Export of internal Abseil changes

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44b312da54263fc7491b5f1e115e49e0c1e2dc10 by Greg Falcon <gfalcon@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 315782632

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27618a3b195f75384ba44e9712ae0b0b7d85937e by Greg Falcon <gfalcon@google.com>:

Update Abseil's internal Invoke() implementation to follow C++17 semantics.

Starting in C++17, when invoke'ing a pointer-to-member, if the object representing the class is a reference_wrapper, that wrapper is unpacked.  Because we implement a number of functional APIs that closely match C++ standard proposals, it is better if we follow the standard's notion of what "invoking" means.

This also makes `absl::base_internal::Invoke()` match `std::invoke()` in C++17.  I intend to make this an alias in a follow-up CL.

PiperOrigin-RevId: 315750659

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059519ea402cd55b1b716403bb680504c6ff5808 by Xiaoyi Zhang <zhangxy@google.com>:

Internal change

PiperOrigin-RevId: 315597064

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5e2042c8520576b2508e2bfb1020a97c7db591da by Titus Winters <titus@google.com>:

Update notes on the delta between absl::Span vs. std::span.

PiperOrigin-RevId: 315518942

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9d3875527b93124f5de5d6a1d575c42199fbf323 by Abseil Team <absl-team@google.com>:

Internal cleanup

PiperOrigin-RevId: 315497633
GitOrigin-RevId: 44b312da54263fc7491b5f1e115e49e0c1e2dc10
Change-Id: I24573f317c8388bd693c0fdab395a7dd419b33b0

1 files changed, 19 insertions, 0 deletions

diff --git a/absl/functional/bind_front_test.cc b/absl/functional/bind_front_test.cc
index 4801a81c..92b6e8e5 100644
--- a/absl/functional/bind_front_test.cc
+++ b/absl/functional/bind_front_test.cc
@@ -228,4 +228,23 @@ TEST(BindTest, Mangling) {
   absl::bind_front(ManglingCall{}, 1, 3.3)("A");
 }
 
+struct Adder {
+  int add(int v2) const { return v + v2; }
+  int v;
+};
+
+TEST(BindTest, InvokeSemantics) {
+  Struct s1 = {"value"};
+  auto f1 = absl::bind_front(&Struct::value);
+  EXPECT_EQ(f1(s1), "value");
+  EXPECT_EQ(f1(&s1), "value");
+  EXPECT_EQ(f1(std::ref(s1)), "value");
+
+  Adder add_100 = {100};
+  auto f2 = absl::bind_front(&Adder::add);
+  EXPECT_EQ(f2(add_100, 23), 123);
+  EXPECT_EQ(f2(&add_100, 45), 145);
+  EXPECT_EQ(f2(std::ref(add_100), 67), 167);
+}
+
 }  // namespace