Add experimental container alias templates for PMRs

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@268841 91177308-0d34-0410-b5e6-96231b3b80d8

include/experimental/unordered_map

@@ -0,0 +1,65 @@
+// -*- C++ -*-
+//===------------------------- unordered_map ------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_EXPERIMENTAL_UNORDERED_MAP
+#define _LIBCPP_EXPERIMENTAL_UNORDERED_MAP
+/*
+    experimental/unordered_map synopsis
+
+// C++1z
+namespace std {
+namespace experimental {
+inline namespace fundamentals_v1 {
+namespace pmr {
+
+  template <class Key, class T,
+            class Hash = hash<Key>,
+            class Pred = equal_to<Key>>
+  using unordered_map =
+    std::unordered_map<Key, T, Hash, Pred,
+                       polymorphic_allocator<pair<const Key,T>>>;
+
+  template <class Key, class T,
+            class Hash = hash<Key>,
+            class Pred = equal_to<Key>>
+  using unordered_multimap =
+    std::unordered_multimap<Key, T, Hash, Pred,
+                            polymorphic_allocator<pair<const Key,T>>>;
+
+} // namespace pmr
+} // namespace fundamentals_v1
+} // namespace experimental
+} // namespace std
+
+ */
+
+#include <experimental/__config>
+#include <unordered_map>
+#include <experimental/memory_resource>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_LFTS_PMR
+
+template <class _Key, class _Value,
+          class _Hash = hash<_Key>, class _Pred = equal_to<_Key>>
+using unordered_map = _VSTD::unordered_map<_Key, _Value, _Hash, _Pred,
+                        polymorphic_allocator<pair<const _Key, _Value>>>;
+
+template <class _Key, class _Value,
+          class _Hash = hash<_Key>, class _Pred = equal_to<_Key>>
+using unordered_multimap = _VSTD::unordered_multimap<_Key, _Value, _Hash, _Pred,
+                        polymorphic_allocator<pair<const _Key, _Value>>>;
+
+_LIBCPP_END_NAMESPACE_LFTS_PMR
+
+#endif /* _LIBCPP_EXPERIMENTAL_UNORDERED_MAP */