -23,6 +23,7 @@
 #include "absl/strings/string_view.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace substitute_internal {
 
 void SubstituteAndAppendArray(std::string* output, absl::string_view format,
@@ -166,4 +167,5 @@ Arg::Arg(Dec dec) {
 }
 
 }  // namespace substitute_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/strings/substitute.h b/absl/strings/substitute.h
index 233e9dcf..766aca42 100644
--- a/absl/strings/substitute.h
+++ b/absl/strings/substitute.h
@@ -86,6 +86,7 @@
 #include "absl/strings/strip.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace substitute_internal {
 
 // Arg
@@ -681,6 +682,7 @@ std::string Substitute(
                      "format std::string doesn't contain all of $0 through $9");
 #endif  // ABSL_BAD_CALL_IF
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_STRINGS_SUBSTITUTE_H_
diff --git a/absl/synchronization/BUILD.bazel b/absl/synchronization/BUILD.bazel
index 36dc98f3..3f876b9f 100644
--- a/absl/synchronization/BUILD.bazel
+++ b/absl/synchronization/BUILD.bazel
@@ -43,6 +43,7 @@ cc_library(
     deps = [
         "//absl/base",
         "//absl/base:base_internal",
+        "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:malloc_internal",
         "//absl/base:raw_logging_internal",
diff --git a/absl/synchronization/CMakeLists.txt b/absl/synchronization/CMakeLists.txt
index 3c47a1bc..dfe5d05d 100644
--- a/absl/synchronization/CMakeLists.txt
+++ b/absl/synchronization/CMakeLists.txt
@@ -26,6 +26,7 @@ absl_cc_library(
   DEPS
     absl::base
     absl::base_internal
+    absl::config
     absl::core_headers
     absl::malloc_internal
     absl::raw_logging_internal
diff --git a/absl/synchronization/barrier.cc b/absl/synchronization/barrier.cc
index c2c539ac..0dfd795e 100644
--- a/absl/synchronization/barrier.cc
+++ b/absl/synchronization/barrier.cc
@@ -18,6 +18,7 @@
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Return whether int *arg is zero.
 static bool IsZero(void *arg) {
@@ -47,4 +48,5 @@ bool Barrier::Block() {
   return this->num_to_exit_ == 0;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/barrier.h b/absl/synchronization/barrier.h
index cb5d821a..d8e75440 100644
--- a/absl/synchronization/barrier.h
+++ b/absl/synchronization/barrier.h
@@ -23,6 +23,7 @@
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Barrier
 //
@@ -73,5 +74,6 @@ class Barrier {
   int num_to_exit_ ABSL_GUARDED_BY(lock_);
 };
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 #endif  // ABSL_SYNCHRONIZATION_BARRIER_H_
diff --git a/absl/synchronization/blocking_counter.cc b/absl/synchronization/blocking_counter.cc
index 481a06b2..3cea7aed 100644
--- a/absl/synchronization/blocking_counter.cc
+++ b/absl/synchronization/blocking_counter.cc
@@ -17,6 +17,7 @@
 #include "absl/base/internal/raw_logging.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Return whether int *arg is zero.
 static bool IsZero(void *arg) {
@@ -52,4 +53,5 @@ void BlockingCounter::Wait() {
   // after we return from this method.
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/blocking_counter.h b/absl/synchronization/blocking_counter.h
index 77560fc0..1f53f9f2 100644
--- a/absl/synchronization/blocking_counter.h
+++ b/absl/synchronization/blocking_counter.h
@@ -24,6 +24,7 @@
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // BlockingCounter
 //
@@ -92,6 +93,7 @@ class BlockingCounter {
   int num_waiting_ ABSL_GUARDED_BY(lock_);
 };
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_SYNCHRONIZATION_BLOCKING_COUNTER_H_
diff --git a/absl/synchronization/blocking_counter_test.cc b/absl/synchronization/blocking_counter_test.cc
index c63e3392..2926224a 100644
--- a/absl/synchronization/blocking_counter_test.cc
+++ b/absl/synchronization/blocking_counter_test.cc
@@ -22,6 +22,7 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 void PauseAndDecreaseCounter(BlockingCounter* counter, int* done) {
@@ -63,4 +64,5 @@ TEST(BlockingCounterTest, BasicFunctionality) {
 }
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/internal/create_thread_identity.cc b/absl/synchronization/internal/create_thread_identity.cc
index ec49d1ca..fa0070a9 100644
--- a/absl/synchronization/internal/create_thread_identity.cc
+++ b/absl/synchronization/internal/create_thread_identity.cc
@@ -27,6 +27,7 @@
 #include "absl/synchronization/internal/per_thread_sem.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 // ThreadIdentity storage is persistent, we maintain a free-list of previously
@@ -133,6 +134,7 @@ base_internal::ThreadIdentity* CreateThreadIdentity() {
 }
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_LOW_LEVEL_ALLOC_MISSING
diff --git a/absl/synchronization/internal/create_thread_identity.h b/absl/synchronization/internal/create_thread_identity.h
index 97237a6e..e121f683 100644
--- a/absl/synchronization/internal/create_thread_identity.h
+++ b/absl/synchronization/internal/create_thread_identity.h
@@ -29,6 +29,7 @@
 #include "absl/base/port.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 // Allocates and attaches a ThreadIdentity object for the calling thread.
@@ -53,6 +54,7 @@ inline base_internal::ThreadIdentity* GetOrCreateCurrentThreadIdentity() {
 }
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_SYNCHRONIZATION_INTERNAL_CREATE_THREAD_IDENTITY_H_
diff --git a/absl/synchronization/internal/graphcycles.cc b/absl/synchronization/internal/graphcycles.cc
index 0c8c7564..6a2bcdf6 100644
--- a/absl/synchronization/internal/graphcycles.cc
+++ b/absl/synchronization/internal/graphcycles.cc
@@ -44,6 +44,7 @@
 // Do not use STL.   This module does not use standard memory allocation.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 namespace {
@@ -690,6 +691,7 @@ int GraphCycles::GetStackTrace(GraphId id, void*** ptr) {
 }
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_LOW_LEVEL_ALLOC_MISSING
diff --git a/absl/synchronization/internal/graphcycles.h b/absl/synchronization/internal/graphcycles.h
index e08dc09d..ceba33e4 100644
--- a/absl/synchronization/internal/graphcycles.h
+++ b/absl/synchronization/internal/graphcycles.h
@@ -40,7 +40,10 @@
 
 #include <cstdint>
 
+#include "absl/base/config.h"
+
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 // Opaque identifier for a graph node.
@@ -132,6 +135,7 @@ class GraphCycles {
 };
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif
diff --git a/absl/synchronization/internal/graphcycles_test.cc b/absl/synchronization/internal/graphcycles_test.cc
index 58e8477b..74eaffe7 100644
--- a/absl/synchronization/internal/graphcycles_test.cc
+++ b/absl/synchronization/internal/graphcycles_test.cc
@@ -25,6 +25,7 @@
 #include "absl/base/macros.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 // We emulate a GraphCycles object with a node vector and an edge vector.
@@ -459,4 +460,5 @@ TEST_F(GraphCyclesTest, ManyEdges) {
 }
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/internal/kernel_timeout.h b/absl/synchronization/internal/kernel_timeout.h
index 61c72e75..d6ac5db0 100644
--- a/absl/synchronization/internal/kernel_timeout.h
+++ b/absl/synchronization/internal/kernel_timeout.h
@@ -34,6 +34,7 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 class Futex;
@@ -148,6 +149,7 @@ class KernelTimeout {
 };
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_SYNCHRONIZATION_INTERNAL_KERNEL_TIMEOUT_H_
diff --git a/absl/synchronization/internal/mutex_nonprod.cc b/absl/synchronization/internal/mutex_nonprod.cc
index 267deaff..4590b98d 100644
--- a/absl/synchronization/internal/mutex_nonprod.cc
+++ b/absl/synchronization/internal/mutex_nonprod.cc
@@ -31,6 +31,7 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 namespace {
@@ -315,4 +316,5 @@ bool Condition::Eval() const {
 
 void RegisterSymbolizer(bool (*)(const void*, char*, int)) {}
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/internal/mutex_nonprod.inc b/absl/synchronization/internal/mutex_nonprod.inc
index b8d5af79..85dae0ff 100644
--- a/absl/synchronization/internal/mutex_nonprod.inc
+++ b/absl/synchronization/internal/mutex_nonprod.inc
@@ -36,6 +36,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 class Condition;
 
 namespace synchronization_internal {
@@ -256,4 +257,5 @@ class SynchronizationStorage {
 };
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/internal/per_thread_sem.cc b/absl/synchronization/internal/per_thread_sem.cc
index 2a78b20f..821ca9b4 100644
--- a/absl/synchronization/internal/per_thread_sem.cc
+++ b/absl/synchronization/internal/per_thread_sem.cc
@@ -25,6 +25,7 @@
 #include "absl/synchronization/internal/waiter.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 void PerThreadSem::SetThreadBlockedCounter(std::atomic<int> *counter) {
@@ -62,6 +63,7 @@ void PerThreadSem::Tick(base_internal::ThreadIdentity *identity) {
 }
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 extern "C" {
diff --git a/absl/synchronization/internal/per_thread_sem.h b/absl/synchronization/internal/per_thread_sem.h
index 113cdfb7..8ab43915 100644
--- a/absl/synchronization/internal/per_thread_sem.h
+++ b/absl/synchronization/internal/per_thread_sem.h
@@ -32,6 +32,7 @@
 #include "absl/synchronization/internal/kernel_timeout.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 class Mutex;
 
@@ -85,6 +86,7 @@ class PerThreadSem {
 };
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // In some build configurations we pass --detect-odr-violations to the
diff --git a/absl/synchronization/internal/per_thread_sem_test.cc b/absl/synchronization/internal/per_thread_sem_test.cc
index dba72390..b5a2f6d4 100644
--- a/absl/synchronization/internal/per_thread_sem_test.cc
+++ b/absl/synchronization/internal/per_thread_sem_test.cc
@@ -33,6 +33,7 @@
 // primitives which might use PerThreadSem, most notably absl::Mutex.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 class SimpleSemaphore {
@@ -175,4 +176,5 @@ TEST_F(PerThreadSemTest, Timeouts) {
 }  // namespace
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/internal/thread_pool.h b/absl/synchronization/internal/thread_pool.h
index a00f2be8..0cb96dac 100644
--- a/absl/synchronization/internal/thread_pool.h
+++ b/absl/synchronization/internal/thread_pool.h
@@ -26,6 +26,7 @@
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 // A simple ThreadPool implementation for tests.
@@ -86,6 +87,7 @@ class ThreadPool {
 };
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_SYNCHRONIZATION_INTERNAL_THREAD_POOL_H_
diff --git a/absl/synchronization/internal/waiter.cc b/absl/synchronization/internal/waiter.cc
index e7000d3a..ddd6081e 100644
--- a/absl/synchronization/internal/waiter.cc
+++ b/absl/synchronization/internal/waiter.cc
@@ -49,6 +49,7 @@
 #include "absl/synchronization/internal/kernel_timeout.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 static void MaybeBecomeIdle() {
@@ -481,4 +482,5 @@ void Waiter::InternalCondVarPoke() {
 #endif
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/internal/waiter.h b/absl/synchronization/internal/waiter.h
index 9540598b..5af5c282 100644
--- a/absl/synchronization/internal/waiter.h
+++ b/absl/synchronization/internal/waiter.h
@@ -62,6 +62,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace synchronization_internal {
 
 // Waiter is an OS-specific semaphore.
@@ -157,6 +158,7 @@ class Waiter {
 };
 
 }  // namespace synchronization_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_SYNCHRONIZATION_INTERNAL_WAITER_H_
diff --git a/absl/synchronization/mutex.cc b/absl/synchronization/mutex.cc
index 100def2d..46af8a52 100644
--- a/absl/synchronization/mutex.cc
+++ b/absl/synchronization/mutex.cc
@@ -71,6 +71,7 @@ ABSL_ATTRIBUTE_WEAK void AbslInternalMutexYield() { std::this_thread::yield(); }
 }  // extern "C"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace {
 
@@ -295,7 +296,7 @@ static struct SynchEvent {     // this is a trivial hash table for the events
   bool log;             // logging turned on
 
   // Constant after initialization
-  char name[1];         // actually longer---null-terminated std::string
+  char name[1];         // actually longer---NUL-terminated std::string
 } * synch_event[kNSynchEvent] ABSL_GUARDED_BY(synch_event_mu);
 
 // Ensure that the object at "addr" has a SynchEvent struct associated with it,
@@ -2720,4 +2721,5 @@ bool Condition::GuaranteedEqual(const Condition *a, const Condition *b) {
          a->arg_ == b->arg_ && a->method_ == b->method_;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/mutex.h b/absl/synchronization/mutex.h
index ccd94618..8c70c4ce 100644
--- a/absl/synchronization/mutex.h
+++ b/absl/synchronization/mutex.h
@@ -82,6 +82,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 class Condition;
 struct SynchWaitParams;
@@ -1000,7 +1001,7 @@ void RegisterCondVarTracer(void (*fn)(const char *msg, const void *cv));
 //
 // 'pc' is the program counter being symbolized, 'out' is the buffer to write
 // into, and 'out_size' is the size of the buffer.  This function can return
-// false if symbolizing failed, or true if a null-terminated symbol was written
+// false if symbolizing failed, or true if a NUL-terminated symbol was written
 // to 'out.'
 //
 // This has the same memory ordering concerns as RegisterMutexProfiler() above.
@@ -1039,6 +1040,7 @@ enum class OnDeadlockCycle {
 // the manner chosen here.
 void SetMutexDeadlockDetectionMode(OnDeadlockCycle mode);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // In some build configurations we pass --detect-odr-violations to the
diff --git a/absl/synchronization/notification.cc b/absl/synchronization/notification.cc
index 1eb7f416..e91b9038 100644
--- a/absl/synchronization/notification.cc
+++ b/absl/synchronization/notification.cc
@@ -22,6 +22,7 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 void Notification::Notify() {
   MutexLock l(&this->mutex_);
@@ -73,4 +74,5 @@ bool Notification::WaitForNotificationWithDeadline(absl::Time deadline) const {
   return notified;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/notification.h b/absl/synchronization/notification.h
index 36c2ce3d..9a354ca2 100644
--- a/absl/synchronization/notification.h
+++ b/absl/synchronization/notification.h
@@ -57,6 +57,7 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // Notification
@@ -116,6 +117,7 @@ class Notification {
   std::atomic<bool> notified_yet_;  // written under mutex_
 };
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_SYNCHRONIZATION_NOTIFICATION_H_
diff --git a/absl/synchronization/notification_test.cc b/absl/synchronization/notification_test.cc
index 059d4cd2..100ea76f 100644
--- a/absl/synchronization/notification_test.cc
+++ b/absl/synchronization/notification_test.cc
@@ -21,6 +21,7 @@
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // A thread-safe class that holds a counter.
 class ThreadSafeCounter {
@@ -128,4 +129,5 @@ TEST(NotificationTest, SanityTest) {
   BasicTests(true, &local_notification2);
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/time/civil_time.cc b/absl/time/civil_time.cc
index 7b86fa8b..ada82cbc 100644
--- a/absl/time/civil_time.cc
+++ b/absl/time/civil_time.cc
@@ -21,6 +21,7 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace {
 
@@ -170,4 +171,5 @@ std::ostream& operator<<(std::ostream& os, CivilSecond s) {
 
 }  // namespace time_internal
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/time/civil_time.h b/absl/time/civil_time.h
index 77c3be2e..bb460044 100644
--- a/absl/time/civil_time.h
+++ b/absl/time/civil_time.h
@@ -76,6 +76,7 @@
 #include "absl/time/internal/cctz/include/cctz/civil_time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace time_internal {
 struct second_tag : cctz::detail::second_tag {};
@@ -531,6 +532,7 @@ std::ostream& operator<<(std::ostream& os, CivilSecond s);
 
 }  // namespace time_internal
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_TIME_CIVIL_TIME_H_
diff --git a/absl/time/clock.cc b/absl/time/clock.cc
index bc6f5ccf..9e9a0386 100644
--- a/absl/time/clock.cc
+++ b/absl/time/clock.cc
@@ -34,6 +34,7 @@
 #include "absl/base/thread_annotations.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 Time Now() {
   // TODO(bww): Get a timespec instead so we don't have to divide.
   int64_t n = absl::GetCurrentTimeNanos();
@@ -43,6 +44,7 @@ Time Now() {
   }
   return time_internal::FromUnixDuration(absl::Nanoseconds(n));
 }
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // Decide if we should use the fast GetCurrentTimeNanos() algorithm
@@ -71,9 +73,11 @@ Time Now() {
 
 #if !ABSL_USE_CYCLECLOCK_FOR_GET_CURRENT_TIME_NANOS
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 int64_t GetCurrentTimeNanos() {
   return GET_CURRENT_TIME_NANOS_FROM_SYSTEM();
 }
+ABSL_NAMESPACE_END
 }  // namespace absl
 #else  // Use the cyclecounter-based implementation below.
 
@@ -91,6 +95,7 @@ static int64_t stats_slow_paths;
 static int64_t stats_fast_slow_paths;
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace time_internal {
 // This is a friend wrapper around UnscaledCycleClock::Now()
 // (needed to access UnscaledCycleClock).
@@ -515,10 +520,12 @@ static uint64_t UpdateLastSample(uint64_t now_cycles, uint64_t now_ns,
 
   return estimated_base_ns;
 }
+ABSL_NAMESPACE_END
 }  // namespace absl
 #endif  // ABSL_USE_CYCLECLOCK_FOR_GET_CURRENT_TIME_NANOS
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 // Returns the maximum duration that SleepOnce() can sleep for.
@@ -546,6 +553,7 @@ void SleepOnce(absl::Duration to_sleep) {
 }
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 extern "C" {
diff --git a/absl/time/clock.h b/absl/time/clock.h
index bb52e4f6..27764a92 100644
--- a/absl/time/clock.h
+++ b/absl/time/clock.h
@@ -26,6 +26,7 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Now()
 //
@@ -49,6 +50,7 @@ int64_t GetCurrentTimeNanos();
 // * Returns immediately when passed a nonpositive duration.
 void SleepFor(absl::Duration duration);
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 // -----------------------------------------------------------------------------
diff --git a/absl/time/duration.cc b/absl/time/duration.cc
index f0b4631d..b1af8406 100644
--- a/absl/time/duration.cc
+++ b/absl/time/duration.cc
@@ -71,6 +71,7 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace {
 
@@ -917,4 +918,5 @@ bool ParseFlag(const std::string& text, Duration* dst, std::string* ) {
 
 std::string UnparseFlag(Duration d) { return FormatDuration(d); }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/time/duration_test.cc b/absl/time/duration_test.cc
index 5dce9ac8..49ebd118 100644
--- a/absl/time/duration_test.cc
+++ b/absl/time/duration_test.cc
@@ -762,11 +762,6 @@ TEST(Duration, DivisionByZero) {
   const double dbl_inf = std::numeric_limits<double>::infinity();
   const double dbl_denorm = std::numeric_limits<double>::denorm_min();
 
-  // IEEE 754 behavior
-  double z = 0.0, two = 2.0;
-  EXPECT_TRUE(std::isinf(two / z));
-  EXPECT_TRUE(std::isnan(z / z));  // We'll return inf
-
   // Operator/(Duration, double)
   EXPECT_EQ(inf, zero / 0.0);
   EXPECT_EQ(-inf, zero / -0.0);
diff --git a/absl/time/format.cc b/absl/time/format.cc
index ebe872cf..5997ef0c 100644
--- a/absl/time/format.cc
+++ b/absl/time/format.cc
@@ -22,6 +22,7 @@
 namespace cctz = absl::time_internal::cctz;
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 extern const char RFC3339_full[] = "%Y-%m-%dT%H:%M:%E*S%Ez";
 extern const char RFC3339_sec[] =  "%Y-%m-%dT%H:%M:%S%Ez";
@@ -145,4 +146,5 @@ std::string UnparseFlag(absl::Time t) {
   return absl::FormatTime(RFC3339_full, t, absl::UTCTimeZone());
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/time/internal/get_current_time_chrono.inc b/absl/time/internal/get_current_time_chrono.inc
index 5180230d..5eeb6406 100644
--- a/absl/time/internal/get_current_time_chrono.inc
+++ b/absl/time/internal/get_current_time_chrono.inc
@@ -16,6 +16,7 @@
 #include <cstdint>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace time_internal {
 
 static int64_t GetCurrentTimeNanosFromSystem() {
@@ -26,4 +27,5 @@ static int64_t GetCurrentTimeNanosFromSystem() {
 }
 
 }  // namespace time_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/time/internal/get_current_time_posix.inc b/absl/time/internal/get_current_time_posix.inc
index 65474ca6..42072000 100644
--- a/absl/time/internal/get_current_time_posix.inc
+++ b/absl/time/internal/get_current_time_posix.inc
@@ -7,6 +7,7 @@
 #include "absl/base/internal/raw_logging.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace time_internal {
 
 static int64_t GetCurrentTimeNanosFromSystem() {
@@ -19,4 +20,5 @@ static int64_t GetCurrentTimeNanosFromSystem() {
 }
 
 }  // namespace time_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/time/internal/test_util.cc b/absl/time/internal/test_util.cc
index fbddbb73..9bffe121 100644
--- a/absl/time/internal/test_util.cc
+++ b/absl/time/internal/test_util.cc
@@ -24,6 +24,7 @@
 namespace cctz = absl::time_internal::cctz;
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace time_internal {
 
 TimeZone LoadTimeZone(const std::string& name) {
@@ -33,9 +34,11 @@ TimeZone LoadTimeZone(const std::string& name) {
 }
 
 }  // namespace time_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace time_internal {
 namespace cctz_extension {
 namespace {
@@ -123,4 +126,5 @@ ZoneInfoSourceFactory zone_info_source_factory = TestFactory;
 
 }  // namespace cctz_extension
 }  // namespace time_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/time/internal/test_util.h b/absl/time/internal/test_util.h
index d7319ea8..5c4bf1f6 100644
--- a/absl/time/internal/test_util.h
+++ b/absl/time/internal/test_util.h
@@ -20,12 +20,14 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace time_internal {
 
 // Loads the named timezone, but dies on any failure.
 absl::TimeZone LoadTimeZone(const std::string& name);
 
 }  // namespace time_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_TIME_INTERNAL_TEST_UTIL_H_
diff --git a/absl/time/time.cc b/absl/time/time.cc
index 60382be7..6bb36cb3 100644
--- a/absl/time/time.cc
+++ b/absl/time/time.cc
@@ -47,6 +47,7 @@
 namespace cctz = absl::time_internal::cctz;
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace {
 
@@ -494,4 +495,5 @@ struct tm ToTM(absl::Time t, absl::TimeZone tz) {
   return tm;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/time/time.h b/absl/time/time.h
index be064813..7507b0cd 100644
--- a/absl/time/time.h
+++ b/absl/time/time.h
@@ -89,6 +89,7 @@ struct timeval;
 #include "absl/time/internal/cctz/include/cctz/time_zone.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 class Duration;  // Defined below
 class Time;      // Defined below
@@ -1574,6 +1575,7 @@ constexpr Time FromTimeT(time_t t) {
   return time_internal::FromUnixDuration(Seconds(t));
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_TIME_TIME_H_
diff --git a/absl/types/any.h b/absl/types/any.h
index f7967694..16bda79c 100644
--- a/absl/types/any.h
+++ b/absl/types/any.h
@@ -61,10 +61,12 @@
 #include <any>  // IWYU pragma: export
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 using std::any;
 using std::any_cast;
 using std::bad_any_cast;
 using std::make_any;
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #else  // ABSL_USES_STD_ANY
@@ -91,6 +93,7 @@ using std::make_any;
 #endif  // !defined(__GNUC__) || defined(__GXX_RTTI)
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace any_internal {
 
@@ -534,6 +537,7 @@ T* any_cast(any* operand) noexcept {
              : nullptr;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #undef ABSL_ANY_DETAIL_HAS_RTTI
diff --git a/absl/types/bad_any_cast.cc b/absl/types/bad_any_cast.cc
index 2a538126..b0592cc9 100644
--- a/absl/types/bad_any_cast.cc
+++ b/absl/types/bad_any_cast.cc
@@ -22,6 +22,7 @@
 #include "absl/base/internal/raw_logging.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 bad_any_cast::~bad_any_cast() = default;
 
@@ -39,6 +40,7 @@ void ThrowBadAnyCast() {
 }
 
 }  // namespace any_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_USES_STD_ANY
diff --git a/absl/types/bad_any_cast.h b/absl/types/bad_any_cast.h
index 6a53c010..114cef80 100644
--- a/absl/types/bad_any_cast.h
+++ b/absl/types/bad_any_cast.h
@@ -30,12 +30,15 @@
 #include <any>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 using std::bad_any_cast;
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #else  // ABSL_USES_STD_ANY
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // bad_any_cast
@@ -64,6 +67,7 @@ namespace any_internal {
 [[noreturn]] void ThrowBadAnyCast();
 
 }  // namespace any_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_USES_STD_ANY
diff --git a/absl/types/bad_optional_access.cc b/absl/types/bad_optional_access.cc
index d9ec21bf..26aca70d 100644
--- a/absl/types/bad_optional_access.cc
+++ b/absl/types/bad_optional_access.cc
@@ -22,6 +22,7 @@
 #include "absl/base/internal/raw_logging.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 bad_optional_access::~bad_optional_access() = default;
 
@@ -41,6 +42,7 @@ void throw_bad_optional_access() {
 }
 
 }  // namespace optional_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_USES_STD_OPTIONAL
diff --git a/absl/types/bad_optional_access.h b/absl/types/bad_optional_access.h
index 32dd6a91..a500286a 100644
--- a/absl/types/bad_optional_access.h
+++ b/absl/types/bad_optional_access.h
@@ -30,12 +30,15 @@
 #include <optional>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 using std::bad_optional_access;
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #else  // ABSL_USES_STD_OPTIONAL
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // bad_optional_access
@@ -67,6 +70,7 @@ namespace optional_internal {
 [[noreturn]] void throw_bad_optional_access();
 
 }  // namespace optional_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_USES_STD_OPTIONAL
diff --git a/absl/types/bad_variant_access.cc b/absl/types/bad_variant_access.cc
index dbaea9e9..3dc88cc0 100644
--- a/absl/types/bad_variant_access.cc
+++ b/absl/types/bad_variant_access.cc
@@ -23,6 +23,7 @@
 #include "absl/base/internal/raw_logging.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 //////////////////////////
 // [variant.bad.access] //
@@ -57,6 +58,7 @@ void Rethrow() {
 }
 
 }  // namespace variant_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_USES_STD_VARIANT
diff --git a/absl/types/bad_variant_access.h b/absl/types/bad_variant_access.h
index 6935d01b..095969f9 100644
--- a/absl/types/bad_variant_access.h
+++ b/absl/types/bad_variant_access.h
@@ -30,12 +30,15 @@
 #include <variant>
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 using std::bad_variant_access;
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #else  // ABSL_USES_STD_VARIANT
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // bad_variant_access
@@ -71,6 +74,7 @@ namespace variant_internal {
 [[noreturn]] void Rethrow();
 
 }  // namespace variant_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_USES_STD_VARIANT
diff --git a/absl/types/compare.h b/absl/types/compare.h
index a213e0b0..c29ced52 100644
--- a/absl/types/compare.h
+++ b/absl/types/compare.h
@@ -39,6 +39,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace compare_internal {
 
 using value_type = int8_t;
@@ -551,6 +552,7 @@ constexpr absl::weak_ordering do_three_way_comparison(const Compare &compare,
 }
 
 }  // namespace compare_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_TYPES_COMPARE_H_
diff --git a/absl/types/compare_test.cc b/absl/types/compare_test.cc
index ee396fc5..955844b5 100644
--- a/absl/types/compare_test.cc
+++ b/absl/types/compare_test.cc
@@ -18,6 +18,7 @@
 #include "absl/base/casts.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 // This is necessary to avoid a bunch of lint warnings suggesting that we use
@@ -334,4 +335,5 @@ TEST(Compare, StaticAsserts) {
 #endif  // __cpp_inline_variables
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/types/internal/conformance_aliases.h b/absl/types/internal/conformance_aliases.h
index 7d5d0e09..0cc6884e 100644
--- a/absl/types/internal/conformance_aliases.h
+++ b/absl/types/internal/conformance_aliases.h
@@ -26,6 +26,7 @@
 #include "absl/types/internal/conformance_profile.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace types_internal {
 
 // Creates both a Profile and a corresponding Archetype with root name "name".
@@ -438,6 +439,7 @@ using ExpandSupportedProfiles = Receiver<
 // (potentially) non-noexcept moves.
 
 }  // namespace types_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #undef ABSL_INTERNAL_PROFILE_AND_ARCHETYPE_ALIAS
diff --git a/absl/types/internal/conformance_archetype.h b/absl/types/internal/conformance_archetype.h
index 97ee7265..2349e0f7 100644
--- a/absl/types/internal/conformance_archetype.h
+++ b/absl/types/internal/conformance_archetype.h
@@ -43,6 +43,7 @@
 #include "absl/types/internal/conformance_profile.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace types_internal {
 
 // A minimum-conforming implementation of a type with properties specified in
@@ -961,6 +962,7 @@ struct EnabledHash {
 };
 
 }  // namespace types_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 namespace std {
diff --git a/absl/types/internal/conformance_profile.h b/absl/types/internal/conformance_profile.h
index dce3bbee..e62004fd 100644
--- a/absl/types/internal/conformance_profile.h
+++ b/absl/types/internal/conformance_profile.h
@@ -44,6 +44,7 @@
 // TODO(calabrese) Add support for extending profiles.
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace types_internal {
 
 template <class T, class /*Enabler*/ = void>
@@ -369,6 +370,7 @@ template <class T>
 struct IsProfile : IsProfileImpl<T>::type {};
 
 }  // namespace types_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_TYPES_INTERNAL_CONFORMANCE_PROFILE_H_
diff --git a/absl/types/internal/optional.h b/absl/types/internal/optional.h
index d41ccc75..92932b60 100644
--- a/absl/types/internal/optional.h
+++ b/absl/types/internal/optional.h
@@ -54,6 +54,7 @@
 #endif
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // Forward declaration
 template <typename T>
@@ -387,6 +388,7 @@ struct optional_hash_base<T, decltype(std::hash<absl::remove_const_t<T> >()(
 };
 
 }  // namespace optional_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #undef ABSL_OPTIONAL_USE_INHERITING_CONSTRUCTORS
diff --git a/absl/types/internal/span.h b/absl/types/internal/span.h
index d203aad5..112612f4 100644
--- a/absl/types/internal/span.h
+++ b/absl/types/internal/span.h
@@ -26,6 +26,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace span_internal {
 // A constexpr min function
@@ -121,6 +122,7 @@ template <typename From, typename To>
 using EnableIfConvertibleTo =
     typename std::enable_if<IsConvertible<From, To>::value>::type;
 }  // namespace span_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_TYPES_INTERNAL_SPAN_H_
diff --git a/absl/types/internal/variant.h b/absl/types/internal/variant.h
index 58b38592..71bd3adf 100644
--- a/absl/types/internal/variant.h
+++ b/absl/types/internal/variant.h
@@ -40,6 +40,7 @@
 #if !defined(ABSL_USES_STD_VARIANT)
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 template <class... Types>
 class variant;
@@ -1638,6 +1639,7 @@ struct VariantHashBase<Variant,
 };
 
 }  // namespace variant_internal
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // !defined(ABSL_USES_STD_VARIANT)
diff --git a/absl/types/optional.h b/absl/types/optional.h
index 14032598..2025e29f 100644
--- a/absl/types/optional.h
+++ b/absl/types/optional.h
@@ -43,11 +43,13 @@
 #include <optional>  // IWYU pragma: export
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 using std::bad_optional_access;
 using std::optional;
 using std::make_optional;
 using std::nullopt_t;
 using std::nullopt;
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #else  // ABSL_USES_STD_OPTIONAL
@@ -65,6 +67,7 @@ using std::nullopt;
 #include "absl/types/internal/optional.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // nullopt_t
 //
@@ -754,6 +757,7 @@ constexpr auto operator>=(const U& v, const optional<T>& x)
   return static_cast<bool>(x) ? static_cast<bool>(v >= *x) : true;
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 namespace std {
diff --git a/absl/types/optional_exception_safety_test.cc b/absl/types/optional_exception_safety_test.cc
index 0f7fae6c..8e5fe851 100644
--- a/absl/types/optional_exception_safety_test.cc
+++ b/absl/types/optional_exception_safety_test.cc
@@ -24,6 +24,7 @@
 #include "absl/base/internal/exception_safety_testing.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 namespace {
 
@@ -285,6 +286,7 @@ TEST(OptionalExceptionSafety, NothrowMoveAssign) {
 
 }  // namespace
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // #if !defined(ABSL_USES_STD_OPTIONAL) && defined(ABSL_HAVE_EXCEPTIONS)
diff --git a/absl/types/span.h b/absl/types/span.h
index b007fc1f..3283145a 100644
--- a/absl/types/span.h
+++ b/absl/types/span.h
@@ -71,6 +71,7 @@
 #include "absl/types/internal/span.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 //------------------------------------------------------------------------------
 // Span
@@ -707,5 +708,6 @@ template <int&... ExplicitArgumentBarrier, typename T, size_t N>
 constexpr Span<const T> MakeConstSpan(const T (&array)[N]) noexcept {
   return Span<const T>(array, N);
 }
+ABSL_NAMESPACE_END
 }  // namespace absl
 #endif  // ABSL_TYPES_SPAN_H_
diff --git a/absl/types/variant.h b/absl/types/variant.h
index f3558703..776d19a1 100644
--- a/absl/types/variant.h
+++ b/absl/types/variant.h
@@ -50,6 +50,7 @@
 #include <variant>  // IWYU pragma: export
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 using std::bad_variant_access;
 using std::get;
 using std::get_if;
@@ -62,6 +63,7 @@ using std::variant_npos;
 using std::variant_size;
 using std::variant_size_v;
 using std::visit;
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #else  // ABSL_USES_STD_VARIANT
@@ -77,6 +79,7 @@ using std::visit;
 #include "absl/types/internal/variant.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // absl::variant
@@ -795,6 +798,7 @@ operator>=(const variant<Types...>& a, const variant<Types...>& b) {
                    a.index());
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 namespace std {
@@ -815,6 +819,7 @@ struct hash<absl::variant<T...>>
 #endif  // ABSL_USES_STD_VARIANT
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace variant_internal {
 
 // Helper visitor for converting a variant<Ts...>` into another type (mostly
@@ -850,6 +855,7 @@ To ConvertVariantTo(Variant&& variant) {
                      std::forward<Variant>(variant));
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_TYPES_VARIANT_H_
diff --git a/absl/types/variant_benchmark.cc b/absl/types/variant_benchmark.cc
index a5f52164..350b1753 100644
--- a/absl/types/variant_benchmark.cc
+++ b/absl/types/variant_benchmark.cc
@@ -28,6 +28,7 @@
 #include "absl/utility/utility.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 template <std::size_t I>
@@ -217,4 +218,5 @@ BENCHMARK_TEMPLATE(BM_RedundantVisit, 4, 2)
     ->DenseRange(0, integral_pow(4, 2) - 1);
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/types/variant_exception_safety_test.cc b/absl/types/variant_exception_safety_test.cc
index b486a71e..439c6e1d 100644
--- a/absl/types/variant_exception_safety_test.cc
+++ b/absl/types/variant_exception_safety_test.cc
@@ -34,6 +34,7 @@
 #if !defined(ABSL_INTERNAL_MSVC_2017_DBG_MODE)
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 using ::testing::MakeExceptionSafetyTester;
@@ -523,6 +524,7 @@ TEST(VariantExceptionSafetyTest, Swap) {
 }
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // !defined(ABSL_INTERNAL_MSVC_2017_DBG_MODE)
diff --git a/absl/types/variant_test.cc b/absl/types/variant_test.cc
index 2913775a..96393333 100644
--- a/absl/types/variant_test.cc
+++ b/absl/types/variant_test.cc
@@ -70,6 +70,7 @@ struct hash<Hashable> {
 struct NonHashable {};
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 namespace {
 
 using ::testing::DoubleEq;
@@ -2709,6 +2710,7 @@ TEST(VariantTest, MoveCtorBug) {
 }
 
 }  // namespace
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // #if !defined(ABSL_USES_STD_VARIANT)
diff --git a/absl/utility/utility.h b/absl/utility/utility.h
index 5a98c2c3..e6647c7b 100644
--- a/absl/utility/utility.h
+++ b/absl/utility/utility.h
@@ -51,6 +51,7 @@
 #include "absl/meta/type_traits.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // integer_sequence
 //
@@ -343,6 +344,7 @@ constexpr T make_from_tuple(Tuple&& tup) {
           std::tuple_size<absl::decay_t<Tuple>>::value>{});
 }
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_UTILITY_UTILITY_H_
-- 
cgit v1.2.3


From b69c7d880caddfc25bf348dbcfe9d45fdd8bc6e6 Mon Sep 17 00:00:00 2001
From: Abseil Team <absl-team@google.com>
Date: Fri, 21 Feb 2020 12:51:36 -0800
Subject: Export of internal Abseil changes

--
00f5301405423005d9129935c05f20155536cc1a by CJ Johnson <johnsoncj@google.com>:

Removes usage of std::aligned_storage from Abseil implementation details

PiperOrigin-RevId: 296492301

--
fc11d15f91764612fba080669d2381dc181df52b by Abseil Team <absl-team@google.com>:

Fix absl::bind_front documentation.

PiperOrigin-RevId: 296482945

--
0164c595c129c46bf21ae74eba5399a1da5f140b by Gennadiy Rozental <rogeeff@google.com>:

Automated g4 rollback of changelist 296320700.

PiperOrigin-RevId: 296439968

--
1eb295700758ca0894d872b2de7c675b4ad679af by Abseil Team <absl-team@google.com>:

Removes duplicate comments.

PiperOrigin-RevId: 296433214

--
c30c01caae02d2fa4ef783d988de6bebb9757c39 by Derek Mauro <dmauro@google.com>:

Merge GitHub #621: Add RISCV support to GetProgramCounter()

Fixes #621

PiperOrigin-RevId: 296351174

--
95d4498167596fd7543e025bdfe9a8da9e2ca3c8 by Abseil Team <absl-team@google.com>:

Automated g4 rollback of changelist 296320700.

PiperOrigin-RevId: 296348701

--
b193f0543e0cec54dddb2ed51f45dc489c8d06d5 by Gennadiy Rozental <rogeeff@google.com>:

Change TryParse interface to return managed value.

In addition introduce companion StoreValue routine which consumes pointer to source value and stores the value inside of FlagImpl. In a follow up CL we will change StoreValue implementation to behave differently depending on "value storage kind".
We also rename default_src_ to default_value_.

PiperOrigin-RevId: 296320700

--
57e942b485d12912a0a8d0d0b35fa2a62847020f by Derek Mauro <dmauro@google.com>:

Merge GitHub #622
 * Add missing #ifdef conditionals for ABSL_HAVE_VDSO_SUPPORT

PiperOrigin-RevId: 296272830
GitOrigin-RevId: 00f5301405423005d9129935c05f20155536cc1a
Change-Id: I1b05eeaf1280f95fb0a2c5f3654995a87c792893
---
 absl/base/exception_safety_testing_test.cc      | 18 +++---
 absl/base/internal/low_level_alloc.cc           | 13 ++--
 absl/base/options.h                             |  8 ---
 absl/container/fixed_array_test.cc              |  7 +--
 absl/container/internal/common.h                |  7 +--
 absl/container/internal/raw_hash_set.h          |  6 +-
 absl/debugging/internal/stacktrace_x86-inl.inc  |  4 +-
 absl/flags/internal/flag.cc                     | 81 +++++++++++--------------
 absl/flags/internal/flag.h                      | 25 ++++----
 absl/flags/internal/type_erased_test.cc         |  7 +++
 absl/functional/bind_front.h                    | 26 ++++++--
 absl/memory/memory_exception_safety_test.cc     |  3 -
 absl/strings/cord.cc                            |  8 +--
 absl/synchronization/internal/mutex_nonprod.inc |  4 +-
 absl/synchronization/internal/waiter.cc         | 34 +++++------
 absl/synchronization/internal/waiter.h          | 13 ++--
 16 files changed, 130 insertions(+), 134 deletions(-)

(limited to 'absl/synchronization/internal/mutex_nonprod.inc')

diff --git a/absl/base/exception_safety_testing_test.cc b/absl/base/exception_safety_testing_test.cc
index 575b535d..a59be29e 100644
--- a/absl/base/exception_safety_testing_test.cc
+++ b/absl/base/exception_safety_testing_test.cc
@@ -328,17 +328,15 @@ TEST(ThrowingValueTest, NonThrowingDelete) {
   UnsetCountdown();
 }
 
-using Storage =
-    absl::aligned_storage_t<sizeof(ThrowingValue<>), alignof(ThrowingValue<>)>;
-
 TEST(ThrowingValueTest, NonThrowingPlacementDelete) {
   constexpr int kArrayLen = 2;
   // We intentionally create extra space to store the tag allocated by placement
   // new[].
   constexpr int kStorageLen = 4;
 
-  Storage buf;
-  Storage array_buf[kStorageLen];
+  alignas(ThrowingValue<>) unsigned char buf[sizeof(ThrowingValue<>)];
+  alignas(ThrowingValue<>) unsigned char
+      array_buf[sizeof(ThrowingValue<>[kStorageLen])];
   auto* placed = new (&buf) ThrowingValue<>(1);
   auto placed_array = new (&array_buf) ThrowingValue<>[kArrayLen];
 
@@ -902,12 +900,12 @@ TEST(ConstructorTrackerTest, CreatedAfter) {
 }
 
 TEST(ConstructorTrackerTest, NotDestroyedAfter) {
-  absl::aligned_storage_t<sizeof(Tracked), alignof(Tracked)> storage;
+  alignas(Tracked) unsigned char storage[sizeof(Tracked)];
   EXPECT_NONFATAL_FAILURE(
       {
         exceptions_internal::ConstructorTracker ct(
             exceptions_internal::countdown);
-        new (&storage) Tracked;
+        new (&storage) Tracked();
       },
       "not destroyed");
 }
@@ -924,11 +922,11 @@ TEST(ConstructorTrackerTest, DestroyedTwice) {
 
 TEST(ConstructorTrackerTest, ConstructedTwice) {
   exceptions_internal::ConstructorTracker ct(exceptions_internal::countdown);
-  absl::aligned_storage_t<sizeof(Tracked), alignof(Tracked)> storage;
+  alignas(Tracked) unsigned char storage[sizeof(Tracked)];
   EXPECT_NONFATAL_FAILURE(
       {
-        new (&storage) Tracked;
-        new (&storage) Tracked;
+        new (&storage) Tracked();
+        new (&storage) Tracked();
         reinterpret_cast<Tracked*>(&storage)->~Tracked();
       },
       "re-constructed");
diff --git a/absl/base/internal/low_level_alloc.cc b/absl/base/internal/low_level_alloc.cc
index 225abc24..1bf94438 100644
--- a/absl/base/internal/low_level_alloc.cc
+++ b/absl/base/internal/low_level_alloc.cc
@@ -220,16 +220,17 @@ struct LowLevelAlloc::Arena {
 };
 
 namespace {
-using ArenaStorage = std::aligned_storage<sizeof(LowLevelAlloc::Arena),
-                                          alignof(LowLevelAlloc::Arena)>::type;
-
 // Static storage space for the lazily-constructed, default global arena
 // instances.  We require this space because the whole point of LowLevelAlloc
 // is to avoid relying on malloc/new.
-ArenaStorage default_arena_storage;
-ArenaStorage unhooked_arena_storage;
+alignas(LowLevelAlloc::Arena) unsigned char default_arena_storage[sizeof(
+    LowLevelAlloc::Arena)];
+alignas(LowLevelAlloc::Arena) unsigned char unhooked_arena_storage[sizeof(
+    LowLevelAlloc::Arena)];
 #ifndef ABSL_LOW_LEVEL_ALLOC_ASYNC_SIGNAL_SAFE_MISSING
-ArenaStorage unhooked_async_sig_safe_arena_storage;
+alignas(
+    LowLevelAlloc::Arena) unsigned char unhooked_async_sig_safe_arena_storage
+    [sizeof(LowLevelAlloc::Arena)];
 #endif
 
 // We must use LowLevelCallOnce here to construct the global arenas, rather than
diff --git a/absl/base/options.h b/absl/base/options.h
index 6868c77b..234137c7 100644
--- a/absl/base/options.h
+++ b/absl/base/options.h
@@ -123,14 +123,6 @@
 // compiler flags passed by the end user.  For more info, see
 // https://abseil.io/about/design/dropin-types.
 
-// A value of 2 means to detect the C++ version being used to compile Abseil,
-// and use an alias only if a working std::optional is available.  This option
-// should not be used when your program is not built from source -- for example,
-// if you are distributing Abseil in a binary package manager -- since in mode
-// 2, absl::optional will name a different template class, with a different
-// mangled name and binary layout, depending on the compiler flags passed by the
-// end user.
-//
 // User code should not inspect this macro.  To check in the preprocessor if
 // absl::optional is a typedef of std::optional, use the feature macro
 // ABSL_USES_STD_OPTIONAL.
diff --git a/absl/container/fixed_array_test.cc b/absl/container/fixed_array_test.cc
index 2b1cf47e..c960fe51 100644
--- a/absl/container/fixed_array_test.cc
+++ b/absl/container/fixed_array_test.cc
@@ -604,19 +604,16 @@ TEST(FixedArrayTest, Fill) {
   empty.fill(fill_val);
 }
 
-// TODO(johnsoncj): Investigate InlinedStorage default initialization in GCC 4.x
 #ifndef __GNUC__
 TEST(FixedArrayTest, DefaultCtorDoesNotValueInit) {
   using T = char;
   constexpr auto capacity = 10;
   using FixedArrType = absl::FixedArray<T, capacity>;
-  using FixedArrBuffType =
-      absl::aligned_storage_t<sizeof(FixedArrType), alignof(FixedArrType)>;
   constexpr auto scrubbed_bits = 0x95;
   constexpr auto length = capacity / 2;
 
-  FixedArrBuffType buff;
-  std::memset(std::addressof(buff), scrubbed_bits, sizeof(FixedArrBuffType));
+  alignas(FixedArrType) unsigned char buff[sizeof(FixedArrType)];
+  std::memset(std::addressof(buff), scrubbed_bits, sizeof(FixedArrType));
 
   FixedArrType* arr =
       ::new (static_cast<void*>(std::addressof(buff))) FixedArrType(length);
diff --git a/absl/container/internal/common.h b/absl/container/internal/common.h
index 853a5b21..5037d803 100644
--- a/absl/container/internal/common.h
+++ b/absl/container/internal/common.h
@@ -56,7 +56,7 @@ class node_handle_base {
  public:
   using allocator_type = Alloc;
 
-  constexpr node_handle_base() {}
+  constexpr node_handle_base() = default;
   node_handle_base(node_handle_base&& other) noexcept {
     *this = std::move(other);
   }
@@ -109,9 +109,8 @@ class node_handle_base {
   allocator_type* alloc() { return std::addressof(*alloc_); }
 
  private:
-  absl::optional<allocator_type> alloc_;
-  mutable absl::aligned_storage_t<sizeof(slot_type), alignof(slot_type)>
-      slot_space_;
+  absl::optional<allocator_type> alloc_ = {};
+  alignas(slot_type) mutable unsigned char slot_space_[sizeof(slot_type)] = {};
 };
 
 // For sets.
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index 0d3d604c..ca7be8d8 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -1067,8 +1067,7 @@ class raw_hash_set {
   template <class... Args, typename std::enable_if<
                                !IsDecomposable<Args...>::value, int>::type = 0>
   std::pair<iterator, bool> emplace(Args&&... args) {
-    typename std::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type
-        raw;
+    alignas(slot_type) unsigned char raw[sizeof(slot_type)];
     slot_type* slot = reinterpret_cast<slot_type*>(&raw);
 
     PolicyTraits::construct(&alloc_ref(), slot, std::forward<Args>(args)...);
@@ -1556,8 +1555,7 @@ class raw_hash_set {
     //       mark target as FULL
     //       repeat procedure for current slot with moved from element (target)
     ConvertDeletedToEmptyAndFullToDeleted(ctrl_, capacity_);
-    typename std::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type
-        raw;
+    alignas(slot_type) unsigned char raw[sizeof(slot_type)];
     size_t total_probe_length = 0;
     slot_type* slot = reinterpret_cast<slot_type*>(&raw);
     for (size_t i = 0; i != capacity_; ++i) {
diff --git a/absl/debugging/internal/stacktrace_x86-inl.inc b/absl/debugging/internal/stacktrace_x86-inl.inc
index f87cafb6..bc320ff7 100644
--- a/absl/debugging/internal/stacktrace_x86-inl.inc
+++ b/absl/debugging/internal/stacktrace_x86-inl.inc
@@ -202,9 +202,9 @@ static void **NextStackFrame(void **old_fp, const void *uc) {
       } else {
         num_push_instructions = 0;
       }
-#else
+#else  // ABSL_HAVE_VDSO_SUPPORT
       num_push_instructions = 0;
-#endif
+#endif  // ABSL_HAVE_VDSO_SUPPORT
     }
     if (num_push_instructions != 0 && kernel_rt_sigreturn_address != nullptr &&
         old_fp[1] == kernel_rt_sigreturn_address) {
diff --git a/absl/flags/internal/flag.cc b/absl/flags/internal/flag.cc
index 83ec8df1..5a921e28 100644
--- a/absl/flags/internal/flag.cc
+++ b/absl/flags/internal/flag.cc
@@ -121,13 +121,21 @@ void FlagImpl::AssertValidType(FlagStaticTypeId type_id) const {
 std::unique_ptr<void, DynValueDeleter> FlagImpl::MakeInitValue() const {
   void* res = nullptr;
   if (DefaultKind() == FlagDefaultKind::kDynamicValue) {
-    res = flags_internal::Clone(op_, default_src_.dynamic_value);
+    res = flags_internal::Clone(op_, default_value_.dynamic_value);
   } else {
-    res = (*default_src_.gen_func)();
+    res = (*default_value_.gen_func)();
   }
   return {res, DynValueDeleter{op_}};
 }
 
+void FlagImpl::StoreValue(const void* src) {
+  flags_internal::Copy(op_, src, value_.dynamic);
+  StoreAtomic();
+  modified_ = true;
+  ++counter_;
+  InvokeCallback();
+}
+
 absl::string_view FlagImpl::Name() const { return name_; }
 
 std::string FlagImpl::Filename() const {
@@ -220,23 +228,19 @@ bool FlagImpl::RestoreState(const void* value, bool modified,
 // argument. If parsing successful, this function replaces the dst with newly
 // parsed value. In case if any error is encountered in either step, the error
 // message is stored in 'err'
-bool FlagImpl::TryParse(void** dst, absl::string_view value,
-                        std::string* err) const {
-  auto tentative_value = MakeInitValue();
+std::unique_ptr<void, DynValueDeleter> FlagImpl::TryParse(
+    absl::string_view value, std::string* err) const {
+  std::unique_ptr<void, DynValueDeleter> tentative_value = MakeInitValue();
 
   std::string parse_err;
   if (!flags_internal::Parse(op_, value, tentative_value.get(), &parse_err)) {
     absl::string_view err_sep = parse_err.empty() ? "" : "; ";
     *err = absl::StrCat("Illegal value '", value, "' specified for flag '",
                         Name(), "'", err_sep, parse_err);
-    return false;
+    return nullptr;
   }
 
-  void* old_val = *dst;
-  *dst = tentative_value.release();
-  tentative_value.reset(old_val);
-
-  return true;
+  return tentative_value;
 }
 
 void FlagImpl::Read(void* dst) const {
@@ -266,22 +270,17 @@ void FlagImpl::Write(const void* src) {
   absl::MutexLock l(DataGuard());
 
   if (ShouldValidateFlagValue(flags_internal::StaticTypeId(op_))) {
-    void* obj = flags_internal::Clone(op_, src);
+    std::unique_ptr<void, DynValueDeleter> obj{flags_internal::Clone(op_, src),
+                                               DynValueDeleter{op_}};
     std::string ignored_error;
     std::string src_as_str = flags_internal::Unparse(op_, src);
-    if (!flags_internal::Parse(op_, src_as_str, obj, &ignored_error)) {
+    if (!flags_internal::Parse(op_, src_as_str, obj.get(), &ignored_error)) {
       ABSL_INTERNAL_LOG(ERROR, absl::StrCat("Attempt to set flag '", Name(),
                                             "' to invalid value ", src_as_str));
     }
-    flags_internal::Delete(op_, obj);
   }
 
-  modified_ = true;
-  counter_++;
-  flags_internal::Copy(op_, src, value_.dynamic);
-
-  StoreAtomic();
-  InvokeCallback();
+  StoreValue(src);
 }
 
 // Sets the value of the flag based on specified string `value`. If the flag
@@ -299,11 +298,10 @@ bool FlagImpl::SetFromString(absl::string_view value, FlagSettingMode set_mode,
   switch (set_mode) {
     case SET_FLAGS_VALUE: {
       // set or modify the flag's value
-      if (!TryParse(&value_.dynamic, value, err)) return false;
-      modified_ = true;
-      counter_++;
-      StoreAtomic();
-      InvokeCallback();
+      auto tentative_value = TryParse(value, err);
+      if (!tentative_value) return false;
+
+      StoreValue(tentative_value.get());
 
       if (source == kCommandLine) {
         on_command_line_ = true;
@@ -312,13 +310,7 @@ bool FlagImpl::SetFromString(absl::string_view value, FlagSettingMode set_mode,
     }
     case SET_FLAG_IF_DEFAULT: {
       // set the flag's value, but only if it hasn't been set by someone else
-      if (!modified_) {
-        if (!TryParse(&value_.dynamic, value, err)) return false;
-        modified_ = true;
-        counter_++;
-        StoreAtomic();
-        InvokeCallback();
-      } else {
+      if (modified_) {
         // TODO(rogeeff): review and fix this semantic. Currently we do not fail
         // in this case if flag is modified. This is misleading since the flag's
         // value is not updated even though we return true.
@@ -327,28 +319,29 @@ bool FlagImpl::SetFromString(absl::string_view value, FlagSettingMode set_mode,
         // return false;
         return true;
       }
+      auto tentative_value = TryParse(value, err);
+      if (!tentative_value) return false;
+
+      StoreValue(tentative_value.get());
       break;
     }
     case SET_FLAGS_DEFAULT: {
+      auto tentative_value = TryParse(value, err);
+      if (!tentative_value) return false;
+
       if (DefaultKind() == FlagDefaultKind::kDynamicValue) {
-        if (!TryParse(&default_src_.dynamic_value, value, err)) {
-          return false;
-        }
+        void* old_value = default_value_.dynamic_value;
+        default_value_.dynamic_value = tentative_value.release();
+        tentative_value.reset(old_value);
       } else {
-        void* new_default_val = nullptr;
-        if (!TryParse(&new_default_val, value, err)) {
-          return false;
-        }
-
-        default_src_.dynamic_value = new_default_val;
+        default_value_.dynamic_value = tentative_value.release();
         def_kind_ = static_cast<uint8_t>(FlagDefaultKind::kDynamicValue);
       }
 
       if (!modified_) {
         // Need to set both default value *and* current, in this case
-        flags_internal::Copy(op_, default_src_.dynamic_value, value_.dynamic);
-        StoreAtomic();
-        InvokeCallback();
+        StoreValue(default_value_.dynamic_value);
+        modified_ = false;
       }
       break;
     }
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index ec673487..c1beda8e 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -363,7 +363,7 @@ struct DynValueDeleter {
     if (op != nullptr) Delete(op, ptr);
   }
 
-  const FlagOpFn op;
+  FlagOpFn op;
 };
 
 class FlagImpl {
@@ -380,7 +380,7 @@ class FlagImpl {
         on_command_line_(false),
         counter_(0),
         callback_(nullptr),
-        default_src_(default_value_gen),
+        default_value_(default_value_gen),
         data_guard_{} {}
 
   // Constant access methods
@@ -392,10 +392,6 @@ class FlagImpl {
   std::string DefaultValue() const ABSL_LOCKS_EXCLUDED(*DataGuard());
   std::string CurrentValue() const ABSL_LOCKS_EXCLUDED(*DataGuard());
   void Read(void* dst) const ABSL_LOCKS_EXCLUDED(*DataGuard());
-  // Attempts to parse supplied `value` std::string. If parsing is successful, then
-  // it replaces `dst` with the new value.
-  bool TryParse(void** dst, absl::string_view value, std::string* err) const
-      ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
 
   template <typename T, typename std::enable_if<
                             !IsAtomicFlagTypeTrait<T>::value, int>::type = 0>
@@ -466,8 +462,15 @@ class FlagImpl {
   // Returns heap allocated value of type T initialized with default value.
   std::unique_ptr<void, DynValueDeleter> MakeInitValue() const
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
-  // Lazy initialization of the Flag's data.
+  // Flag initialization called via absl::call_once.
   void Init();
+  // Attempts to parse supplied `value` std::string. If parsing is successful,
+  // returns new value. Otherwsie returns nullptr.
+  std::unique_ptr<void, DynValueDeleter> TryParse(absl::string_view value,
+                                                  std::string* err) const
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
+  // Stores the flag value based on the pointer to the source.
+  void StoreValue(const void* src) ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
 
   FlagHelpKind HelpSourceKind() const {
     return static_cast<FlagHelpKind>(help_source_kind_);
@@ -511,7 +514,7 @@ class FlagImpl {
 
   // Mutable flag's state (guarded by `data_guard_`).
 
-  // If def_kind_ == kDynamicValue, default_src_ holds a dynamically allocated
+  // If def_kind_ == kDynamicValue, default_value_ holds a dynamically allocated
   // value.
   uint8_t def_kind_ : 1 ABSL_GUARDED_BY(*DataGuard());
   // Has this flag's value been modified?
@@ -527,7 +530,7 @@ class FlagImpl {
   // value specified in ABSL_FLAG or pointer to the dynamically set default
   // value via SetCommandLineOptionWithMode. def_kind_ is used to distinguish
   // these two cases.
-  FlagDefaultSrc default_src_ ABSL_GUARDED_BY(*DataGuard());
+  FlagDefaultSrc default_value_ ABSL_GUARDED_BY(*DataGuard());
   // Current Flag Value
   FlagValue value_;
 
@@ -542,8 +545,8 @@ class FlagImpl {
 };
 
 ///////////////////////////////////////////////////////////////////////////////
-// The "unspecified" implementation of Flag object parameterized by the
-// flag's value type.
+// The Flag object parameterized by the flag's value type. This class implements
+// flag reflection handle interface.
 
 template <typename T>
 class Flag final : public flags_internal::CommandLineFlag {
diff --git a/absl/flags/internal/type_erased_test.cc b/absl/flags/internal/type_erased_test.cc
index 033e00e4..4ce59810 100644
--- a/absl/flags/internal/type_erased_test.cc
+++ b/absl/flags/internal/type_erased_test.cc
@@ -119,6 +119,13 @@ TEST_F(TypeErasedTest, TestSetCommandLineOptionWithMode_SET_FLAGS_DEFAULT) {
   EXPECT_TRUE(flags::SetCommandLineOptionWithMode("int_flag", "101",
                                                   flags::SET_FLAGS_DEFAULT));
 
+  // Set it again to ensure that resetting logic is covered.
+  EXPECT_TRUE(flags::SetCommandLineOptionWithMode("int_flag", "102",
+                                                  flags::SET_FLAGS_DEFAULT));
+
+  EXPECT_TRUE(flags::SetCommandLineOptionWithMode("int_flag", "103",
+                                                  flags::SET_FLAGS_DEFAULT));
+
   EXPECT_TRUE(flags::SetCommandLineOptionWithMode("string_flag", "asdfgh",
                                                   flags::SET_FLAGS_DEFAULT));
   EXPECT_EQ(absl::GetFlag(FLAGS_string_flag), "asdfgh");
diff --git a/absl/functional/bind_front.h b/absl/functional/bind_front.h
index 8448d7b3..5b47970e 100644
--- a/absl/functional/bind_front.h
+++ b/absl/functional/bind_front.h
@@ -38,9 +38,7 @@ ABSL_NAMESPACE_BEGIN
 
 // bind_front()
 //
-// Binds the first N arguments of an invocable object and stores them by value,
-// except types of `std::reference_wrapper` which are 'unwound' and stored by
-// reference.
+// Binds the first N arguments of an invocable object and stores them by value.
 //
 // Like `std::bind()`, `absl::bind_front()` is implicitly convertible to
 // `std::function`.  In particular, it may be used as a simpler replacement for
@@ -140,7 +138,9 @@ ABSL_NAMESPACE_BEGIN
 //
 // Example: Storing bound arguments by reference.
 //
-//   void Print(const string& a, const string& b) { LOG(INFO) << a << b; }
+//   void Print(const std::string& a, const std::string& b) {
+//     std::cerr << a << b;
+//   }
 //
 //   std::string hi = "Hello, ";
 //   std::vector<std::string> names = {"Chuk", "Gek"};
@@ -152,6 +152,24 @@ ABSL_NAMESPACE_BEGIN
 //   // dangling references.
 //   foo->DoInFuture(absl::bind_front(Print, std::ref(hi), "Guest"));  // BAD!
 //   auto f = absl::bind_front(Print, std::ref(hi), "Guest"); // BAD!
+//
+// Example: Storing reference-like types.
+//
+//   void Print(absl::string_view a, const std::string& b) {
+//     std::cerr << a << b;
+//   }
+//
+//   std::string hi = "Hello, ";
+//   // Copies "hi".
+//   absl::bind_front(Print, hi)("Chuk");
+//
+//   // Compile error: std::reference_wrapper<const string> is not implicitly
+//   // convertible to string_view.
+//   // absl::bind_front(Print, std::cref(hi))("Chuk");
+//
+//   // Doesn't copy "hi".
+//   absl::bind_front(Print, absl::string_view(hi))("Chuk");
+//
 template <class F, class... BoundArgs>
 constexpr functional_internal::bind_front_t<F, BoundArgs...> bind_front(
     F&& func, BoundArgs&&... args) {
diff --git a/absl/memory/memory_exception_safety_test.cc b/absl/memory/memory_exception_safety_test.cc
index c0910dc7..1df72614 100644
--- a/absl/memory/memory_exception_safety_test.cc
+++ b/absl/memory/memory_exception_safety_test.cc
@@ -27,9 +27,6 @@ namespace {
 
 constexpr int kLength = 50;
 using Thrower = testing::ThrowingValue<testing::TypeSpec::kEverythingThrows>;
-using ThrowerStorage =
-    absl::aligned_storage_t<sizeof(Thrower), alignof(Thrower)>;
-using ThrowerList = std::array<ThrowerStorage, kLength>;
 
 TEST(MakeUnique, CheckForLeaks) {
   constexpr int kValue = 321;
diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc
index cc0cc9d7..d9503ae3 100644
--- a/absl/strings/cord.cc
+++ b/absl/strings/cord.cc
@@ -63,16 +63,16 @@ namespace {
 // Type used with std::allocator for allocating and deallocating
 // `CordRepExternal`. std::allocator is used because it opaquely handles the
 // different new / delete overloads available on a given platform.
-using ExternalAllocType =
-    absl::aligned_storage_t<absl::cord_internal::ExternalRepAlignment(),
-                            absl::cord_internal::ExternalRepAlignment()>;
+struct alignas(absl::cord_internal::ExternalRepAlignment()) ExternalAllocType {
+  unsigned char value[absl::cord_internal::ExternalRepAlignment()];
+};
 
 // Returns the number of objects to pass in to std::allocator<ExternalAllocType>
 // allocate() and deallocate() to create enough room for `CordRepExternal` with
 // `releaser_size` bytes on the end.
 constexpr size_t GetExternalAllocNumObjects(size_t releaser_size) {
   // Be sure to round up since `releaser_size` could be smaller than
-  // sizeof(ExternalAllocType)`.
+  // `sizeof(ExternalAllocType)`.
   return (sizeof(CordRepExternal) + releaser_size + sizeof(ExternalAllocType) -
           1) /
          sizeof(ExternalAllocType);
diff --git a/absl/synchronization/internal/mutex_nonprod.inc b/absl/synchronization/internal/mutex_nonprod.inc
index 85dae0ff..a1502e72 100644
--- a/absl/synchronization/internal/mutex_nonprod.inc
+++ b/absl/synchronization/internal/mutex_nonprod.inc
@@ -252,8 +252,8 @@ class SynchronizationStorage {
 
   absl::once_flag once_;
 
-  // An aligned space for T.
-  typename std::aligned_storage<sizeof(T), alignof(T)>::type space_;
+  // An aligned space for the T.
+  alignas(T) unsigned char space_[sizeof(T)];
 };
 
 }  // namespace synchronization_internal
diff --git a/absl/synchronization/internal/waiter.cc b/absl/synchronization/internal/waiter.cc
index ddd6081e..2949f5a8 100644
--- a/absl/synchronization/internal/waiter.cc
+++ b/absl/synchronization/internal/waiter.cc
@@ -368,31 +368,29 @@ class Waiter::WinHelper {
     return reinterpret_cast<CONDITION_VARIABLE *>(&w->cv_storage_);
   }
 
-  static_assert(sizeof(SRWLOCK) == sizeof(Waiter::SRWLockStorage),
-                "SRWLockStorage does not have the same size as SRWLOCK");
+  static_assert(sizeof(SRWLOCK) == sizeof(void *),
+                "`mu_storage_` does not have the same size as SRWLOCK");
+  static_assert(alignof(SRWLOCK) == alignof(void *),
+                "`mu_storage_` does not have the same alignment as SRWLOCK");
+
+  static_assert(sizeof(CONDITION_VARIABLE) == sizeof(void *),
+                "`ABSL_CONDITION_VARIABLE_STORAGE` does not have the same size "
+                "as `CONDITION_VARIABLE`");
   static_assert(
-      alignof(SRWLOCK) == alignof(Waiter::SRWLockStorage),
-      "SRWLockStorage does not have the same alignment as SRWLOCK");
-
-  static_assert(sizeof(CONDITION_VARIABLE) ==
-                    sizeof(Waiter::ConditionVariableStorage),
-                "ABSL_CONDITION_VARIABLE_STORAGE does not have the same size "
-                "as CONDITION_VARIABLE");
-  static_assert(alignof(CONDITION_VARIABLE) ==
-                    alignof(Waiter::ConditionVariableStorage),
-                "ConditionVariableStorage does not have the same "
-                "alignment as CONDITION_VARIABLE");
+      alignof(CONDITION_VARIABLE) == alignof(void *),
+      "`cv_storage_` does not have the same alignment as `CONDITION_VARIABLE`");
 
   // The SRWLOCK and CONDITION_VARIABLE types must be trivially constructible
   // and destructible because we never call their constructors or destructors.
   static_assert(std::is_trivially_constructible<SRWLOCK>::value,
-                "The SRWLOCK type must be trivially constructible");
-  static_assert(std::is_trivially_constructible<CONDITION_VARIABLE>::value,
-                "The CONDITION_VARIABLE type must be trivially constructible");
+                "The `SRWLOCK` type must be trivially constructible");
+  static_assert(
+      std::is_trivially_constructible<CONDITION_VARIABLE>::value,
+      "The `CONDITION_VARIABLE` type must be trivially constructible");
   static_assert(std::is_trivially_destructible<SRWLOCK>::value,
-                "The SRWLOCK type must be trivially destructible");
+                "The `SRWLOCK` type must be trivially destructible");
   static_assert(std::is_trivially_destructible<CONDITION_VARIABLE>::value,
-                "The CONDITION_VARIABLE type must be trivially destructible");
+                "The `CONDITION_VARIABLE` type must be trivially destructible");
 };
 
 class LockHolder {
diff --git a/absl/synchronization/internal/waiter.h b/absl/synchronization/internal/waiter.h
index 5af5c282..a6e6d4c7 100644
--- a/absl/synchronization/internal/waiter.h
+++ b/absl/synchronization/internal/waiter.h
@@ -133,13 +133,6 @@ class Waiter {
   std::atomic<int> wakeups_;
 
 #elif ABSL_WAITER_MODE == ABSL_WAITER_MODE_WIN32
-  // We can't include Windows.h in our headers, so we use aligned storage
-  // buffers to define the storage of SRWLOCK and CONDITION_VARIABLE.
-  using SRWLockStorage =
-      typename std::aligned_storage<sizeof(void*), alignof(void*)>::type;
-  using ConditionVariableStorage =
-      typename std::aligned_storage<sizeof(void*), alignof(void*)>::type;
-
   // WinHelper - Used to define utilities for accessing the lock and
   // condition variable storage once the types are complete.
   class WinHelper;
@@ -147,8 +140,10 @@ class Waiter {
   // REQUIRES: WinHelper::GetLock(this) must be held.
   void InternalCondVarPoke();
 
-  SRWLockStorage mu_storage_;
-  ConditionVariableStorage cv_storage_;
+  // We can't include Windows.h in our headers, so we use aligned charachter
+  // buffers to define the storage of SRWLOCK and CONDITION_VARIABLE.
+  alignas(void*) unsigned char mu_storage_[sizeof(void*)];
+  alignas(void*) unsigned char cv_storage_[sizeof(void*)];
   int waiter_count_;
   int wakeup_count_;
 
-- 
cgit v1.2.3


From d118d4bb115387cc52c5338221f2554a940e6d90 Mon Sep 17 00:00:00 2001
From: Abseil Team <absl-team@google.com>
Date: Thu, 14 May 2020 16:04:20 -0700
Subject: Export of internal Abseil changes

--
b8e6b64b604449bb51ed0ba8e9439097f3aa8773 by Abseil Team <absl-team@google.com>:

fix typo 'implentation' -> 'implementation'

PiperOrigin-RevId: 311623471

--
2b9262a311f3329c8006835a79498edd90568acd by Matt Kulukundis <kfm@google.com>:

Internal cleanup

PiperOrigin-RevId: 311549039

--
7507ed3c28113e28f993aa634bd44a9a0d4c4a2c by Derek Mauro <dmauro@google.com>:

Delete LinkerInitialized

Now that all SpinLocks have the same scheduling mode for
their entire lives, the scheduling mode does not need to
be re-tested in the loop in LockSlow.

PiperOrigin-RevId: 311521474

--
abf5fae67e21b38cda4083aaafd7012e2c6fbb7d by Andy Getzendanner <durandal@google.com>:

Fix public target name of the random library

Import of https://github.com/abseil/abseil-cpp/pull/684

PiperOrigin-RevId: 311429555
GitOrigin-RevId: b8e6b64b604449bb51ed0ba8e9439097f3aa8773
Change-Id: Ic48f671846bda059cc46f4a0b967cc3b1a733ba0
---
 absl/base/internal/spinlock.cc                  | 37 ++++++-------------------
 absl/base/internal/spinlock.h                   | 19 -------------
 absl/base/macros.h                              | 30 --------------------
 absl/flags/flag.h                               |  1 +
 absl/hash/hash_test.cc                          |  2 +-
 absl/synchronization/internal/mutex_nonprod.inc | 20 +++----------
 6 files changed, 14 insertions(+), 95 deletions(-)

(limited to 'absl/synchronization/internal/mutex_nonprod.inc')

diff --git a/absl/base/internal/spinlock.cc b/absl/base/internal/spinlock.cc
index 7cac72f9..a7d44f3e 100644
--- a/absl/base/internal/spinlock.cc
+++ b/absl/base/internal/spinlock.cc
@@ -79,29 +79,6 @@ SpinLock::SpinLock(base_internal::SchedulingMode mode)
   ABSL_TSAN_MUTEX_CREATE(this, __tsan_mutex_not_static);
 }
 
-SpinLock::SpinLock(base_internal::LinkerInitialized,
-                   base_internal::SchedulingMode mode) {
-  ABSL_TSAN_MUTEX_CREATE(this, 0);
-  if (IsCooperative(mode)) {
-    InitLinkerInitializedAndCooperative();
-  }
-  // Otherwise, lockword_ is already initialized.
-}
-
-// Static (linker initialized) spinlocks always start life as functional
-// non-cooperative locks.  When their static constructor does run, it will call
-// this initializer to augment the lockword with the cooperative bit.  By
-// actually taking the lock when we do this we avoid the need for an atomic
-// operation in the regular unlock path.
-//
-// SlowLock() must be careful to re-test for this bit so that any outstanding
-// waiters may be upgraded to cooperative status.
-void SpinLock::InitLinkerInitializedAndCooperative() {
-  Lock();
-  lockword_.fetch_or(kSpinLockCooperative, std::memory_order_relaxed);
-  Unlock();
-}
-
 // Monitor the lock to see if its value changes within some time period
 // (adaptive_spin_count loop iterations). The last value read from the lock
 // is returned from the method.
@@ -128,6 +105,14 @@ void SpinLock::SlowLock() {
   if ((lock_value & kSpinLockHeld) == 0) {
     return;
   }
+
+  base_internal::SchedulingMode scheduling_mode;
+  if ((lock_value & kSpinLockCooperative) != 0) {
+    scheduling_mode = base_internal::SCHEDULE_COOPERATIVE_AND_KERNEL;
+  } else {
+    scheduling_mode = base_internal::SCHEDULE_KERNEL_ONLY;
+  }
+
   // The lock was not obtained initially, so this thread needs to wait for
   // it.  Record the current timestamp in the local variable wait_start_time
   // so the total wait time can be stored in the lockword once this thread
@@ -158,12 +143,6 @@ void SpinLock::SlowLock() {
       }
     }
 
-    base_internal::SchedulingMode scheduling_mode;
-    if ((lock_value & kSpinLockCooperative) != 0) {
-      scheduling_mode = base_internal::SCHEDULE_COOPERATIVE_AND_KERNEL;
-    } else {
-      scheduling_mode = base_internal::SCHEDULE_KERNEL_ONLY;
-    }
     // SpinLockDelay() calls into fiber scheduler, we need to see
     // synchronization there to avoid false positives.
     ABSL_TSAN_MUTEX_PRE_DIVERT(this, 0);
diff --git a/absl/base/internal/spinlock.h b/absl/base/internal/spinlock.h
index 2b08a2d6..2222398b 100644
--- a/absl/base/internal/spinlock.h
+++ b/absl/base/internal/spinlock.h
@@ -56,27 +56,9 @@ class ABSL_LOCKABLE SpinLock {
     ABSL_TSAN_MUTEX_CREATE(this, __tsan_mutex_not_static);
   }
 
-  // Special constructor for use with static SpinLock objects.  E.g.,
-  //
-  //    static SpinLock lock(base_internal::kLinkerInitialized);
-  //
-  // When initialized using this constructor, we depend on the fact
-  // that the linker has already initialized the memory appropriately. The lock
-  // is initialized in non-cooperative mode.
-  //
-  // A SpinLock constructed like this can be freely used from global
-  // initializers without worrying about the order in which global
-  // initializers run.
-  explicit SpinLock(base_internal::LinkerInitialized) {
-    // Does nothing; lockword_ is already initialized
-    ABSL_TSAN_MUTEX_CREATE(this, 0);
-  }
-
   // Constructors that allow non-cooperative spinlocks to be created for use
   // inside thread schedulers.  Normal clients should not use these.
   explicit SpinLock(base_internal::SchedulingMode mode);
-  SpinLock(base_internal::LinkerInitialized,
-           base_internal::SchedulingMode mode);
 
   // Constructor for global SpinLock instances.  See absl/base/const_init.h.
   constexpr SpinLock(absl::ConstInitType, base_internal::SchedulingMode mode)
@@ -168,7 +150,6 @@ class ABSL_LOCKABLE SpinLock {
   }
 
   uint32_t TryLockInternal(uint32_t lock_value, uint32_t wait_cycles);
-  void InitLinkerInitializedAndCooperative();
   void SlowLock() ABSL_ATTRIBUTE_COLD;
   void SlowUnlock(uint32_t lock_value) ABSL_ATTRIBUTE_COLD;
   uint32_t SpinLoop();
diff --git a/absl/base/macros.h b/absl/base/macros.h
index 2c4e3570..ea1da65b 100644
--- a/absl/base/macros.h
+++ b/absl/base/macros.h
@@ -55,36 +55,6 @@ auto ArraySizeHelper(const T (&array)[N]) -> char (&)[N];
 ABSL_NAMESPACE_END
 }  // namespace absl
 
-// kLinkerInitialized
-//
-// An enum used only as a constructor argument to indicate that a variable has
-// static storage duration, and that the constructor should do nothing to its
-// state. Use of this macro indicates to the reader that it is legal to
-// declare a static instance of the class, provided the constructor is given
-// the absl::base_internal::kLinkerInitialized argument.
-//
-// Normally, it is unsafe to declare a static variable that has a constructor or
-// a destructor because invocation order is undefined. However, if the type can
-// be zero-initialized (which the loader does for static variables) into a valid
-// state and the type's destructor does not affect storage, then a constructor
-// for static initialization can be declared.
-//
-// Example:
-//       // Declaration
-//       explicit MyClass(absl::base_internal:LinkerInitialized x) {}
-//
-//       // Invocation
-//       static MyClass my_global(absl::base_internal::kLinkerInitialized);
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace base_internal {
-enum LinkerInitialized {
-  kLinkerInitialized = 0,
-};
-}  // namespace base_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
-
 // ABSL_FALLTHROUGH_INTENDED
 //
 // Annotates implicit fall-through between switch labels, allowing a case to
diff --git a/absl/flags/flag.h b/absl/flags/flag.h
index 8dd1b9be..ca7d581f 100644
--- a/absl/flags/flag.h
+++ b/absl/flags/flag.h
@@ -41,6 +41,7 @@
 #include "absl/flags/internal/flag.h"
 #include "absl/flags/internal/registry.h"
 #include "absl/flags/marshalling.h"
+#include "absl/strings/string_view.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
diff --git a/absl/hash/hash_test.cc b/absl/hash/hash_test.cc
index 5e6a8b18..b38d46d4 100644
--- a/absl/hash/hash_test.cc
+++ b/absl/hash/hash_test.cc
@@ -407,7 +407,7 @@ using IntSequenceTypes =
 INSTANTIATE_TYPED_TEST_CASE_P(My, HashValueSequenceTest, IntSequenceTypes);
 
 // Private type that only supports AbslHashValue to make sure our chosen hash
-// implentation is recursive within absl::Hash.
+// implementation is recursive within absl::Hash.
 // It uses std::abs() on the value to provide different bitwise representations
 // of the same logical value.
 struct Private {
diff --git a/absl/synchronization/internal/mutex_nonprod.inc b/absl/synchronization/internal/mutex_nonprod.inc
index a1502e72..d83bc8a9 100644
--- a/absl/synchronization/internal/mutex_nonprod.inc
+++ b/absl/synchronization/internal/mutex_nonprod.inc
@@ -209,31 +209,22 @@ class SynchronizationStorage {
   // Instances allocated on the heap or on the stack should use the default
   // constructor.
   SynchronizationStorage()
-      : is_dynamic_(true), once_() {}
-
-  // Instances allocated in static storage (not on the heap, not on the
-  // stack) should use this constructor.
-  explicit SynchronizationStorage(base_internal::LinkerInitialized) {}
+      : destruct_(true), once_() {}
 
   constexpr explicit SynchronizationStorage(absl::ConstInitType)
-      : is_dynamic_(false), once_(), space_{{0}} {}
+      : destruct_(false), once_(), space_{{0}} {}
 
   SynchronizationStorage(SynchronizationStorage&) = delete;
   SynchronizationStorage& operator=(SynchronizationStorage&) = delete;
 
   ~SynchronizationStorage() {
-    if (is_dynamic_) {
+    if (destruct_) {
       get()->~T();
     }
   }
 
   // Retrieve the object in storage. This is fast and thread safe, but does
   // incur the cost of absl::call_once().
-  //
-  // For instances in static storage constructed with the
-  // LinkerInitialized constructor, may be called at any time without
-  // regard for order of dynamic initialization or destruction of objects
-  // in static storage. See the class comment for caveats.
   T* get() {
     absl::call_once(once_, SynchronizationStorage::Construct, this);
     return reinterpret_cast<T*>(&space_);
@@ -245,10 +236,7 @@ class SynchronizationStorage {
   }
 
   // When true, T's destructor is run when this is destructed.
-  //
-  // The LinkerInitialized constructor assumes this value will be set
-  // false by static initialization.
-  bool is_dynamic_;
+  const bool destruct_;
 
   absl::once_flag once_;
 
-- 
cgit v1.2.3


From d1de75bf540f091b4dfc860713d556e578c0f158 Mon Sep 17 00:00:00 2001
From: Abseil Team <absl-team@google.com>
Date: Fri, 25 Sep 2020 10:29:25 -0700
Subject: Export of internal Abseil changes

--
f50d25c8f8491ef7031cbbcad78edd15f98c2bd1 by Abseil Team <absl-team@google.com>:

Add myriad2 to HAVE_MMAP
Remove mutex_nonprod and associated defines.

PiperOrigin-RevId: 333759830

--
25ef4c577ea983aa3fcd6cfe2af6cdc62a06f520 by Samuel Benzaquen <sbenza@google.com>:

Internal refactor.
Represent the data with a union to allow for better constexpr support in the future.

PiperOrigin-RevId: 333756733
GitOrigin-RevId: f50d25c8f8491ef7031cbbcad78edd15f98c2bd1
Change-Id: Ieecd2c47cb20de638726eb3f9fc2e5682d05dcca
---
 absl/base/config.h                              |   2 +-
 absl/strings/cord.cc                            |  85 +++----
 absl/strings/cord.h                             |  95 ++++---
 absl/strings/internal/cord_internal.h           |  39 +++
 absl/synchronization/BUILD.bazel                |   6 +-
 absl/synchronization/CMakeLists.txt             |   1 -
 absl/synchronization/internal/mutex_nonprod.cc  | 325 ------------------------
 absl/synchronization/internal/mutex_nonprod.inc | 249 ------------------
 absl/synchronization/mutex.h                    |  34 ---
 absl/synchronization/mutex_test.cc              |   4 -
 10 files changed, 128 insertions(+), 712 deletions(-)
 delete mode 100644 absl/synchronization/internal/mutex_nonprod.cc
 delete mode 100644 absl/synchronization/internal/mutex_nonprod.inc

(limited to 'absl/synchronization/internal/mutex_nonprod.inc')

diff --git a/absl/base/config.h b/absl/base/config.h
index c1d0494e..3f7f32b9 100644
--- a/absl/base/config.h
+++ b/absl/base/config.h
@@ -364,7 +364,7 @@ static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' ||
 #elif defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) ||   \
     defined(__ros__) || defined(__native_client__) || defined(__asmjs__) || \
     defined(__wasm__) || defined(__Fuchsia__) || defined(__sun) || \
-    defined(__ASYLO__)
+    defined(__ASYLO__) || defined(__myriad2__)
 #define ABSL_HAVE_MMAP 1
 #endif
 
diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc
index 763dcc45..5092fd14 100644
--- a/absl/strings/cord.cc
+++ b/absl/strings/cord.cc
@@ -50,16 +50,10 @@ using ::absl::cord_internal::CordRepConcat;
 using ::absl::cord_internal::CordRepExternal;
 using ::absl::cord_internal::CordRepSubstring;
 
-// Various representations that we allow
-enum CordRepKind {
-  CONCAT        = 0,
-  EXTERNAL      = 1,
-  SUBSTRING     = 2,
-
-  // We have different tags for different sized flat arrays,
-  // starting with FLAT
-  FLAT          = 3,
-};
+using ::absl::cord_internal::CONCAT;
+using ::absl::cord_internal::EXTERNAL;
+using ::absl::cord_internal::FLAT;
+using ::absl::cord_internal::SUBSTRING;
 
 namespace cord_internal {
 
@@ -447,48 +441,49 @@ inline void Cord::InlineRep::set_data(const char* data, size_t n,
                                       bool nullify_tail) {
   static_assert(kMaxInline == 15, "set_data is hard-coded for a length of 15");
 
-  cord_internal::SmallMemmove(data_, data, n, nullify_tail);
-  data_[kMaxInline] = static_cast<char>(n);
+  cord_internal::SmallMemmove(data_.as_chars, data, n, nullify_tail);
+  set_tagged_size(static_cast<char>(n));
 }
 
 inline char* Cord::InlineRep::set_data(size_t n) {
   assert(n <= kMaxInline);
-  memset(data_, 0, sizeof(data_));
-  data_[kMaxInline] = static_cast<char>(n);
-  return data_;
+  ResetToEmpty();
+  set_tagged_size(static_cast<char>(n));
+  return data_.as_chars;
 }
 
 inline CordRep* Cord::InlineRep::force_tree(size_t extra_hint) {
-  size_t len = data_[kMaxInline];
-  CordRep* result;
+  size_t len = tagged_size();
   if (len > kMaxInline) {
-    memcpy(&result, data_, sizeof(result));
-  } else {
-    result = NewFlat(len + extra_hint);
-    result->length = len;
-    memcpy(result->data, data_, len);
-    set_tree(result);
+    return data_.as_tree.rep;
   }
+
+  CordRep* result = NewFlat(len + extra_hint);
+  result->length = len;
+  static_assert(kMinFlatLength >= sizeof(data_.as_chars), "");
+  memcpy(result->data, data_.as_chars, sizeof(data_.as_chars));
+  set_tree(result);
   return result;
 }
 
 inline void Cord::InlineRep::reduce_size(size_t n) {
-  size_t tag = data_[kMaxInline];
+  size_t tag = tagged_size();
   assert(tag <= kMaxInline);
   assert(tag >= n);
   tag -= n;
-  memset(data_ + tag, 0, n);
-  data_[kMaxInline] = static_cast<char>(tag);
+  memset(data_.as_chars + tag, 0, n);
+  set_tagged_size(static_cast<char>(tag));
 }
 
 inline void Cord::InlineRep::remove_prefix(size_t n) {
-  cord_internal::SmallMemmove(data_, data_ + n, data_[kMaxInline] - n);
+  cord_internal::SmallMemmove(data_.as_chars, data_.as_chars + n,
+                              tagged_size() - n);
   reduce_size(n);
 }
 
 void Cord::InlineRep::AppendTree(CordRep* tree) {
   if (tree == nullptr) return;
-  size_t len = data_[kMaxInline];
+  size_t len = tagged_size();
   if (len == 0) {
     set_tree(tree);
   } else {
@@ -498,7 +493,7 @@ void Cord::InlineRep::AppendTree(CordRep* tree) {
 
 void Cord::InlineRep::PrependTree(CordRep* tree) {
   assert(tree != nullptr);
-  size_t len = data_[kMaxInline];
+  size_t len = tagged_size();
   if (len == 0) {
     set_tree(tree);
   } else {
@@ -554,11 +549,11 @@ void Cord::InlineRep::GetAppendRegion(char** region, size_t* size,
   }
 
   // Try to fit in the inline buffer if possible.
-  size_t inline_length = data_[kMaxInline];
+  size_t inline_length = tagged_size();
   if (inline_length < kMaxInline && max_length <= kMaxInline - inline_length) {
-    *region = data_ + inline_length;
+    *region = data_.as_chars + inline_length;
     *size = max_length;
-    data_[kMaxInline] = static_cast<char>(inline_length + max_length);
+    set_tagged_size(static_cast<char>(inline_length + max_length));
     return;
   }
 
@@ -582,11 +577,11 @@ void Cord::InlineRep::GetAppendRegion(char** region, size_t* size) {
   const size_t max_length = std::numeric_limits<size_t>::max();
 
   // Try to fit in the inline buffer if possible.
-  size_t inline_length = data_[kMaxInline];
+  size_t inline_length = tagged_size();
   if (inline_length < kMaxInline) {
-    *region = data_ + inline_length;
+    *region = data_.as_chars + inline_length;
     *size = kMaxInline - inline_length;
-    data_[kMaxInline] = kMaxInline;
+    set_tagged_size(kMaxInline);
     return;
   }
 
@@ -621,7 +616,7 @@ static bool RepMemoryUsageLeaf(const CordRep* rep, size_t* total_mem_usage) {
 void Cord::InlineRep::AssignSlow(const Cord::InlineRep& src) {
   ClearSlow();
 
-  memcpy(data_, src.data_, sizeof(data_));
+  data_ = src.data_;
   if (is_tree()) {
     Ref(tree());
   }
@@ -631,7 +626,7 @@ void Cord::InlineRep::ClearSlow() {
   if (is_tree()) {
     Unref(tree());
   }
-  memset(data_, 0, sizeof(data_));
+  ResetToEmpty();
 }
 
 // --------------------------------------------------------------------
@@ -735,11 +730,11 @@ template Cord& Cord::operator=(std::string&& src);
 void Cord::InlineRep::AppendArray(const char* src_data, size_t src_size) {
   if (src_size == 0) return;  // memcpy(_, nullptr, 0) is undefined.
   // Try to fit in the inline buffer if possible.
-  size_t inline_length = data_[kMaxInline];
+  size_t inline_length = tagged_size();
   if (inline_length < kMaxInline && src_size <= kMaxInline - inline_length) {
     // Append new data to embedded array
-    data_[kMaxInline] = static_cast<char>(inline_length + src_size);
-    memcpy(data_ + inline_length, src_data, src_size);
+    set_tagged_size(static_cast<char>(inline_length + src_size));
+    memcpy(data_.as_chars + inline_length, src_data, src_size);
     return;
   }
 
@@ -762,7 +757,7 @@ void Cord::InlineRep::AppendArray(const char* src_data, size_t src_size) {
     const size_t size2 = inline_length + src_size / 10;
     root = NewFlat(std::max<size_t>(size1, size2));
     appended = std::min(src_size, TagToLength(root->tag) - inline_length);
-    memcpy(root->data, data_, inline_length);
+    memcpy(root->data, data_.as_chars, inline_length);
     memcpy(root->data + inline_length, src_data, appended);
     root->length = inline_length + appended;
     set_tree(root);
@@ -1071,7 +1066,7 @@ Cord Cord::Subcord(size_t pos, size_t new_size) const {
   } else if (new_size <= InlineRep::kMaxInline) {
     Cord::ChunkIterator it = chunk_begin();
     it.AdvanceBytes(pos);
-    char* dest = sub_cord.contents_.data_;
+    char* dest = sub_cord.contents_.data_.as_chars;
     size_t remaining_size = new_size;
     while (remaining_size > it->size()) {
       cord_internal::SmallMemmove(dest, it->data(), it->size());
@@ -1080,7 +1075,7 @@ Cord Cord::Subcord(size_t pos, size_t new_size) const {
       ++it;
     }
     cord_internal::SmallMemmove(dest, it->data(), remaining_size);
-    sub_cord.contents_.data_[InlineRep::kMaxInline] = new_size;
+    sub_cord.contents_.set_tagged_size(new_size);
   } else {
     sub_cord.contents_.set_tree(NewSubRange(tree, pos, new_size));
   }
@@ -1269,9 +1264,9 @@ bool ComputeCompareResult<bool>(int memcmp_res) {
 // Helper routine. Locates the first flat chunk of the Cord without
 // initializing the iterator.
 inline absl::string_view Cord::InlineRep::FindFlatStartPiece() const {
-  size_t n = data_[kMaxInline];
+  size_t n = tagged_size();
   if (n <= kMaxInline) {
-    return absl::string_view(data_, n);
+    return absl::string_view(data_.as_chars, n);
   }
 
   CordRep* node = tree();
diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index b8b251b0..653a1181 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -644,14 +644,12 @@ class Cord {
   // InlineRep holds either a tree pointer, or an array of kMaxInline bytes.
   class InlineRep {
    public:
-    static constexpr unsigned char kMaxInline = 15;
+    static constexpr unsigned char kMaxInline = cord_internal::kMaxInline;
     static_assert(kMaxInline >= sizeof(absl::cord_internal::CordRep*), "");
-    // Tag byte & kMaxInline means we are storing a pointer.
-    static constexpr unsigned char kTreeFlag = 1 << 4;
-    // Tag byte & kProfiledFlag means we are profiling the Cord.
-    static constexpr unsigned char kProfiledFlag = 1 << 5;
+    static constexpr unsigned char kTreeFlag = cord_internal::kTreeFlag;
+    static constexpr unsigned char kProfiledFlag = cord_internal::kProfiledFlag;
 
-    constexpr InlineRep() : data_{} {}
+    constexpr InlineRep() : data_() {}
     InlineRep(const InlineRep& src);
     InlineRep(InlineRep&& src);
     InlineRep& operator=(const InlineRep& src);
@@ -684,16 +682,16 @@ class Cord {
     void GetAppendRegion(char** region, size_t* size, size_t max_length);
     void GetAppendRegion(char** region, size_t* size);
     bool IsSame(const InlineRep& other) const {
-      return memcmp(data_, other.data_, sizeof(data_)) == 0;
+      return memcmp(&data_, &other.data_, sizeof(data_)) == 0;
     }
     int BitwiseCompare(const InlineRep& other) const {
       uint64_t x, y;
-      // Use memcpy to avoid anti-aliasing issues.
-      memcpy(&x, data_, sizeof(x));
-      memcpy(&y, other.data_, sizeof(y));
+      // Use memcpy to avoid aliasing issues.
+      memcpy(&x, &data_, sizeof(x));
+      memcpy(&y, &other.data_, sizeof(y));
       if (x == y) {
-        memcpy(&x, data_ + 8, sizeof(x));
-        memcpy(&y, other.data_ + 8, sizeof(y));
+        memcpy(&x, reinterpret_cast<const char*>(&data_) + 8, sizeof(x));
+        memcpy(&y, reinterpret_cast<const char*>(&other.data_) + 8, sizeof(y));
         if (x == y) return 0;
       }
       return absl::big_endian::FromHost64(x) < absl::big_endian::FromHost64(y)
@@ -706,16 +704,16 @@ class Cord {
       // to 15 bytes does not cause a memory allocation.
       absl::strings_internal::STLStringResizeUninitialized(dst,
                                                            sizeof(data_) - 1);
-      memcpy(&(*dst)[0], data_, sizeof(data_) - 1);
+      memcpy(&(*dst)[0], &data_, sizeof(data_) - 1);
       // erase is faster than resize because the logic for memory allocation is
       // not needed.
-      dst->erase(data_[kMaxInline]);
+      dst->erase(tagged_size());
     }
 
     // Copies the inline contents into `dst`. Assumes the cord is not empty.
     void CopyToArray(char* dst) const;
 
-    bool is_tree() const { return data_[kMaxInline] > kMaxInline; }
+    bool is_tree() const { return tagged_size() > kMaxInline; }
 
    private:
     friend class Cord;
@@ -724,10 +722,18 @@ class Cord {
     // Unrefs the tree, stops profiling, and zeroes the contents
     void ClearSlow();
 
-    // If the data has length <= kMaxInline, we store it in data_[0..len-1],
-    // and store the length in data_[kMaxInline].  Else we store it in a tree
-    // and store a pointer to that tree in data_[0..sizeof(CordRep*)-1].
-    alignas(absl::cord_internal::CordRep*) char data_[kMaxInline + 1];
+    void ResetToEmpty() { data_ = {}; }
+
+    // This uses reinterpret_cast instead of the union to avoid accessing the
+    // inactive union element. The tagged size is not a common prefix.
+    void set_tagged_size(char new_tag) {
+      reinterpret_cast<char*>(&data_)[kMaxInline] = new_tag;
+    }
+    char tagged_size() const {
+      return reinterpret_cast<const char*>(&data_)[kMaxInline];
+    }
+
+    cord_internal::InlineData data_;
   };
   InlineRep contents_;
 
@@ -879,12 +885,12 @@ Cord MakeCordFromExternal(absl::string_view data, Releaser&& releaser) {
 }
 
 inline Cord::InlineRep::InlineRep(const Cord::InlineRep& src) {
-  cord_internal::SmallMemmove(data_, src.data_, sizeof(data_));
+  data_ = src.data_;
 }
 
 inline Cord::InlineRep::InlineRep(Cord::InlineRep&& src) {
-  memcpy(data_, src.data_, sizeof(data_));
-  memset(src.data_, 0, sizeof(data_));
+  data_ = src.data_;
+  src.ResetToEmpty();
 }
 
 inline Cord::InlineRep& Cord::InlineRep::operator=(const Cord::InlineRep& src) {
@@ -892,7 +898,7 @@ inline Cord::InlineRep& Cord::InlineRep::operator=(const Cord::InlineRep& src) {
     return *this;
   }
   if (!is_tree() && !src.is_tree()) {
-    cord_internal::SmallMemmove(data_, src.data_, sizeof(data_));
+    data_ = src.data_;
     return *this;
   }
   AssignSlow(src);
@@ -904,8 +910,8 @@ inline Cord::InlineRep& Cord::InlineRep::operator=(
   if (is_tree()) {
     ClearSlow();
   }
-  memcpy(data_, src.data_, sizeof(data_));
-  memset(src.data_, 0, sizeof(data_));
+  data_ = src.data_;
+  src.ResetToEmpty();
   return *this;
 }
 
@@ -914,43 +920,39 @@ inline void Cord::InlineRep::Swap(Cord::InlineRep* rhs) {
     return;
   }
 
-  Cord::InlineRep tmp;
-  cord_internal::SmallMemmove(tmp.data_, data_, sizeof(data_));
-  cord_internal::SmallMemmove(data_, rhs->data_, sizeof(data_));
-  cord_internal::SmallMemmove(rhs->data_, tmp.data_, sizeof(data_));
+  std::swap(data_, rhs->data_);
 }
 
 inline const char* Cord::InlineRep::data() const {
-  return is_tree() ? nullptr : data_;
+  return is_tree() ? nullptr : data_.as_chars;
 }
 
 inline absl::cord_internal::CordRep* Cord::InlineRep::tree() const {
   if (is_tree()) {
-    absl::cord_internal::CordRep* rep;
-    memcpy(&rep, data_, sizeof(rep));
-    return rep;
+    return data_.as_tree.rep;
   } else {
     return nullptr;
   }
 }
 
-inline bool Cord::InlineRep::empty() const { return data_[kMaxInline] == 0; }
+inline bool Cord::InlineRep::empty() const { return tagged_size() == 0; }
 
 inline size_t Cord::InlineRep::size() const {
-  const char tag = data_[kMaxInline];
+  const char tag = tagged_size();
   if (tag <= kMaxInline) return tag;
   return static_cast<size_t>(tree()->length);
 }
 
 inline void Cord::InlineRep::set_tree(absl::cord_internal::CordRep* rep) {
   if (rep == nullptr) {
-    memset(data_, 0, sizeof(data_));
+    ResetToEmpty();
   } else {
     bool was_tree = is_tree();
-    memcpy(data_, &rep, sizeof(rep));
-    memset(data_ + sizeof(rep), 0, sizeof(data_) - sizeof(rep) - 1);
+    data_.as_tree = {rep, {}, tagged_size()};
     if (!was_tree) {
-      data_[kMaxInline] = kTreeFlag;
+      // If we were not a tree already, set the tag.
+      // Otherwise, leave it alone because it might have the profile bit on.
+      set_tagged_size(kTreeFlag);
     }
   }
 }
@@ -961,25 +963,20 @@ inline void Cord::InlineRep::replace_tree(absl::cord_internal::CordRep* rep) {
     set_tree(rep);
     return;
   }
-  memcpy(data_, &rep, sizeof(rep));
-  memset(data_ + sizeof(rep), 0, sizeof(data_) - sizeof(rep) - 1);
+  data_.as_tree = {rep, {}, tagged_size()};
 }
 
 inline absl::cord_internal::CordRep* Cord::InlineRep::clear() {
-  const char tag = data_[kMaxInline];
-  absl::cord_internal::CordRep* result = nullptr;
-  if (tag > kMaxInline) {
-    memcpy(&result, data_, sizeof(result));
-  }
-  memset(data_, 0, sizeof(data_));  // Clear the cord
+  absl::cord_internal::CordRep* result = tree();
+  ResetToEmpty();
   return result;
 }
 
 inline void Cord::InlineRep::CopyToArray(char* dst) const {
   assert(!is_tree());
-  size_t n = data_[kMaxInline];
+  size_t n = tagged_size();
   assert(n != 0);
-  cord_internal::SmallMemmove(dst, data_, n);
+  cord_internal::SmallMemmove(dst, data_.as_chars, n);
 }
 
 constexpr inline Cord::Cord() noexcept {}
diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index d456eef8..00b9baa9 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -85,6 +85,17 @@ struct CordRepConcat;
 struct CordRepSubstring;
 struct CordRepExternal;
 
+// Various representations that we allow
+enum CordRepKind {
+  CONCAT        = 0,
+  EXTERNAL      = 1,
+  SUBSTRING     = 2,
+
+  // We have different tags for different sized flat arrays,
+  // starting with FLAT
+  FLAT          = 3,
+};
+
 struct CordRep {
   // The following three fields have to be less than 32 bytes since
   // that is the smallest supported flat node size.
@@ -167,6 +178,34 @@ struct CordRepExternalImpl
   }
 };
 
+enum {
+  kMaxInline = 15,
+  // Tag byte & kMaxInline means we are storing a pointer.
+  kTreeFlag = 1 << 4,
+  // Tag byte & kProfiledFlag means we are profiling the Cord.
+  kProfiledFlag = 1 << 5
+};
+
+// If the data has length <= kMaxInline, we store it in `as_chars`, and
+// store the size in `tagged_size`.
+// Else we store it in a tree and store a pointer to that tree in
+// `as_tree.rep` and store a tag in `tagged_size`.
+struct AsTree {
+  absl::cord_internal::CordRep* rep;
+  char padding[kMaxInline + 1 - sizeof(absl::cord_internal::CordRep*) - 1];
+  char tagged_size;
+};
+union InlineData {
+  constexpr InlineData() : as_chars{} {}
+  explicit constexpr InlineData(AsTree tree) : as_tree(tree) {}
+
+  AsTree as_tree;
+  char as_chars[kMaxInline + 1];
+};
+static_assert(sizeof(InlineData) == kMaxInline + 1, "");
+static_assert(sizeof(AsTree) == sizeof(InlineData), "");
+static_assert(offsetof(AsTree, tagged_size) == kMaxInline, "");
+
 }  // namespace cord_internal
 ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/synchronization/BUILD.bazel b/absl/synchronization/BUILD.bazel
index 4d4d6806..b2df4131 100644
--- a/absl/synchronization/BUILD.bazel
+++ b/absl/synchronization/BUILD.bazel
@@ -73,15 +73,13 @@ cc_library(
         "internal/create_thread_identity.cc",
         "internal/per_thread_sem.cc",
         "internal/waiter.cc",
+        "mutex.cc",
         "notification.cc",
-    ] + select({
-        "//conditions:default": ["mutex.cc"],
-    }),
+    ],
     hdrs = [
         "barrier.h",
         "blocking_counter.h",
         "internal/create_thread_identity.h",
-        "internal/mutex_nonprod.inc",
         "internal/per_thread_sem.h",
         "internal/waiter.h",
         "mutex.h",
diff --git a/absl/synchronization/CMakeLists.txt b/absl/synchronization/CMakeLists.txt
index e5bc52fb..c255b03e 100644
--- a/absl/synchronization/CMakeLists.txt
+++ b/absl/synchronization/CMakeLists.txt
@@ -52,7 +52,6 @@ absl_cc_library(
     "barrier.h"
     "blocking_counter.h"
     "internal/create_thread_identity.h"
-    "internal/mutex_nonprod.inc"
     "internal/per_thread_sem.h"
     "internal/waiter.h"
     "mutex.h"
diff --git a/absl/synchronization/internal/mutex_nonprod.cc b/absl/synchronization/internal/mutex_nonprod.cc
deleted file mode 100644
index 334c3bc0..00000000
--- a/absl/synchronization/internal/mutex_nonprod.cc
+++ /dev/null
@@ -1,325 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Implementation of a small subset of Mutex and CondVar functionality
-// for platforms where the production implementation hasn't been fully
-// ported yet.
-
-#include "absl/synchronization/mutex.h"
-
-#if defined(_WIN32)
-#include <chrono>  // NOLINT(build/c++11)
-#else
-#include <sys/time.h>
-#include <time.h>
-#endif
-
-#include <algorithm>
-
-#include "absl/base/config.h"
-#include "absl/base/internal/raw_logging.h"
-#include "absl/time/time.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-
-void SetMutexDeadlockDetectionMode(OnDeadlockCycle) {}
-void EnableMutexInvariantDebugging(bool) {}
-
-namespace synchronization_internal {
-
-namespace {
-
-// Return the current time plus the timeout.
-absl::Time DeadlineFromTimeout(absl::Duration timeout) {
-  return absl::Now() + timeout;
-}
-
-// Limit the deadline to a positive, 32-bit time_t value to accommodate
-// implementation restrictions.  This also deals with InfinitePast and
-// InfiniteFuture.
-absl::Time LimitedDeadline(absl::Time deadline) {
-  deadline = std::max(absl::FromTimeT(0), deadline);
-  deadline = std::min(deadline, absl::FromTimeT(0x7fffffff));
-  return deadline;
-}
-
-}  // namespace
-
-#if defined(_WIN32)
-
-MutexImpl::MutexImpl() {}
-
-MutexImpl::~MutexImpl() {
-  if (locked_) {
-    std_mutex_.unlock();
-  }
-}
-
-void MutexImpl::Lock() {
-  std_mutex_.lock();
-  locked_ = true;
-}
-
-bool MutexImpl::TryLock() {
-  bool locked = std_mutex_.try_lock();
-  if (locked) locked_ = true;
-  return locked;
-}
-
-void MutexImpl::Unlock() {
-  locked_ = false;
-  released_.SignalAll();
-  std_mutex_.unlock();
-}
-
-CondVarImpl::CondVarImpl() {}
-
-CondVarImpl::~CondVarImpl() {}
-
-void CondVarImpl::Signal() { std_cv_.notify_one(); }
-
-void CondVarImpl::SignalAll() { std_cv_.notify_all(); }
-
-void CondVarImpl::Wait(MutexImpl* mu) {
-  mu->released_.SignalAll();
-  std_cv_.wait(mu->std_mutex_);
-}
-
-bool CondVarImpl::WaitWithDeadline(MutexImpl* mu, absl::Time deadline) {
-  mu->released_.SignalAll();
-  time_t when = ToTimeT(deadline);
-  int64_t nanos = ToInt64Nanoseconds(deadline - absl::FromTimeT(when));
-  std::chrono::system_clock::time_point deadline_tp =
-      std::chrono::system_clock::from_time_t(when) +
-      std::chrono::duration_cast<std::chrono::system_clock::duration>(
-          std::chrono::nanoseconds(nanos));
-  auto deadline_since_epoch =
-      std::chrono::duration_cast<std::chrono::duration<double>>(
-          deadline_tp - std::chrono::system_clock::from_time_t(0));
-  return std_cv_.wait_until(mu->std_mutex_, deadline_tp) ==
-         std::cv_status::timeout;
-}
-
-#else  // ! _WIN32
-
-MutexImpl::MutexImpl() {
-  ABSL_RAW_CHECK(pthread_mutex_init(&pthread_mutex_, nullptr) == 0,
-                 "pthread error");
-}
-
-MutexImpl::~MutexImpl() {
-  if (locked_) {
-    ABSL_RAW_CHECK(pthread_mutex_unlock(&pthread_mutex_) == 0, "pthread error");
-  }
-  ABSL_RAW_CHECK(pthread_mutex_destroy(&pthread_mutex_) == 0, "pthread error");
-}
-
-void MutexImpl::Lock() {
-  ABSL_RAW_CHECK(pthread_mutex_lock(&pthread_mutex_) == 0, "pthread error");
-  locked_ = true;
-}
-
-bool MutexImpl::TryLock() {
-  bool locked = (0 == pthread_mutex_trylock(&pthread_mutex_));
-  if (locked) locked_ = true;
-  return locked;
-}
-
-void MutexImpl::Unlock() {
-  locked_ = false;
-  released_.SignalAll();
-  ABSL_RAW_CHECK(pthread_mutex_unlock(&pthread_mutex_) == 0, "pthread error");
-}
-
-CondVarImpl::CondVarImpl() {
-  ABSL_RAW_CHECK(pthread_cond_init(&pthread_cv_, nullptr) == 0,
-                 "pthread error");
-}
-
-CondVarImpl::~CondVarImpl() {
-  ABSL_RAW_CHECK(pthread_cond_destroy(&pthread_cv_) == 0, "pthread error");
-}
-
-void CondVarImpl::Signal() {
-  ABSL_RAW_CHECK(pthread_cond_signal(&pthread_cv_) == 0, "pthread error");
-}
-
-void CondVarImpl::SignalAll() {
-  ABSL_RAW_CHECK(pthread_cond_broadcast(&pthread_cv_) == 0, "pthread error");
-}
-
-void CondVarImpl::Wait(MutexImpl* mu) {
-  mu->released_.SignalAll();
-  ABSL_RAW_CHECK(pthread_cond_wait(&pthread_cv_, &mu->pthread_mutex_) == 0,
-                 "pthread error");
-}
-
-bool CondVarImpl::WaitWithDeadline(MutexImpl* mu, absl::Time deadline) {
-  mu->released_.SignalAll();
-  struct timespec ts = ToTimespec(deadline);
-  int rc = pthread_cond_timedwait(&pthread_cv_, &mu->pthread_mutex_, &ts);
-  if (rc == ETIMEDOUT) return true;
-  ABSL_RAW_CHECK(rc == 0, "pthread error");
-  return false;
-}
-
-#endif  // ! _WIN32
-
-void MutexImpl::Await(const Condition& cond) {
-  if (cond.Eval()) return;
-  released_.SignalAll();
-  do {
-    released_.Wait(this);
-  } while (!cond.Eval());
-}
-
-bool MutexImpl::AwaitWithDeadline(const Condition& cond, absl::Time deadline) {
-  if (cond.Eval()) return true;
-  released_.SignalAll();
-  while (true) {
-    if (released_.WaitWithDeadline(this, deadline)) return false;
-    if (cond.Eval()) return true;
-  }
-}
-
-}  // namespace synchronization_internal
-
-Mutex::Mutex() {}
-
-Mutex::~Mutex() {}
-
-void Mutex::Lock() { impl()->Lock(); }
-
-void Mutex::Unlock() { impl()->Unlock(); }
-
-bool Mutex::TryLock() { return impl()->TryLock(); }
-
-void Mutex::ReaderLock() { Lock(); }
-
-void Mutex::ReaderUnlock() { Unlock(); }
-
-void Mutex::Await(const Condition& cond) { impl()->Await(cond); }
-
-void Mutex::LockWhen(const Condition& cond) {
-  Lock();
-  Await(cond);
-}
-
-bool Mutex::AwaitWithDeadline(const Condition& cond, absl::Time deadline) {
-  return impl()->AwaitWithDeadline(
-      cond, synchronization_internal::LimitedDeadline(deadline));
-}
-
-bool Mutex::AwaitWithTimeout(const Condition& cond, absl::Duration timeout) {
-  return AwaitWithDeadline(
-      cond, synchronization_internal::DeadlineFromTimeout(timeout));
-}
-
-bool Mutex::LockWhenWithDeadline(const Condition& cond, absl::Time deadline) {
-  Lock();
-  return AwaitWithDeadline(cond, deadline);
-}
-
-bool Mutex::LockWhenWithTimeout(const Condition& cond, absl::Duration timeout) {
-  return LockWhenWithDeadline(
-      cond, synchronization_internal::DeadlineFromTimeout(timeout));
-}
-
-void Mutex::ReaderLockWhen(const Condition& cond) {
-  ReaderLock();
-  Await(cond);
-}
-
-bool Mutex::ReaderLockWhenWithTimeout(const Condition& cond,
-                                      absl::Duration timeout) {
-  return LockWhenWithTimeout(cond, timeout);
-}
-bool Mutex::ReaderLockWhenWithDeadline(const Condition& cond,
-                                       absl::Time deadline) {
-  return LockWhenWithDeadline(cond, deadline);
-}
-
-void Mutex::EnableDebugLog(const char*) {}
-void Mutex::EnableInvariantDebugging(void (*)(void*), void*) {}
-void Mutex::ForgetDeadlockInfo() {}
-void Mutex::AssertHeld() const {}
-void Mutex::AssertReaderHeld() const {}
-void Mutex::AssertNotHeld() const {}
-
-CondVar::CondVar() {}
-
-CondVar::~CondVar() {}
-
-void CondVar::Signal() { impl()->Signal(); }
-
-void CondVar::SignalAll() { impl()->SignalAll(); }
-
-void CondVar::Wait(Mutex* mu) { return impl()->Wait(mu->impl()); }
-
-bool CondVar::WaitWithDeadline(Mutex* mu, absl::Time deadline) {
-  return impl()->WaitWithDeadline(
-      mu->impl(), synchronization_internal::LimitedDeadline(deadline));
-}
-
-bool CondVar::WaitWithTimeout(Mutex* mu, absl::Duration timeout) {
-  return WaitWithDeadline(mu, absl::Now() + timeout);
-}
-
-void CondVar::EnableDebugLog(const char*) {}
-
-#ifdef ABSL_HAVE_THREAD_SANITIZER
-extern "C" void __tsan_read1(void *addr);
-#else
-#define __tsan_read1(addr)  // do nothing if TSan not enabled
-#endif
-
-// A function that just returns its argument, dereferenced
-static bool Dereference(void *arg) {
-  // ThreadSanitizer does not instrument this file for memory accesses.
-  // This function dereferences a user variable that can participate
-  // in a data race, so we need to manually tell TSan about this memory access.
-  __tsan_read1(arg);
-  return *(static_cast<bool *>(arg));
-}
-
-Condition::Condition() {}   // null constructor, used for kTrue only
-const Condition Condition::kTrue;
-
-Condition::Condition(bool (*func)(void *), void *arg)
-    : eval_(&CallVoidPtrFunction),
-      function_(func),
-      method_(nullptr),
-      arg_(arg) {}
-
-bool Condition::CallVoidPtrFunction(const Condition *c) {
-  return (*c->function_)(c->arg_);
-}
-
-Condition::Condition(const bool *cond)
-    : eval_(CallVoidPtrFunction),
-      function_(Dereference),
-      method_(nullptr),
-      // const_cast is safe since Dereference does not modify arg
-      arg_(const_cast<bool *>(cond)) {}
-
-bool Condition::Eval() const {
-  // eval_ == null for kTrue
-  return (this->eval_ == nullptr) || (*this->eval_)(this);
-}
-
-void RegisterSymbolizer(bool (*)(const void*, char*, int)) {}
-
-ABSL_NAMESPACE_END
-}  // namespace absl
diff --git a/absl/synchronization/internal/mutex_nonprod.inc b/absl/synchronization/internal/mutex_nonprod.inc
deleted file mode 100644
index d83bc8a9..00000000
--- a/absl/synchronization/internal/mutex_nonprod.inc
+++ /dev/null
@@ -1,249 +0,0 @@
-// Do not include.  This is an implementation detail of base/mutex.h.
-//
-// Declares three classes:
-//
-// base::internal::MutexImpl - implementation helper for Mutex
-// base::internal::CondVarImpl - implementation helper for CondVar
-// base::internal::SynchronizationStorage<T> - implementation helper for
-//                                             Mutex, CondVar
-
-#include <type_traits>
-
-#if defined(_WIN32)
-#include <condition_variable>
-#include <mutex>
-#else
-#include <pthread.h>
-#endif
-
-#include "absl/base/call_once.h"
-#include "absl/time/time.h"
-
-// Declare that Mutex::ReaderLock is actually Lock().  Intended primarily
-// for tests, and even then as a last resort.
-#ifdef ABSL_MUTEX_READER_LOCK_IS_EXCLUSIVE
-#error ABSL_MUTEX_READER_LOCK_IS_EXCLUSIVE cannot be directly set
-#else
-#define ABSL_MUTEX_READER_LOCK_IS_EXCLUSIVE 1
-#endif
-
-// Declare that Mutex::EnableInvariantDebugging is not implemented.
-// Intended primarily for tests, and even then as a last resort.
-#ifdef ABSL_MUTEX_ENABLE_INVARIANT_DEBUGGING_NOT_IMPLEMENTED
-#error ABSL_MUTEX_ENABLE_INVARIANT_DEBUGGING_NOT_IMPLEMENTED cannot be directly set
-#else
-#define ABSL_MUTEX_ENABLE_INVARIANT_DEBUGGING_NOT_IMPLEMENTED 1
-#endif
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-class Condition;
-
-namespace synchronization_internal {
-
-class MutexImpl;
-
-// Do not use this implementation detail of CondVar. Provides most of the
-// implementation, but should not be placed directly in static storage
-// because it will not linker initialize properly. See
-// SynchronizationStorage<T> below for what we mean by linker
-// initialization.
-class CondVarImpl {
- public:
-  CondVarImpl();
-  CondVarImpl(const CondVarImpl&) = delete;
-  CondVarImpl& operator=(const CondVarImpl&) = delete;
-  ~CondVarImpl();
-
-  void Signal();
-  void SignalAll();
-  void Wait(MutexImpl* mutex);
-  bool WaitWithDeadline(MutexImpl* mutex, absl::Time deadline);
-
- private:
-#if defined(_WIN32)
-  std::condition_variable_any std_cv_;
-#else
-  pthread_cond_t pthread_cv_;
-#endif
-};
-
-// Do not use this implementation detail of Mutex. Provides most of the
-// implementation, but should not be placed directly in static storage
-// because it will not linker initialize properly. See
-// SynchronizationStorage<T> below for what we mean by linker
-// initialization.
-class MutexImpl {
- public:
-  MutexImpl();
-  MutexImpl(const MutexImpl&) = delete;
-  MutexImpl& operator=(const MutexImpl&) = delete;
-  ~MutexImpl();
-
-  void Lock();
-  bool TryLock();
-  void Unlock();
-  void Await(const Condition& cond);
-  bool AwaitWithDeadline(const Condition& cond, absl::Time deadline);
-
- private:
-  friend class CondVarImpl;
-
-#if defined(_WIN32)
-  std::mutex std_mutex_;
-#else
-  pthread_mutex_t pthread_mutex_;
-#endif
-
-  // True if the underlying mutex is locked.  If the destructor is entered
-  // while locked_, the underlying mutex is unlocked.  Mutex supports
-  // destruction while locked, but the same is undefined behavior for both
-  // pthread_mutex_t and std::mutex.
-  bool locked_ = false;
-
-  // Signaled before releasing the lock, in support of Await.
-  CondVarImpl released_;
-};
-
-// Do not use this implementation detail of CondVar and Mutex.  A storage
-// space for T that supports a LinkerInitialized constructor. T must
-// have a default constructor, which is called by the first call to
-// get(). T's destructor is never called if the LinkerInitialized
-// constructor is called.
-//
-// Objects constructed with the default constructor are constructed and
-// destructed like any other object, and should never be allocated in
-// static storage.
-//
-// Objects constructed with the LinkerInitialized constructor should
-// always be in static storage. For such objects, calls to get() are always
-// valid, except from signal handlers.
-//
-// Note that this implementation relies on undefined language behavior that
-// are known to hold for the set of supported compilers. An analysis
-// follows.
-//
-// From the C++11 standard:
-//
-// [basic.life] says an object has non-trivial initialization if it is of
-// class type and it is initialized by a constructor other than a trivial
-// default constructor.  (the LinkerInitialized constructor is
-// non-trivial)
-//
-// [basic.life] says the lifetime of an object with a non-trivial
-// constructor begins when the call to the constructor is complete.
-//
-// [basic.life] says the lifetime of an object with non-trivial destructor
-// ends when the call to the destructor begins.
-//
-// [basic.life] p5 specifies undefined behavior when accessing non-static
-// members of an instance outside its
-// lifetime. (SynchronizationStorage::get() access non-static members)
-//
-// So, LinkerInitialized object of SynchronizationStorage uses a
-// non-trivial constructor, which is called at some point during dynamic
-// initialization, and is therefore subject to order of dynamic
-// initialization bugs, where get() is called before the object's
-// constructor is, resulting in undefined behavior.
-//
-// Similarly, a LinkerInitialized SynchronizationStorage object has a
-// non-trivial destructor, and so its lifetime ends at some point during
-// destruction of objects with static storage duration [basic.start.term]
-// p4. There is a window where other exit code could call get() after this
-// occurs, resulting in undefined behavior.
-//
-// Combined, these statements imply that LinkerInitialized instances
-// of SynchronizationStorage<T> rely on undefined behavior.
-//
-// However, in practice, the implementation works on all supported
-// compilers. Specifically, we rely on:
-//
-// a) zero-initialization being sufficient to initialize
-// LinkerInitialized instances for the purposes of calling
-// get(), regardless of when the constructor is called. This is
-// because the is_dynamic_ boolean is correctly zero-initialized to
-// false.
-//
-// b) the LinkerInitialized constructor is a NOP, and immaterial to
-// even to concurrent calls to get().
-//
-// c) the destructor being a NOP for LinkerInitialized objects
-// (guaranteed by a check for !is_dynamic_), and so any concurrent and
-// subsequent calls to get() functioning as if the destructor were not
-// called, by virtue of the instances' storage remaining valid after the
-// destructor runs.
-//
-// d) That a-c apply transitively when SynchronizationStorage<T> is the
-// only member of a class allocated in static storage.
-//
-// Nothing in the language standard guarantees that a-d hold.  In practice,
-// these hold in all supported compilers.
-//
-// Future direction:
-//
-// Ideally, we would simply use std::mutex or a similar class, which when
-// allocated statically would support use immediately after static
-// initialization up until static storage is reclaimed (i.e. the properties
-// we require of all "linker initialized" instances).
-//
-// Regarding construction in static storage, std::mutex is required to
-// provide a constexpr default constructor [thread.mutex.class], which
-// ensures the instance's lifetime begins with static initialization
-// [basic.start.init], and so is immune to any problems caused by the order
-// of dynamic initialization. However, as of this writing Microsoft's
-// Visual Studio does not provide a constexpr constructor for std::mutex.
-// See
-// https://blogs.msdn.microsoft.com/vcblog/2015/06/02/constexpr-complete-for-vs-2015-rtm-c11-compiler-c17-stl/
-//
-// Regarding destruction of instances in static storage, [basic.life] does
-// say an object ends when storage in which the occupies is released, in
-// the case of non-trivial destructor. However, std::mutex is not specified
-// to have a trivial destructor.
-//
-// So, we would need a class with a constexpr default constructor and a
-// trivial destructor. Today, we can achieve neither desired property using
-// std::mutex directly.
-template <typename T>
-class SynchronizationStorage {
- public:
-  // Instances allocated on the heap or on the stack should use the default
-  // constructor.
-  SynchronizationStorage()
-      : destruct_(true), once_() {}
-
-  constexpr explicit SynchronizationStorage(absl::ConstInitType)
-      : destruct_(false), once_(), space_{{0}} {}
-
-  SynchronizationStorage(SynchronizationStorage&) = delete;
-  SynchronizationStorage& operator=(SynchronizationStorage&) = delete;
-
-  ~SynchronizationStorage() {
-    if (destruct_) {
-      get()->~T();
-    }
-  }
-
-  // Retrieve the object in storage. This is fast and thread safe, but does
-  // incur the cost of absl::call_once().
-  T* get() {
-    absl::call_once(once_, SynchronizationStorage::Construct, this);
-    return reinterpret_cast<T*>(&space_);
-  }
-
- private:
-  static void Construct(SynchronizationStorage<T>* self) {
-    new (&self->space_) T();
-  }
-
-  // When true, T's destructor is run when this is destructed.
-  const bool destruct_;
-
-  absl::once_flag once_;
-
-  // An aligned space for the T.
-  alignas(T) unsigned char space_[sizeof(T)];
-};
-
-}  // namespace synchronization_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
diff --git a/absl/synchronization/mutex.h b/absl/synchronization/mutex.h
index 52401fe3..6340bd63 100644
--- a/absl/synchronization/mutex.h
+++ b/absl/synchronization/mutex.h
@@ -72,15 +72,6 @@
 #include "absl/synchronization/internal/per_thread_sem.h"
 #include "absl/time/time.h"
 
-// Decide if we should use the non-production implementation because
-// the production implementation hasn't been fully ported yet.
-#ifdef ABSL_INTERNAL_USE_NONPROD_MUTEX
-#error ABSL_INTERNAL_USE_NONPROD_MUTEX cannot be directly set
-#elif defined(ABSL_LOW_LEVEL_ALLOC_MISSING)
-#define ABSL_INTERNAL_USE_NONPROD_MUTEX 1
-#include "absl/synchronization/internal/mutex_nonprod.inc"
-#endif
-
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 
@@ -461,15 +452,6 @@ class ABSL_LOCKABLE Mutex {
   static void InternalAttemptToUseMutexInFatalSignalHandler();
 
  private:
-#ifdef ABSL_INTERNAL_USE_NONPROD_MUTEX
-  friend class CondVar;
-
-  synchronization_internal::MutexImpl *impl() { return impl_.get(); }
-
-  synchronization_internal::SynchronizationStorage<
-      synchronization_internal::MutexImpl>
-      impl_;
-#else
   std::atomic<intptr_t> mu_;  // The Mutex state.
 
   // Post()/Wait() versus associated PerThreadSem; in class for required
@@ -504,7 +486,6 @@ class ABSL_LOCKABLE Mutex {
   void Trans(MuHow how);  // used for CondVar->Mutex transfer
   void Fer(
       base_internal::PerThreadSynch *w);  // used for CondVar->Mutex transfer
-#endif
 
   // Catch the error of writing Mutex when intending MutexLock.
   Mutex(const volatile Mutex * /*ignored*/) {}  // NOLINT(runtime/explicit)
@@ -838,17 +819,10 @@ class CondVar {
   void EnableDebugLog(const char *name);
 
  private:
-#ifdef ABSL_INTERNAL_USE_NONPROD_MUTEX
-  synchronization_internal::CondVarImpl *impl() { return impl_.get(); }
-  synchronization_internal::SynchronizationStorage<
-      synchronization_internal::CondVarImpl>
-      impl_;
-#else
   bool WaitCommon(Mutex *mutex, synchronization_internal::KernelTimeout t);
   void Remove(base_internal::PerThreadSynch *s);
   void Wakeup(base_internal::PerThreadSynch *w);
   std::atomic<intptr_t> cv_;  // Condition variable state.
-#endif
   CondVar(const CondVar&) = delete;
   CondVar& operator=(const CondVar&) = delete;
 };
@@ -906,12 +880,6 @@ class ABSL_SCOPED_LOCKABLE ReleasableMutexLock {
   ReleasableMutexLock& operator=(ReleasableMutexLock&&) = delete;
 };
 
-#ifdef ABSL_INTERNAL_USE_NONPROD_MUTEX
-
-inline constexpr Mutex::Mutex(absl::ConstInitType) : impl_(absl::kConstInit) {}
-
-#else
-
 inline Mutex::Mutex() : mu_(0) {
   ABSL_TSAN_MUTEX_CREATE(this, __tsan_mutex_not_static);
 }
@@ -920,8 +888,6 @@ inline constexpr Mutex::Mutex(absl::ConstInitType) : mu_(0) {}
 
 inline CondVar::CondVar() : cv_(0) {}
 
-#endif  // ABSL_INTERNAL_USE_NONPROD_MUTEX
-
 // static
 template <typename T>
 bool Condition::CastAndCallMethod(const Condition *c) {
diff --git a/absl/synchronization/mutex_test.cc b/absl/synchronization/mutex_test.cc
index 16fc9058..66d5f2aa 100644
--- a/absl/synchronization/mutex_test.cc
+++ b/absl/synchronization/mutex_test.cc
@@ -1002,9 +1002,6 @@ TEST(Mutex, AcquireFromCondition) {
   x.mu0.Unlock();
 }
 
-// The deadlock detector is not part of non-prod builds, so do not test it.
-#if !defined(ABSL_INTERNAL_USE_NONPROD_MUTEX)
-
 TEST(Mutex, DeadlockDetector) {
   absl::SetMutexDeadlockDetectionMode(absl::OnDeadlockCycle::kAbort);
 
@@ -1158,7 +1155,6 @@ TEST(Mutex, DeadlockIdBug) ABSL_NO_THREAD_SAFETY_ANALYSIS {
   c.Lock();
   c.Unlock();
 }
-#endif  // !defined(ABSL_INTERNAL_USE_NONPROD_MUTEX)
 
 // --------------------------------------------------------
 // Test for timeouts/deadlines on condition waits that are specified using
-- 
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