Export of internal Abseil changes

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7f6c15aadc4d97e217dd446518dbb4fdc86b36a3 by Derek Mauro <dmauro@google.com>:

Upgrade GCC automated testing to use GCC 9.2 and Cmake 3.16.2

PiperOrigin-RevId: 288488783

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a978cee848d3cf65b0826c981bfd81022fc36660 by Abseil Team <absl-team@google.com>:

Removing formatting traits that were only used internally. ON_CALL/EXPECT_CALL do a sufficient job here.

PiperOrigin-RevId: 288386509

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fdec6f40293d5883220f1f0ea1261f7c5b60a66e by Derek Mauro <dmauro@google.com>:

Upgrade MacOS tests to use Bazel 2.0.0

PiperOrigin-RevId: 288373298

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465865c4123e9481ab50ea0527e92b39519704dd by Derek Mauro <dmauro@google.com>:

Changes to support GCC 9
 * Fix several -Wredundant-move warnings
 * Remove FlatHashMap.Any test, which basically doesn't work on any platform
   any more (see https://cplusplus.github.io/LWG/lwg-active.html#3121)
 * Fix a constant sign-compare warning
 * Conditionally compile out the PoisonHash test which doesn't build

PiperOrigin-RevId: 288360204

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57c4bb07fc58e7dd2a04f3c45027aab5ecaccf25 by Andy Soffer <asoffer@google.com>:

Deflaking MockingBitGen test. Because MockingBitGen can return random values,
it is inherently flaky. For log-unifrom, 2040 is a common enough value that
tests failed unreasonably frequently. Replacing it with a significantly larger
value so as to be much less common. 50000 is a good choice because it is (tied for) the least likely to occur randomly from this distribution, but is still in the distribution.

PiperOrigin-RevId: 288360112

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86f38e4109899d972de353b1c556c018cfe37956 by Matt Calabrese <calabrese@google.com>:

Remove construction tests for the internal `CompressedTuple<std::any>` instantiation. This was not guaranteed to work for the reasons that `std::tuple<std::any>` copy construction does not actually work by standard specification (some implementations introduce workarounds for this). In GCC9, `CompressedTuple<std::any>` and `std::tuple<std::any>` both fail for the same reasons, and a proper "fix" requires updating `std::any`, which is out of our control.

PiperOrigin-RevId: 288351977
GitOrigin-RevId: 7f6c15aadc4d97e217dd446518dbb4fdc86b36a3
Change-Id: I5d5c62bd297dc0ff1f2970ff076bb5cd088a7e4c

absl/hash/hash_test.cc

@@ -460,7 +460,7 @@ struct DummyFooBar {
     const char* bar = "bar";
     h = H::combine_contiguous(std::move(h), foo, 3);
     h = H::combine_contiguous(std::move(h), bar, 3);
-    return std::move(h);
+    return h;
   }
 };
 
@@ -595,7 +595,10 @@ TEST(IsHashableTest, PoisonHash) {
   EXPECT_FALSE(absl::is_copy_assignable<absl::Hash<X>>::value);
   EXPECT_FALSE(absl::is_move_assignable<absl::Hash<X>>::value);
   EXPECT_FALSE(IsHashCallable<X>::value);
+#if !defined(__GNUC__) || __GNUC__ < 9
+  // This doesn't compile on GCC 9.
   EXPECT_FALSE(IsAggregateInitializable<absl::Hash<X>>::value);
+#endif
 }
 #endif  // ABSL_META_INTERNAL_STD_HASH_SFINAE_FRIENDLY_
 

absl/hash/internal/hash.h

@@ -57,7 +57,7 @@ class PiecewiseCombiner;
 
 // Internal detail: Large buffers are hashed in smaller chunks.  This function
 // returns the size of these chunks.
-constexpr int PiecewiseChunkSize() { return 1024; }
+constexpr size_t PiecewiseChunkSize() { return 1024; }
 
 // HashStateBase
 //
@@ -951,7 +951,7 @@ H PiecewiseCombiner::add_buffer(H state, const unsigned char* data,
     // This partial chunk does not fill our existing buffer
     memcpy(buf_ + position_, data, size);
     position_ += size;
-    return std::move(state);
+    return state;
   }
 
   // Complete the buffer and hash it
@@ -970,7 +970,7 @@ H PiecewiseCombiner::add_buffer(H state, const unsigned char* data,
   // Fill the buffer with the remainder
   memcpy(buf_, data, size);
   position_ = size;
-  return std::move(state);
+  return state;
 }
 
 // HashStateBase::PiecewiseCombiner::finalize()