Implement P0513R0 - "Poisoning the Hash"

Summary:
Exactly what the title says.

This patch also adds a `std::hash<nullptr_t>` specialization in C++17, but it was not added by this paper and I can't find the actual paper that adds it.

See http://wg21.link/P0513R0 for more info.

If there are no comments in the next couple of days I'll commit this

Reviewers: mclow.lists, K-ballo, EricWF

Reviewed By: EricWF

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D28938

llvm-svn: 292684

23 files changed, 812 insertions, 47 deletions

diff --git a/libcxx/test/libcxx/test/config.py b/libcxx/test/libcxx/test/config.py
index ae48c735a23..0d90258267a 100644
--- a/libcxx/test/libcxx/test/config.py
+++ b/libcxx/test/libcxx/test/config.py
@@ -423,15 +423,6 @@ class Configuration(object):
         if not std:
             # Choose the newest possible language dialect if none is given.
             possible_stds = ['c++1z', 'c++14', 'c++11', 'c++03']
-            if self.cxx.type == 'gcc':
-                maj_v, _, _ = self.cxx.version
-                maj_v = int(maj_v)
-                if maj_v < 7:
-                    possible_stds.remove('c++1z')
-                # FIXME: How many C++14 tests actually fail under GCC 5 and 6?
-                # Should we XFAIL them individually instead?
-                if maj_v <= 6:
-                    possible_stds.remove('c++14')
             for s in possible_stds:
                 if self.cxx.hasCompileFlag('-std=%s' % s):
                     std = s
diff --git a/libcxx/test/std/containers/sequences/vector.bool/enabled_hash.pass.cpp b/libcxx/test/std/containers/sequences/vector.bool/enabled_hash.pass.cpp
new file mode 100644
index 00000000000..f8a8dbd8d6d
--- /dev/null
+++ b/libcxx/test/std/containers/sequences/vector.bool/enabled_hash.pass.cpp
@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <vector>
+
+// Test that <vector> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <vector>
+
+#include "poisoned_hash_helper.hpp"
+#include "min_allocator.h"
+
+int main() {
+  test_library_hash_specializations_available();
+  {
+    test_hash_enabled_for_type<std::vector<bool> >();
+    test_hash_enabled_for_type<std::vector<bool, min_allocator<bool>>>();
+  }
+}
diff --git a/libcxx/test/std/diagnostics/syserr/syserr.hash/enabled_hash.pass.cpp b/libcxx/test/std/diagnostics/syserr/syserr.hash/enabled_hash.pass.cpp
new file mode 100644
index 00000000000..f1b46057591
--- /dev/null
+++ b/libcxx/test/std/diagnostics/syserr/syserr.hash/enabled_hash.pass.cpp
@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <system_error>
+
+// Test that <system_error> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <system_error>
+
+#include "poisoned_hash_helper.hpp"
+
+int main() {
+  test_library_hash_specializations_available();
+  {
+    test_hash_enabled_for_type<std::error_code>();
+    test_hash_enabled_for_type<std::error_condition>();
+  }
+}
diff --git a/libcxx/test/std/strings/basic.string.hash/enabled_hashes.pass.cpp b/libcxx/test/std/strings/basic.string.hash/enabled_hashes.pass.cpp
new file mode 100644
index 00000000000..01f01218999
--- /dev/null
+++ b/libcxx/test/std/strings/basic.string.hash/enabled_hashes.pass.cpp
@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <string>
+
+// Test that <string> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <string>
+
+#include "poisoned_hash_helper.hpp"
+
+int main() {
+  test_library_hash_specializations_available();
+  {
+    test_hash_enabled_for_type<std::string>();
+    test_hash_enabled_for_type<std::wstring>();
+#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
+    test_hash_enabled_for_type<std::u16string>();
+    test_hash_enabled_for_type<std::u32string>();
+#endif
+  }
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.hash/enabled_hashes.pass.cpp b/libcxx/test/std/strings/string.view/string.view.hash/enabled_hashes.pass.cpp
new file mode 100644
index 00000000000..2e9ebcb4c03
--- /dev/null
+++ b/libcxx/test/std/strings/string.view/string.view.hash/enabled_hashes.pass.cpp
@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <string_view>
+
+// Test that <string_view> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <string_view>
+
+#include "poisoned_hash_helper.hpp"
+
+int main() {
+  test_library_hash_specializations_available();
+  {
+    test_hash_enabled_for_type<std::string_view>();
+    test_hash_enabled_for_type<std::wstring_view>();
+#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
+    test_hash_enabled_for_type<std::u16string_view>();
+    test_hash_enabled_for_type<std::u32string_view>();
+#endif
+  }
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.hash/string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.hash/string_view.pass.cpp
index 63099e2c886..d0766482551 100644
--- a/libcxx/test/std/strings/string.view/string.view.hash/string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.hash/string_view.pass.cpp
@@ -19,29 +19,38 @@
 // Not very portable
 
 #include <string_view>
+#include <string>
 #include <cassert>
 #include <type_traits>
 
 using std::string_view;
 
-template <class T>
+template <class SV>
 void
 test()
 {
-    typedef std::hash<T> H;
-    static_assert((std::is_same<typename H::argument_type, T>::value), "" );
+    typedef std::hash<SV> H;
+    static_assert((std::is_same<typename H::argument_type, SV>::value), "" );
     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
-    H h;
-//     std::string g1 = "1234567890";
-//     std::string g2 = "1234567891";
-    typedef typename T::value_type char_type;
+
+    typedef typename SV::value_type char_type;
+    typedef std::basic_string<char_type> String;
+    typedef std::hash<String> SH;
+
     char_type g1 [ 10 ];
     char_type g2 [ 10 ];
     for ( int i = 0; i < 10; ++i )
         g1[i] = g2[9-i] = static_cast<char_type>('0' + i);
-    T s1(g1, 10);
-    T s2(g2, 10);
+    H h;
+    SH sh;
+    SV s1(g1, 10);
+    String ss1(s1);
+    SV s2(g2, 10);
+    String ss2(s2);
+    assert(h(s1) == h(s1));
     assert(h(s1) != h(s2));
+    assert(sh(ss1) == h(s1));
+    assert(sh(ss2) == h(s2));
 }
 
 int main()
diff --git a/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/enabled_hashes.pass.cpp b/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/enabled_hashes.pass.cpp
new file mode 100644
index 00000000000..9799467c452
--- /dev/null
+++ b/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/enabled_hashes.pass.cpp
@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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: libcpp-has-no-threads
+// UNSUPPORTED: c++98, c++03
+
+// <thread>
+
+// Test that <thread> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <thread>
+
+#include "poisoned_hash_helper.hpp"
+
+int main() {
+  test_library_hash_specializations_available();
+  {
+    test_hash_enabled_for_type<std::thread::id>();
+  }
+}
diff --git a/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/thread_id.pass.cpp b/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/thread_id.pass.cpp
index 106c69e2e4a..f7d4deb8f98 100644
--- a/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/thread_id.pass.cpp
+++ b/libcxx/test/std/thread/thread.threads/thread.thread.class/thread.thread.id/thread_id.pass.cpp
@@ -9,7 +9,7 @@
 //
 // UNSUPPORTED: libcpp-has-no-threads
 
-// <functional>
+// <thread>
 
 // template <class T>
 // struct hash
diff --git a/libcxx/test/std/utilities/function.objects/unord.hash/enabled_hashes.pass.cpp b/libcxx/test/std/utilities/function.objects/unord.hash/enabled_hashes.pass.cpp
new file mode 100644
index 00000000000..775247fc80b
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/unord.hash/enabled_hashes.pass.cpp
@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <functional>
+
+// Test that <functional> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <functional>
+
+#include "poisoned_hash_helper.hpp"
+
+int main() {
+  test_library_hash_specializations_available();
+}
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/enabled_hash.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/enabled_hash.pass.cpp
new file mode 100644
index 00000000000..e9237c534fb
--- /dev/null
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/enabled_hash.pass.cpp
@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <memory>
+
+// Test that <memory> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <memory>
+
+#include "poisoned_hash_helper.hpp"
+
+int main() {
+  test_library_hash_specializations_available();
+}
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/hash_shared_ptr.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/hash_shared_ptr.pass.cpp
index 990cb58722b..5fba1fc0460 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/hash_shared_ptr.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/hash_shared_ptr.pass.cpp
@@ -20,11 +20,25 @@
 #include <memory>
 #include <cassert>
 
+#if TEST_STD_VER >= 11
+#include "poisoned_hash_helper.hpp"
+
+struct A {};
+#endif
+
 int main()
 {
+  {
     int* ptr = new int;
     std::shared_ptr<int> p(ptr);
     std::hash<std::shared_ptr<int> > f;
     std::size_t h = f(p);
     assert(h == std::hash<int*>()(ptr));
+  }
+#if TEST_STD_VER >= 11
+  {
+    test_hash_enabled_for_type<std::shared_ptr<int>>();
+    test_hash_enabled_for_type<std::shared_ptr<A>>();
+  }
+#endif
 }
diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/hash_unique_ptr.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/hash_unique_ptr.pass.cpp
index 5cd4ab1f83d..f989a017348 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/hash_unique_ptr.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.hash/hash_unique_ptr.pass.cpp
@@ -20,11 +20,76 @@
 #include <memory>
 #include <cassert>
 
+#include "test_macros.h"
+
+#if TEST_STD_VER >= 11
+#include "poisoned_hash_helper.hpp"
+#include "deleter_types.h"
+#include "min_allocator.h"
+
+template <class ValueT, class Del>
+void test_enabled_with_deleter() {
+  using UPtr = std::unique_ptr<ValueT, Del>;
+  using pointer = typename UPtr::pointer;
+  using RawDel = typename std::decay<Del>::type;
+  RawDel d(1);
+  UPtr p(nullptr, std::forward<Del>(d));
+  test_hash_enabled_for_type<UPtr>(p);
+  test_hash_enabled_for_type<pointer>();
+}
+
+template <class ValueT, class Del>
+void test_disabled_with_deleter() {
+  using UPtr = std::unique_ptr<ValueT, Del>;
+  using pointer = typename UPtr::pointer;
+  test_hash_disabled_for_type<UPtr>();
+  test_hash_disabled_for_type<pointer>();
+}
+
+template <class T>
+struct std::hash<min_pointer<T, std::integral_constant<size_t, 1>>> {
+  size_t operator()(min_pointer<T, std::integral_constant<size_t, 1>> p) const {
+    if (!p) return 0;
+    return std::hash<T*>{}(std::addressof(*p));
+  }
+};
+
+struct A {};
+
+#endif // TEST_STD_VER >= 11
+
 int main()
 {
+  {
     int* ptr = new int;
     std::unique_ptr<int> p(ptr);
     std::hash<std::unique_ptr<int> > f;
     std::size_t h = f(p);
     assert(h == std::hash<int*>()(ptr));
+  }
+#if TEST_STD_VER >= 11
+  {
+    test_enabled_with_deleter<int, Deleter<int>>();
+    test_enabled_with_deleter<int[], Deleter<int[]>>();
+    test_enabled_with_deleter<int, CopyDeleter<int>>();
+    test_enabled_with_deleter<int, CopyDeleter<int[]>>();
+    test_enabled_with_deleter<int, NCDeleter<int>&>();
+    test_enabled_with_deleter<int[], NCDeleter<int[]>&>();
+    test_enabled_with_deleter<int, NCConstDeleter<int> const&>();
+    test_enabled_with_deleter<int[], NCConstDeleter<int[]> const&>();
+  }
+  {
+    test_enabled_with_deleter<int, PointerDeleter<int, 1>>();
+    test_enabled_with_deleter<int[], PointerDeleter<int[], 1>>();
+    test_enabled_with_deleter<A, PointerDeleter<A, 1>>();
+    test_enabled_with_deleter<A[], PointerDeleter<A[], 1>>();
+
+#if TEST_STD_VER > 14
+    test_disabled_with_deleter<int, PointerDeleter<int, 0>>();
+    test_disabled_with_deleter<int[], PointerDeleter<int[], 0>>();
+    test_disabled_with_deleter<A, PointerDeleter<A, 0>>();
+    test_disabled_with_deleter<A[], PointerDeleter<A[], 0>>();
+#endif
+  }
+#endif
 }
diff --git a/libcxx/test/std/utilities/optional/optional.hash/enabled_hash.pass.cpp b/libcxx/test/std/utilities/optional/optional.hash/enabled_hash.pass.cpp
new file mode 100644
index 00000000000..e54a4ced841
--- /dev/null
+++ b/libcxx/test/std/utilities/optional/optional.hash/enabled_hash.pass.cpp
@@ -0,0 +1,26 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <optional>
+
+// Test that <optional> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <optional>
+
+#include "poisoned_hash_helper.hpp"
+
+int main() {
+  test_library_hash_specializations_available();
+  {
+
+  }
+}
diff --git a/libcxx/test/std/utilities/optional/optional.hash/hash.pass.cpp b/libcxx/test/std/utilities/optional/optional.hash/hash.pass.cpp
index dfdd07ddf45..ea89dc3bd92 100644
--- a/libcxx/test/std/utilities/optional/optional.hash/hash.pass.cpp
+++ b/libcxx/test/std/utilities/optional/optional.hash/hash.pass.cpp
@@ -17,6 +17,15 @@
 #include <memory>
 #include <cassert>
 
+#include "poisoned_hash_helper.hpp"
+
+struct A {};
+struct B {};
+
+template <>
+struct std::hash<B> {
+  size_t operator()(B const&) { return 0; }
+};
 
 int main()
 {
@@ -45,4 +54,16 @@ int main()
         opt = std::unique_ptr<int>(new int(3));
         assert(std::hash<optional<T>>{}(opt) == std::hash<T>{}(*opt));
     }
+    {
+      test_hash_enabled_for_type<std::optional<int> >();
+      test_hash_enabled_for_type<std::optional<int*> >();
+      test_hash_enabled_for_type<std::optional<const int> >();
+      test_hash_enabled_for_type<std::optional<int* const> >();
+
+      test_hash_disabled_for_type<std::optional<A>>();
+      test_hash_disabled_for_type<std::optional<const A>>();
+
+      test_hash_enabled_for_type<std::optional<B>>();
+      test_hash_enabled_for_type<std::optional<const B>>();
+    }
 }
diff --git a/libcxx/test/std/utilities/template.bitset/bitset.hash/enabled_hash.pass.cpp b/libcxx/test/std/utilities/template.bitset/bitset.hash/enabled_hash.pass.cpp
new file mode 100644
index 00000000000..1d8bff41ae5
--- /dev/null
+++ b/libcxx/test/std/utilities/template.bitset/bitset.hash/enabled_hash.pass.cpp
@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <bitset>
+
+// Test that <bitset> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <bitset>
+
+#include "poisoned_hash_helper.hpp"
+
+int main() {
+  test_library_hash_specializations_available();
+  {
+    test_hash_enabled_for_type<std::bitset<0> >();
+    test_hash_enabled_for_type<std::bitset<1> >();
+    test_hash_enabled_for_type<std::bitset<1024> >();
+    test_hash_enabled_for_type<std::bitset<100000> >();
+  }
+}
diff --git a/libcxx/test/std/utilities/type.index/type.index.hash/enabled_hash.pass.cpp b/libcxx/test/std/utilities/type.index/type.index.hash/enabled_hash.pass.cpp
new file mode 100644
index 00000000000..26bada38fdd
--- /dev/null
+++ b/libcxx/test/std/utilities/type.index/type.index.hash/enabled_hash.pass.cpp
@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <typeindex>
+
+// Test that <typeindex> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <typeindex>
+
+#include "poisoned_hash_helper.hpp"
+
+int main() {
+  test_library_hash_specializations_available();
+}
diff --git a/libcxx/test/std/utilities/type.index/type.index.synopsis/hash_type_index.pass.cpp b/libcxx/test/std/utilities/type.index/type.index.synopsis/hash_type_index.pass.cpp
index 6d353f1d305..0fe020bf3d4 100644
--- a/libcxx/test/std/utilities/type.index/type.index.synopsis/hash_type_index.pass.cpp
+++ b/libcxx/test/std/utilities/type.index/type.index.synopsis/hash_type_index.pass.cpp
@@ -18,9 +18,19 @@
 #include <typeindex>
 #include <type_traits>
 
+#include "test_macros.h"
+#if TEST_STD_VER >= 11
+#include "poisoned_hash_helper.hpp"
+#endif
+
 int main()
 {
+  {
     typedef std::hash<std::type_index> H;
     static_assert((std::is_same<typename H::argument_type, std::type_index>::value), "" );
     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
+  }
+  {
+    test_hash_enabled_for_type<std::type_index>(std::type_index(typeid(int)));
+  }
 }
diff --git a/libcxx/test/std/utilities/variant/variant.hash/enabled_hash.pass.cpp b/libcxx/test/std/utilities/variant/variant.hash/enabled_hash.pass.cpp
new file mode 100644
index 00000000000..826dcbae6b9
--- /dev/null
+++ b/libcxx/test/std/utilities/variant/variant.hash/enabled_hash.pass.cpp
@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// <variant>
+
+// Test that <variant> provides all of the arithmetic, enum, and pointer
+// hash specializations.
+
+#include <variant>
+
+#include "poisoned_hash_helper.hpp"
+
+int main() {
+  test_library_hash_specializations_available();
+}
diff --git a/libcxx/test/std/utilities/variant/variant.hash/hash.pass.cpp b/libcxx/test/std/utilities/variant/variant.hash/hash.pass.cpp
index d807a7c7e2e..96ef967f6c1 100644
--- a/libcxx/test/std/utilities/variant/variant.hash/hash.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.hash/hash.pass.cpp
@@ -21,6 +21,7 @@
 
 #include "test_macros.h"
 #include "variant_test_helpers.hpp"
+#include "poisoned_hash_helper.hpp"
 
 #ifndef TEST_HAS_NO_EXCEPTIONS
 namespace std {
@@ -103,6 +104,9 @@ void test_hash_monostate() {
     ASSERT_SAME_TYPE(decltype(h(m1)), std::size_t);
     static_assert(std::is_copy_constructible<H>::value, "");
   }
+  {
+    test_hash_enabled_for_type<std::monostate>();
+  }
 }
 
 void test_hash_variant_duplicate_elements() {
@@ -117,8 +121,34 @@ void test_hash_variant_duplicate_elements() {
     LIBCPP_ASSERT(h(v1) != h(v2));
 }
 
+struct A {};
+struct B {};
+
+template <>
+struct std::hash<B> {
+  size_t operator()(B const&) const {
+    return 0;
+  }
+};
+
+void test_hash_variant_enabled() {
+  {
+    test_hash_enabled_for_type<std::variant<int> >();
+    test_hash_enabled_for_type<std::variant<int*, long, double, const int> >();
+  }
+  {
+    test_hash_disabled_for_type<std::variant<int, A>>();
+    test_hash_disabled_for_type<std::variant<const A, void*>>();
+  }
+  {
+    test_hash_enabled_for_type<std::variant<int, B>>();
+    test_hash_enabled_for_type<std::variant<const B, int>>();
+  }
+}
+
 int main() {
   test_hash_variant();
   test_hash_variant_duplicate_elements();
   test_hash_monostate();
+  test_hash_variant_enabled();
 }
diff --git a/libcxx/test/support/deleter_types.h b/libcxx/test/support/deleter_types.h
index c8b38202352..f7cdb624e4f 100644
--- a/libcxx/test/support/deleter_types.h
+++ b/libcxx/test/support/deleter_types.h
@@ -21,6 +21,7 @@
 #include <cassert>
 
 #include "test_macros.h"
+#include "min_allocator.h"
 
 #if TEST_STD_VER >= 11
 
@@ -379,4 +380,63 @@ swap(test_deleter<T>& x, test_deleter<T>& y)
     y = std::move(t);
 }
 
+#if TEST_STD_VER >= 11
+
+template <class T, size_t ID = 0>
+class PointerDeleter
+{
+    PointerDeleter(const PointerDeleter&);
+    PointerDeleter& operator=(const PointerDeleter&);
+
+public:
+    typedef min_pointer<T, std::integral_constant<size_t, ID>> pointer;
+
+    PointerDeleter() = default;
+    PointerDeleter(PointerDeleter&&) = default;
+    PointerDeleter& operator=(PointerDeleter&&) = default;
+    explicit PointerDeleter(int) {}
+
+    template <class U>
+        PointerDeleter(PointerDeleter<U, ID>&&,
+            typename std::enable_if<!std::is_same<U, T>::value>::type* = 0)
+    {}
+
+    void operator()(pointer p) { if (p) { delete std::addressof(*p); }}
+
+private:
+    template <class U>
+        PointerDeleter(const PointerDeleter<U, ID>&,
+            typename std::enable_if<!std::is_same<U, T>::value>::type* = 0);
+};
+
+
+template <class T, size_t ID>
+class PointerDeleter<T[], ID>
+{
+    PointerDeleter(const PointerDeleter&);
+    PointerDeleter& operator=(const PointerDeleter&);
+
+public:
+    typedef min_pointer<T, std::integral_constant<size_t, ID> > pointer;
+
+    PointerDeleter() = default;
+    PointerDeleter(PointerDeleter&&) = default;
+    PointerDeleter& operator=(PointerDeleter&&) = default;
+    explicit PointerDeleter(int) {}
+
+    template <class U>
+        PointerDeleter(PointerDeleter<U, ID>&&,
+            typename std::enable_if<!std::is_same<U, T>::value>::type* = 0)
+    {}
+
+    void operator()(pointer p) { if (p) { delete [] std::addressof(*p); }}
+
+private:
+    template <class U>
+        PointerDeleter(const PointerDeleter<U, ID>&,
+            typename std::enable_if<!std::is_same<U, T>::value>::type* = 0);
+};
+
+#endif // TEST_STD_VER >= 11
+
 #endif  // SUPPORT_DELETER_TYPES_H
diff --git a/libcxx/test/support/min_allocator.h b/libcxx/test/support/min_allocator.h
index d518e4a6d77..a3af9e1db66 100644
--- a/libcxx/test/support/min_allocator.h
+++ b/libcxx/test/support/min_allocator.h
@@ -136,31 +136,31 @@ public:
 
 #include <memory>
 
-template <class T> class min_pointer;
-template <class T> class min_pointer<const T>;
-template <> class min_pointer<void>;
-template <> class min_pointer<const void>;
+template <class T, class = std::integral_constant<size_t, 0> > class min_pointer;
+template <class T, class ID> class min_pointer<const T, ID>;
+template <class ID> class min_pointer<void, ID>;
+template <class ID> class min_pointer<const void, ID>;
 template <class T> class min_allocator;
 
-template <>
-class min_pointer<const void>
+template <class ID>
+class min_pointer<const void, ID>
 {
     const void* ptr_;
 public:
     min_pointer() TEST_NOEXCEPT = default;
     min_pointer(std::nullptr_t) TEST_NOEXCEPT : ptr_(nullptr) {}
     template <class T>
-    min_pointer(min_pointer<T> p) TEST_NOEXCEPT : ptr_(p.ptr_) {}
+    min_pointer(min_pointer<T, ID> p) TEST_NOEXCEPT : ptr_(p.ptr_) {}
 
     explicit operator bool() const {return ptr_ != nullptr;}
 
     friend bool operator==(min_pointer x, min_pointer y) {return x.ptr_ == y.ptr_;}
     friend bool operator!=(min_pointer x, min_pointer y) {return !(x == y);}
-    template <class U> friend class min_pointer;
+    template <class U, class XID> friend class min_pointer;
 };
 
-template <>
-class min_pointer<void>
+template <class ID>
+class min_pointer<void, ID>
 {
     void* ptr_;
 public:
@@ -172,16 +172,16 @@ public:
                             !std::is_const<T>::value
                        >::type
              >
-    min_pointer(min_pointer<T> p) TEST_NOEXCEPT : ptr_(p.ptr_) {}
+    min_pointer(min_pointer<T, ID> p) TEST_NOEXCEPT : ptr_(p.ptr_) {}
 
     explicit operator bool() const {return ptr_ != nullptr;}
 
     friend bool operator==(min_pointer x, min_pointer y) {return x.ptr_ == y.ptr_;}
     friend bool operator!=(min_pointer x, min_pointer y) {return !(x == y);}
-    template <class U> friend class min_pointer;
+    template <class U, class XID> friend class min_pointer;
 };
 
-template <class T>
+template <class T, class ID>
 class min_pointer
 {
     T* ptr_;
@@ -190,7 +190,7 @@ class min_pointer
 public:
     min_pointer() TEST_NOEXCEPT = default;
     min_pointer(std::nullptr_t) TEST_NOEXCEPT : ptr_(nullptr) {}
-    explicit min_pointer(min_pointer<void> p) TEST_NOEXCEPT : ptr_(static_cast<T*>(p.ptr_)) {}
+    explicit min_pointer(min_pointer<void, ID> p) TEST_NOEXCEPT : ptr_(static_cast<T*>(p.ptr_)) {}
 
     explicit operator bool() const {return ptr_ != nullptr;}
 
@@ -247,12 +247,12 @@ public:
 
     friend bool operator==(min_pointer x, min_pointer y) {return x.ptr_ == y.ptr_;}
     friend bool operator!=(min_pointer x, min_pointer y) {return !(x == y);}
-    template <class U> friend class min_pointer;
+    template <class U, class XID> friend class min_pointer;
     template <class U> friend class min_allocator;
 };
 
-template <class T>
-class min_pointer<const T>
+template <class T, class ID>
+class min_pointer<const T, ID>
 {
     const T* ptr_;
 
@@ -260,8 +260,8 @@ class min_pointer<const T>
 public:
     min_pointer() TEST_NOEXCEPT = default;
     min_pointer(std::nullptr_t) : ptr_(nullptr) {}
-    min_pointer(min_pointer<T> p) : ptr_(p.ptr_) {}
-    explicit min_pointer(min_pointer<const void> p) : ptr_(static_cast<const T*>(p.ptr_)) {}
+    min_pointer(min_pointer<T, ID> p) : ptr_(p.ptr_) {}
+    explicit min_pointer(min_pointer<const void, ID> p) : ptr_(static_cast<const T*>(p.ptr_)) {}
 
     explicit operator bool() const {return ptr_ != nullptr;}
 
@@ -318,37 +318,37 @@ public:
 
     friend bool operator==(min_pointer x, min_pointer y) {return x.ptr_ == y.ptr_;}
     friend bool operator!=(min_pointer x, min_pointer y) {return !(x == y);}
-    template <class U> friend class min_pointer;
+    template <class U, class XID> friend class min_pointer;
 };
 
-template <class T>
+template <class T, class ID>
 inline
 bool
-operator==(min_pointer<T> x, std::nullptr_t)
+operator==(min_pointer<T, ID> x, std::nullptr_t)
 {
     return !static_cast<bool>(x);
 }
 
-template <class T>
+template <class T, class ID>
 inline
 bool
-operator==(std::nullptr_t, min_pointer<T> x)
+operator==(std::nullptr_t, min_pointer<T, ID> x)
 {
     return !static_cast<bool>(x);
 }
 
-template <class T>
+template <class T, class ID>
 inline
 bool
-operator!=(min_pointer<T> x, std::nullptr_t)
+operator!=(min_pointer<T, ID> x, std::nullptr_t)
 {
     return static_cast<bool>(x);
 }
 
-template <class T>
+template <class T, class ID>
 inline
 bool
-operator!=(std::nullptr_t, min_pointer<T> x)
+operator!=(std::nullptr_t, min_pointer<T, ID> x)
 {
     return static_cast<bool>(x);
 }
diff --git a/libcxx/test/support/poisoned_hash_helper.hpp b/libcxx/test/support/poisoned_hash_helper.hpp
new file mode 100644
index 00000000000..0a5675a2c5a
--- /dev/null
+++ b/libcxx/test/support/poisoned_hash_helper.hpp
@@ -0,0 +1,244 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+//                     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 SUPPORT_POISONED_HASH_HELPER_HPP
+#define SUPPORT_POISONED_HASH_HELPER_HPP
+
+#include <type_traits>
+#include <cassert>
+
+#include "test_macros.h"
+
+#if TEST_STD_VER < 11
+#error this header may only be used in C++11 or newer
+#endif
+
+template <class ...Args> struct TypeList;
+
+// Test that the specified Hash meets the requirements of an enabled hash
+template <class Hash, class Key, class InputKey = Key>
+void test_hash_enabled(InputKey const& key = InputKey{});
+
+template <class T, class InputKey = T>
+void test_hash_enabled_for_type(InputKey const& key = InputKey{}) {
+  return test_hash_enabled<std::hash<T>, T, InputKey>(key);
+}
+
+// Test that the specified Hash meets the requirements of a disabled hash.
+template <class Hash, class Key>
+void test_hash_disabled();
+
+template <class T>
+void test_hash_disabled_for_type() {
+  return test_hash_disabled<std::hash<T>, T>();
+}
+
+namespace PoisonedHashDetail {
+  enum Enum {};
+  enum EnumClass : bool {};
+  struct Class {};
+}
+
+// Each header that declares the template hash provides enabled
+// specializations of hash for nullptr t and all cv-unqualified
+// arithmetic, enumeration, and pointer types.
+using LibraryHashTypes = TypeList<
+#if TEST_STD_VER > 14
+      decltype(nullptr),
+#endif
+      bool,
+      char,
+      signed char,
+      unsigned char,
+      wchar_t,
+#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
+      char16_t,
+      char32_t,
+#endif
+      short,
+      unsigned short,
+      int,
+      unsigned int,
+      long,
+      unsigned long,
+      long long,
+      unsigned long long,
+#ifndef _LIBCPP_HAS_NO_INT128
+      __int128_t,
+      __uint128_t,
+#endif
+      float,
+      double,
+      long double,
+#if TEST_STD_VER >= 14
+      // Enum types
+      PoisonedHashDetail::Enum,
+      PoisonedHashDetail::EnumClass,
+#endif
+      // pointer types
+      void*,
+      void const*,
+      PoisonedHashDetail::Class*
+    >;
+
+
+// Test that each of the library hash specializations for  arithmetic types,
+// enum types, and pointer types are available and enabled.
+template <class Types = LibraryHashTypes>
+void test_library_hash_specializations_available(Types = Types{});
+
+
+namespace PoisonedHashDetail {
+
+template <class T, class = typename T::foo_bar_baz>
+constexpr bool instantiate(int) { return true; }
+template <class> constexpr bool instantiate(long) { return true; }
+template <class T> constexpr bool instantiate() { return instantiate<T>(0); }
+
+template <class To>
+struct ConvertibleToSimple {
+  operator To() const {
+    return To{};
+  }
+};
+
+template <class To>
+struct ConvertibleTo {
+  To to{};
+  operator To&() & { return to; }
+  operator To const&() const & { return to; }
+  operator To&&() && { return std::move(to); }
+  operator To const&&() const && { return std::move(to); }
+};
+
+template <class HashExpr,
+         class Res = typename std::result_of<HashExpr>::type>
+constexpr bool can_hash(int) {
+  return std::is_same<Res, size_t>::value;
+}
+template <class> constexpr bool can_hash(long) { return false; }
+template <class T> constexpr bool can_hash() { return can_hash<T>(0); }
+
+} // namespace PoisonedHashDetail
+
+template <class Hash, class Key, class InputKey>
+void test_hash_enabled(InputKey const& key) {
+  using namespace PoisonedHashDetail;
+
+  static_assert(std::is_destructible<Hash>::value, "");
+  // Enabled hash requirements
+  static_assert(std::is_default_constructible<Hash>::value, "");
+  static_assert(std::is_copy_constructible<Hash>::value, "");
+  static_assert(std::is_move_constructible<Hash>::value, "");
+  static_assert(std::is_copy_assignable<Hash>::value, "");
+  static_assert(std::is_move_assignable<Hash>::value, "");
+
+#if TEST_STD_VER > 14
+  static_assert(std::is_swappable<Hash>::value, "");
+#elif defined(_LIBCPP_VERSION)
+  static_assert(std::__is_swappable<Hash>::value, "");
+#endif
+
+  // Hashable requirements
+  using CKey = ConvertibleTo<Key>;
+  static_assert(can_hash<Hash(Key&)>(), "");
+  static_assert(can_hash<Hash(Key const&)>(), "");
+  static_assert(can_hash<Hash(Key&&)>(), "");
+  static_assert(can_hash<Hash const&(Key&)>(), "");
+  static_assert(can_hash<Hash const&(Key const&)>(), "");
+  static_assert(can_hash<Hash const&(Key&&)>(), "");
+
+  static_assert(can_hash<Hash(ConvertibleToSimple<Key>&)>(), "");
+  static_assert(can_hash<Hash(ConvertibleToSimple<Key> const&)>(), "");
+  static_assert(can_hash<Hash(ConvertibleToSimple<Key>&&)>(), "");
+
+  static_assert(can_hash<Hash(ConvertibleTo<Key>&)>(), "");
+  static_assert(can_hash<Hash(ConvertibleTo<Key> const&)>(), "");
+  static_assert(can_hash<Hash(ConvertibleTo<Key> &&)>(), "");
+  static_assert(can_hash<Hash(ConvertibleTo<Key> const&&)>(), "");
+
+  const Hash h;
+  assert(h(key) == h(key));
+
+}
+
+template <class Hash, class Key>
+void test_hash_disabled() {
+  using namespace PoisonedHashDetail;
+
+  // Disabled hash requirements
+  static_assert(!std::is_default_constructible<Hash>::value, "");
+  static_assert(!std::is_copy_constructible<Hash>::value, "");
+  static_assert(!std::is_move_constructible<Hash>::value, "");
+  static_assert(!std::is_copy_assignable<Hash>::value, "");
+  static_assert(!std::is_move_assignable<Hash>::value, "");
+
+  static_assert(!std::is_function<
+      typename std::remove_pointer<
+          typename std::remove_reference<Hash>::type
+      >::type
+    >::value, "");
+
+  // Hashable requirements
+  using CKey = ConvertibleTo<Key>;
+  static_assert(!can_hash<Hash(Key&)>(), "");
+  static_assert(!can_hash<Hash(Key const&)>(), "");
+  static_assert(!can_hash<Hash(Key&&)>(), "");
+  static_assert(!can_hash<Hash const&(Key&)>(), "");
+  static_assert(!can_hash<Hash const&(Key const&)>(), "");
+  static_assert(!can_hash<Hash const&(Key&&)>(), "");
+
+  static_assert(!can_hash<Hash(ConvertibleToSimple<Key>&)>(), "");
+  static_assert(!can_hash<Hash(ConvertibleToSimple<Key> const&)>(), "");
+  static_assert(!can_hash<Hash(ConvertibleToSimple<Key>&&)>(), "");
+
+  static_assert(!can_hash<Hash(ConvertibleTo<Key>&)>(), "");
+  static_assert(!can_hash<Hash(ConvertibleTo<Key> const&)>(), "");
+  static_assert(!can_hash<Hash(ConvertibleTo<Key> &&)>(), "");
+  static_assert(!can_hash<Hash(ConvertibleTo<Key> const&&)>(), "");
+}
+
+
+template <class First, class ...Rest>
+struct TypeList<First, Rest...> {
+  template <template <class> class Trait, bool Expect = true>
+  static constexpr bool assertTrait() {
+    static_assert(Trait<First>::value == Expect, "");
+    return TypeList<Rest...>::template assertTrait<Trait, Expect>();
+  }
+
+  template <class Trait>
+  static void applyTrait() {
+    Trait::template apply<First>();
+    TypeList<Rest...>::template applyTrait<Trait>();
+  }
+};
+
+template <>
+struct TypeList<> {
+  template <template <class> class Trait, bool Expect = true>
+  static constexpr bool assertTrait() {
+    return true;
+  }
+  template <class Trait>
+  static void applyTrait() {}
+};
+
+
+struct TestLibraryTrait {
+    template <class Type>
+    static void apply() { test_hash_enabled<std::hash<Type>, Type>(); }
+};
+
+template <class Types>
+void test_library_hash_specializations_available(Types) {
+  Types::template applyTrait<TestLibraryTrait >();
+}
+
+#endif // SUPPORT_POISONED_HASH_HELPER_HPP
diff --git a/libcxx/test/support/test.support/test_poisoned_hash_helper.pass.cpp b/libcxx/test/support/test.support/test_poisoned_hash_helper.pass.cpp
new file mode 100644
index 00000000000..4dffae6dbdf
--- /dev/null
+++ b/libcxx/test/support/test.support/test_poisoned_hash_helper.pass.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+
+// Test that the header `poisoned_hash_helper.hpp` doesn't include any
+// headers that provide hash<T> specializations. This is required so that the
+// 'test_library_hash_specializations_available()' function returns false
+// by default, unless a STL header providing hash has already been included.
+
+#include "poisoned_hash_helper.hpp"
+
+template <class T, size_t = sizeof(T)>
+constexpr bool is_complete_imp(int) { return true; }
+template <class> constexpr bool is_complete_imp(long) { return false; }
+template <class T> constexpr bool is_complete() { return is_complete_imp<T>(0); }
+
+template <class T> struct has_complete_hash {
+  enum { value = is_complete<std::hash<T> >() };
+};
+
+int main() {
+  static_assert(LibraryHashTypes::assertTrait<has_complete_hash, false>(), "");
+}