1 files changed, 140 insertions, 0 deletions
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_set/modifiers/merge.cc b/libstdc++-v3/testsuite/23_containers/unordered_set/modifiers/merge.cc
new file mode 100644
index 00000000000..29387dd21f6
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/unordered_set/modifiers/merge.cc
@@ -0,0 +1,140 @@
+// Copyright (C) 2016 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+
+#include <unordered_set>
+#include <algorithm>
+#include <testsuite_hooks.h>
+
+using test_type = std::unordered_set<int>;
+
+struct hash {
+  auto operator()(int i) const noexcept { return ~std::hash<int>()(i); }
+};
+struct equal : std::equal_to<> { };
+
+template<typename C1, typename C2>
+bool equal_elements(const C1& c1, const C2& c2)
+{
+  if (c2.size() != c1.size())
+    return false;
+  for (auto& i : c1)
+    if (c2.count(i) != c1.count(i))
+      return false;
+  return true;
+}
+
+void
+test01()
+{
+  bool test __attribute__((unused)) = true;
+
+  const test_type c0{ 1, 2, 3, };
+  test_type c1 = c0, c2 = c0;
+
+  c1.merge(c2);
+  VERIFY( c1 == c0 );
+  VERIFY( c2 == c0 );
+
+  c1.clear();
+  c1.merge(c2);
+  VERIFY( c1 == c0 );
+  VERIFY( c2.empty() );
+
+  c2.merge(std::move(c1));
+  VERIFY( c1.empty() );
+  VERIFY( c2 == c0 );
+}
+
+void
+test02()
+{
+  bool test __attribute__((unused)) = true;
+
+  const test_type c0{ 1, 2, 3, };
+  test_type c1 = c0;
+  std::unordered_set<int, hash, equal> c2( c0.begin(), c0.end() );
+
+  c1.merge(c2);
+  VERIFY( c1 == c0 );
+  VERIFY( equal_elements(c2, c0) );
+
+  c1.clear();
+  c1.merge(c2);
+  VERIFY( c1 == c0 );
+  VERIFY( c2.empty() );
+
+  c2.merge(c1);
+  VERIFY( c1.empty() );
+  VERIFY( equal_elements(c2, c0) );
+
+  c1.merge(std::move(c2));
+  VERIFY( c2.empty() );
+  VERIFY( c1 == c0 );
+}
+
+void
+test03()
+{
+  bool test __attribute__((unused)) = true;
+
+  const test_type c0{ 1, 2, 3, };
+  test_type c1 = c0;
+  std::unordered_multiset<int, hash, equal> c2( c0.begin(), c0.end() );
+  c1.merge(c2);
+  VERIFY( c1 == c0 );
+  VERIFY( equal_elements(c2, c0) );
+
+  c1.clear();
+  c1.merge(c2);
+  VERIFY( c1 == c0 );
+  VERIFY( c2.empty() );
+
+  c2.merge(c1);
+  VERIFY( c1.empty() );
+  VERIFY( equal_elements(c2, c0) );
+
+  c1 = c0;
+  c2.merge(c1);
+  VERIFY( c1.empty() );
+  VERIFY( c2.size() == (2 * c0.size()) );
+  VERIFY( c2.count(1) == 2 );
+  VERIFY( c2.count(2) == 2 );
+  VERIFY( c2.count(3) == 2 );
+
+  c1.merge(c2);
+  VERIFY( c1 == c0 );
+  VERIFY( equal_elements(c2, c0) );
+
+  c1.merge(std::move(c2));
+  VERIFY( c1 == c0 );
+  VERIFY( equal_elements(c2, c0) );
+
+  c1.clear();
+  c1.merge(std::move(c2));
+  VERIFY( c1 == c0 );
+  VERIFY( c2.empty() );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+  test03();
+}