Export of internal Abseil changes.

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

Internal change

PiperOrigin-RevId: 231627312

--
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

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

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

PiperOrigin-RevId: 231477871

--
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

--
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

4 files changed, 25 insertions, 35 deletions

diff --git a/absl/types/internal/variant.h b/absl/types/internal/variant.h
index 477e5895ed73..a0ab1e8fdb26 100644
--- a/absl/types/internal/variant.h
+++ b/absl/types/internal/variant.h
@@ -1605,11 +1605,12 @@ struct VariantHashVisitor {
 template <typename Variant, typename... Ts>
 struct VariantHashBase<Variant,
                        absl::enable_if_t<absl::conjunction<
-                           type_traits_internal::IsHashEnabled<Ts>...>::value>,
+                           type_traits_internal::IsHashable<Ts>...>::value>,
                        Ts...> {
   using argument_type = Variant;
   using result_type = size_t;
   size_t operator()(const Variant& var) const {
+    type_traits_internal::AssertHashEnabled<Ts...>();
     if (var.valueless_by_exception()) {
       return 239799884;
     }
diff --git a/absl/types/optional.h b/absl/types/optional.h
index 7677fe52c0e5..fd185f353f3e 100644
--- a/absl/types/optional.h
+++ b/absl/types/optional.h
@@ -467,6 +467,7 @@ struct optional_hash_base<T, decltype(std::hash<absl::remove_const_t<T> >()(
   using argument_type = absl::optional<T>;
   using result_type = size_t;
   size_t operator()(const absl::optional<T>& opt) const {
+    absl::type_traits_internal::AssertHashEnabled<absl::remove_const_t<T>>();
     if (opt) {
       return std::hash<absl::remove_const_t<T> >()(*opt);
     } else {
diff --git a/absl/types/optional_test.cc b/absl/types/optional_test.cc
index fc4f00a4f52f..bedf5b0e043e 100644
--- a/absl/types/optional_test.cc
+++ b/absl/types/optional_test.cc
@@ -1504,18 +1504,19 @@ TEST(optionalTest, Hash) {
 
   static_assert(is_hash_enabled_for<absl::optional<int>>::value, "");
   static_assert(is_hash_enabled_for<absl::optional<Hashable>>::value, "");
+  static_assert(
+      absl::type_traits_internal::IsHashable<absl::optional<int>>::value, "");
+  static_assert(
+      absl::type_traits_internal::IsHashable<absl::optional<Hashable>>::value,
+      "");
+  absl::type_traits_internal::AssertHashEnabled<absl::optional<int>>();
+  absl::type_traits_internal::AssertHashEnabled<absl::optional<Hashable>>();
 
-#if defined(_MSC_VER) || (defined(_LIBCPP_VERSION) && \
-                          _LIBCPP_VERSION < 4000 && _LIBCPP_STD_VER > 11)
-  // For MSVC and libc++ (< 4.0 and c++14), std::hash primary template has a
-  // static_assert to catch any user-defined type that doesn't provide a hash
-  // specialization. So instantiating std::hash<absl::optional<T>> will result
-  // in a hard error which is not SFINAE friendly.
-#define ABSL_STD_HASH_NOT_SFINAE_FRIENDLY 1
-#endif
-
-#ifndef ABSL_STD_HASH_NOT_SFINAE_FRIENDLY
+#if ABSL_META_INTERNAL_STD_HASH_SFINAE_FRIENDLY_
   static_assert(!is_hash_enabled_for<absl::optional<NonHashable>>::value, "");
+  static_assert(!absl::type_traits_internal::IsHashable<
+                    absl::optional<NonHashable>>::value,
+                "");
 #endif
 
   // libstdc++ std::optional is missing remove_const_t, i.e. it's using
diff --git a/absl/types/variant_test.cc b/absl/types/variant_test.cc
index 80e8467e1f14..463d775a85fe 100644
--- a/absl/types/variant_test.cc
+++ b/absl/types/variant_test.cc
@@ -1977,29 +1977,17 @@ TEST(VariantTest, MonostateHash) {
 }
 
 TEST(VariantTest, Hash) {
-  static_assert(type_traits_internal::IsHashEnabled<variant<int>>::value, "");
-  static_assert(type_traits_internal::IsHashEnabled<variant<Hashable>>::value,
+  static_assert(type_traits_internal::IsHashable<variant<int>>::value, "");
+  static_assert(type_traits_internal::IsHashable<variant<Hashable>>::value, "");
+  static_assert(type_traits_internal::IsHashable<variant<int, Hashable>>::value,
                 "");
-  static_assert(
-      type_traits_internal::IsHashEnabled<variant<int, Hashable>>::value, "");
-
-#if defined(_MSC_VER) ||                                   \
-    (defined(_LIBCPP_VERSION) && _LIBCPP_VERSION < 4000 && \
-     _LIBCPP_STD_VER > 11) ||                              \
-    defined(__APPLE__)
-  // For MSVC and libc++ (< 4.0 and c++14), std::hash primary template has a
-  // static_assert to catch any user-defined type T that doesn't provide a hash
-  // specialization. So instantiating std::hash<variant<T>> will result
-  // in a hard error which is not SFINAE friendly.
-#define ABSL_STD_HASH_NOT_SFINAE_FRIENDLY 1
-#endif
 
-#ifndef ABSL_STD_HASH_NOT_SFINAE_FRIENDLY
-  static_assert(
-      !type_traits_internal::IsHashEnabled<variant<NonHashable>>::value, "");
-  static_assert(!type_traits_internal::IsHashEnabled<
-                    variant<Hashable, NonHashable>>::value,
+#if ABSL_META_INTERNAL_STD_HASH_SFINAE_FRIENDLY_
+  static_assert(!type_traits_internal::IsHashable<variant<NonHashable>>::value,
                 "");
+  static_assert(
+      !type_traits_internal::IsHashable<variant<Hashable, NonHashable>>::value,
+      "");
 #endif
 
 // MSVC std::hash<std::variant> does not use the index, thus produce the same
@@ -2023,11 +2011,10 @@ TEST(VariantTest, Hash) {
     EXPECT_GT(hashcodes.size(), 90);
 
     // test const-qualified
+    static_assert(type_traits_internal::IsHashable<variant<const int>>::value,
+                  "");
     static_assert(
-        type_traits_internal::IsHashEnabled<variant<const int>>::value, "");
-    static_assert(
-        type_traits_internal::IsHashEnabled<variant<const Hashable>>::value,
-        "");
+        type_traits_internal::IsHashable<variant<const Hashable>>::value, "");
     std::hash<absl::variant<const int>> c_hash;
     for (int i = 0; i < 100; ++i) {
       EXPECT_EQ(hash(i), c_hash(i));