vendor/libc++/libc++-trunk-r305145

13 files changed, 1178 insertions, 65 deletions

diff --git a/test/std/localization/locale.categories/category.ctype/locale.codecvt.byname/ctor_char.pass.cpp b/test/std/localization/locale.categories/category.ctype/locale.codecvt.byname/ctor_char.pass.cpp
index 349577835ec6..24c2f23f0db7 100644
--- a/test/std/localization/locale.categories/category.ctype/locale.codecvt.byname/ctor_char.pass.cpp
+++ b/test/std/localization/locale.categories/category.ctype/locale.codecvt.byname/ctor_char.pass.cpp
@@ -17,6 +17,8 @@
 #include <locale>
 #include <cassert>
 
+#include "platform_support.h"
+
 typedef std::codecvt_byname<char, char, std::mbstate_t> F;
 
 class my_facet
@@ -38,12 +40,12 @@ int my_facet::count = 0;
 int main()
 {
     {
-        std::locale l(std::locale::classic(), new my_facet("en_US"));
+        std::locale l(std::locale::classic(), new my_facet(LOCALE_en_US));
         assert(my_facet::count == 1);
     }
     assert(my_facet::count == 0);
     {
-        my_facet f("en_US", 1);
+        my_facet f(LOCALE_en_US, 1);
         assert(my_facet::count == 1);
         {
             std::locale l(std::locale::classic(), &f);
@@ -53,12 +55,12 @@ int main()
     }
     assert(my_facet::count == 0);
     {
-        std::locale l(std::locale::classic(), new my_facet(std::string("en_US")));
+        std::locale l(std::locale::classic(), new my_facet(std::string(LOCALE_en_US)));
         assert(my_facet::count == 1);
     }
     assert(my_facet::count == 0);
     {
-        my_facet f(std::string("en_US"), 1);
+        my_facet f(std::string(LOCALE_en_US), 1);
         assert(my_facet::count == 1);
         {
             std::locale l(std::locale::classic(), &f);
diff --git a/test/std/numerics/numeric.ops/exclusive.scan/exclusive_scan_iter_iter_iter.pass.cpp b/test/std/numerics/numeric.ops/exclusive.scan/exclusive_scan_iter_iter_iter.pass.cpp
new file mode 100644
index 000000000000..6fdd288e2d6a
--- /dev/null
+++ b/test/std/numerics/numeric.ops/exclusive.scan/exclusive_scan_iter_iter_iter.pass.cpp
@@ -0,0 +1,97 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <numeric>
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// template<class InputIterator, class OutputIterator, class T>
+//     OutputIterator exclusive_scan(InputIterator first, InputIterator last,
+//                                   OutputIterator result, T init);
+// 
+
+#include <numeric>
+#include <vector>
+#include <cassert>
+
+#include "test_iterators.h"
+
+template <class Iter1, class T, class Iter2>
+void
+test(Iter1 first, Iter1 last, T init, Iter2 rFirst, Iter2 rLast)
+{
+    std::vector<typename std::iterator_traits<Iter1>::value_type> v;
+    
+//  Not in place
+    std::exclusive_scan(first, last, std::back_inserter(v), init);
+    assert(std::equal(v.begin(), v.end(), rFirst, rLast));
+
+//  In place
+    v.clear();
+    v.assign(first, last);
+    std::exclusive_scan(v.begin(), v.end(), v.begin(), init);
+    assert(std::equal(v.begin(), v.end(), rFirst, rLast));  
+}
+
+
+template <class Iter>
+void
+test()
+{
+          int ia[]   = {1, 3, 5, 7,  9};
+    const int pRes[] = {0, 1, 4, 9, 16};
+    const unsigned sa = sizeof(ia) / sizeof(ia[0]);
+    static_assert(sa == sizeof(pRes) / sizeof(pRes[0]));       // just to be sure
+
+    for (unsigned int i = 0; i < sa; ++i )
+        test(Iter(ia), Iter(ia + i), 0, pRes, pRes + i);
+}
+
+int triangle(int n) { return n*(n+1)/2; }
+
+//  Basic sanity
+void basic_tests()
+{
+    {
+    std::vector<int> v(10);
+    std::fill(v.begin(), v.end(), 3);
+    std::exclusive_scan(v.begin(), v.end(), v.begin(), 50);
+    for (size_t i = 0; i < v.size(); ++i)
+        assert(v[i] == 50 + (int) i * 3);
+    }
+
+    {
+    std::vector<int> v(10);
+    std::iota(v.begin(), v.end(), 0);
+    std::exclusive_scan(v.begin(), v.end(), v.begin(), 30);
+    for (size_t i = 0; i < v.size(); ++i)
+        assert(v[i] == 30 + triangle(i-1));
+    }
+
+    {
+    std::vector<int> v(10);
+    std::iota(v.begin(), v.end(), 1);
+    std::exclusive_scan(v.begin(), v.end(), v.begin(), 40);
+    for (size_t i = 0; i < v.size(); ++i)
+        assert(v[i] == 40 + triangle(i));
+    }
+
+}
+
+int main()
+{
+    basic_tests();
+
+//  All the iterator categories
+    test<input_iterator        <const int*> >();
+    test<forward_iterator      <const int*> >();
+    test<bidirectional_iterator<const int*> >();
+    test<random_access_iterator<const int*> >();
+    test<const int*>();
+    test<      int*>();
+}
diff --git a/test/std/numerics/numeric.ops/exclusive.scan/exclusive_scan_iter_iter_iter_init_op.pass.cpp b/test/std/numerics/numeric.ops/exclusive.scan/exclusive_scan_iter_iter_iter_init_op.pass.cpp
new file mode 100644
index 000000000000..ba1673fe467f
--- /dev/null
+++ b/test/std/numerics/numeric.ops/exclusive.scan/exclusive_scan_iter_iter_iter_init_op.pass.cpp
@@ -0,0 +1,87 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <numeric>
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// template<class InputIterator, class OutputIterator, class T, class BinaryOperation>
+//     OutputIterator
+//     exclusive_scan(InputIterator first, InputIterator last,
+//                    OutputIterator result, 
+//                    T init, BinaryOperation binary_op); // C++17
+
+#include <numeric>
+#include <vector>
+#include <cassert>
+
+#include "test_iterators.h"
+
+template <class Iter1, class T, class Op, class Iter2>
+void
+test(Iter1 first, Iter1 last, T init, Op op, Iter2 rFirst, Iter2 rLast)
+{
+    std::vector<typename std::iterator_traits<Iter1>::value_type> v;
+
+//  Not in place
+    std::exclusive_scan(first, last, std::back_inserter(v), init, op);
+    assert(std::equal(v.begin(), v.end(), rFirst, rLast));
+
+//  In place
+    v.clear();
+    v.assign(first, last);
+    std::exclusive_scan(v.begin(), v.end(), v.begin(), init, op);
+    assert(std::equal(v.begin(), v.end(), rFirst, rLast));  
+}
+
+
+template <class Iter>
+void
+test()
+{
+          int ia[]   = {1, 3, 5,  7,   9};
+    const int pRes[] = {0, 1, 4,  9,  16};
+    const int mRes[] = {1, 1, 3, 15, 105};
+    const unsigned sa = sizeof(ia) / sizeof(ia[0]);
+    static_assert(sa == sizeof(pRes) / sizeof(pRes[0]));       // just to be sure
+    static_assert(sa == sizeof(mRes) / sizeof(mRes[0]));       // just to be sure
+
+    for (unsigned int i = 0; i < sa; ++i ) {
+        test(Iter(ia), Iter(ia + i), 0, std::plus<>(),       pRes, pRes + i);
+        test(Iter(ia), Iter(ia + i), 1, std::multiplies<>(), mRes, mRes + i);
+        }
+}
+
+int main()
+{
+//  All the iterator categories
+    test<input_iterator        <const int*> >();
+    test<forward_iterator      <const int*> >();
+    test<bidirectional_iterator<const int*> >();
+    test<random_access_iterator<const int*> >();
+    test<const int*>();
+    test<      int*>();
+
+//  Make sure that the calculations are done using the init typedef
+    {
+    std::vector<unsigned char> v(10);
+    std::iota(v.begin(), v.end(), 1);
+    std::vector<int> res;
+    std::exclusive_scan(v.begin(), v.end(), std::back_inserter(res), 1, std::multiplies<>());
+
+    assert(res.size() == 10);
+    int j = 1;
+    assert(res[0] == 1);
+    for (size_t i = 1; i < v.size(); ++i)
+    {
+        j *= i;
+        assert(res[i] == j);
+    }
+    }
+}
+ 
\ No newline at end of file
diff --git a/test/std/numerics/numeric.ops/transform.exclusive.scan/transform_exclusive_scan_iter_iter_iter_init_bop_uop.pass.cpp b/test/std/numerics/numeric.ops/transform.exclusive.scan/transform_exclusive_scan_iter_iter_iter_init_bop_uop.pass.cpp
new file mode 100644
index 000000000000..3bfb336a03f9
--- /dev/null
+++ b/test/std/numerics/numeric.ops/transform.exclusive.scan/transform_exclusive_scan_iter_iter_iter_init_bop_uop.pass.cpp
@@ -0,0 +1,154 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <numeric>
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// template<class InputIterator, class OutputIterator, class T, 
+//          class BinaryOperation, class UnaryOperation>
+//   OutputIterator transform_exclusive_scan(InputIterator first, InputIterator last,
+//                                           OutputIterator result, T init,
+//                                           BinaryOperation binary_op,
+//                                           UnaryOperation unary_op);
+
+
+#include <numeric>
+#include <vector>
+#include <cassert>
+#include <iostream>
+
+#include "test_iterators.h"
+
+template <class _Tp = void>
+struct identity : std::unary_function<_Tp, _Tp>
+{
+    constexpr const _Tp& operator()(const _Tp& __x) const { return __x;}
+};
+
+template <>
+struct identity<void>
+{
+    template <class _Tp>
+    constexpr auto operator()(_Tp&& __x) const
+    _NOEXCEPT_(noexcept(_VSTD::forward<_Tp>(__x)))
+    -> decltype        (_VSTD::forward<_Tp>(__x))
+        { return        _VSTD::forward<_Tp>(__x); }
+};
+
+template <class Iter1, class BOp, class UOp, class T, class Iter2>
+void
+test(Iter1 first, Iter1 last, BOp bop, UOp uop, T init, Iter2 rFirst, Iter2 rLast)
+{
+    std::vector<typename std::iterator_traits<Iter1>::value_type> v;
+//  Test not in-place
+    std::transform_exclusive_scan(first, last, std::back_inserter(v), init, bop, uop);
+    assert(std::equal(v.begin(), v.end(), rFirst, rLast));
+
+//  Test in-place
+    v.clear();
+    v.assign(first, last);
+    std::transform_exclusive_scan(v.begin(), v.end(), v.begin(), init, bop, uop);
+    assert(std::equal(v.begin(), v.end(), rFirst, rLast));
+}
+
+
+template <class Iter>
+void
+test()
+{
+          int ia[]     = { 1,  3,  5,   7,   9};
+    const int pResI0[] = { 0,  1,  4,   9,  16};        // with identity
+    const int mResI0[] = { 0,  0,  0,   0,   0};        
+    const int pResN0[] = { 0, -1, -4,  -9, -16};        // with negate
+    const int mResN0[] = { 0,  0,  0,   0,   0};
+    const int pResI2[] = { 2,  3,  6,  11,  18};        // with identity
+    const int mResI2[] = { 2,  2,  6,  30, 210};        
+    const int pResN2[] = { 2,  1, -2,  -7, -14};        // with negate
+    const int mResN2[] = { 2, -2,  6, -30, 210};
+    const unsigned sa = sizeof(ia) / sizeof(ia[0]);
+    static_assert(sa == sizeof(pResI0) / sizeof(pResI0[0]));       // just to be sure
+    static_assert(sa == sizeof(mResI0) / sizeof(mResI0[0]));       // just to be sure
+    static_assert(sa == sizeof(pResN0) / sizeof(pResN0[0]));       // just to be sure
+    static_assert(sa == sizeof(mResN0) / sizeof(mResN0[0]));       // just to be sure
+    static_assert(sa == sizeof(pResI2) / sizeof(pResI2[0]));       // just to be sure
+    static_assert(sa == sizeof(mResI2) / sizeof(mResI2[0]));       // just to be sure
+    static_assert(sa == sizeof(pResN2) / sizeof(pResN2[0]));       // just to be sure
+    static_assert(sa == sizeof(mResN2) / sizeof(mResN2[0]));       // just to be sure
+
+    for (unsigned int i = 0; i < sa; ++i ) {
+        test(Iter(ia), Iter(ia + i), std::plus<>(),       identity<>(),    0, pResI0, pResI0 + i);
+        test(Iter(ia), Iter(ia + i), std::multiplies<>(), identity<>(),    0, mResI0, mResI0 + i);
+        test(Iter(ia), Iter(ia + i), std::plus<>(),       std::negate<>(), 0, pResN0, pResN0 + i);
+        test(Iter(ia), Iter(ia + i), std::multiplies<>(), std::negate<>(), 0, mResN0, mResN0 + i);
+        test(Iter(ia), Iter(ia + i), std::plus<>(),       identity<>(),    2, pResI2, pResI2 + i);
+        test(Iter(ia), Iter(ia + i), std::multiplies<>(), identity<>(),    2, mResI2, mResI2 + i);
+        test(Iter(ia), Iter(ia + i), std::plus<>(),       std::negate<>(), 2, pResN2, pResN2 + i);
+        test(Iter(ia), Iter(ia + i), std::multiplies<>(), std::negate<>(), 2, mResN2, mResN2 + i);
+        }
+}
+
+int triangle(int n) { return n*(n+1)/2; }
+
+//  Basic sanity
+void basic_tests()
+{
+    {
+    std::vector<int> v(10);
+    std::fill(v.begin(), v.end(), 3);
+    std::transform_exclusive_scan(v.begin(), v.end(), v.begin(), 50, std::plus<>(), identity<>());
+    for (size_t i = 0; i < v.size(); ++i)
+        assert(v[i] == 50 + (int) i * 3);
+    }
+
+    {
+    std::vector<int> v(10);
+    std::iota(v.begin(), v.end(), 0);
+    std::transform_exclusive_scan(v.begin(), v.end(), v.begin(), 30, std::plus<>(), identity<>());
+    for (size_t i = 0; i < v.size(); ++i)
+        assert(v[i] == 30 + triangle(i-1));
+    }
+
+    {
+    std::vector<int> v(10);
+    std::iota(v.begin(), v.end(), 1);
+    std::transform_exclusive_scan(v.begin(), v.end(), v.begin(), 40, std::plus<>(), identity<>());
+    for (size_t i = 0; i < v.size(); ++i)
+        assert(v[i] == 40 + triangle(i));
+    }
+
+//  Make sure that the calculations are done using the init typedef
+    {
+    std::vector<unsigned char> v(10);
+    std::iota(v.begin(), v.end(), 1);
+    std::vector<int> res;
+    std::transform_exclusive_scan(v.begin(), v.end(), std::back_inserter(res), 1, std::multiplies<>(), identity<>());
+
+    assert(res.size() == 10);
+    int j = 1;
+    assert(res[0] == 1);
+    for (size_t i = 1; i < res.size(); ++i)
+    {
+        j *= i;
+        assert(res[i] == j);
+    }
+    }
+}
+
+int main()
+{
+    basic_tests();
+    
+//  All the iterator categories
+    test<input_iterator        <const int*> >();
+    test<forward_iterator      <const int*> >();
+    test<bidirectional_iterator<const int*> >();
+    test<random_access_iterator<const int*> >();
+    test<const int*>();
+    test<      int*>();
+}
diff --git a/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/default.pass.cpp b/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/default.pass.cpp
index 4de42fbd0243..48c3a73a06cc 100644
--- a/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/default.pass.cpp
+++ b/test/std/thread/thread.mutex/thread.mutex.requirements/thread.mutex.requirements.mutex/thread.mutex.class/default.pass.cpp
@@ -16,8 +16,10 @@
 // mutex();
 
 #include <mutex>
+#include <type_traits>
 
 int main()
 {
+    static_assert(std::is_nothrow_default_constructible<std::mutex>::value, "");
     std::mutex m;
 }
diff --git a/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp b/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp
index cee73da849b6..8fcd1860843d 100644
--- a/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp
+++ b/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp
@@ -48,7 +48,6 @@ int main()
         assert(X::dtor_called == false);
         assert(static_cast<bool>(opt) == false);
     }
-    assert(X::dtor_called == false); // TRANSITION, Clang/C2 VSO#239997
     {
         optional<X> opt(X{});
         X::dtor_called = false;
@@ -57,5 +56,4 @@ int main()
         assert(static_cast<bool>(opt) == false);
         X::dtor_called = false;
     }
-    assert(X::dtor_called == false); // TRANSITION, Clang/C2 VSO#239997
 }
diff --git a/test/std/utilities/optional/optional.object/optional.object.observe/value_or.pass.cpp b/test/std/utilities/optional/optional.object/optional.object.observe/value_or.pass.cpp
index c219e9704716..f94dcabde513 100644
--- a/test/std/utilities/optional/optional.object/optional.object.observe/value_or.pass.cpp
+++ b/test/std/utilities/optional/optional.object/optional.object.observe/value_or.pass.cpp
@@ -10,7 +10,7 @@
 // UNSUPPORTED: c++98, c++03, c++11, c++14
 // <optional>
 
-// template <class U> T optional<T>::value_or(U&& v) &&;
+// template <class U> constexpr T optional<T>::value_or(U&& v) &&;
 
 #include <optional>
 #include <type_traits>
@@ -26,22 +26,22 @@ struct Y
 {
     int i_;
 
-    Y(int i) : i_(i) {}
+    constexpr Y(int i) : i_(i) {}
 };
 
 struct X
 {
     int i_;
 
-    X(int i) : i_(i) {}
-    X(X&& x) : i_(x.i_) {x.i_ = 0;}
-    X(const Y& y) : i_(y.i_) {}
-    X(Y&& y) : i_(y.i_+1) {}
+    constexpr X(int i) : i_(i) {}
+    constexpr X(X&& x) : i_(x.i_) {x.i_ = 0;}
+    constexpr X(const Y& y) : i_(y.i_) {}
+    constexpr X(Y&& y) : i_(y.i_+1) {}
     friend constexpr bool operator==(const X& x, const X& y)
         {return x.i_ == y.i_;}
 };
 
-int main()
+constexpr int test()
 {
     {
         optional<X> opt(in_place, 2);
@@ -65,4 +65,10 @@ int main()
         assert(std::move(opt).value_or(Y(3)) == 4);
         assert(!opt);
     }
+    return 0;
+}
+
+int main()
+{
+    static_assert(test() == 0);
 }
diff --git a/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/implicit_deduction_guides.pass.cpp b/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/implicit_deduction_guides.pass.cpp
new file mode 100644
index 000000000000..7b9c061b3ae8
--- /dev/null
+++ b/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/implicit_deduction_guides.pass.cpp
@@ -0,0 +1,155 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+// UNSUPPORTED: libcpp-no-deduction-guides
+
+// GCC's implementation of class template deduction is still immature and runs
+// into issues with libc++. However GCC accepts this code when compiling
+// against libstdc++.
+// XFAIL: gcc
+
+// <string>
+
+// Test that the constructors offered by std::basic_string are formulated
+// so they're compatible with implicit deduction guides.
+
+#include <tuple>
+#include <memory>
+#include <cassert>
+
+#include "test_macros.h"
+#include "archetypes.hpp"
+
+
+// Overloads
+//  using A = Allocator
+//  using AT = std::allocator_arg_t
+// ---------------
+// (1)  tuple(const Types&...) -> tuple<Types...>
+// (2)  explicit tuple(const Types&...) -> tuple<Types...>
+// (3)  tuple(AT, A const&, Types const&...) -> tuple<Types...>
+// (4)  explicit tuple(AT, A const&, Types const&...) -> tuple<Types...>
+// (5)  tuple(tuple const& t) -> decltype(t)
+// (6)  tuple(tuple&& t) -> decltype(t)
+// (7)  tuple(AT, A const&, tuple const& t) -> decltype(t)
+// (8)  tuple(AT, A const&, tuple&& t) -> decltype(t)
+void test_primary_template()
+{
+  const std::allocator<int> A;
+  const auto AT = std::allocator_arg;
+  { // Testing (1)
+    int x = 101;
+    std::tuple t1(42);
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<int>);
+    std::tuple t2(x, 0.0, nullptr);
+    ASSERT_SAME_TYPE(decltype(t2), std::tuple<int, double, decltype(nullptr)>);
+  }
+  { // Testing (2)
+    using T = ExplicitTestTypes::TestType;
+    static_assert(!std::is_convertible<T const&, T>::value, "");
+
+    std::tuple t1(T{});
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<T>);
+
+    const T v{};
+    std::tuple t2(T{}, 101l, v);
+    ASSERT_SAME_TYPE(decltype(t2), std::tuple<T, long, T>);
+  }
+  { // Testing (3)
+    int x = 101;
+    std::tuple t1(AT, A, 42);
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<int>);
+
+    std::tuple t2(AT, A, 42, 0.0, x);
+    ASSERT_SAME_TYPE(decltype(t2), std::tuple<int, double, int>);
+  }
+  { // Testing (4)
+    using T = ExplicitTestTypes::TestType;
+    static_assert(!std::is_convertible<T const&, T>::value, "");
+
+    std::tuple t1(AT, A, T{});
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<T>);
+
+    const T v{};
+    std::tuple t2(AT, A, T{}, 101l, v);
+    ASSERT_SAME_TYPE(decltype(t2), std::tuple<T, long, T>);
+  }
+  { // Testing (5)
+    using Tup = std::tuple<int, decltype(nullptr)>;
+    const Tup t(42, nullptr);
+
+    std::tuple t1(t);
+    ASSERT_SAME_TYPE(decltype(t1), Tup);
+  }
+  { // Testing (6)
+    using Tup = std::tuple<void*, unsigned, char>;
+    std::tuple t1(Tup(nullptr, 42, 'a'));
+    ASSERT_SAME_TYPE(decltype(t1), Tup);
+  }
+  { // Testing (7)
+    using Tup = std::tuple<int, decltype(nullptr)>;
+    const Tup t(42, nullptr);
+
+    std::tuple t1(AT, A, t);
+    ASSERT_SAME_TYPE(decltype(t1), Tup);
+  }
+  { // Testing (8)
+    using Tup = std::tuple<void*, unsigned, char>;
+    std::tuple t1(AT, A, Tup(nullptr, 42, 'a'));
+    ASSERT_SAME_TYPE(decltype(t1), Tup);
+  }
+}
+
+// Overloads
+//  using A = Allocator
+//  using AT = std::allocator_arg_t
+// ---------------
+// (1)  tuple() -> tuple<>
+// (2)  tuple(AT, A const&) -> tuple<>
+// (3)  tuple(tuple const&) -> tuple<>
+// (4)  tuple(tuple&&) -> tuple<>
+// (5)  tuple(AT, A const&, tuple const&) -> tuple<>
+// (6)  tuple(AT, A const&, tuple&&) -> tuple<>
+void test_empty_specialization()
+{
+  std::allocator<int> A;
+  const auto AT = std::allocator_arg;
+  { // Testing (1)
+    std::tuple t1{};
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+  { // Testing (2)
+    std::tuple t1{AT, A};
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+  { // Testing (3)
+    const std::tuple<> t{};
+    std::tuple t1(t);
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+  { // Testing (4)
+    std::tuple t1(std::tuple<>{});
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+  { // Testing (5)
+    const std::tuple<> t{};
+    std::tuple t1(AT, A, t);
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+  { // Testing (6)
+    std::tuple t1(AT, A, std::tuple<>{});
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+}
+
+int main() {
+  test_primary_template();
+  test_empty_specialization();
+}
diff --git a/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp b/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
index dd5880ea6635..29228e562d69 100644
--- a/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
+++ b/test/std/utilities/variant/variant.variant/variant.assign/T.pass.cpp
@@ -68,6 +68,28 @@ struct ThrowsCtorT {
   }
 };
 
+struct MoveCrashes {
+  int value;
+  MoveCrashes(int v = 0) noexcept : value{v} {}
+  MoveCrashes(MoveCrashes &&) noexcept { assert(false); }
+  MoveCrashes &operator=(MoveCrashes &&) noexcept { assert(false); return *this; }
+  MoveCrashes &operator=(int v) noexcept {
+    value = v;
+    return *this;
+  }
+};
+
+struct ThrowsCtorTandMove {
+  int value;
+  ThrowsCtorTandMove() : value(0) {}
+  ThrowsCtorTandMove(int) noexcept(false) { throw 42; }
+  ThrowsCtorTandMove(ThrowsCtorTandMove &&) noexcept(false) { assert(false); }
+  ThrowsCtorTandMove &operator=(int v) noexcept {
+    value = v;
+    return *this;
+  }
+};
+
 struct ThrowsAssignT {
   int value;
   ThrowsAssignT() : value(0) {}
@@ -126,7 +148,7 @@ void test_T_assignment_sfinae() {
     using V = std::variant<int, const int &>;
     static_assert(!std::is_assignable<V, int>::value, "ambiguous");
   }
-#endif
+#endif // TEST_VARIANT_HAS_NO_REFERENCES
 }
 
 void test_T_assignment_basic() {
@@ -163,7 +185,7 @@ void test_T_assignment_basic() {
     assert(v.index() == 2);
     assert(std::get<2>(v) == 42);
   }
-#endif
+#endif // TEST_VARIANT_HAS_NO_REFERENCES
 }
 
 void test_T_assignment_performs_construction() {
@@ -174,9 +196,11 @@ void test_T_assignment_performs_construction() {
     V v(std::in_place_type<std::string>, "hello");
     try {
       v = 42;
+      assert(false);
     } catch (...) { /* ... */
     }
-    assert(v.valueless_by_exception());
+    assert(v.index() == 0);
+    assert(std::get<0>(v) == "hello");
   }
   {
     using V = std::variant<ThrowsAssignT, std::string>;
@@ -185,7 +209,7 @@ void test_T_assignment_performs_construction() {
     assert(v.index() == 0);
     assert(std::get<0>(v).value == 42);
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
 }
 
 void test_T_assignment_performs_assignment() {
@@ -227,7 +251,7 @@ void test_T_assignment_performs_assignment() {
     assert(v.index() == 1);
     assert(std::get<1>(v).value == 100);
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
 }
 
 int main() {
diff --git a/test/std/utilities/variant/variant.variant/variant.assign/copy.pass.cpp b/test/std/utilities/variant/variant.variant/variant.assign/copy.pass.cpp
index 4f0009d9d620..068b9a201566 100644
--- a/test/std/utilities/variant/variant.variant/variant.assign/copy.pass.cpp
+++ b/test/std/utilities/variant/variant.variant/variant.assign/copy.pass.cpp
@@ -10,6 +10,10 @@
 
 // UNSUPPORTED: c++98, c++03, c++11, c++14
 
+// The following compilers don't generate constexpr special members correctly.
+// XFAIL: clang-3.5, clang-3.6, clang-3.7, clang-3.8
+// XFAIL: apple-clang-6, apple-clang-7, apple-clang-8.0
+
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
@@ -35,11 +39,6 @@ struct NoCopy {
   NoCopy &operator=(const NoCopy &) = default;
 };
 
-struct NothrowCopy {
-  NothrowCopy(const NothrowCopy &) noexcept = default;
-  NothrowCopy &operator=(const NothrowCopy &) noexcept = default;
-};
-
 struct CopyOnly {
   CopyOnly(const CopyOnly &) = default;
   CopyOnly(CopyOnly &&) = delete;
@@ -73,7 +72,7 @@ struct CopyAssign {
     ++alive;
     ++copy_construct;
   }
-  CopyAssign(CopyAssign &&o) : value(o.value) {
+  CopyAssign(CopyAssign &&o) noexcept : value(o.value) {
     o.value = -1;
     ++alive;
     ++move_construct;
@@ -83,7 +82,7 @@ struct CopyAssign {
     ++copy_assign;
     return *this;
   }
-  CopyAssign &operator=(CopyAssign &&o) {
+  CopyAssign &operator=(CopyAssign &&o) noexcept {
     value = o.value;
     o.value = -1;
     ++move_assign;
@@ -108,6 +107,48 @@ struct CopyDoesThrow {
   CopyDoesThrow &operator=(const CopyDoesThrow &) noexcept(false);
 };
 
+
+struct NTCopyAssign {
+  constexpr NTCopyAssign(int v) : value(v) {}
+  NTCopyAssign(const NTCopyAssign &) = default;
+  NTCopyAssign(NTCopyAssign &&) = default;
+  NTCopyAssign &operator=(const NTCopyAssign &that) {
+    value = that.value;
+    return *this;
+  };
+  NTCopyAssign &operator=(NTCopyAssign &&) = delete;
+  int value;
+};
+
+static_assert(!std::is_trivially_copy_assignable<NTCopyAssign>::value, "");
+static_assert(std::is_copy_assignable<NTCopyAssign>::value, "");
+
+struct TCopyAssign {
+  constexpr TCopyAssign(int v) : value(v) {}
+  TCopyAssign(const TCopyAssign &) = default;
+  TCopyAssign(TCopyAssign &&) = default;
+  TCopyAssign &operator=(const TCopyAssign &) = default;
+  TCopyAssign &operator=(TCopyAssign &&) = delete;
+  int value;
+};
+
+static_assert(std::is_trivially_copy_assignable<TCopyAssign>::value, "");
+
+struct TCopyAssignNTMoveAssign {
+  constexpr TCopyAssignNTMoveAssign(int v) : value(v) {}
+  TCopyAssignNTMoveAssign(const TCopyAssignNTMoveAssign &) = default;
+  TCopyAssignNTMoveAssign(TCopyAssignNTMoveAssign &&) = default;
+  TCopyAssignNTMoveAssign &operator=(const TCopyAssignNTMoveAssign &) = default;
+  TCopyAssignNTMoveAssign &operator=(TCopyAssignNTMoveAssign &&that) {
+    value = that.value;
+    that.value = -1;
+    return *this;
+  }
+  int value;
+};
+
+static_assert(std::is_trivially_copy_assignable_v<TCopyAssignNTMoveAssign>, "");
+
 #ifndef TEST_HAS_NO_EXCEPTIONS
 struct CopyThrows {
   CopyThrows() = default;
@@ -115,6 +156,17 @@ struct CopyThrows {
   CopyThrows &operator=(const CopyThrows &) { throw 42; }
 };
 
+struct CopyCannotThrow {
+  static int alive;
+  CopyCannotThrow() { ++alive; }
+  CopyCannotThrow(const CopyCannotThrow &) noexcept { ++alive; }
+  CopyCannotThrow(CopyCannotThrow &&) noexcept { assert(false); }
+  CopyCannotThrow &operator=(const CopyCannotThrow &) noexcept = default;
+  CopyCannotThrow &operator=(CopyCannotThrow &&) noexcept { assert(false); return *this; }
+};
+
+int CopyCannotThrow::alive = 0;
+
 struct MoveThrows {
   static int alive;
   MoveThrows() { ++alive; }
@@ -146,7 +198,7 @@ int MakeEmptyT::alive = 0;
 template <class Variant> void makeEmpty(Variant &v) {
   Variant v2(std::in_place_type<MakeEmptyT>);
   try {
-    v = v2;
+    v = std::move(v2);
     assert(false);
   } catch (...) {
     assert(v.valueless_by_exception());
@@ -171,10 +223,8 @@ void test_copy_assignment_sfinae() {
     static_assert(std::is_copy_assignable<V>::value, "");
   }
   {
-    // variant only provides copy assignment when both the copy and move
-    // constructors are well formed
     using V = std::variant<int, CopyOnly>;
-    static_assert(!std::is_copy_assignable<V>::value, "");
+    static_assert(std::is_copy_assignable<V>::value, "");
   }
   {
     using V = std::variant<int, NoCopy>;
@@ -188,6 +238,29 @@ void test_copy_assignment_sfinae() {
     using V = std::variant<int, MoveOnlyNT>;
     static_assert(!std::is_copy_assignable<V>::value, "");
   }
+
+  // The following tests are for not-yet-standardized behavior (P0602):
+  {
+    using V = std::variant<int, long>;
+    static_assert(std::is_trivially_copy_assignable<V>::value, "");
+  }
+  {
+    using V = std::variant<int, NTCopyAssign>;
+    static_assert(!std::is_trivially_copy_assignable<V>::value, "");
+    static_assert(std::is_copy_assignable<V>::value, "");
+  }
+  {
+    using V = std::variant<int, TCopyAssign>;
+    static_assert(std::is_trivially_copy_assignable<V>::value, "");
+  }
+  {
+    using V = std::variant<int, TCopyAssignNTMoveAssign>;
+    static_assert(std::is_trivially_copy_assignable<V>::value, "");
+  }
+  {
+    using V = std::variant<int, CopyOnly>;
+    static_assert(std::is_trivially_copy_assignable<V>::value, "");
+  }
 }
 
 void test_copy_assignment_empty_empty() {
@@ -204,7 +277,7 @@ void test_copy_assignment_empty_empty() {
     assert(v1.valueless_by_exception());
     assert(v1.index() == std::variant_npos);
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
 }
 
 void test_copy_assignment_non_empty_empty() {
@@ -230,7 +303,7 @@ void test_copy_assignment_non_empty_empty() {
     assert(v1.valueless_by_exception());
     assert(v1.index() == std::variant_npos);
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
 }
 
 void test_copy_assignment_empty_non_empty() {
@@ -256,9 +329,11 @@ void test_copy_assignment_empty_non_empty() {
     assert(v1.index() == 2);
     assert(std::get<2>(v1) == "hello");
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
 }
 
+template <typename T> struct Result { size_t index; T value; };
+
 void test_copy_assignment_same_index() {
   {
     using V = std::variant<int>;
@@ -306,7 +381,65 @@ void test_copy_assignment_same_index() {
     assert(v1.index() == 1);
     assert(&std::get<1>(v1) == &mref);
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
+
+  // The following tests are for not-yet-standardized behavior (P0602):
+  {
+    struct {
+      constexpr Result<int> operator()() const {
+        using V = std::variant<int>;
+        V v(43);
+        V v2(42);
+        v = v2;
+        return {v.index(), std::get<0>(v)};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 0, "");
+    static_assert(result.value == 42, "");
+  }
+  {
+    struct {
+      constexpr Result<long> operator()() const {
+        using V = std::variant<int, long, unsigned>;
+        V v(43l);
+        V v2(42l);
+        v = v2;
+        return {v.index(), std::get<1>(v)};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value == 42l, "");
+  }
+  {
+    struct {
+      constexpr Result<int> operator()() const {
+        using V = std::variant<int, TCopyAssign, unsigned>;
+        V v(std::in_place_type<TCopyAssign>, 43);
+        V v2(std::in_place_type<TCopyAssign>, 42);
+        v = v2;
+        return {v.index(), std::get<1>(v).value};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value == 42, "");
+  }
+  {
+    struct {
+      constexpr Result<int> operator()() const {
+        using V = std::variant<int, TCopyAssignNTMoveAssign, unsigned>;
+        V v(std::in_place_type<TCopyAssignNTMoveAssign>, 43);
+        V v2(std::in_place_type<TCopyAssignNTMoveAssign>, 42);
+        v = v2;
+        return {v.index(), std::get<1>(v).value};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value == 42, "");
+  }
 }
 
 void test_copy_assignment_different_index() {
@@ -338,8 +471,6 @@ void test_copy_assignment_different_index() {
   }
 #ifndef TEST_HAS_NO_EXCEPTIONS
   {
-    // Test that if copy construction throws then original value is
-    // unchanged.
     using V = std::variant<int, CopyThrows, std::string>;
     V v1(std::in_place_type<std::string>, "hello");
     V v2(std::in_place_type<CopyThrows>);
@@ -348,24 +479,31 @@ void test_copy_assignment_different_index() {
       assert(false);
     } catch (...) { /* ... */
     }
-    assert(v1.index() == 2);
-    assert(std::get<2>(v1) == "hello");
+    // Test that copy construction is used directly if move construction may throw,
+    // resulting in a valueless variant if copy throws.
+    assert(v1.valueless_by_exception());
   }
   {
-    // Test that if move construction throws then the variant is left
-    // valueless by exception.
     using V = std::variant<int, MoveThrows, std::string>;
     V v1(std::in_place_type<std::string>, "hello");
     V v2(std::in_place_type<MoveThrows>);
     assert(MoveThrows::alive == 1);
-    try {
-      v1 = v2;
-      assert(false);
-    } catch (...) { /* ... */
-    }
-    assert(v1.valueless_by_exception());
+    // Test that copy construction is used directly if move construction may throw.
+    v1 = v2;
+    assert(v1.index() == 1);
     assert(v2.index() == 1);
-    assert(MoveThrows::alive == 1);
+    assert(MoveThrows::alive == 2);
+  }
+  {
+    // Test that direct copy construction is preferred when it cannot throw.
+    using V = std::variant<int, CopyCannotThrow, std::string>;
+    V v1(std::in_place_type<std::string>, "hello");
+    V v2(std::in_place_type<CopyCannotThrow>);
+    assert(CopyCannotThrow::alive == 1);
+    v1 = v2;
+    assert(v1.index() == 1);
+    assert(v2.index() == 1);
+    assert(CopyCannotThrow::alive == 2);
   }
   {
     using V = std::variant<int, CopyThrows, std::string>;
@@ -389,9 +527,60 @@ void test_copy_assignment_different_index() {
     assert(v2.index() == 2);
     assert(std::get<2>(v2) == "hello");
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
+
+  // The following tests are for not-yet-standardized behavior (P0602):
+  {
+    struct {
+      constexpr Result<long> operator()() const {
+        using V = std::variant<int, long, unsigned>;
+        V v(43);
+        V v2(42l);
+        v = v2;
+        return {v.index(), std::get<1>(v)};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value == 42l, "");
+  }
+  {
+    struct {
+      constexpr Result<int> operator()() const {
+        using V = std::variant<int, TCopyAssign, unsigned>;
+        V v(std::in_place_type<unsigned>, 43);
+        V v2(std::in_place_type<TCopyAssign>, 42);
+        v = v2;
+        return {v.index(), std::get<1>(v).value};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value == 42, "");
+  }
+}
+
+template <size_t NewIdx, class ValueType>
+constexpr bool test_constexpr_assign_extension_imp(
+    std::variant<long, void*, int>&& v, ValueType&& new_value)
+{
+  const std::variant<long, void*, int> cp(
+      std::forward<ValueType>(new_value));
+  v = cp;
+  return v.index() == NewIdx &&
+        std::get<NewIdx>(v) == std::get<NewIdx>(cp);
 }
 
+void test_constexpr_copy_assignment_extension() {
+  // The following tests are for not-yet-standardized behavior (P0602):
+  using V = std::variant<long, void*, int>;
+  static_assert(std::is_trivially_copyable<V>::value, "");
+  static_assert(std::is_trivially_copy_assignable<V>::value, "");
+  static_assert(test_constexpr_assign_extension_imp<0>(V(42l), 101l), "");
+  static_assert(test_constexpr_assign_extension_imp<0>(V(nullptr), 101l), "");
+  static_assert(test_constexpr_assign_extension_imp<1>(V(42l), nullptr), "");
+  static_assert(test_constexpr_assign_extension_imp<2>(V(42l), 101), "");
+}
 
 int main() {
   test_copy_assignment_empty_empty();
@@ -401,4 +590,5 @@ int main() {
   test_copy_assignment_different_index();
   test_copy_assignment_sfinae();
   test_copy_assignment_not_noexcept();
+  test_constexpr_copy_assignment_extension();
 }
diff --git a/test/std/utilities/variant/variant.variant/variant.assign/move.pass.cpp b/test/std/utilities/variant/variant.variant/variant.assign/move.pass.cpp
index c1ba87be76d1..c410b4b8f3ef 100644
--- a/test/std/utilities/variant/variant.variant/variant.assign/move.pass.cpp
+++ b/test/std/utilities/variant/variant.variant/variant.assign/move.pass.cpp
@@ -10,6 +10,10 @@
 
 // UNSUPPORTED: c++98, c++03, c++11, c++14
 
+// The following compilers don't generate constexpr special members correctly.
+// XFAIL: clang-3.5, clang-3.6, clang-3.7, clang-3.8
+// XFAIL: apple-clang-6, apple-clang-7, apple-clang-8.0
+
 // XFAIL: with_system_cxx_lib=macosx10.12
 // XFAIL: with_system_cxx_lib=macosx10.11
 // XFAIL: with_system_cxx_lib=macosx10.10
@@ -91,6 +95,60 @@ struct MoveAssign {
 int MoveAssign::move_construct = 0;
 int MoveAssign::move_assign = 0;
 
+struct NTMoveAssign {
+  constexpr NTMoveAssign(int v) : value(v) {}
+  NTMoveAssign(const NTMoveAssign &) = default;
+  NTMoveAssign(NTMoveAssign &&) = default;
+  NTMoveAssign &operator=(const NTMoveAssign &that) = default;
+  NTMoveAssign &operator=(NTMoveAssign &&that) {
+    value = that.value;
+    that.value = -1;
+    return *this;
+  };
+  int value;
+};
+
+static_assert(!std::is_trivially_move_assignable<NTMoveAssign>::value, "");
+static_assert(std::is_move_assignable<NTMoveAssign>::value, "");
+
+struct TMoveAssign {
+  constexpr TMoveAssign(int v) : value(v) {}
+  TMoveAssign(const TMoveAssign &) = delete;
+  TMoveAssign(TMoveAssign &&) = default;
+  TMoveAssign &operator=(const TMoveAssign &) = delete;
+  TMoveAssign &operator=(TMoveAssign &&) = default;
+  int value;
+};
+
+static_assert(std::is_trivially_move_assignable<TMoveAssign>::value, "");
+
+struct TMoveAssignNTCopyAssign {
+  constexpr TMoveAssignNTCopyAssign(int v) : value(v) {}
+  TMoveAssignNTCopyAssign(const TMoveAssignNTCopyAssign &) = default;
+  TMoveAssignNTCopyAssign(TMoveAssignNTCopyAssign &&) = default;
+  TMoveAssignNTCopyAssign &operator=(const TMoveAssignNTCopyAssign &that) {
+    value = that.value;
+    return *this;
+  }
+  TMoveAssignNTCopyAssign &operator=(TMoveAssignNTCopyAssign &&) = default;
+  int value;
+};
+
+static_assert(std::is_trivially_move_assignable_v<TMoveAssignNTCopyAssign>, "");
+
+struct TrivialCopyNontrivialMove {
+  TrivialCopyNontrivialMove(TrivialCopyNontrivialMove const&) = default;
+  TrivialCopyNontrivialMove(TrivialCopyNontrivialMove&&) noexcept {}
+  TrivialCopyNontrivialMove& operator=(TrivialCopyNontrivialMove const&) = default;
+  TrivialCopyNontrivialMove& operator=(TrivialCopyNontrivialMove&&) noexcept {
+    return *this;
+  }
+};
+
+static_assert(std::is_trivially_copy_assignable_v<TrivialCopyNontrivialMove>, "");
+static_assert(!std::is_trivially_move_assignable_v<TrivialCopyNontrivialMove>, "");
+
+
 void test_move_assignment_noexcept() {
   {
     using V = std::variant<int>;
@@ -124,10 +182,8 @@ void test_move_assignment_sfinae() {
     static_assert(std::is_move_assignable<V>::value, "");
   }
   {
-    // variant only provides move assignment when both the move constructor
-    // and move assignment operator are well formed.
     using V = std::variant<int, CopyOnly>;
-    static_assert(!std::is_move_assignable<V>::value, "");
+    static_assert(std::is_move_assignable<V>::value, "");
   }
   {
     using V = std::variant<int, NoCopy>;
@@ -147,6 +203,33 @@ void test_move_assignment_sfinae() {
     using V = std::variant<int, MoveAssignOnly>;
     static_assert(!std::is_move_assignable<V>::value, "");
   }
+
+  // The following tests are for not-yet-standardized behavior (P0602):
+  {
+    using V = std::variant<int, long>;
+    static_assert(std::is_trivially_move_assignable<V>::value, "");
+  }
+  {
+    using V = std::variant<int, NTMoveAssign>;
+    static_assert(!std::is_trivially_move_assignable<V>::value, "");
+    static_assert(std::is_move_assignable<V>::value, "");
+  }
+  {
+    using V = std::variant<int, TMoveAssign>;
+    static_assert(std::is_trivially_move_assignable<V>::value, "");
+  }
+  {
+    using V = std::variant<int, TMoveAssignNTCopyAssign>;
+    static_assert(std::is_trivially_move_assignable<V>::value, "");
+  }
+  {
+    using V = std::variant<int, TrivialCopyNontrivialMove>;
+    static_assert(!std::is_trivially_move_assignable<V>::value, "");
+  }
+  {
+    using V = std::variant<int, CopyOnly>;
+    static_assert(std::is_trivially_move_assignable<V>::value, "");
+  }
 }
 
 void test_move_assignment_empty_empty() {
@@ -163,7 +246,7 @@ void test_move_assignment_empty_empty() {
     assert(v1.valueless_by_exception());
     assert(v1.index() == std::variant_npos);
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
 }
 
 void test_move_assignment_non_empty_empty() {
@@ -189,7 +272,7 @@ void test_move_assignment_non_empty_empty() {
     assert(v1.valueless_by_exception());
     assert(v1.index() == std::variant_npos);
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
 }
 
 void test_move_assignment_empty_non_empty() {
@@ -215,9 +298,11 @@ void test_move_assignment_empty_non_empty() {
     assert(v1.index() == 2);
     assert(std::get<2>(v1) == "hello");
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
 }
 
+template <typename T> struct Result { size_t index; T value; };
+
 void test_move_assignment_same_index() {
   {
     using V = std::variant<int>;
@@ -264,7 +349,51 @@ void test_move_assignment_same_index() {
     assert(v1.index() == 1);
     assert(&std::get<1>(v1) == &mref);
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
+
+  // The following tests are for not-yet-standardized behavior (P0602):
+  {
+    struct {
+      constexpr Result<int> operator()() const {
+        using V = std::variant<int>;
+        V v(43);
+        V v2(42);
+        v = std::move(v2);
+        return {v.index(), std::get<0>(v)};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 0, "");
+    static_assert(result.value == 42, "");
+  }
+  {
+    struct {
+      constexpr Result<long> operator()() const {
+        using V = std::variant<int, long, unsigned>;
+        V v(43l);
+        V v2(42l);
+        v = std::move(v2);
+        return {v.index(), std::get<1>(v)};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value == 42l, "");
+  }
+  {
+    struct {
+      constexpr Result<int> operator()() const {
+        using V = std::variant<int, TMoveAssign, unsigned>;
+        V v(std::in_place_type<TMoveAssign>, 43);
+        V v2(std::in_place_type<TMoveAssign>, 42);
+        v = std::move(v2);
+        return {v.index(), std::get<1>(v).value};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value == 42, "");
+  }
 }
 
 void test_move_assignment_different_index() {
@@ -312,7 +441,60 @@ void test_move_assignment_different_index() {
     assert(v1.index() == 2);
     assert(std::get<2>(v1) == "hello");
   }
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
+
+  // The following tests are for not-yet-standardized behavior (P0602):
+  {
+    struct {
+      constexpr Result<long> operator()() const {
+        using V = std::variant<int, long, unsigned>;
+        V v(43);
+        V v2(42l);
+        v = std::move(v2);
+        return {v.index(), std::get<1>(v)};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value == 42l, "");
+  }
+  {
+    struct {
+      constexpr Result<long> operator()() const {
+        using V = std::variant<int, TMoveAssign, unsigned>;
+        V v(std::in_place_type<unsigned>, 43);
+        V v2(std::in_place_type<TMoveAssign>, 42);
+        v = std::move(v2);
+        return {v.index(), std::get<1>(v).value};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value == 42, "");
+  }
+}
+
+template <size_t NewIdx, class ValueType>
+constexpr bool test_constexpr_assign_extension_imp(
+    std::variant<long, void*, int>&& v, ValueType&& new_value)
+{
+  std::variant<long, void*, int> v2(
+      std::forward<ValueType>(new_value));
+  const auto cp = v2;
+  v = std::move(v2);
+  return v.index() == NewIdx &&
+        std::get<NewIdx>(v) == std::get<NewIdx>(cp);
+}
+
+void test_constexpr_move_assignment_extension() {
+  // The following tests are for not-yet-standardized behavior (P0602):
+  using V = std::variant<long, void*, int>;
+  static_assert(std::is_trivially_copyable<V>::value, "");
+  static_assert(std::is_trivially_move_assignable<V>::value, "");
+  static_assert(test_constexpr_assign_extension_imp<0>(V(42l), 101l), "");
+  static_assert(test_constexpr_assign_extension_imp<0>(V(nullptr), 101l), "");
+  static_assert(test_constexpr_assign_extension_imp<1>(V(42l), nullptr), "");
+  static_assert(test_constexpr_assign_extension_imp<2>(V(42l), 101), "");
 }
 
 int main() {
@@ -323,4 +505,5 @@ int main() {
   test_move_assignment_different_index();
   test_move_assignment_sfinae();
   test_move_assignment_noexcept();
+  test_constexpr_move_assignment_extension();
 }
diff --git a/test/std/utilities/variant/variant.variant/variant.ctor/copy.pass.cpp b/test/std/utilities/variant/variant.variant/variant.ctor/copy.pass.cpp
index 3b20c369c638..f3113435f3ce 100644
--- a/test/std/utilities/variant/variant.variant/variant.ctor/copy.pass.cpp
+++ b/test/std/utilities/variant/variant.variant/variant.ctor/copy.pass.cpp
@@ -51,6 +51,34 @@ struct MoveOnlyNT {
   MoveOnlyNT(MoveOnlyNT &&) {}
 };
 
+struct NTCopy {
+  constexpr NTCopy(int v) : value(v) {}
+  NTCopy(const NTCopy &that) : value(that.value) {}
+  NTCopy(NTCopy &&) = delete;
+  int value;
+};
+
+static_assert(!std::is_trivially_copy_constructible<NTCopy>::value, "");
+static_assert(std::is_copy_constructible<NTCopy>::value, "");
+
+struct TCopy {
+  constexpr TCopy(int v) : value(v) {}
+  TCopy(TCopy const &) = default;
+  TCopy(TCopy &&) = delete;
+  int value;
+};
+
+static_assert(std::is_trivially_copy_constructible<TCopy>::value, "");
+
+struct TCopyNTMove {
+  constexpr TCopyNTMove(int v) : value(v) {}
+  TCopyNTMove(const TCopyNTMove&) = default;
+  TCopyNTMove(TCopyNTMove&& that) : value(that.value) { that.value = -1; }
+  int value;
+};
+
+static_assert(std::is_trivially_copy_constructible<TCopyNTMove>::value, "");
+
 #ifndef TEST_HAS_NO_EXCEPTIONS
 struct MakeEmptyT {
   static int alive;
@@ -71,7 +99,7 @@ int MakeEmptyT::alive = 0;
 template <class Variant> void makeEmpty(Variant &v) {
   Variant v2(std::in_place_type<MakeEmptyT>);
   try {
-    v = v2;
+    v = std::move(v2);
     assert(false);
   } catch (...) {
     assert(v.valueless_by_exception());
@@ -96,6 +124,25 @@ void test_copy_ctor_sfinae() {
     using V = std::variant<int, MoveOnlyNT>;
     static_assert(!std::is_copy_constructible<V>::value, "");
   }
+
+  // The following tests are for not-yet-standardized behavior (P0602):
+  {
+    using V = std::variant<int, long>;
+    static_assert(std::is_trivially_copy_constructible<V>::value, "");
+  }
+  {
+    using V = std::variant<int, NTCopy>;
+    static_assert(!std::is_trivially_copy_constructible<V>::value, "");
+    static_assert(std::is_copy_constructible<V>::value, "");
+  }
+  {
+    using V = std::variant<int, TCopy>;
+    static_assert(std::is_trivially_copy_constructible<V>::value, "");
+  }
+  {
+    using V = std::variant<int, TCopyNTMove>;
+    static_assert(std::is_trivially_copy_constructible<V>::value, "");
+  }
 }
 
 void test_copy_ctor_basic() {
@@ -125,6 +172,50 @@ void test_copy_ctor_basic() {
     assert(v2.index() == 1);
     assert(std::get<1>(v2).value == 42);
   }
+
+  // The following tests are for not-yet-standardized behavior (P0602):
+  {
+    constexpr std::variant<int> v(std::in_place_index<0>, 42);
+    static_assert(v.index() == 0, "");
+    constexpr std::variant<int> v2 = v;
+    static_assert(v2.index() == 0, "");
+    static_assert(std::get<0>(v2) == 42, "");
+  }
+  {
+    constexpr std::variant<int, long> v(std::in_place_index<1>, 42);
+    static_assert(v.index() == 1, "");
+    constexpr std::variant<int, long> v2 = v;
+    static_assert(v2.index() == 1, "");
+    static_assert(std::get<1>(v2) == 42, "");
+  }
+  {
+    constexpr std::variant<TCopy> v(std::in_place_index<0>, 42);
+    static_assert(v.index() == 0, "");
+    constexpr std::variant<TCopy> v2(v);
+    static_assert(v2.index() == 0, "");
+    static_assert(std::get<0>(v2).value == 42, "");
+  }
+  {
+    constexpr std::variant<int, TCopy> v(std::in_place_index<1>, 42);
+    static_assert(v.index() == 1, "");
+    constexpr std::variant<int, TCopy> v2(v);
+    static_assert(v2.index() == 1, "");
+    static_assert(std::get<1>(v2).value == 42, "");
+  }
+  {
+    constexpr std::variant<TCopyNTMove> v(std::in_place_index<0>, 42);
+    static_assert(v.index() == 0, "");
+    constexpr std::variant<TCopyNTMove> v2(v);
+    static_assert(v2.index() == 0, "");
+    static_assert(std::get<0>(v2).value == 42, "");
+  }
+  {
+    constexpr std::variant<int, TCopyNTMove> v(std::in_place_index<1>, 42);
+    static_assert(v.index() == 1, "");
+    constexpr std::variant<int, TCopyNTMove> v2(v);
+    static_assert(v2.index() == 1, "");
+    static_assert(std::get<1>(v2).value == 42, "");
+  }
 }
 
 void test_copy_ctor_valueless_by_exception() {
@@ -135,7 +226,7 @@ void test_copy_ctor_valueless_by_exception() {
   const V &cv1 = v1;
   V v(cv1);
   assert(v.valueless_by_exception());
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
 }
 
 template <size_t Idx>
@@ -149,7 +240,7 @@ constexpr bool test_constexpr_copy_ctor_extension_imp(
 }
 
 void test_constexpr_copy_ctor_extension() {
-  // NOTE: This test is for not yet standardized behavior.
+  // NOTE: This test is for not yet standardized behavior. (P0602)
   using V = std::variant<long, void*, const int>;
 #ifdef TEST_WORKAROUND_C1XX_BROKEN_IS_TRIVIALLY_COPYABLE
   static_assert(std::is_trivially_destructible<V>::value, "");
@@ -157,9 +248,9 @@ void test_constexpr_copy_ctor_extension() {
   static_assert(std::is_trivially_move_constructible<V>::value, "");
   static_assert(!std::is_copy_assignable<V>::value, "");
   static_assert(!std::is_move_assignable<V>::value, "");
-#else
+#else // TEST_WORKAROUND_C1XX_BROKEN_IS_TRIVIALLY_COPYABLE
   static_assert(std::is_trivially_copyable<V>::value, "");
-#endif
+#endif // TEST_WORKAROUND_C1XX_BROKEN_IS_TRIVIALLY_COPYABLE
   static_assert(test_constexpr_copy_ctor_extension_imp<0>(V(42l)), "");
   static_assert(test_constexpr_copy_ctor_extension_imp<1>(V(nullptr)), "");
   static_assert(test_constexpr_copy_ctor_extension_imp<2>(V(101)), "");
diff --git a/test/std/utilities/variant/variant.variant/variant.ctor/move.pass.cpp b/test/std/utilities/variant/variant.variant/variant.ctor/move.pass.cpp
index a5de1f77334e..6b392068d5a9 100644
--- a/test/std/utilities/variant/variant.variant/variant.ctor/move.pass.cpp
+++ b/test/std/utilities/variant/variant.variant/variant.ctor/move.pass.cpp
@@ -53,6 +53,34 @@ struct MoveOnlyNT {
   MoveOnlyNT(MoveOnlyNT &&other) : value(other.value) { other.value = -1; }
 };
 
+struct NTMove {
+  constexpr NTMove(int v) : value(v) {}
+  NTMove(const NTMove &) = delete;
+  NTMove(NTMove &&that) : value(that.value) { that.value = -1; }
+  int value;
+};
+
+static_assert(!std::is_trivially_move_constructible<NTMove>::value, "");
+static_assert(std::is_move_constructible<NTMove>::value, "");
+
+struct TMove {
+  constexpr TMove(int v) : value(v) {}
+  TMove(const TMove &) = delete;
+  TMove(TMove &&) = default;
+  int value;
+};
+
+static_assert(std::is_trivially_move_constructible<TMove>::value, "");
+
+struct TMoveNTCopy {
+  constexpr TMoveNTCopy(int v) : value(v) {}
+  TMoveNTCopy(const TMoveNTCopy& that) : value(that.value) {}
+  TMoveNTCopy(TMoveNTCopy&&) = default;
+  int value;
+};
+
+static_assert(std::is_trivially_move_constructible<TMoveNTCopy>::value, "");
+
 #ifndef TEST_HAS_NO_EXCEPTIONS
 struct MakeEmptyT {
   static int alive;
@@ -73,7 +101,7 @@ int MakeEmptyT::alive = 0;
 template <class Variant> void makeEmpty(Variant &v) {
   Variant v2(std::in_place_type<MakeEmptyT>);
   try {
-    v = v2;
+    v = std::move(v2);
     assert(false);
   } catch (...) {
     assert(v.valueless_by_exception());
@@ -117,8 +145,30 @@ void test_move_ctor_sfinae() {
     using V = std::variant<int, NoCopy>;
     static_assert(!std::is_move_constructible<V>::value, "");
   }
+
+  // The following tests are for not-yet-standardized behavior (P0602):
+  {
+    using V = std::variant<int, long>;
+    static_assert(std::is_trivially_move_constructible<V>::value, "");
+  }
+  {
+    using V = std::variant<int, NTMove>;
+    static_assert(!std::is_trivially_move_constructible<V>::value, "");
+    static_assert(std::is_move_constructible<V>::value, "");
+  }
+  {
+    using V = std::variant<int, TMove>;
+    static_assert(std::is_trivially_move_constructible<V>::value, "");
+  }
+  {
+    using V = std::variant<int, TMoveNTCopy>;
+    static_assert(std::is_trivially_move_constructible<V>::value, "");
+  }
 }
 
+template <typename T>
+struct Result { size_t index; T value; };
+
 void test_move_ctor_basic() {
   {
     std::variant<int> v(std::in_place_index<0>, 42);
@@ -162,6 +212,80 @@ void test_move_ctor_basic() {
     assert(std::get<1>(v).value == -1);
     assert(std::get<1>(v2).value == 42);
   }
+
+  // The following tests are for not-yet-standardized behavior (P0602):
+  {
+    struct {
+      constexpr Result<int> operator()() const {
+        std::variant<int> v(std::in_place_index<0>, 42);
+        std::variant<int> v2 = std::move(v);
+        return {v2.index(), std::get<0>(std::move(v2))};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 0, "");
+    static_assert(result.value == 42, "");
+  }
+  {
+    struct {
+      constexpr Result<long> operator()() const {
+        std::variant<int, long> v(std::in_place_index<1>, 42);
+        std::variant<int, long> v2 = std::move(v);
+        return {v2.index(), std::get<1>(std::move(v2))};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value == 42, "");
+  }
+  {
+    struct {
+      constexpr Result<TMove> operator()() const {
+        std::variant<TMove> v(std::in_place_index<0>, 42);
+        std::variant<TMove> v2(std::move(v));
+        return {v2.index(), std::get<0>(std::move(v2))};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 0, "");
+    static_assert(result.value.value == 42, "");
+  }
+  {
+    struct {
+      constexpr Result<TMove> operator()() const {
+        std::variant<int, TMove> v(std::in_place_index<1>, 42);
+        std::variant<int, TMove> v2(std::move(v));
+        return {v2.index(), std::get<1>(std::move(v2))};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value.value == 42, "");
+  }
+  {
+    struct {
+      constexpr Result<TMoveNTCopy> operator()() const {
+        std::variant<TMoveNTCopy> v(std::in_place_index<0>, 42);
+        std::variant<TMoveNTCopy> v2(std::move(v));
+        return {v2.index(), std::get<0>(std::move(v2))};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 0, "");
+    static_assert(result.value.value == 42, "");
+  }
+  {
+    struct {
+      constexpr Result<TMoveNTCopy> operator()() const {
+        std::variant<int, TMoveNTCopy> v(std::in_place_index<1>, 42);
+        std::variant<int, TMoveNTCopy> v2(std::move(v));
+        return {v2.index(), std::get<1>(std::move(v2))};
+      }
+    } test;
+    constexpr auto result = test();
+    static_assert(result.index == 1, "");
+    static_assert(result.value.value == 42, "");
+  }
 }
 
 void test_move_ctor_valueless_by_exception() {
@@ -171,7 +295,7 @@ void test_move_ctor_valueless_by_exception() {
   makeEmpty(v1);
   V v(std::move(v1));
   assert(v.valueless_by_exception());
-#endif
+#endif // TEST_HAS_NO_EXCEPTIONS
 }
 
 template <size_t Idx>
@@ -186,7 +310,7 @@ constexpr bool test_constexpr_ctor_extension_imp(
 }
 
 void test_constexpr_move_ctor_extension() {
-  // NOTE: This test is for not yet standardized behavior.
+  // NOTE: This test is for not yet standardized behavior. (P0602)
   using V = std::variant<long, void*, const int>;
 #ifdef TEST_WORKAROUND_C1XX_BROKEN_IS_TRIVIALLY_COPYABLE
   static_assert(std::is_trivially_destructible<V>::value, "");
@@ -194,9 +318,9 @@ void test_constexpr_move_ctor_extension() {
   static_assert(std::is_trivially_move_constructible<V>::value, "");
   static_assert(!std::is_copy_assignable<V>::value, "");
   static_assert(!std::is_move_assignable<V>::value, "");
-#else
+#else // TEST_WORKAROUND_C1XX_BROKEN_IS_TRIVIALLY_COPYABLE
   static_assert(std::is_trivially_copyable<V>::value, "");
-#endif
+#endif // TEST_WORKAROUND_C1XX_BROKEN_IS_TRIVIALLY_COPYABLE
   static_assert(std::is_trivially_move_constructible<V>::value, "");
   static_assert(test_constexpr_ctor_extension_imp<0>(V(42l)), "");
   static_assert(test_constexpr_ctor_extension_imp<1>(V(nullptr)), "");