Export of internal Abseil changes.

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5755b40f6025f3ca126070fc68adb8fde9a7f01b by Abseil Team <absl-team@google.com>:

Fix -Wextra-semi error.

PiperOrigin-RevId: 243215850

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3b6b6e18df9fbd233943cae460f0063f4efaa7c7 by Eric Fiselier <ericwf@google.com>:

Internal Change.

PiperOrigin-RevId: 243152671

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82eef03f246009c806c25607c5682547cb4ad21e by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 243151861

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c14e6340fca7070634e0ecfdf97833d930dd0e5d by Samuel Benzaquen <sbenza@google.com>:

Internal change

PiperOrigin-RevId: 243123590

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9abb7a6b22457c0aa72d72b3b9392efd226d302a by Andy Getzendanner <durandal@google.com>:

Implement operator<<(std::ostream &, absl::LogSeverity) so that absl::LogSeverity values can be streamed.

PiperOrigin-RevId: 243117646
GitOrigin-RevId: 5755b40f6025f3ca126070fc68adb8fde9a7f01b
Change-Id: I7ea607d8a4e803ad15a3090139271f58ad4173a3

1 files changed, 43 insertions, 0 deletions

diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h
index fbdc921f..a8068e31 100644
--- a/absl/meta/type_traits.h
+++ b/absl/meta/type_traits.h
@@ -341,6 +341,49 @@ struct is_trivially_copy_assignable
 #endif  // ABSL_HAVE_STD_IS_TRIVIALLY_ASSIGNABLE
 };
 
+namespace type_traits_internal {
+// is_trivially_copyable()
+//
+// Determines whether the passed type `T` is trivially copyable.
+//
+// This metafunction is designed to be a drop-in replacement for the C++11
+// `std::is_trivially_copyable()` metafunction for platforms that have
+// incomplete C++11 support (such as libstdc++ 4.x). We use the C++17 definition
+// of TriviallyCopyable.
+//
+// NOTE: `is_trivially_copyable<T>::value` is `true` if all of T's copy/move
+// constructors/assignment operators are trivial or deleted, T has at least
+// one non-deleted copy/move constructor/assignment operator, and T is trivially
+// destructible. Arrays of trivially copyable types are trivially copyable.
+//
+// We expose this metafunction only for internal use within absl.
+template <typename T>
+class is_trivially_copyable_impl {
+  using ExtentsRemoved = typename std::remove_all_extents<T>::type;
+  static constexpr bool kIsCopyOrMoveConstructible =
+      std::is_copy_constructible<ExtentsRemoved>::value ||
+      std::is_move_constructible<ExtentsRemoved>::value;
+  static constexpr bool kIsCopyOrMoveAssignable =
+      absl::is_copy_assignable<ExtentsRemoved>::value ||
+      absl::is_move_assignable<ExtentsRemoved>::value;
+
+ public:
+  static constexpr bool kValue =
+      (__has_trivial_copy(ExtentsRemoved) || !kIsCopyOrMoveConstructible) &&
+      (__has_trivial_assign(ExtentsRemoved) || !kIsCopyOrMoveAssignable) &&
+      (kIsCopyOrMoveConstructible || kIsCopyOrMoveAssignable) &&
+      is_trivially_destructible<ExtentsRemoved>::value &&
+      // We need to check for this explicitly because otherwise we'll say
+      // references are trivial copyable when compiled by MSVC.
+      !std::is_reference<ExtentsRemoved>::value;
+};
+
+template <typename T>
+struct is_trivially_copyable
+    : std::integral_constant<
+          bool, type_traits_internal::is_trivially_copyable_impl<T>::kValue> {};
+}  // namespace type_traits_internal
+
 // -----------------------------------------------------------------------------
 // C++14 "_t" trait aliases
 // -----------------------------------------------------------------------------