Export of internal Abseil changes

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cfb567ed02096320663d882d2c0c2fb7db7af1e4 by Derek Mauro <dmauro@google.com>:

Upgrade to GCC 10.2.0, Bazel 3.5.0, and CMake 3.18.2

PiperOrigin-RevId: 330847323

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5dcb9ce14d92315163079366a91c43cbd5184ea4 by Evan Brown <ezb@google.com>:

Optimize equal_range() by avoiding the call to upper_bound() when possible.

We need to support heterogeneous comparators that have different behavior when comparing key_type to non-key_type. See the new test.

Also update the comment for `key_compare_to_adapter`.

PiperOrigin-RevId: 330794444

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744405dbda5513527d74094a5c3b9db1e0927693 by Gennadiy Rozental <rogeeff@google.com>:

Introduce trampoline for friend access to avoid friending routines and classes from different namespace.

PiperOrigin-RevId: 330773156

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a195d1226576f8a7bb5671f3e42d1021b827fad9 by Abseil Team <absl-team@google.com>:

Fix an incorrect version number test for std::variant availability in tvOs.

PiperOrigin-RevId: 330759480

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58b02eb9159a577953676d9928cb26b30068b847 by Derek Mauro <dmauro@google.com>:

Use c++20 instead of c++2a now that it is supported by GCC

PiperOrigin-RevId: 330559797
GitOrigin-RevId: cfb567ed02096320663d882d2c0c2fb7db7af1e4
Change-Id: I0e0d68409c95da42f5609920155ba5694ade8df0

1 files changed, 34 insertions, 0 deletions

diff --git a/absl/container/btree_test.cc b/absl/container/btree_test.cc
index 43704206..1bfa0c20 100644
--- a/absl/container/btree_test.cc
+++ b/absl/container/btree_test.cc
@@ -2580,6 +2580,40 @@ TEST(Btree, NodeHandleMutableKeyAccess) {
 }
 #endif
 
+struct MultiKey {
+  int i1;
+  int i2;
+};
+
+struct MultiKeyComp {
+  using is_transparent = void;
+  bool operator()(const MultiKey a, const MultiKey b) const {
+    if (a.i1 != b.i1) return a.i1 < b.i1;
+    return a.i2 < b.i2;
+  }
+  bool operator()(const int a, const MultiKey b) const { return a < b.i1; }
+  bool operator()(const MultiKey a, const int b) const { return a.i1 < b; }
+};
+
+// Test that when there's a heterogeneous comparator that behaves differently
+// for some heterogeneous operators, we get equal_range() right.
+TEST(Btree, MultiKeyEqualRange) {
+  absl::btree_set<MultiKey, MultiKeyComp> set;
+
+  for (int i = 0; i < 100; ++i) {
+    for (int j = 0; j < 100; ++j) {
+      set.insert({i, j});
+    }
+  }
+
+  for (int i = 0; i < 100; ++i) {
+    auto equal_range = set.equal_range(i);
+    EXPECT_EQ(equal_range.first->i1, i);
+    EXPECT_EQ(equal_range.first->i2, 0);
+    EXPECT_EQ(std::distance(equal_range.first, equal_range.second), 100) << i;
+  }
+}
+
 }  // namespace
 }  // namespace container_internal
 ABSL_NAMESPACE_END