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

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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

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

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

PiperOrigin-RevId: 285036610

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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

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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

4 files changed, 8 insertions, 0 deletions

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_