Export of internal Abseil changes

--
5f3c139695d5c497ca030e95a607537a7be7caa7 by Benjamin Barenblat <bbaren@google.com>:

Don’t examine irrelevant destination buckets in DiscreteDistributionTest

Abseil generates discrete distributions using Walker’s aliasing
algorithm. This creates uniformly distributed buckets, each with a
probability of sending traffic to a different bucket. Abseil represents
a bucket as a pair

    (probability of retaining traffic ×
     alternate bucket if traffic is passed)

and a distribution as a vector of such pairs. For example, {(0.3, 1),
(1.0, 1)} represents a distribution with two buckets, the zeroth of
which passes 70% of its traffic to bucket 1 and the first of which holds
on to all its traffic.

This representation is not unique: When a bucket retains traffic with
probability 1, the alternate bucket is irrelevant. Continuing the
example above, {(0.3, 1), (1.0, 0)} _also_ represents a two-bucket
distribution where the zeroth bucket passes 70% of its traffic to the
first and the first hangs on to all traffic. Exactly what representation
Abseil generates for a given input is related to how much precision is
used in intermediate floating-point operations, which is an
architectural implementation detail. Remove sensitivity to that detail
by not examining the alternate bucket when the retention probability is
1.0.

PiperOrigin-RevId: 372993410

--
062ac80699f748831c09a061538abffec2cdea5c by Martijn Vels <mvels@google.com>:

Avoid alredy sampled cord remaining sampled if not picked or source is sampled

PiperOrigin-RevId: 372985990

--
a9f3537e1110b7bb6450fd72a03f0c5dc6b8c89b by Evan Brown <ezb@google.com>:

Add tests for function pointer comparators, comparators that have SFINAE-visible comparison operators that are unimplemented, and for implicit construction from unadapted comparators.

PiperOrigin-RevId: 372927616
GitOrigin-RevId: 5f3c139695d5c497ca030e95a607537a7be7caa7
Change-Id: I996a8452e7bd88f9dd2e59633b01bbc09f42620d

1 files changed, 4 insertions, 3 deletions

diff --git a/absl/random/discrete_distribution_test.cc b/absl/random/discrete_distribution_test.cc
index 6d007006..415b14cc 100644
--- a/absl/random/discrete_distribution_test.cc
+++ b/absl/random/discrete_distribution_test.cc
@@ -99,6 +99,7 @@ TYPED_TEST(DiscreteDistributionTypeTest, Constructor) {
 }
 
 TEST(DiscreteDistributionTest, InitDiscreteDistribution) {
+  using testing::_;
   using testing::Pair;
 
   {
@@ -111,8 +112,8 @@ TEST(DiscreteDistributionTest, InitDiscreteDistribution) {
     // Each bucket is p=1/3, so bucket 0 will send half it's traffic
     // to bucket 2, while the rest will retain all of their traffic.
     EXPECT_THAT(q, testing::ElementsAre(Pair(0.5, 2),  //
-                                        Pair(1.0, 1),  //
-                                        Pair(1.0, 2)));
+                                        Pair(1.0, _),  //
+                                        Pair(1.0, _)));
   }
 
   {
@@ -135,7 +136,7 @@ TEST(DiscreteDistributionTest, InitDiscreteDistribution) {
 
     EXPECT_THAT(q, testing::ElementsAre(Pair(b0, 3),   //
                                         Pair(b1, 3),   //
-                                        Pair(1.0, 2),  //
+                                        Pair(1.0, _),  //
                                         Pair(b3, 2),   //
                                         Pair(b1, 3)));
   }