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

66 files changed, 162 insertions, 8 deletions

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_