Export of internal Abseil changes.

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5dc8d7504b7c11710b19365a6582c288c8992366 by Derek Mauro <dmauro@google.com>:

Fix constexpr Span::last under MSVC and add Span constexpr tests.

PiperOrigin-RevId: 237515952

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5ea8c146e653bbc49ff7e698699478242df7de35 by Derek Mauro <dmauro@google.com>:

Implement Span::first and Span::last from C++20.
https://github.com/abseil/abseil-cpp/pull/274

PiperOrigin-RevId: 237494399

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08db3417f1d8fe4556255d57a2f0df51b09bdd9a by Derek Mauro <dmauro@google.com>:

HTTPS in more URLs.

PiperOrigin-RevId: 237486823

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83ec63a7f8e47b62af619546f9f7b3bf72e74e86 by Derek Mauro <dmauro@google.com>:

Changed HTTP URLs to HTTPS where possible.
https://github.com/abseil/abseil-cpp/pull/270

PiperOrigin-RevId: 237445310

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220bf279c14cb31efa239500d1a70e0ac0c32e3c by Abseil Team <absl-team@google.com>:

Support parsing decltype(nullptr) as a type.

PiperOrigin-RevId: 237336739

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ced234bbe78f5d495c3f6f6a9c2e0a95f7c080a5 by Gennadiy Rozental <rogeeff@google.com>:

Introduce internal interface for setting environment variable value in scope

PiperOrigin-RevId: 237275806

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1f1acb4e294af24d9f7598e85163d5e1d9958ae9 by Samuel Benzaquen <sbenza@google.com>:

Avoid using aliases in the SFINAE expressions to make it more compatible with MSVC.
Turn on the tests in MSVC.

PiperOrigin-RevId: 237261456

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06cf7de6250a0572ef90fa1176f742ca0451ce71 by Derek Mauro <dmauro@google.com>:

Fix unused variable warning.

PiperOrigin-RevId: 237108006
GitOrigin-RevId: 5dc8d7504b7c11710b19365a6582c288c8992366
Change-Id: Ife5182c80942945c4e8700844c8febb482d6ad82

1 files changed, 9 insertions, 13 deletions

diff --git a/absl/hash/hash_test.cc b/absl/hash/hash_test.cc
index d9ebd30f69c4..a2430e7a653d 100644
--- a/absl/hash/hash_test.cc
+++ b/absl/hash/hash_test.cc
@@ -165,9 +165,6 @@ TEST(HashValueTest, PointerAlignment) {
   }
 }
 
-// TODO(EricWF): MSVC 15 has a bug that causes it to incorrectly evaluate the
-// SFINAE in internal/hash.h, causing this test to fail.
-#if !defined(_MSC_VER)
 TEST(HashValueTest, PairAndTuple) {
   EXPECT_TRUE((is_hashable<std::pair<int, int>>::value));
   EXPECT_TRUE((is_hashable<std::pair<const int&, const int&>>::value));
@@ -196,7 +193,6 @@ TEST(HashValueTest, PairAndTuple) {
       std::forward_as_tuple(42, 0, 0), std::forward_as_tuple(3, 9, 9),
       std::forward_as_tuple(0, 0, -42))));
 }
-#endif  // !defined(_MSC_VER)
 
 TEST(HashValueTest, CombineContiguousWorks) {
   std::vector<std::tuple<int>> v1 = {std::make_tuple(1), std::make_tuple(3)};
@@ -304,16 +300,12 @@ TEST(HashValueTest, Strings) {
             SpyHash(absl::string_view("ABC")));
 }
 
-// TODO(EricWF): MSVC 15 has a bug that causes it to incorrectly evaluate the
-// SFINAE in internal/hash.h, causing this test to fail.
-#if !defined(_MSC_VER)
 TEST(HashValueTest, StdArray) {
   EXPECT_TRUE((is_hashable<std::array<int, 3>>::value));
 
   EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly(
       std::make_tuple(std::array<int, 3>{}, std::array<int, 3>{{0, 23, 42}})));
 }
-#endif  // !defined(_MSC_VER)
 
 TEST(HashValueTest, StdBitset) {
   EXPECT_TRUE((is_hashable<std::bitset<257>>::value));
@@ -414,9 +406,6 @@ TEST(HashValueTest, Variant) {
 #endif
 }
 
-// TODO(EricWF): MSVC 15 has a bug that causes it to incorrectly evaluate the
-// SFINAE in internal/hash.h, causing this test to fail.
-#if !defined(_MSC_VER)
 TEST(HashValueTest, Maps) {
   EXPECT_TRUE((is_hashable<std::map<int, std::string>>::value));
 
@@ -433,7 +422,6 @@ TEST(HashValueTest, Maps) {
       MM{{0, "foo"}, {42, "bar"}}, MM{{1, "foo"}, {42, "bar"}},
       MM{{1, "foo"}, {1, "foo"}, {43, "bar"}}, MM{{1, "foo"}, {43, "baz"}})));
 }
-#endif  // !defined(_MSC_VER)
 
 template <typename T, typename = void>
 struct IsHashCallble : std::false_type {};
@@ -511,8 +499,16 @@ struct CombineVariadic {
                              Int(4));
   }
 };
+enum class InvokeTag {
+  kUniquelyRepresented,
+  kHashValue,
+#if ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
+  kLegacyHash,
+#endif  // ABSL_HASH_INTERNAL_SUPPORT_LEGACY_HASH_
+  kStdHash,
+  kNone
+};
 
-using InvokeTag = absl::hash_internal::InvokeHashTag;
 template <InvokeTag T>
 using InvokeTagConstant = std::integral_constant<InvokeTag, T>;