Second half of C++17's splicing maps and sets

This commit adds a merge member function to all the map and set containers,
which splices nodes from the source container. This completes support for
P0083r3.

Differential revision: https://reviews.llvm.org/D48896

llvm-svn: 345744

8 files changed, 1232 insertions, 0 deletions

diff --git a/libcxx/test/std/containers/associative/map/map.modifiers/merge.pass.cpp b/libcxx/test/std/containers/associative/map/map.modifiers/merge.pass.cpp
new file mode 100644
index 00000000000..4fef2425a39
--- /dev/null
+++ b/libcxx/test/std/containers/associative/map/map.modifiers/merge.pass.cpp
@@ -0,0 +1,149 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <map>
+
+// class map
+
+// template <class C2>
+//   void merge(map<key_type, value_type, C2, allocator_type>& source);
+// template <class C2>
+//   void merge(map<key_type, value_type, C2, allocator_type>&& source);
+// template <class C2>
+//   void merge(multimap<key_type, value_type, C2, allocator_type>& source);
+// template <class C2>
+//   void merge(multimap<key_type, value_type, C2, allocator_type>&& source);
+
+#include <map>
+#include "test_macros.h"
+#include "Counter.h"
+
+template <class Map>
+bool map_equal(const Map& map, Map other)
+{
+    return map == other;
+}
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+struct throw_comparator
+{
+    bool& should_throw_;
+
+    throw_comparator(bool& should_throw) : should_throw_(should_throw) {}
+
+    template <class T>
+    bool operator()(const T& lhs, const T& rhs) const
+    {
+        if (should_throw_)
+            throw 0;
+        return lhs < rhs;
+    }
+};
+#endif
+
+int main()
+{
+    {
+        std::map<int, int> src{{1, 0}, {3, 0}, {5, 0}};
+        std::map<int, int> dst{{2, 0}, {4, 0}, {5, 0}};
+        dst.merge(src);
+        assert(map_equal(src, {{5,0}}));
+        assert(map_equal(dst, {{1, 0}, {2, 0}, {3, 0}, {4, 0}, {5, 0}}));
+    }
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        bool do_throw = false;
+        typedef std::map<Counter<int>, int, throw_comparator> map_type;
+        map_type src({{1, 0}, {3, 0}, {5, 0}}, throw_comparator(do_throw));
+        map_type dst({{2, 0}, {4, 0}, {5, 0}}, throw_comparator(do_throw));
+
+        assert(Counter_base::gConstructed == 6);
+
+        do_throw = true;
+        try
+        {
+            dst.merge(src);
+        }
+        catch (int)
+        {
+            do_throw = false;
+        }
+        assert(!do_throw);
+        assert(map_equal(src, map_type({{1, 0}, {3, 0}, {5, 0}}, throw_comparator(do_throw))));
+        assert(map_equal(dst, map_type({{2, 0}, {4, 0}, {5, 0}}, throw_comparator(do_throw))));
+    }
+#endif
+    assert(Counter_base::gConstructed == 0);
+    struct comparator
+    {
+        comparator() = default;
+
+        bool operator()(const Counter<int>& lhs, const Counter<int>& rhs) const
+        {
+            return lhs < rhs;
+        }
+    };
+    {
+        typedef std::map<Counter<int>, int, std::less<Counter<int>>> first_map_type;
+        typedef std::map<Counter<int>, int, comparator> second_map_type;
+        typedef std::multimap<Counter<int>, int, comparator> third_map_type;
+
+        {
+            first_map_type first{{1, 0}, {2, 0}, {3, 0}};
+            second_map_type second{{2, 0}, {3, 0}, {4, 0}};
+            third_map_type third{{1, 0}, {3, 0}};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(second);
+            first.merge(third);
+
+            assert(map_equal(first, {{1, 0}, {2, 0}, {3, 0}, {4, 0}}));
+            assert(map_equal(second, {{2, 0}, {3, 0}}));
+            assert(map_equal(third, {{1, 0}, {3, 0}}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+        {
+            first_map_type first{{1, 0}, {2, 0}, {3, 0}};
+            second_map_type second{{2, 0}, {3, 0}, {4, 0}};
+            third_map_type third{{1, 0}, {3, 0}};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(std::move(second));
+            first.merge(std::move(third));
+
+            assert(map_equal(first, {{1, 0}, {2, 0}, {3, 0}, {4, 0}}));
+            assert(map_equal(second, {{2, 0}, {3, 0}}));
+            assert(map_equal(third, {{1, 0}, {3, 0}}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+    }
+    assert(Counter_base::gConstructed == 0);
+    {
+        std::map<int, int> first;
+        {
+            std::map<int, int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+        {
+            std::multimap<int, int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+    }
+}
diff --git a/libcxx/test/std/containers/associative/multimap/multimap.modifiers/merge.pass.cpp b/libcxx/test/std/containers/associative/multimap/multimap.modifiers/merge.pass.cpp
new file mode 100644
index 00000000000..71f3c0b393b
--- /dev/null
+++ b/libcxx/test/std/containers/associative/multimap/multimap.modifiers/merge.pass.cpp
@@ -0,0 +1,149 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <map>
+
+// class multimap
+
+// template <class C2>
+//   void merge(map<key_type, value_type, C2, allocator_type>& source);
+// template <class C2>
+//   void merge(map<key_type, value_type, C2, allocator_type>&& source);
+// template <class C2>
+//   void merge(multimap<key_type, value_type, C2, allocator_type>& source);
+// template <class C2>
+//   void merge(multimap<key_type, value_type, C2, allocator_type>&& source);
+
+#include <map>
+#include "test_macros.h"
+#include "Counter.h"
+
+template <class Map>
+bool map_equal(const Map& map, Map other)
+{
+    return map == other;
+}
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+struct throw_comparator
+{
+    bool& should_throw_;
+
+    throw_comparator(bool& should_throw) : should_throw_(should_throw) {}
+
+    template <class T>
+    bool operator()(const T& lhs, const T& rhs) const
+    {
+        if (should_throw_)
+            throw 0;
+        return lhs < rhs;
+    }
+};
+#endif
+
+int main()
+{
+    {
+        std::multimap<int, int> src{{1, 0}, {3, 0}, {5, 0}};
+        std::multimap<int, int> dst{{2, 0}, {4, 0}, {5, 0}};
+        dst.merge(src);
+        assert(map_equal(src, {}));
+        assert(map_equal(dst, {{1, 0}, {2, 0}, {3, 0}, {4, 0}, {5, 0}, {5, 0}}));
+    }
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        bool do_throw = false;
+        typedef std::multimap<Counter<int>, int, throw_comparator> map_type;
+        map_type src({{1, 0}, {3, 0}, {5, 0}}, throw_comparator(do_throw));
+        map_type dst({{2, 0}, {4, 0}, {5, 0}}, throw_comparator(do_throw));
+
+        assert(Counter_base::gConstructed == 6);
+
+        do_throw = true;
+        try
+        {
+            dst.merge(src);
+        }
+        catch (int)
+        {
+            do_throw = false;
+        }
+        assert(!do_throw);
+        assert(map_equal(src, map_type({{1, 0}, {3, 0}, {5, 0}}, throw_comparator(do_throw))));
+        assert(map_equal(dst, map_type({{2, 0}, {4, 0}, {5, 0}}, throw_comparator(do_throw))));
+    }
+#endif
+    assert(Counter_base::gConstructed == 0);
+    struct comparator
+    {
+        comparator() = default;
+
+        bool operator()(const Counter<int>& lhs, const Counter<int>& rhs) const
+        {
+            return lhs < rhs;
+        }
+    };
+    {
+        typedef std::multimap<Counter<int>, int, std::less<Counter<int>>> first_map_type;
+        typedef std::multimap<Counter<int>, int, comparator> second_map_type;
+        typedef std::map<Counter<int>, int, comparator> third_map_type;
+
+        {
+            first_map_type first{{1, 0}, {2, 0}, {3, 0}};
+            second_map_type second{{2, 0}, {3, 0}, {4, 0}};
+            third_map_type third{{1, 0}, {3, 0}};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(second);
+            first.merge(third);
+
+            assert(map_equal(first, {{1, 0}, {1, 0}, {2, 0}, {2, 0}, {3, 0}, {3, 0}, {3, 0}, {4, 0}}));
+            assert(map_equal(second, {}));
+            assert(map_equal(third, {}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+        {
+            first_map_type first{{1, 0}, {2, 0}, {3, 0}};
+            second_map_type second{{2, 0}, {3, 0}, {4, 0}};
+            third_map_type third{{1, 0}, {3, 0}};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(std::move(second));
+            first.merge(std::move(third));
+
+            assert(map_equal(first, {{1, 0}, {1, 0}, {2, 0}, {2, 0}, {3, 0}, {3, 0}, {3, 0}, {4, 0}}));
+            assert(map_equal(second, {}));
+            assert(map_equal(third, {}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+    }
+    assert(Counter_base::gConstructed == 0);
+    {
+        std::multimap<int, int> first;
+        {
+            std::multimap<int, int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+        {
+            std::multimap<int, int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+    }
+}
diff --git a/libcxx/test/std/containers/associative/multiset/merge.pass.cpp b/libcxx/test/std/containers/associative/multiset/merge.pass.cpp
new file mode 100644
index 00000000000..516e27de3a0
--- /dev/null
+++ b/libcxx/test/std/containers/associative/multiset/merge.pass.cpp
@@ -0,0 +1,148 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <set>
+
+// class multiset
+
+// template <class C2>
+//   void merge(set<Key, C2, Allocator>& source);
+// template <class C2>
+//   void merge(set<Key, C2, Allocator>&& source);
+// template <class C2>
+//   void merge(multiset<Key, C2, Allocator>& source);
+// template <class C2>
+//   void merge(multiset<Key, C2, Allocator>&& source);
+
+#include <set>
+#include "test_macros.h"
+#include "Counter.h"
+
+template <class Set>
+bool set_equal(const Set& set, Set other)
+{
+    return set == other;
+}
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+struct throw_comparator
+{
+    bool& should_throw_;
+
+    throw_comparator(bool& should_throw) : should_throw_(should_throw) {}
+
+    template <class T>
+    bool operator()(const T& lhs, const T& rhs) const
+    {
+        if (should_throw_)
+            throw 0;
+        return lhs < rhs;
+    }
+};
+#endif
+
+int main()
+{
+    {
+        std::multiset<int> src{1, 3, 5};
+        std::multiset<int> dst{2, 4, 5};
+        dst.merge(src);
+        assert(set_equal(src, {}));
+        assert(set_equal(dst, {1, 2, 3, 4, 5, 5}));
+    }
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        bool do_throw = false;
+        typedef std::multiset<Counter<int>, throw_comparator> set_type;
+        set_type src({1, 3, 5}, throw_comparator(do_throw));
+        set_type dst({2, 4, 5}, throw_comparator(do_throw));
+
+        assert(Counter_base::gConstructed == 6);
+
+        do_throw = true;
+        try
+        {
+            dst.merge(src);
+        }
+        catch (int)
+        {
+            do_throw = false;
+        }
+        assert(!do_throw);
+        assert(set_equal(src, set_type({1, 3, 5}, throw_comparator(do_throw))));
+        assert(set_equal(dst, set_type({2, 4, 5}, throw_comparator(do_throw))));
+    }
+#endif
+    assert(Counter_base::gConstructed == 0);
+    struct comparator
+    {
+        comparator() = default;
+
+        bool operator()(const Counter<int>& lhs, const Counter<int>& rhs) const
+        {
+            return lhs < rhs;
+        }
+    };
+    {
+        typedef std::multiset<Counter<int>, std::less<Counter<int>>> first_set_type;
+        typedef std::multiset<Counter<int>, comparator> second_set_type;
+        typedef std::set<Counter<int>, comparator> third_set_type;
+
+        {
+            first_set_type first{1, 2, 3};
+            second_set_type second{2, 3, 4};
+            third_set_type third{1, 3};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(second);
+            first.merge(third);
+
+            assert(set_equal(first, {1, 1, 2, 2, 3, 3, 3, 4}));
+            assert(set_equal(second, {}));
+            assert(set_equal(third, {}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+        {
+            first_set_type first{1, 2, 3};
+            second_set_type second{2, 3, 4};
+            third_set_type third{1, 3};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(std::move(second));
+            first.merge(std::move(third));
+
+            assert(set_equal(first, {1, 1, 2, 2, 3, 3, 3, 4}));
+            assert(set_equal(second, {}));
+            assert(set_equal(third, {}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+    }
+    {
+        std::multiset<int> first;
+        {
+            std::multiset<int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+        {
+            std::set<int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+    }
+}
diff --git a/libcxx/test/std/containers/associative/set/merge.pass.cpp b/libcxx/test/std/containers/associative/set/merge.pass.cpp
new file mode 100644
index 00000000000..0896596d94f
--- /dev/null
+++ b/libcxx/test/std/containers/associative/set/merge.pass.cpp
@@ -0,0 +1,148 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <set>
+
+// class set
+
+// template <class C2>
+//   void merge(set<key_type, C2, allocator_type>& source);
+// template <class C2>
+//   void merge(set<key_type, C2, allocator_type>&& source);
+// template <class C2>
+//   void merge(multiset<key_type, C2, allocator_type>& source);
+// template <class C2>
+//   void merge(multiset<key_type, C2, allocator_type>&& source);
+
+#include <set>
+#include "test_macros.h"
+#include "Counter.h"
+
+template <class Set>
+bool set_equal(const Set& set, Set other)
+{
+    return set == other;
+}
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+struct throw_comparator
+{
+    bool& should_throw_;
+
+    throw_comparator(bool& should_throw) : should_throw_(should_throw) {}
+
+    template <class T>
+    bool operator()(const T& lhs, const T& rhs) const
+    {
+        if (should_throw_)
+            throw 0;
+        return lhs < rhs;
+    }
+};
+#endif
+
+int main()
+{
+    {
+        std::set<int> src{1, 3, 5};
+        std::set<int> dst{2, 4, 5};
+        dst.merge(src);
+        assert(set_equal(src, {5}));
+        assert(set_equal(dst, {1, 2, 3, 4, 5}));
+    }
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        bool do_throw = false;
+        typedef std::set<Counter<int>, throw_comparator> set_type;
+        set_type src({1, 3, 5}, throw_comparator(do_throw));
+        set_type dst({2, 4, 5}, throw_comparator(do_throw));
+
+        assert(Counter_base::gConstructed == 6);
+
+        do_throw = true;
+        try
+        {
+            dst.merge(src);
+        }
+        catch (int)
+        {
+            do_throw = false;
+        }
+        assert(!do_throw);
+        assert(set_equal(src, set_type({1, 3, 5}, throw_comparator(do_throw))));
+        assert(set_equal(dst, set_type({2, 4, 5}, throw_comparator(do_throw))));
+    }
+#endif
+    assert(Counter_base::gConstructed == 0);
+    struct comparator
+    {
+        comparator() = default;
+
+        bool operator()(const Counter<int>& lhs, const Counter<int>& rhs) const
+        {
+            return lhs < rhs;
+        }
+    };
+    {
+        typedef std::set<Counter<int>, std::less<Counter<int>>> first_set_type;
+        typedef std::set<Counter<int>, comparator> second_set_type;
+        typedef std::multiset<Counter<int>, comparator> third_set_type;
+
+        {
+            first_set_type first{1, 2, 3};
+            second_set_type second{2, 3, 4};
+            third_set_type third{1, 3};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(second);
+            first.merge(third);
+
+            assert(set_equal(first, {1, 2, 3, 4}));
+            assert(set_equal(second, {2, 3}));
+            assert(set_equal(third, {1, 3}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+        {
+            first_set_type first{1, 2, 3};
+            second_set_type second{2, 3, 4};
+            third_set_type third{1, 3};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(std::move(second));
+            first.merge(std::move(third));
+
+            assert(set_equal(first, {1, 2, 3, 4}));
+            assert(set_equal(second, {2, 3}));
+            assert(set_equal(third, {1, 3}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+    }
+    {
+        std::set<int> first;
+        {
+            std::set<int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+        {
+            std::multiset<int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+    }
+}
diff --git a/libcxx/test/std/containers/unord/unord.map/unord.map.modifiers/merge.pass.cpp b/libcxx/test/std/containers/unord/unord.map/unord.map.modifiers/merge.pass.cpp
new file mode 100644
index 00000000000..d525b1addfb
--- /dev/null
+++ b/libcxx/test/std/containers/unord/unord.map/unord.map.modifiers/merge.pass.cpp
@@ -0,0 +1,161 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <unordered_map>
+
+// class unordered_map
+
+// template <class H2, class P2>
+//   void merge(unordered_map<key_type, value_type, H2, P2, allocator_type>& source);
+// template <class H2, class P2>
+//   void merge(unordered_map<key_type, value_type, H2, P2, allocator_type>&& source);
+// template <class H2, class P2>
+//   void merge(unordered_multimap<key_type, value_type, H2, P2, allocator_type>& source);
+// template <class H2, class P2>
+//   void merge(unordered_multimap<key_type, value_type, H2, P2, allocator_type>&& source);
+
+#include <unordered_map>
+#include "test_macros.h"
+#include "Counter.h"
+
+template <class Map>
+bool map_equal(const Map& map, Map other)
+{
+    return map == other;
+}
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+template <class T>
+struct throw_hasher
+{
+    bool& should_throw_;
+
+    throw_hasher(bool& should_throw) : should_throw_(should_throw) {}
+
+    typedef size_t result_type;
+    typedef T argument_type;
+
+    size_t operator()(const T& p) const
+    {
+        if (should_throw_)
+            throw 0;
+        return std::hash<T>()(p);
+    }
+};
+#endif
+
+int main()
+{
+    {
+        std::unordered_map<int, int> src{{1, 0}, {3, 0}, {5, 0}};
+        std::unordered_map<int, int> dst{{2, 0}, {4, 0}, {5, 0}};
+        dst.merge(src);
+        assert(map_equal(src, {{5,0}}));
+        assert(map_equal(dst, {{1, 0}, {2, 0}, {3, 0}, {4, 0}, {5, 0}}));
+    }
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        bool do_throw = false;
+        typedef std::unordered_map<Counter<int>, int, throw_hasher<Counter<int>>> map_type;
+        map_type src({{1, 0}, {3, 0}, {5, 0}}, 0, throw_hasher<Counter<int>>(do_throw));
+        map_type dst({{2, 0}, {4, 0}, {5, 0}}, 0, throw_hasher<Counter<int>>(do_throw));
+
+        assert(Counter_base::gConstructed == 6);
+
+        do_throw = true;
+        try
+        {
+            dst.merge(src);
+        }
+        catch (int)
+        {
+            do_throw = false;
+        }
+        assert(!do_throw);
+        assert(map_equal(src, map_type({{1, 0}, {3, 0}, {5, 0}}, 0, throw_hasher<Counter<int>>(do_throw))));
+        assert(map_equal(dst, map_type({{2, 0}, {4, 0}, {5, 0}}, 0, throw_hasher<Counter<int>>(do_throw))));
+    }
+#endif
+    assert(Counter_base::gConstructed == 0);
+    struct equal
+    {
+        equal() = default;
+
+        bool operator()(const Counter<int>& lhs, const Counter<int>& rhs) const
+        {
+            return lhs == rhs;
+        }
+    };
+    struct hasher
+    {
+        hasher() = default;
+        typedef Counter<int> argument_type;
+        typedef size_t result_type;
+        size_t operator()(const Counter<int>& p) const
+        {
+            return std::hash<Counter<int>>()(p);
+        }
+    };
+    {
+        typedef std::unordered_map<Counter<int>, int, std::hash<Counter<int>>, std::equal_to<Counter<int>>> first_map_type;
+        typedef std::unordered_map<Counter<int>, int, hasher, equal> second_map_type;
+        typedef std::unordered_multimap<Counter<int>, int, hasher, equal> third_map_type;
+
+        {
+            first_map_type first{{1, 0}, {2, 0}, {3, 0}};
+            second_map_type second{{2, 0}, {3, 0}, {4, 0}};
+            third_map_type third{{1, 0}, {3, 0}};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(second);
+            first.merge(third);
+
+            assert(map_equal(first, {{1, 0}, {2, 0}, {3, 0}, {4, 0}}));
+            assert(map_equal(second, {{2, 0}, {3, 0}}));
+            assert(map_equal(third, {{1, 0}, {3, 0}}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+        {
+            first_map_type first{{1, 0}, {2, 0}, {3, 0}};
+            second_map_type second{{2, 0}, {3, 0}, {4, 0}};
+            third_map_type third{{1, 0}, {3, 0}};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(std::move(second));
+            first.merge(std::move(third));
+
+            assert(map_equal(first, {{1, 0}, {2, 0}, {3, 0}, {4, 0}}));
+            assert(map_equal(second, {{2, 0}, {3, 0}}));
+            assert(map_equal(third, {{1, 0}, {3, 0}}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+    }
+    {
+        std::unordered_map<int, int> first;
+        {
+            std::unordered_map<int, int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+        {
+            std::unordered_multimap<int, int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+    }
+}
diff --git a/libcxx/test/std/containers/unord/unord.multimap/unord.multimap.modifiers/merge.pass.cpp b/libcxx/test/std/containers/unord/unord.multimap/unord.multimap.modifiers/merge.pass.cpp
new file mode 100644
index 00000000000..d018620947b
--- /dev/null
+++ b/libcxx/test/std/containers/unord/unord.multimap/unord.multimap.modifiers/merge.pass.cpp
@@ -0,0 +1,161 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <unordered_map>
+
+// class unordered_multimap
+
+// template <class H2, class P2>
+//   void merge(unordered_map<key_type, value_type, H2, P2, allocator_type>& source);
+// template <class H2, class P2>
+//   void merge(unordered_map<key_type, value_type, H2, P2, allocator_type>&& source);
+// template <class H2, class P2>
+//   void merge(unordered_multimap<key_type, value_type, H2, P2, allocator_type>& source);
+// template <class H2, class P2>
+//   void merge(unordered_multimap<key_type, value_type, H2, P2, allocator_type>&& source);
+
+#include <unordered_map>
+#include "test_macros.h"
+#include "Counter.h"
+
+template <class Map>
+bool map_equal(const Map& map, Map other)
+{
+    return map == other;
+}
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+template <class T>
+struct throw_hasher
+{
+    bool& should_throw_;
+
+    throw_hasher(bool& should_throw) : should_throw_(should_throw) {}
+
+    typedef size_t result_type;
+    typedef T argument_type;
+
+    size_t operator()(const T& p) const
+    {
+        if (should_throw_)
+            throw 0;
+        return std::hash<T>()(p);
+    }
+};
+#endif
+
+int main()
+{
+    {
+        std::unordered_multimap<int, int> src{{1, 0}, {3, 0}, {5, 0}};
+        std::unordered_multimap<int, int> dst{{2, 0}, {4, 0}, {5, 0}};
+        dst.merge(src);
+        assert(map_equal(src, {}));
+        assert(map_equal(dst, {{1, 0}, {2, 0}, {3, 0}, {4, 0}, {5, 0}, {5, 0}}));
+    }
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        bool do_throw = false;
+        typedef std::unordered_multimap<Counter<int>, int, throw_hasher<Counter<int>>> map_type;
+        map_type src({{1, 0}, {3, 0}, {5, 0}}, 0, throw_hasher<Counter<int>>(do_throw));
+        map_type dst({{2, 0}, {4, 0}, {5, 0}}, 0, throw_hasher<Counter<int>>(do_throw));
+
+        assert(Counter_base::gConstructed == 6);
+
+        do_throw = true;
+        try
+        {
+            dst.merge(src);
+        }
+        catch (int)
+        {
+            do_throw = false;
+        }
+        assert(!do_throw);
+        assert(map_equal(src, map_type({{1, 0}, {3, 0}, {5, 0}}, 0, throw_hasher<Counter<int>>(do_throw))));
+        assert(map_equal(dst, map_type({{2, 0}, {4, 0}, {5, 0}}, 0, throw_hasher<Counter<int>>(do_throw))));
+    }
+#endif
+    assert(Counter_base::gConstructed == 0);
+    struct equal
+    {
+        equal() = default;
+
+        bool operator()(const Counter<int>& lhs, const Counter<int>& rhs) const
+        {
+            return lhs == rhs;
+        }
+    };
+    struct hasher
+    {
+        hasher() = default;
+        typedef Counter<int> argument_type;
+        typedef size_t result_type;
+        size_t operator()(const Counter<int>& p) const
+        {
+            return std::hash<Counter<int>>()(p);
+        }
+    };
+    {
+        typedef std::unordered_multimap<Counter<int>, int, std::hash<Counter<int>>, std::equal_to<Counter<int>>> first_map_type;
+        typedef std::unordered_multimap<Counter<int>, int, hasher, equal> second_map_type;
+        typedef std::unordered_map<Counter<int>, int, hasher, equal> third_map_type;
+
+        {
+            first_map_type first{{1, 0}, {2, 0}, {3, 0}};
+            second_map_type second{{2, 0}, {3, 0}, {4, 0}};
+            third_map_type third{{1, 0}, {3, 0}};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(second);
+            first.merge(third);
+
+            assert(map_equal(first, {{1, 0}, {2, 0}, {3, 0}, {4, 0}, {2, 0}, {3, 0}, {1, 0}, {3, 0}}));
+            assert(map_equal(second, {}));
+            assert(map_equal(third, {}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+        {
+            first_map_type first{{1, 0}, {2, 0}, {3, 0}};
+            second_map_type second{{2, 0}, {3, 0}, {4, 0}};
+            third_map_type third{{1, 0}, {3, 0}};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(std::move(second));
+            first.merge(std::move(third));
+
+            assert(map_equal(first, {{1, 0}, {2, 0}, {3, 0}, {4, 0}, {2, 0}, {3, 0}, {1, 0}, {3, 0}}));
+            assert(map_equal(second, {}));
+            assert(map_equal(third, {}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+    }
+    {
+        std::unordered_multimap<int, int> first;
+        {
+            std::unordered_multimap<int, int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+        {
+            std::unordered_map<int, int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+    }
+}
diff --git a/libcxx/test/std/containers/unord/unord.multiset/merge.pass.cpp b/libcxx/test/std/containers/unord/unord.multiset/merge.pass.cpp
new file mode 100644
index 00000000000..0bf8d358f44
--- /dev/null
+++ b/libcxx/test/std/containers/unord/unord.multiset/merge.pass.cpp
@@ -0,0 +1,158 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <unordered_set>
+
+// class unordered_multiset
+
+// template <class H2, class P2>
+//   void merge(unordered_set<key_type, H2, P2, allocator_type>& source);
+// template <class H2, class P2>
+//   void merge(unordered_set<key_type, H2, P2, allocator_type>&& source);
+// template <class H2, class P2>
+//   void merge(unordered_multiset<key_type, H2, P2, allocator_type>& source);
+// template <class H2, class P2>
+//   void merge(unordered_multiset<key_type, H2, P2, allocator_type>&& source);
+
+#include <unordered_set>
+#include "test_macros.h"
+#include "Counter.h"
+
+template <class Set>
+bool set_equal(const Set& set, Set other)
+{
+    return set == other;
+}
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+template <class T>
+struct throw_hasher
+{
+    bool& should_throw_;
+
+    throw_hasher(bool& should_throw) : should_throw_(should_throw) {}
+
+    typedef size_t result_type;
+    typedef T argument_type;
+
+    size_t operator()(const T& p) const
+    {
+        if (should_throw_)
+            throw 0;
+        return std::hash<T>()(p);
+    }
+};
+#endif
+
+int main()
+{
+    {
+        std::unordered_multiset<int> src{1, 3, 5};
+        std::unordered_multiset<int> dst{2, 4, 5};
+        dst.merge(src);
+        assert(set_equal(src, {}));
+        assert(set_equal(dst, {1, 2, 3, 4, 5, 5}));
+    }
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        bool do_throw = false;
+        typedef std::unordered_multiset<Counter<int>, throw_hasher<Counter<int>>> set_type;
+        set_type src({1, 3, 5}, 0, throw_hasher<Counter<int>>(do_throw));
+        set_type dst({2, 4, 5}, 0, throw_hasher<Counter<int>>(do_throw));
+
+        assert(Counter_base::gConstructed == 6);
+
+        do_throw = true;
+        try
+        {
+            dst.merge(src);
+        }
+        catch (int)
+        {
+            do_throw = false;
+        }
+        assert(!do_throw);
+        assert(set_equal(src, set_type({1, 3, 5}, 0, throw_hasher<Counter<int>>(do_throw))));
+        assert(set_equal(dst, set_type({2, 4, 5}, 0, throw_hasher<Counter<int>>(do_throw))));
+    }
+#endif
+    assert(Counter_base::gConstructed == 0);
+    struct equal
+    {
+        equal() = default;
+
+        bool operator()(const Counter<int>& lhs, const Counter<int>& rhs) const
+        {
+            return lhs == rhs;
+        }
+    };
+    struct hasher
+    {
+        hasher() = default;
+        typedef Counter<int> argument_type;
+        typedef size_t result_type;
+        size_t operator()(const Counter<int>& p) const { return std::hash<Counter<int>>()(p); }
+    };
+    {
+        typedef std::unordered_multiset<Counter<int>, std::hash<Counter<int>>, std::equal_to<Counter<int>>> first_set_type;
+        typedef std::unordered_multiset<Counter<int>, hasher, equal> second_set_type;
+        typedef std::unordered_set<Counter<int>, hasher, equal> third_set_type;
+
+        {
+            first_set_type first{1, 2, 3};
+            second_set_type second{2, 3, 4};
+            third_set_type third{1, 3};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(second);
+            first.merge(third);
+
+            assert(set_equal(first, {1, 2, 3, 4, 2, 3, 1, 3}));
+            assert(set_equal(second, {}));
+            assert(set_equal(third, {}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+        {
+            first_set_type first{1, 2, 3};
+            second_set_type second{2, 3, 4};
+            third_set_type third{1, 3};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(std::move(second));
+            first.merge(std::move(third));
+
+            assert(set_equal(first, {1, 2, 3, 4, 2, 3, 1, 3}));
+            assert(set_equal(second, {}));
+            assert(set_equal(third, {}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+    }
+    {
+        std::unordered_multiset<int> first;
+        {
+            std::unordered_multiset<int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+        {
+            std::unordered_set<int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+    }
+}
diff --git a/libcxx/test/std/containers/unord/unord.set/merge.pass.cpp b/libcxx/test/std/containers/unord/unord.set/merge.pass.cpp
new file mode 100644
index 00000000000..ebf03cd565a
--- /dev/null
+++ b/libcxx/test/std/containers/unord/unord.set/merge.pass.cpp
@@ -0,0 +1,158 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <unordered_set>
+
+// class unordered_set
+
+// template <class H2, class P2>
+//   void merge(unordered_set<key_type, H2, P2, allocator_type>& source);
+// template <class H2, class P2>
+//   void merge(unordered_set<key_type, H2, P2, allocator_type>&& source);
+// template <class H2, class P2>
+//   void merge(unordered_multiset<key_type, H2, P2, allocator_type>& source);
+// template <class H2, class P2>
+//   void merge(unordered_multiset<key_type, H2, P2, allocator_type>&& source);
+
+#include <unordered_set>
+#include "test_macros.h"
+#include "Counter.h"
+
+template <class Set>
+bool set_equal(const Set& set, Set other)
+{
+    return set == other;
+}
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+template <class T>
+struct throw_hasher
+{
+    bool& should_throw_;
+
+    throw_hasher(bool& should_throw) : should_throw_(should_throw) {}
+
+    typedef size_t result_type;
+    typedef T argument_type;
+
+    size_t operator()(const T& p) const
+    {
+        if (should_throw_)
+            throw 0;
+        return std::hash<T>()(p);
+    }
+};
+#endif
+
+int main()
+{
+    {
+        std::unordered_set<int> src{1, 3, 5};
+        std::unordered_set<int> dst{2, 4, 5};
+        dst.merge(src);
+        assert(set_equal(src, {5}));
+        assert(set_equal(dst, {1, 2, 3, 4, 5}));
+    }
+
+#ifndef TEST_HAS_NO_EXCEPTIONS
+    {
+        bool do_throw = false;
+        typedef std::unordered_set<Counter<int>, throw_hasher<Counter<int>>> set_type;
+        set_type src({1, 3, 5}, 0, throw_hasher<Counter<int>>(do_throw));
+        set_type dst({2, 4, 5}, 0, throw_hasher<Counter<int>>(do_throw));
+
+        assert(Counter_base::gConstructed == 6);
+
+        do_throw = true;
+        try
+        {
+            dst.merge(src);
+        }
+        catch (int)
+        {
+            do_throw = false;
+        }
+        assert(!do_throw);
+        assert(set_equal(src, set_type({1, 3, 5}, 0, throw_hasher<Counter<int>>(do_throw))));
+        assert(set_equal(dst, set_type({2, 4, 5}, 0, throw_hasher<Counter<int>>(do_throw))));
+    }
+#endif
+    assert(Counter_base::gConstructed == 0);
+    struct equal
+    {
+        equal() = default;
+
+        bool operator()(const Counter<int>& lhs, const Counter<int>& rhs) const
+        {
+            return lhs == rhs;
+        }
+    };
+    struct hasher
+    {
+        hasher() = default;
+        typedef Counter<int> argument_type;
+        typedef size_t result_type;
+        size_t operator()(const Counter<int>& p) const { return std::hash<Counter<int>>()(p); }
+    };
+    {
+        typedef std::unordered_set<Counter<int>, std::hash<Counter<int>>, std::equal_to<Counter<int>>> first_set_type;
+        typedef std::unordered_set<Counter<int>, hasher, equal> second_set_type;
+        typedef std::unordered_multiset<Counter<int>, hasher, equal> third_set_type;
+
+        {
+            first_set_type first{1, 2, 3};
+            second_set_type second{2, 3, 4};
+            third_set_type third{1, 3};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(second);
+            first.merge(third);
+
+            assert(set_equal(first, {1, 2, 3, 4}));
+            assert(set_equal(second, {2, 3}));
+            assert(set_equal(third, {1, 3}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+        {
+            first_set_type first{1, 2, 3};
+            second_set_type second{2, 3, 4};
+            third_set_type third{1, 3};
+
+            assert(Counter_base::gConstructed == 8);
+
+            first.merge(std::move(second));
+            first.merge(std::move(third));
+
+            assert(set_equal(first, {1, 2, 3, 4}));
+            assert(set_equal(second, {2, 3}));
+            assert(set_equal(third, {1, 3}));
+
+            assert(Counter_base::gConstructed == 8);
+        }
+        assert(Counter_base::gConstructed == 0);
+    }
+    {
+        std::unordered_set<int> first;
+        {
+            std::unordered_set<int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+        {
+            std::unordered_multiset<int> second;
+            first.merge(second);
+            first.merge(std::move(second));
+        }
+    }
+}