Improving flat containers interface.

base/containers/flat_set_unittest.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/containers/flat_set.h"
 
 #include <string>
 #include <vector>
 
 #include "base/containers/container_test_utils.h"
@@ skipping 72 matching lines @@
 
   copy.erase(copy.begin());
   copy.insert(10);
   EXPECT_THAT(copy, ElementsAre(2, 10));
 
   original.swap(copy);
   EXPECT_THAT(original, ElementsAre(2, 10));
   EXPECT_THAT(copy, ElementsAre(1, 2));
 }
 
+TEST(FlatSet, UniquePtrs) {
+  using ExplicitInt = base::MoveOnlyInt;
+  base::flat_set<ExplicitInt> s;
+  const auto& s1 = s;
+  int x = 0;
+  s.count(x);

[vmpstr, 2017/06/23 21:45:14]

Can you leave a comment that this is checking if things compile and what exactly
it's checking

+  s1.count(x);
+  s.find(x);
+  s1.find(x);
+  s.equal_range(x);
+  s1.equal_range(x);
+  s.lower_bound(x);
+  s1.lower_bound(x);
+  s.upper_bound(x);
+  s1.upper_bound(x);
+  s.erase(x);
+
+  // Check if we broke overload resolution.
+  s.emplace(0);
+  s.emplace(1);
+  s.erase(s.begin());
+  s.erase(s.cbegin());
+}
+
 }  // namespace base