Export of internal Abseil changes

--
430bda42820b619b346201bc42769d014228e825 by Gennadiy Rozental <rogeeff@google.com>:

Update version for CMake and Bazel

PiperOrigin-RevId: 336089889

--
0a36f989acb0e6f7d2f04039c600b0934c44ffed by Abseil Team <absl-team@google.com>:

changes how non-equality is evaluated

absl::c_mismatch is based on std::mismatch, which requires that its
iterators' reference types meet the requirements of
Cpp17EqualityComparable[1]. The previous CL mistakenly wrote
absl::c_mismatch using `*first1 != *first2` which assumes that the
reference types model std::equality_comparable[2] (which was only added
in C++20).

This CL reverts that behaviour.

[0]: http://wg21.link/mismatch
[1]: http://wg21.link/utility.arg.requirements#tab:cpp17.equalitycomparable
[2]: http://wg21.link/concept.equalitycomparable

PiperOrigin-RevId: 335897465

--
7cb902f079838081a15f8b72e0cef46beab653f2 by Derek Mauro <dmauro@google.com>:

Disable a raw_hash_map_allocator.cc test that doesn't build
due to a noexcept bug in gcc 5.4 and 5.5

PiperOrigin-RevId: 335876843
GitOrigin-RevId: 430bda42820b619b346201bc42769d014228e825
Change-Id: I94d5b8e03e0a91d81923aa831f6f63c625e0b836

3 files changed, 18 insertions, 1 deletions

diff --git a/absl/algorithm/container.h b/absl/algorithm/container.h
index 3c4fd733..bb3d1c7c 100644
--- a/absl/algorithm/container.h
+++ b/absl/algorithm/container.h
@@ -351,7 +351,9 @@ c_mismatch(C1& c1, C2& c2) {
   auto last2 = container_algorithm_internal::c_end(c2);
 
   for (; first1 != last1 && first2 != last2; ++first1, (void)++first2) {
-    if (*first1 != *first2) {
+    // Negates equality because Cpp17EqualityComparable doesn't require clients
+    // to overload both `operator==` and `operator!=`.
+    if (!(*first1 == *first2)) {
       break;
     }
   }
diff --git a/absl/algorithm/container_test.cc b/absl/algorithm/container_test.cc
index fb940560..605afc80 100644
--- a/absl/algorithm/container_test.cc
+++ b/absl/algorithm/container_test.cc
@@ -183,6 +183,17 @@ TEST_F(NonMutatingTest, Mismatch) {
     EXPECT_EQ(result.first, sequence_.end());
     EXPECT_EQ(result.second, std::prev(vector_.end()));
   }
+  {
+    struct NoNotEquals {
+      constexpr bool operator==(NoNotEquals) const { return true; }
+      constexpr bool operator!=(NoNotEquals) const = delete;
+    };
+    std::vector<NoNotEquals> first;
+    std::list<NoNotEquals> second;
+
+    // Check this still compiles.
+    absl::c_mismatch(first, second);
+  }
 }
 
 TEST_F(NonMutatingTest, MismatchWithPredicate) {
diff --git a/absl/container/internal/raw_hash_set_allocator_test.cc b/absl/container/internal/raw_hash_set_allocator_test.cc
index 1a036085..e73f53fd 100644
--- a/absl/container/internal/raw_hash_set_allocator_test.cc
+++ b/absl/container/internal/raw_hash_set_allocator_test.cc
@@ -466,6 +466,9 @@ class PAlloc {
   size_t id_ = std::numeric_limits<size_t>::max();
 };
 
+// This doesn't compile with GCC 5.4 and 5.5 due to a bug in noexcept handing.
+#if !defined(__GNUC__) || __GNUC__ != 5 || (__GNUC_MINOR__ != 4 && \
+    __GNUC_MINOR__ != 5)
 TEST(NoPropagateOn, Swap) {
   using PA = PAlloc<char>;
   using Table = raw_hash_set<Policy, Identity, std::equal_to<int32_t>, PA>;
@@ -475,6 +478,7 @@ TEST(NoPropagateOn, Swap) {
   EXPECT_EQ(t1.get_allocator(), PA(1));
   EXPECT_EQ(t2.get_allocator(), PA(2));
 }
+#endif
 
 TEST(NoPropagateOn, CopyConstruct) {
   using PA = PAlloc<char>;