Export of internal Abseil changes

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9c9eb300c95024ea4242bbb4835595f555cb1eed by Derek Mauro <dmauro@google.com>:

Sync string_view comments from the internal copy

PiperOrigin-RevId: 328582796

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c0bc4e77a46889430a1a40d836a5ff426a4a5bc9 by Xiaoyi Zhang <zhangxy@google.com>:

Make `absl::allocator_traits` an alias to `std::allocator_traits` for C++17 or
above. `std::allocator_traits` should have all its members since C++17 so we
don't need a backport.

PiperOrigin-RevId: 328258154

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5599a3c0f2d865128057b5e267a397011cd032d0 by Derek Mauro <dmauro@google.com>:

Fix an #endif comment

Reported at https://groups.google.com/g/abseil-io/c/GRUdB0bBrG8/m/852HrgchCQAJ

PiperOrigin-RevId: 328247093

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abd7e98088267f436e6c10779e574153ece015be by Abseil Team <absl-team@google.com>:

Don't call win32 APIs for UWP builds

symbolize.cc is including symbolize_win32.inc for all Windows builds,
including UWP builds. However, UWP doesn't have access to win32 APIs, so
it should instead include symbolize_unimplemented.inc.

This allows the necessary functions to still exist and be called, but
the win32 calls are not made.

This is part of the effort to enable Abseil in ANGLE:
https://anglebug.com/4873

PiperOrigin-RevId: 328226766

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f622d3dfb804a6f427c1fd86ee69f47785b49483 by Greg Falcon <gfalcon@google.com>:

Remove incorrect claims of HASH_NAMESPACE support in Abseil hash.

The documentation presently claims that absl::Hash will look for legacy hashers (e.g, in the __gnu_cxx namespace) as controlled by the HASH_NAMESPACE preprocessor define, but this has never been true.

(Vestigial support for this appears in the form `ABSL_INTERNAL_LEGACY_HASH_NAMESPACE`, but this is not a supported extension point, as indicated by the use of `INTERNAL` in the name.)

PiperOrigin-RevId: 328154123

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32b40a25efe1f7f7da98ce8faf3482c825464ed4 by Abseil Team <absl-team@google.com>:

Switch ABSL_INTERNAL_IGNORE_READS_ATTRIBUTE_ENABLED checks to defined().

PiperOrigin-RevId: 328151556
GitOrigin-RevId: 9c9eb300c95024ea4242bbb4835595f555cb1eed
Change-Id: Ib0686286f7889a976311e8cd2b35655765a8d033

2 files changed, 5 insertions, 1 deletions

diff --git a/absl/memory/memory.h b/absl/memory/memory.h
index 513f7103..2b5ff623 100644
--- a/absl/memory/memory.h
+++ b/absl/memory/memory.h
@@ -420,6 +420,9 @@ struct pointer_traits<T*> {
 //
 // A C++11 compatible implementation of C++17's std::allocator_traits.
 //
+#if __cplusplus >= 201703L
+using std::allocator_traits;
+#else  // __cplusplus >= 201703L
 template <typename Alloc>
 struct allocator_traits {
   using allocator_type = Alloc;
@@ -609,6 +612,7 @@ struct allocator_traits {
     return a;
   }
 };
+#endif  // __cplusplus >= 201703L
 
 namespace memory_internal {
 
diff --git a/absl/memory/memory_test.cc b/absl/memory/memory_test.cc
index 0d2e13bd..1990c7ba 100644
--- a/absl/memory/memory_test.cc
+++ b/absl/memory/memory_test.cc
@@ -555,7 +555,7 @@ TEST(AllocatorTraits, FunctionsMinimal) {
   EXPECT_CALL(mock, deallocate(&x, 7));
 
   EXPECT_EQ(&x, Traits::allocate(mock, 7));
-  Traits::allocate(mock, 7, static_cast<const void*>(&hint));
+  static_cast<void>(Traits::allocate(mock, 7, static_cast<const void*>(&hint)));
   EXPECT_EQ(&x, Traits::allocate(mock, 7, static_cast<const void*>(&hint)));
   Traits::deallocate(mock, &x, 7);