Export of internal Abseil changes.

--
6fdf24a197b964f9bacbebd0ceca305aef1654fc by Shaindel Schwartz <shaindel@google.com>:

Internal change

PiperOrigin-RevId: 231627312

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65f7faf52bff01384171efb85fee159378dedf70 by CJ Johnson <johnsoncj@google.com>:

Relocates the definitions of the InputIterator-accepting parts of the InlinedVector API into the top-level. The removed functions had no other callers so there was no reason to keep the layer of indirection in the form of the function call.

PiperOrigin-RevId: 231527459

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30e105b749b5ecc50fdaf26c7da589617efce425 by CJ Johnson <johnsoncj@google.com>:

Relocates closing brace for absl namespace in InlinedVector to the correct end location

PiperOrigin-RevId: 231477871

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063c1e8b9d1f032662c46d574e20ecc357b87d0c by Eric Fiselier <ericwf@google.com>:

Cleanup std::hash probing metafunctions.

Previously there were two different ways to probe for
std::hash. One in hash.h and another in type_traits.h,
and they were both implemented differently, and neither
correctly worked around bad STL implementations.

This patch unifies the implementations into a single IsHashable trait.
It also:

* Correctly checks for old libc++ versions where this won't work.
* Avoids undefined behavior which resulted from calling std::is_constructible
  incomplete types.
* Unifies the feature test macro used in the headers and the tests.

Additionally it also slightly changes the behavior of when absl::variant
is hashable. Previously we disable hashing when std::hash<T>()(key) was
formed but when std::hash<T> couldn't be destructed. This seems wrong. If a
user provides a evil specialization of std::hash, then it's OK for variant's
hash to blow up.

PiperOrigin-RevId: 231468345

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05d75dd4b07c893de9b104731644d0d207b01253 by Abseil Team <absl-team@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 231397518

--
a0ee9032f9e04039f3410ed17fcf45ae1a3868f5 by CJ Johnson <johnsoncj@google.com>:

Remove unused EnableIfAtLeastInputIterator from InlinedVector

PiperOrigin-RevId: 231348903

--
4dcd4e9a6780a81d7a6974c7bf22a037e6482b49 by Abseil Team <absl-team@google.com>:

Remove unnecessary register keyword from absl/base/internal/endian.h.

PiperOrigin-RevId: 231316570

--
c8584836caa3a10f90a8604a85d4b831310b72ee by Abseil Team <absl-team@google.com>:

Fix hashtablez_sampler compilation on older Android NDK builds

PiperOrigin-RevId: 231283542
GitOrigin-RevId: 6fdf24a197b964f9bacbebd0ceca305aef1654fc
Change-Id: I185b12fb8347e3ad0ffcb2cbb83a53450e5eb938

2 files changed, 3 insertions, 18 deletions

diff --git a/absl/hash/internal/hash.h b/absl/hash/internal/hash.h
index 6c00f35413d1..ba6d7468e1b8 100644
--- a/absl/hash/internal/hash.h
+++ b/absl/hash/internal/hash.h
@@ -541,17 +541,8 @@ hash_range_or_bytes(H hash_state, const T* data, size_t size) {
 //   * If is_uniquely_represented, hash bytes directly.
 //   * ADL AbslHashValue(H, const T&) call.
 //   * std::hash<T>
-
-// In MSVC we can't probe std::hash or stdext::hash because it triggers a
-// static_assert instead of failing substitution.
-#if defined(_MSC_VER)
-#define ABSL_HASH_INTERNAL_CAN_POISON_ 0
-#else   // _MSC_VER
-#define ABSL_HASH_INTERNAL_CAN_POISON_ 1
-#endif  // _MSC_VER
-
 #if defined(ABSL_INTERNAL_LEGACY_HASH_NAMESPACE) && \
-    ABSL_HASH_INTERNAL_CAN_POISON_
+    ABSL_META_INTERNAL_STD_HASH_SFINAE_FRIENDLY_
 #define ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_ 1
 #else
 #define ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_ 0
@@ -616,13 +607,7 @@ struct HashSelect {
 #endif  // ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
 
   template <typename U>
-  using ProbeStdHash =
-#if ABSL_HASH_INTERNAL_CAN_POISON_
-      std::is_convertible<decltype(std::hash<U>()(std::declval<const U&>())),
-                          size_t>;
-#else   // ABSL_HASH_INTERNAL_CAN_POISON_
-      std::true_type;
-#endif  // ABSL_HASH_INTERNAL_CAN_POISON_
+  using ProbeStdHash = absl::type_traits_internal::IsHashable<U>;
 
   template <typename U>
   using ProbeNone = std::true_type;
diff --git a/absl/hash/internal/spy_hash_state.h b/absl/hash/internal/spy_hash_state.h
index 03d795b09001..e7d1dfef37ee 100644
--- a/absl/hash/internal/spy_hash_state.h
+++ b/absl/hash/internal/spy_hash_state.h
@@ -200,7 +200,7 @@ bool RunOnStartup<f>::run = (f(), true);
 template <
     typename T, typename U,
     // Only trigger for when (T != U),
-    absl::enable_if_t<!std::is_same<T, U>::value, int> = 0,
+    typename = absl::enable_if_t<!std::is_same<T, U>::value>,
     // This statement works in two ways:
     //  - First, it instantiates RunOnStartup and forces the initialization of
     //    `run`, which set the global variable.