Removed extension in [unordered_][multi]map which allowed one to emplace using just an argument for the key, as opposed to using piecewise_construct. However a bug report exposed that this created an unfortunate ambiguity. People who are currently using the extension will be notified the next time they compile, and will have to change to using piecewise_construct. There are no ABI issues with the removal of this extension. This fixes http://llvm.org/bugs/show_bug.cgi?id=16542

llvm-svn: 185666

12 files changed, 179 insertions, 174 deletions

diff --git a/libcxx/include/map b/libcxx/include/map
index d0cd0c6b844..4107eadd754 100644
--- a/libcxx/include/map
+++ b/libcxx/include/map
@@ -1003,26 +1003,14 @@ private:
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     __node_holder __construct_node();
     template <class _A0>
-        typename enable_if
-        <
-            is_constructible<value_type, _A0>::value,
-            __node_holder
-        >::type
-         __construct_node(_A0&& __a0);
-    template <class _A0>
-        typename enable_if
-        <
-            is_constructible<key_type, _A0>::value,
-            __node_holder
-        >::type
-         __construct_node(_A0&& __a0);
+        __node_holder __construct_node(_A0&& __a0);
+    __node_holder __construct_node_with_key(key_type&& __k);
 #ifndef _LIBCPP_HAS_NO_VARIADICS
     template <class _A0, class _A1, class ..._Args>
         __node_holder __construct_node(_A0&& __a0, _A1&& __a1, _Args&& ...__args);
 #endif  // _LIBCPP_HAS_NO_VARIADICS
-#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
-    __node_holder __construct_node(const key_type& __k);
 #endif
+    __node_holder __construct_node_with_key(const key_type& __k);
 
     __node_base_pointer&
         __find_equal_key(__node_base_pointer& __parent, const key_type& __k);
@@ -1150,11 +1138,7 @@ map<_Key, _Tp, _Compare, _Allocator>::__construct_node()
 
 template <class _Key, class _Tp, class _Compare, class _Allocator>
 template <class _A0>
-typename enable_if
-<
-    is_constructible<pair<const _Key, _Tp>, _A0>::value,
-    typename map<_Key, _Tp, _Compare, _Allocator>::__node_holder
->::type
+typename map<_Key, _Tp, _Compare, _Allocator>::__node_holder
 map<_Key, _Tp, _Compare, _Allocator>::__construct_node(_A0&& __a0)
 {
     __node_allocator& __na = __tree_.__node_alloc();
@@ -1166,21 +1150,16 @@ map<_Key, _Tp, _Compare, _Allocator>::__construct_node(_A0&& __a0)
 }
 
 template <class _Key, class _Tp, class _Compare, class _Allocator>
-template <class _A0>
-typename enable_if
-<
-    is_constructible<_Key, _A0>::value,
-    typename map<_Key, _Tp, _Compare, _Allocator>::__node_holder
->::type
-map<_Key, _Tp, _Compare, _Allocator>::__construct_node(_A0&& __a0)
+typename map<_Key, _Tp, _Compare, _Allocator>::__node_holder
+map<_Key, _Tp, _Compare, _Allocator>::__construct_node_with_key(key_type&& __k)
 {
     __node_allocator& __na = __tree_.__node_alloc();
     __node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
-    __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.first), _VSTD::forward<_A0>(__a0));
+    __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.first), _VSTD::move(__k));
     __h.get_deleter().__first_constructed = true;
     __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.second));
     __h.get_deleter().__second_constructed = true;
-    return __h;
+    return _VSTD::move(__h);
 }
 
 #ifndef _LIBCPP_HAS_NO_VARIADICS
@@ -1202,11 +1181,11 @@ map<_Key, _Tp, _Compare, _Allocator>::__construct_node(_A0&& __a0, _A1&& __a1, _
 
 #endif  // _LIBCPP_HAS_NO_VARIADICS
 
-#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
 template <class _Key, class _Tp, class _Compare, class _Allocator>
 typename map<_Key, _Tp, _Compare, _Allocator>::__node_holder
-map<_Key, _Tp, _Compare, _Allocator>::__construct_node(const key_type& __k)
+map<_Key, _Tp, _Compare, _Allocator>::__construct_node_with_key(const key_type& __k)
 {
     __node_allocator& __na = __tree_.__node_alloc();
     __node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
@@ -1217,8 +1196,6 @@ map<_Key, _Tp, _Compare, _Allocator>::__construct_node(const key_type& __k)
     return _VSTD::move(__h);
 }
 
-#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
-
 template <class _Key, class _Tp, class _Compare, class _Allocator>
 _Tp&
 map<_Key, _Tp, _Compare, _Allocator>::operator[](const key_type& __k)
@@ -1228,7 +1205,7 @@ map<_Key, _Tp, _Compare, _Allocator>::operator[](const key_type& __k)
     __node_pointer __r = static_cast<__node_pointer>(__child);
     if (__child == nullptr)
     {
-        __node_holder __h = __construct_node(__k);
+        __node_holder __h = __construct_node_with_key(__k);
         __tree_.__insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
         __r = __h.release();
     }
@@ -1246,7 +1223,7 @@ map<_Key, _Tp, _Compare, _Allocator>::operator[](key_type&& __k)
     __node_pointer __r = static_cast<__node_pointer>(__child);
     if (__child == nullptr)
     {
-        __node_holder __h = __construct_node(_VSTD::move(__k));
+        __node_holder __h = __construct_node_with_key(_VSTD::move(__k));
         __tree_.__insert_node_at(__parent, __child, static_cast<__node_base_pointer>(__h.get()));
         __r = __h.release();
     }
@@ -1733,18 +1710,7 @@ private:
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     __node_holder __construct_node();
     template <class _A0>
-        typename enable_if
-        <
-            is_constructible<value_type, _A0>::value,
-            __node_holder
-        >::type
-         __construct_node(_A0&& __a0);
-    template <class _A0>
-        typename enable_if
-        <
-            is_constructible<key_type, _A0>::value,
-            __node_holder
-        >::type
+        __node_holder
          __construct_node(_A0&& __a0);
 #ifndef _LIBCPP_HAS_NO_VARIADICS
     template <class _A0, class _A1, class ..._Args>
@@ -1783,11 +1749,7 @@ multimap<_Key, _Tp, _Compare, _Allocator>::__construct_node()
 
 template <class _Key, class _Tp, class _Compare, class _Allocator>
 template <class _A0>
-typename enable_if
-<
-    is_constructible<pair<const _Key, _Tp>, _A0>::value,
-    typename multimap<_Key, _Tp, _Compare, _Allocator>::__node_holder
->::type
+typename multimap<_Key, _Tp, _Compare, _Allocator>::__node_holder
 multimap<_Key, _Tp, _Compare, _Allocator>::__construct_node(_A0&& __a0)
 {
     __node_allocator& __na = __tree_.__node_alloc();
@@ -1798,24 +1760,6 @@ multimap<_Key, _Tp, _Compare, _Allocator>::__construct_node(_A0&& __a0)
     return __h;
 }
 
-template <class _Key, class _Tp, class _Compare, class _Allocator>
-template <class _A0>
-typename enable_if
-<
-    is_constructible<_Key, _A0>::value,
-    typename multimap<_Key, _Tp, _Compare, _Allocator>::__node_holder
->::type
-multimap<_Key, _Tp, _Compare, _Allocator>::__construct_node(_A0&& __a0)
-{
-    __node_allocator& __na = __tree_.__node_alloc();
-    __node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
-    __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.first), _VSTD::forward<_A0>(__a0));
-    __h.get_deleter().__first_constructed = true;
-    __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.second));
-    __h.get_deleter().__second_constructed = true;
-    return __h;
-}
-
 #ifndef _LIBCPP_HAS_NO_VARIADICS
 
 template <class _Key, class _Tp, class _Compare, class _Allocator>
diff --git a/libcxx/include/unordered_map b/libcxx/include/unordered_map
index cc30d763424..0d2ce292076 100644
--- a/libcxx/include/unordered_map
+++ b/libcxx/include/unordered_map
@@ -917,26 +917,15 @@ private:
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     __node_holder __construct_node();
     template <class _A0>
-        typename enable_if
-        <
-            is_constructible<value_type, _A0>::value,
-            __node_holder
-        >::type
-         __construct_node(_A0&& __a0);
-    template <class _A0>
-        typename enable_if
-        <
-            is_constructible<key_type, _A0>::value,
-            __node_holder
-        >::type
+        __node_holder
          __construct_node(_A0&& __a0);
+    __node_holder __construct_node_with_key(key_type&& __k);
 #ifndef _LIBCPP_HAS_NO_VARIADICS
     template <class _A0, class _A1, class ..._Args>
         __node_holder __construct_node(_A0&& __a0, _A1&& __a1, _Args&& ...__args);
 #endif  // _LIBCPP_HAS_NO_VARIADICS
-#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
-    __node_holder __construct_node(const key_type& __k);
-#endif
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+    __node_holder __construct_node_with_key(const key_type& __k);
 };
 
 template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
@@ -1115,11 +1104,7 @@ unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node()
 
 template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
 template <class _A0>
-typename enable_if
-<
-    is_constructible<pair<const _Key, _Tp>, _A0>::value,
-    typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
->::type
+typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
 unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node(_A0&& __a0)
 {
     __node_allocator& __na = __table_.__node_alloc();
@@ -1132,22 +1117,16 @@ unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node(_A0&& __a0)
 }
 
 template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
-template <class _A0>
-typename enable_if
-<
-    is_constructible<_Key, _A0>::value,
-    typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
->::type
-unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node(_A0&& __a0)
+typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
+unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node_with_key(key_type&& __k)
 {
     __node_allocator& __na = __table_.__node_alloc();
     __node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
-    __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.first),
-                             _VSTD::forward<_A0>(__a0));
+    __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.first), _VSTD::move(__k));
     __h.get_deleter().__first_constructed = true;
     __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.second));
     __h.get_deleter().__second_constructed = true;
-    return __h;
+    return _VSTD::move(__h);
 }
 
 #ifndef _LIBCPP_HAS_NO_VARIADICS
@@ -1182,11 +1161,11 @@ unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::emplace(_Args&&... __args)
 }
 
 #endif  // _LIBCPP_HAS_NO_VARIADICS
-#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
 template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
 typename unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
-unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node(const key_type& __k)
+unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node_with_key(const key_type& __k)
 {
     __node_allocator& __na = __table_.__node_alloc();
     __node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
@@ -1197,8 +1176,6 @@ unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node(const key_type&
     return _VSTD::move(__h);
 }
 
-#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
-
 template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
 template <class _InputIterator>
 inline _LIBCPP_INLINE_VISIBILITY
@@ -1217,7 +1194,7 @@ unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::operator[](const key_type& __k)
     iterator __i = find(__k);
     if (__i != end())
         return __i->second;
-    __node_holder __h = __construct_node(__k);
+    __node_holder __h = __construct_node_with_key(__k);
     pair<iterator, bool> __r = __table_.__node_insert_unique(__h.get());
     __h.release();
     return __r.first->second;
@@ -1232,7 +1209,7 @@ unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::operator[](key_type&& __k)
     iterator __i = find(__k);
     if (__i != end())
         return __i->second;
-    __node_holder __h = __construct_node(_VSTD::move(__k));
+    __node_holder __h = __construct_node_with_key(_VSTD::move(__k));
     pair<iterator, bool> __r = __table_.__node_insert_unique(__h.get());
     __h.release();
     return __r.first->second;
@@ -1595,18 +1572,7 @@ private:
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     __node_holder __construct_node();
     template <class _A0>
-        typename enable_if
-        <
-            is_constructible<value_type, _A0>::value,
-            __node_holder
-        >::type
-         __construct_node(_A0&& __a0);
-    template <class _A0>
-        typename enable_if
-        <
-            is_constructible<key_type, _A0>::value,
-            __node_holder
-        >::type
+        __node_holder
          __construct_node(_A0&& __a0);
 #ifndef _LIBCPP_HAS_NO_VARIADICS
     template <class _A0, class _A1, class ..._Args>
@@ -1793,11 +1759,7 @@ unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node()
 
 template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
 template <class _A0>
-typename enable_if
-<
-    is_constructible<pair<const _Key, _Tp>, _A0>::value,
-    typename unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
->::type
+typename unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
 unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node(_A0&& __a0)
 {
     __node_allocator& __na = __table_.__node_alloc();
@@ -1809,25 +1771,6 @@ unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node(_A0&& __a0
     return __h;
 }
 
-template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
-template <class _A0>
-typename enable_if
-<
-    is_constructible<_Key, _A0>::value,
-    typename unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::__node_holder
->::type
-unordered_multimap<_Key, _Tp, _Hash, _Pred, _Alloc>::__construct_node(_A0&& __a0)
-{
-    __node_allocator& __na = __table_.__node_alloc();
-    __node_holder __h(__node_traits::allocate(__na, 1), _Dp(__na));
-    __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.first),
-                             _VSTD::forward<_A0>(__a0));
-    __h.get_deleter().__first_constructed = true;
-    __node_traits::construct(__na, _VSTD::addressof(__h->__value_.__cc.second));
-    __h.get_deleter().__second_constructed = true;
-    return __h;
-}
-
 #ifndef _LIBCPP_HAS_NO_VARIADICS
 
 template <class _Key, class _Tp, class _Hash, class _Pred, class _Alloc>
diff --git a/libcxx/test/containers/associative/map/map.access/index_tuple.pass.cpp b/libcxx/test/containers/associative/map/map.access/index_tuple.pass.cpp
new file mode 100644
index 00000000000..9a00829eadd
--- /dev/null
+++ b/libcxx/test/containers/associative/map/map.access/index_tuple.pass.cpp
@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <map>
+
+// class map
+
+// mapped_type& operator[](const key_type& k);
+
+// http://llvm.org/bugs/show_bug.cgi?id=16542
+
+#include <map>
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+#include <tuple>
+
+#endif
+
+int main()
+{
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+    using namespace std;
+    map<tuple<int,int>, size_t> m;
+    m[make_tuple(2,3)]=7;
+#endif
+}
diff --git a/libcxx/test/containers/associative/map/map.modifiers/emplace.pass.cpp b/libcxx/test/containers/associative/map/map.modifiers/emplace.pass.cpp
index 3ade69db72e..9a87becf684 100644
--- a/libcxx/test/containers/associative/map/map.modifiers/emplace.pass.cpp
+++ b/libcxx/test/containers/associative/map/map.modifiers/emplace.pass.cpp
@@ -37,14 +37,16 @@ int main()
         assert(m.begin()->first == 0);
         assert(m.begin()->second == DefaultOnly());
         assert(DefaultOnly::count == 1);
-        r = m.emplace(1);
+        r = m.emplace(std::piecewise_construct, std::forward_as_tuple(1),
+                                                std::forward_as_tuple());
         assert(r.second);
         assert(r.first == next(m.begin()));
         assert(m.size() == 2);
         assert(next(m.begin())->first == 1);
         assert(next(m.begin())->second == DefaultOnly());
         assert(DefaultOnly::count == 2);
-        r = m.emplace(1);
+        r = m.emplace(std::piecewise_construct, std::forward_as_tuple(1),
+                                                std::forward_as_tuple());
         assert(!r.second);
         assert(r.first == next(m.begin()));
         assert(m.size() == 2);
@@ -57,7 +59,8 @@ int main()
         typedef std::map<int, Emplaceable> M;
         typedef std::pair<M::iterator, bool> R;
         M m;
-        R r = m.emplace(2);
+        R r = m.emplace(std::piecewise_construct, std::forward_as_tuple(2),
+                                                  std::forward_as_tuple());
         assert(r.second);
         assert(r.first == m.begin());
         assert(m.size() == 1);
@@ -102,14 +105,16 @@ int main()
         assert(m.begin()->first == 0);
         assert(m.begin()->second == DefaultOnly());
         assert(DefaultOnly::count == 1);
-        r = m.emplace(1);
+        r = m.emplace(std::piecewise_construct, std::forward_as_tuple(1),
+                                                std::forward_as_tuple());
         assert(r.second);
         assert(r.first == next(m.begin()));
         assert(m.size() == 2);
         assert(next(m.begin())->first == 1);
         assert(next(m.begin())->second == DefaultOnly());
         assert(DefaultOnly::count == 2);
-        r = m.emplace(1);
+        r = m.emplace(std::piecewise_construct, std::forward_as_tuple(1),
+                                                std::forward_as_tuple());
         assert(!r.second);
         assert(r.first == next(m.begin()));
         assert(m.size() == 2);
@@ -122,7 +127,8 @@ int main()
         typedef std::map<int, Emplaceable, std::less<int>, min_allocator<std::pair<const int, Emplaceable>>> M;
         typedef std::pair<M::iterator, bool> R;
         M m;
-        R r = m.emplace(2);
+        R r = m.emplace(std::piecewise_construct, std::forward_as_tuple(2),
+                                                  std::forward_as_tuple());
         assert(r.second);
         assert(r.first == m.begin());
         assert(m.size() == 1);
diff --git a/libcxx/test/containers/associative/map/map.modifiers/emplace_hint.pass.cpp b/libcxx/test/containers/associative/map/map.modifiers/emplace_hint.pass.cpp
index e1eb586d487..bf8173f770d 100644
--- a/libcxx/test/containers/associative/map/map.modifiers/emplace_hint.pass.cpp
+++ b/libcxx/test/containers/associative/map/map.modifiers/emplace_hint.pass.cpp
@@ -35,13 +35,17 @@ int main()
         assert(m.begin()->first == 0);
         assert(m.begin()->second == DefaultOnly());
         assert(DefaultOnly::count == 1);
-        r = m.emplace_hint(m.end(), 1);
+        r = m.emplace_hint(m.end(), std::piecewise_construct,
+                                       std::forward_as_tuple(1),
+                                       std::forward_as_tuple());
         assert(r == next(m.begin()));
         assert(m.size() == 2);
         assert(next(m.begin())->first == 1);
         assert(next(m.begin())->second == DefaultOnly());
         assert(DefaultOnly::count == 2);
-        r = m.emplace_hint(m.end(), 1);
+        r = m.emplace_hint(m.end(), std::piecewise_construct,
+                                       std::forward_as_tuple(1),
+                                       std::forward_as_tuple());
         assert(r == next(m.begin()));
         assert(m.size() == 2);
         assert(next(m.begin())->first == 1);
@@ -53,7 +57,9 @@ int main()
         typedef std::map<int, Emplaceable> M;
         typedef M::iterator R;
         M m;
-        R r = m.emplace_hint(m.end(), 2);
+        R r = m.emplace_hint(m.end(), std::piecewise_construct,
+                                       std::forward_as_tuple(2),
+                                       std::forward_as_tuple());
         assert(r == m.begin());
         assert(m.size() == 1);
         assert(m.begin()->first == 2);
@@ -95,13 +101,17 @@ int main()
         assert(m.begin()->first == 0);
         assert(m.begin()->second == DefaultOnly());
         assert(DefaultOnly::count == 1);
-        r = m.emplace_hint(m.end(), 1);
+        r = m.emplace_hint(m.end(), std::piecewise_construct,
+                                       std::forward_as_tuple(1),
+                                       std::forward_as_tuple());
         assert(r == next(m.begin()));
         assert(m.size() == 2);
         assert(next(m.begin())->first == 1);
         assert(next(m.begin())->second == DefaultOnly());
         assert(DefaultOnly::count == 2);
-        r = m.emplace_hint(m.end(), 1);
+        r = m.emplace_hint(m.end(), std::piecewise_construct,
+                                       std::forward_as_tuple(1),
+                                       std::forward_as_tuple());
         assert(r == next(m.begin()));
         assert(m.size() == 2);
         assert(next(m.begin())->first == 1);
@@ -113,7 +123,9 @@ int main()
         typedef std::map<int, Emplaceable, std::less<int>, min_allocator<std::pair<const int, Emplaceable>>> M;
         typedef M::iterator R;
         M m;
-        R r = m.emplace_hint(m.end(), 2);
+        R r = m.emplace_hint(m.end(), std::piecewise_construct,
+                                       std::forward_as_tuple(2),
+                                       std::forward_as_tuple());
         assert(r == m.begin());
         assert(m.size() == 1);
         assert(m.begin()->first == 2);
diff --git a/libcxx/test/containers/associative/multimap/multimap.modifiers/emplace.pass.cpp b/libcxx/test/containers/associative/multimap/multimap.modifiers/emplace.pass.cpp
index c91909e7224..7af44261b43 100644
--- a/libcxx/test/containers/associative/multimap/multimap.modifiers/emplace.pass.cpp
+++ b/libcxx/test/containers/associative/multimap/multimap.modifiers/emplace.pass.cpp
@@ -35,13 +35,15 @@ int main()
         assert(m.begin()->first == 0);
         assert(m.begin()->second == DefaultOnly());
         assert(DefaultOnly::count == 1);
-        r = m.emplace(1);
+        r = m.emplace(std::piecewise_construct, std::forward_as_tuple(1),
+                                                std::forward_as_tuple());
         assert(r == next(m.begin()));
         assert(m.size() == 2);
         assert(next(m.begin())->first == 1);
         assert(next(m.begin())->second == DefaultOnly());
         assert(DefaultOnly::count == 2);
-        r = m.emplace(1);
+        r = m.emplace(std::piecewise_construct, std::forward_as_tuple(1),
+                                                std::forward_as_tuple());
         assert(r == next(m.begin(), 2));
         assert(m.size() == 3);
         assert(next(m.begin(), 2)->first == 1);
@@ -53,7 +55,8 @@ int main()
         typedef std::multimap<int, Emplaceable> M;
         typedef M::iterator R;
         M m;
-        R r = m.emplace(2);
+        R r = m.emplace(std::piecewise_construct, std::forward_as_tuple(2),
+                                                  std::forward_as_tuple());
         assert(r == m.begin());
         assert(m.size() == 1);
         assert(m.begin()->first == 2);
@@ -93,13 +96,15 @@ int main()
         assert(m.begin()->first == 0);
         assert(m.begin()->second == DefaultOnly());
         assert(DefaultOnly::count == 1);
-        r = m.emplace(1);
+        r = m.emplace(std::piecewise_construct, std::forward_as_tuple(1),
+                                                std::forward_as_tuple());
         assert(r == next(m.begin()));
         assert(m.size() == 2);
         assert(next(m.begin())->first == 1);
         assert(next(m.begin())->second == DefaultOnly());
         assert(DefaultOnly::count == 2);
-        r = m.emplace(1);
+        r = m.emplace(std::piecewise_construct, std::forward_as_tuple(1),
+                                                std::forward_as_tuple());
         assert(r == next(m.begin(), 2));
         assert(m.size() == 3);
         assert(next(m.begin(), 2)->first == 1);
@@ -111,7 +116,8 @@ int main()
         typedef std::multimap<int, Emplaceable, std::less<int>, min_allocator<std::pair<const int, Emplaceable>>> M;
         typedef M::iterator R;
         M m;
-        R r = m.emplace(2);
+        R r = m.emplace(std::piecewise_construct, std::forward_as_tuple(2),
+                                                  std::forward_as_tuple());
         assert(r == m.begin());
         assert(m.size() == 1);
         assert(m.begin()->first == 2);
diff --git a/libcxx/test/containers/associative/multimap/multimap.modifiers/emplace_hint.pass.cpp b/libcxx/test/containers/associative/multimap/multimap.modifiers/emplace_hint.pass.cpp
index 8dc3195b711..3f94c03a3e5 100644
--- a/libcxx/test/containers/associative/multimap/multimap.modifiers/emplace_hint.pass.cpp
+++ b/libcxx/test/containers/associative/multimap/multimap.modifiers/emplace_hint.pass.cpp
@@ -35,13 +35,17 @@ int main()
         assert(m.begin()->first == 0);
         assert(m.begin()->second == DefaultOnly());
         assert(DefaultOnly::count == 1);
-        r = m.emplace_hint(m.cend(), 1);
+        r = m.emplace_hint(m.cend(), std::piecewise_construct,
+                                       std::forward_as_tuple(1),
+                                       std::forward_as_tuple());
         assert(r == next(m.begin()));
         assert(m.size() == 2);
         assert(next(m.begin())->first == 1);
         assert(next(m.begin())->second == DefaultOnly());
         assert(DefaultOnly::count == 2);
-        r = m.emplace_hint(m.cend(), 1);
+        r = m.emplace_hint(m.cend(), std::piecewise_construct,
+                                       std::forward_as_tuple(1),
+                                       std::forward_as_tuple());
         assert(r == next(m.begin(), 2));
         assert(m.size() == 3);
         assert(next(m.begin(), 2)->first == 1);
@@ -53,7 +57,9 @@ int main()
         typedef std::multimap<int, Emplaceable> M;
         typedef M::iterator R;
         M m;
-        R r = m.emplace_hint(m.cend(), 2);
+        R r = m.emplace_hint(m.cend(), std::piecewise_construct,
+                                       std::forward_as_tuple(2),
+                                       std::forward_as_tuple());
         assert(r == m.begin());
         assert(m.size() == 1);
         assert(m.begin()->first == 2);
@@ -95,13 +101,17 @@ int main()
         assert(m.begin()->first == 0);
         assert(m.begin()->second == DefaultOnly());
         assert(DefaultOnly::count == 1);
-        r = m.emplace_hint(m.cend(), 1);
+        r = m.emplace_hint(m.cend(), std::piecewise_construct,
+                                       std::forward_as_tuple(1),
+                                       std::forward_as_tuple());
         assert(r == next(m.begin()));
         assert(m.size() == 2);
         assert(next(m.begin())->first == 1);
         assert(next(m.begin())->second == DefaultOnly());
         assert(DefaultOnly::count == 2);
-        r = m.emplace_hint(m.cend(), 1);
+        r = m.emplace_hint(m.cend(), std::piecewise_construct,
+                                       std::forward_as_tuple(1),
+                                       std::forward_as_tuple());
         assert(r == next(m.begin(), 2));
         assert(m.size() == 3);
         assert(next(m.begin(), 2)->first == 1);
@@ -113,7 +123,9 @@ int main()
         typedef std::multimap<int, Emplaceable, std::less<int>, min_allocator<std::pair<const int, Emplaceable>>> M;
         typedef M::iterator R;
         M m;
-        R r = m.emplace_hint(m.cend(), 2);
+        R r = m.emplace_hint(m.cend(), std::piecewise_construct,
+                                       std::forward_as_tuple(2),
+                                       std::forward_as_tuple());
         assert(r == m.begin());
         assert(m.size() == 1);
         assert(m.begin()->first == 2);
diff --git a/libcxx/test/containers/unord/unord.map/unord.map.elem/index_tuple.pass.cpp b/libcxx/test/containers/unord/unord.map/unord.map.elem/index_tuple.pass.cpp
new file mode 100644
index 00000000000..c319b5c30b2
--- /dev/null
+++ b/libcxx/test/containers/unord/unord.map/unord.map.elem/index_tuple.pass.cpp
@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <unordered_map>
+
+// template <class Key, class T, class Hash = hash<Key>, class Pred = equal_to<Key>,
+//           class Alloc = allocator<pair<const Key, T>>>
+// class unordered_map
+
+// mapped_type& operator[](const key_type& k);
+
+// http://llvm.org/bugs/show_bug.cgi?id=16542
+
+#include <unordered_map>
+
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+
+#include <tuple>
+
+using namespace std;
+
+struct my_hash
+{
+    size_t operator()(const tuple<int,int>&) const {return 0;}
+};
+
+#endif
+
+int main()
+{
+#ifndef _LIBCPP_HAS_NO_VARIADICS
+    unordered_map<tuple<int,int>, size_t, my_hash> m;
+    m[make_tuple(2,3)]=7;
+#endif
+}
diff --git a/libcxx/test/containers/unord/unord.map/unorder.map.modifiers/emplace.pass.cpp b/libcxx/test/containers/unord/unord.map/unorder.map.modifiers/emplace.pass.cpp
index 515b32925ca..a115101d761 100644
--- a/libcxx/test/containers/unord/unord.map/unorder.map.modifiers/emplace.pass.cpp
+++ b/libcxx/test/containers/unord/unord.map/unorder.map.modifiers/emplace.pass.cpp
@@ -29,7 +29,8 @@ int main()
         typedef std::unordered_map<int, Emplaceable> C;
         typedef std::pair<C::iterator, bool> R;
         C c;
-        R r = c.emplace(3);
+        R r = c.emplace(std::piecewise_construct, std::forward_as_tuple(3),
+                                                  std::forward_as_tuple());
         assert(r.second);
         assert(c.size() == 1);
         assert(r.first->first == 3);
@@ -54,7 +55,8 @@ int main()
                             min_allocator<std::pair<const int, Emplaceable>>> C;
         typedef std::pair<C::iterator, bool> R;
         C c;
-        R r = c.emplace(3);
+        R r = c.emplace(std::piecewise_construct, std::forward_as_tuple(3),
+                                                  std::forward_as_tuple());
         assert(r.second);
         assert(c.size() == 1);
         assert(r.first->first == 3);
diff --git a/libcxx/test/containers/unord/unord.map/unorder.map.modifiers/emplace_hint.pass.cpp b/libcxx/test/containers/unord/unord.map/unorder.map.modifiers/emplace_hint.pass.cpp
index 6c2a75a2913..6d6f3315e1a 100644
--- a/libcxx/test/containers/unord/unord.map/unorder.map.modifiers/emplace_hint.pass.cpp
+++ b/libcxx/test/containers/unord/unord.map/unorder.map.modifiers/emplace_hint.pass.cpp
@@ -30,7 +30,8 @@ int main()
         typedef C::iterator R;
         C c;
         C::const_iterator e = c.end();
-        R r = c.emplace_hint(e, 3);
+        R r = c.emplace_hint(e, std::piecewise_construct, std::forward_as_tuple(3),
+                                                          std::forward_as_tuple());
         assert(c.size() == 1);
         assert(r->first == 3);
         assert(r->second == Emplaceable());
@@ -53,7 +54,8 @@ int main()
         typedef C::iterator R;
         C c;
         C::const_iterator e = c.end();
-        R r = c.emplace_hint(e, 3);
+        R r = c.emplace_hint(e, std::piecewise_construct, std::forward_as_tuple(3),
+                                                          std::forward_as_tuple());
         assert(c.size() == 1);
         assert(r->first == 3);
         assert(r->second == Emplaceable());
diff --git a/libcxx/test/containers/unord/unord.multimap/unord.multimap.modifiers/emplace.pass.cpp b/libcxx/test/containers/unord/unord.multimap/unord.multimap.modifiers/emplace.pass.cpp
index 244419dc221..80453b199d7 100644
--- a/libcxx/test/containers/unord/unord.multimap/unord.multimap.modifiers/emplace.pass.cpp
+++ b/libcxx/test/containers/unord/unord.multimap/unord.multimap.modifiers/emplace.pass.cpp
@@ -29,7 +29,8 @@ int main()
         typedef std::unordered_multimap<int, Emplaceable> C;
         typedef C::iterator R;
         C c;
-        R r = c.emplace(3);
+        R r = c.emplace(std::piecewise_construct, std::forward_as_tuple(3),
+                                                  std::forward_as_tuple());
         assert(c.size() == 1);
         assert(r->first == 3);
         assert(r->second == Emplaceable());
@@ -51,7 +52,8 @@ int main()
                             min_allocator<std::pair<const int, Emplaceable>>> C;
         typedef C::iterator R;
         C c;
-        R r = c.emplace(3);
+        R r = c.emplace(std::piecewise_construct, std::forward_as_tuple(3),
+                                                  std::forward_as_tuple());
         assert(c.size() == 1);
         assert(r->first == 3);
         assert(r->second == Emplaceable());
diff --git a/libcxx/test/containers/unord/unord.multimap/unord.multimap.modifiers/emplace_hint.pass.cpp b/libcxx/test/containers/unord/unord.multimap/unord.multimap.modifiers/emplace_hint.pass.cpp
index 576be4e37aa..bad1ee28f22 100644
--- a/libcxx/test/containers/unord/unord.multimap/unord.multimap.modifiers/emplace_hint.pass.cpp
+++ b/libcxx/test/containers/unord/unord.multimap/unord.multimap.modifiers/emplace_hint.pass.cpp
@@ -30,7 +30,8 @@ int main()
         typedef C::iterator R;
         C c;
         C::const_iterator e = c.end();
-        R r = c.emplace_hint(e, 3);
+        R r = c.emplace_hint(e, std::piecewise_construct, std::forward_as_tuple(3),
+                                                          std::forward_as_tuple());
         assert(c.size() == 1);
         assert(r->first == 3);
         assert(r->second == Emplaceable());
@@ -61,7 +62,8 @@ int main()
         typedef C::iterator R;
         C c;
         C::const_iterator e = c.end();
-        R r = c.emplace_hint(e, 3);
+        R r = c.emplace_hint(e, std::piecewise_construct, std::forward_as_tuple(3),
+                                                          std::forward_as_tuple());
         assert(c.size() == 1);
         assert(r->first == 3);
         assert(r->second == Emplaceable());