Implement the first part of N4258: 'Cleaning up noexcept in the Library'. This patch deals with swapping containers, and implements a more strict noexcept specification (a conforming extension) than the standard mandates.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@242056 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/containers/associative/map/map.special/swap_noexcept.pass.cpp

@@ -12,6 +12,10 @@
 // void swap(map& c)
 //     noexcept(!allocator_type::propagate_on_container_swap::value ||
 //              __is_nothrow_swappable<allocator_type>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::is_always_equal::value &&
+//              noexcept(swap(declval<Compare&>(), declval<Compare&>())));                 
 
 // This tests a conforming extension
 
@@ -33,6 +37,60 @@ struct some_comp
     typedef std::true_type propagate_on_container_swap;
 };
 
+template <class T>
+struct some_comp2
+{
+    typedef T value_type;
+    
+    some_comp2() {}
+    some_comp2(const some_comp2&) {}
+    void deallocate(void*, unsigned) {}
+    typedef std::true_type propagate_on_container_swap;
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_comp2<T>&, some_comp2<T>&) noexcept {}
+#endif
+
+template <class T>
+struct some_alloc
+{
+    typedef T value_type;
+    
+    some_alloc() {}
+    some_alloc(const some_alloc&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::true_type propagate_on_container_swap;
+};
+
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
+template <class T>
+struct some_alloc3
+{
+    typedef T value_type;
+    
+    some_alloc3() {}
+    some_alloc3(const some_alloc3&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::false_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -56,5 +114,35 @@ int main()
         C c1, c2;
         static_assert(!noexcept(swap(c1, c2)), "");
     }
+
+#if TEST_STD_VER >= 14
+    { // POCS allocator, throwable swap for comp
+    typedef std::map<MoveOnly, MoveOnly, some_comp <MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for comp
+    typedef std::map<MoveOnly, MoveOnly, some_comp <MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for comp
+    typedef std::map<MoveOnly, MoveOnly, some_comp2<MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for comp
+    typedef std::map<MoveOnly, MoveOnly, some_comp2<MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+
+    { // NOT always equal allocator, nothrow swap for comp
+    typedef std::map<MoveOnly, MoveOnly, some_comp2<MoveOnly>, some_alloc3<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+#endif
+
 #endif
 }

test/std/containers/associative/multimap/multimap.special/swap_noexcept.pass.cpp

@@ -12,6 +12,10 @@
 // void swap(multimap& c)
 //     noexcept(!allocator_type::propagate_on_container_swap::value ||
 //              __is_nothrow_swappable<allocator_type>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::is_always_equal::value &&
+//              noexcept(swap(declval<Compare&>(), declval<Compare&>())));                 
 
 // This tests a conforming extension
 
@@ -33,6 +37,60 @@ struct some_comp
     typedef std::true_type propagate_on_container_swap;
 };
 
+template <class T>
+struct some_comp2
+{
+    typedef T value_type;
+    
+    some_comp2() {}
+    some_comp2(const some_comp2&) {}
+    void deallocate(void*, unsigned) {}
+    typedef std::true_type propagate_on_container_swap;
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_comp2<T>&, some_comp2<T>&) noexcept {}
+#endif
+
+template <class T>
+struct some_alloc
+{
+    typedef T value_type;
+    
+    some_alloc() {}
+    some_alloc(const some_alloc&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::true_type propagate_on_container_swap;
+};
+
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
+template <class T>
+struct some_alloc3
+{
+    typedef T value_type;
+    
+    some_alloc3() {}
+    some_alloc3(const some_alloc3&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::false_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -56,5 +114,35 @@ int main()
         C c1, c2;
         static_assert(!noexcept(swap(c1, c2)), "");
     }
+
+#if TEST_STD_VER >= 14
+    { // POCS allocator, throwable swap for comp
+    typedef std::multimap<MoveOnly, MoveOnly, some_comp <MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for comp
+    typedef std::multimap<MoveOnly, MoveOnly, some_comp <MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for comp
+    typedef std::multimap<MoveOnly, MoveOnly, some_comp2<MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for comp
+    typedef std::multimap<MoveOnly, MoveOnly, some_comp2<MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+
+    { // NOT always equal allocator, nothrow swap for comp
+    typedef std::map<MoveOnly, MoveOnly, some_comp2<MoveOnly>, some_alloc3<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+#endif
+
 #endif
 }

test/std/containers/associative/multiset/multiset.special/swap_noexcept.pass.cpp

@@ -12,6 +12,10 @@
 // void swap(multiset& c)
 //     noexcept(!allocator_type::propagate_on_container_swap::value ||
 //              __is_nothrow_swappable<allocator_type>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::is_always_equal::value &&
+//              noexcept(swap(declval<Compare&>(), declval<Compare&>())));                 
 
 // This tests a conforming extension
 
@@ -33,6 +37,60 @@ struct some_comp
     typedef std::true_type propagate_on_container_swap;
 };
 
+template <class T>
+struct some_comp2
+{
+    typedef T value_type;
+    
+    some_comp2() {}
+    some_comp2(const some_comp2&) {}
+    void deallocate(void*, unsigned) {}
+    typedef std::true_type propagate_on_container_swap;
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_comp2<T>&, some_comp2<T>&) noexcept {}
+#endif
+
+template <class T>
+struct some_alloc
+{
+    typedef T value_type;
+    
+    some_alloc() {}
+    some_alloc(const some_alloc&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::true_type propagate_on_container_swap;
+};
+
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
+template <class T>
+struct some_alloc3
+{
+    typedef T value_type;
+    
+    some_alloc3() {}
+    some_alloc3(const some_alloc3&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::false_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -56,5 +114,35 @@ int main()
         C c1, c2;
         static_assert(!noexcept(swap(c1, c2)), "");
     }
+
+#if TEST_STD_VER >= 14
+    { // POCS allocator, throwable swap for comp
+    typedef std::multiset<MoveOnly, some_comp <MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for comp
+    typedef std::multiset<MoveOnly, some_comp <MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for comp
+    typedef std::multiset<MoveOnly, some_comp2<MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for comp
+    typedef std::multiset<MoveOnly, some_comp2<MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+
+    { // NOT always equal allocator, nothrow swap for comp
+    typedef std::multiset<MoveOnly, some_comp2<MoveOnly>, some_alloc3<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+#endif
+
 #endif
 }

test/std/containers/associative/set/set.special/swap_noexcept.pass.cpp

@@ -12,6 +12,10 @@
 // void swap(set& c)
 //     noexcept(!allocator_type::propagate_on_container_swap::value ||
 //              __is_nothrow_swappable<allocator_type>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::is_always_equal::value &&
+//              noexcept(swap(declval<Compare&>(), declval<Compare&>())));                 
 
 // This tests a conforming extension
 
@@ -33,6 +37,60 @@ struct some_comp
     typedef std::true_type propagate_on_container_swap;
 };
 
+template <class T>
+struct some_comp2
+{
+    typedef T value_type;
+    
+    some_comp2() {}
+    some_comp2(const some_comp2&) {}
+    void deallocate(void*, unsigned) {}
+    typedef std::true_type propagate_on_container_swap;
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_comp2<T>&, some_comp2<T>&) noexcept {}
+#endif
+
+template <class T>
+struct some_alloc
+{
+    typedef T value_type;
+    
+    some_alloc() {}
+    some_alloc(const some_alloc&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::true_type propagate_on_container_swap;
+};
+
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
+template <class T>
+struct some_alloc3
+{
+    typedef T value_type;
+    
+    some_alloc3() {}
+    some_alloc3(const some_alloc3&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::false_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -56,5 +114,35 @@ int main()
         C c1, c2;
         static_assert(!noexcept(swap(c1, c2)), "");
     }
+
+#if TEST_STD_VER >= 14
+    { // POCS allocator, throwable swap for comp
+    typedef std::set<MoveOnly, some_comp <MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for comp
+    typedef std::set<MoveOnly, some_comp <MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for comp
+    typedef std::set<MoveOnly, some_comp2<MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for comp
+    typedef std::set<MoveOnly, some_comp2<MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+
+    { // NOT always equal allocator, nothrow swap for comp
+    typedef std::set<MoveOnly, some_comp2<MoveOnly>, some_alloc3<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+#endif
+
 #endif
 }

test/std/containers/sequences/deque/deque.special/swap_noexcept.pass.cpp

@@ -12,6 +12,9 @@
 // void swap(deque& c)
 //     noexcept(!allocator_type::propagate_on_container_swap::value ||
 //              __is_nothrow_swappable<allocator_type>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::is_always_equal::value);
 
 // This tests a conforming extension
 
@@ -33,6 +36,19 @@ struct some_alloc
     typedef std::true_type propagate_on_container_swap;
 };
 
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -54,7 +70,21 @@ int main()
     {
         typedef std::deque<MoveOnly, some_alloc<MoveOnly>> C;
         C c1, c2;
+#if TEST_STD_VER >= 14
+    //  In c++14, if POCS is set, swapping the allocator is required not to throw
+        static_assert( noexcept(swap(c1, c2)), "");
+#else
         static_assert(!noexcept(swap(c1, c2)), "");
+#endif
+    }
+#if TEST_STD_VER >= 14
+    {
+        typedef std::deque<MoveOnly, some_alloc2<MoveOnly>> C;
+        C c1, c2;
+    //  if the allocators are always equal, then the swap can be noexcept
+        static_assert( noexcept(swap(c1, c2)), "");
     }
 #endif
+
+#endif
 }

test/std/containers/sequences/forwardlist/forwardlist.spec/swap_noexcept.pass.cpp

@@ -12,6 +12,9 @@
 // void swap(forward_list& c)
 //     noexcept(!allocator_type::propagate_on_container_swap::value ||
 //              __is_nothrow_swappable<allocator_type>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(is_always_equal<allocator_type>::value);
 
 // This tests a conforming extension
 
@@ -33,6 +36,19 @@ struct some_alloc
     typedef std::true_type propagate_on_container_swap;
 };
 
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -54,7 +70,21 @@ int main()
     {
         typedef std::forward_list<MoveOnly, some_alloc<MoveOnly>> C;
         C c1, c2;
+#if TEST_STD_VER >= 14
+    //  In c++14, if POCS is set, swapping the allocator is required not to throw
+        static_assert( noexcept(swap(c1, c2)), "");
+#else
         static_assert(!noexcept(swap(c1, c2)), "");
+#endif
+    }
+#if TEST_STD_VER >= 14
+    {
+        typedef std::forward_list<MoveOnly, some_alloc2<MoveOnly>> C;
+        C c1, c2;
+    //  if the allocators are always equal, then the swap can be noexcept
+        static_assert( noexcept(swap(c1, c2)), "");
     }
 #endif
+
+#endif
 }

test/std/containers/sequences/list/list.special/swap_noexcept.pass.cpp

@@ -12,6 +12,9 @@
 // void swap(list& c)
 //     noexcept(!allocator_type::propagate_on_container_swap::value ||
 //              __is_nothrow_swappable<allocator_type>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::is_always_equal::value);
 
 // This tests a conforming extension
 
@@ -33,6 +36,19 @@ struct some_alloc
     typedef std::true_type propagate_on_container_swap;
 };
 
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -54,7 +70,21 @@ int main()
     {
         typedef std::list<MoveOnly, some_alloc<MoveOnly>> C;
         C c1, c2;
+#if TEST_STD_VER >= 14
+    //  In c++14, if POCS is set, swapping the allocator is required not to throw
+        static_assert( noexcept(swap(c1, c2)), "");
+#else
         static_assert(!noexcept(swap(c1, c2)), "");
+#endif
+    }
+#if TEST_STD_VER >= 14
+    {
+        typedef std::list<MoveOnly, some_alloc2<MoveOnly>> C;
+        C c1, c2;
+    //  if the allocators are always equal, then the swap can be noexcept
+        static_assert( noexcept(swap(c1, c2)), "");
     }
 #endif
+
+#endif
 }

test/std/containers/sequences/vector.bool/swap_noexcept.pass.cpp

@@ -12,6 +12,10 @@
 // void swap(vector& c)
 //     noexcept(!allocator_type::propagate_on_container_swap::value ||
 //              __is_nothrow_swappable<allocator_type>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value ||
+//              allocator_traits<Allocator>::is_always_equal::value);
 
 // This tests a conforming extension
 
@@ -32,6 +36,19 @@ struct some_alloc
     typedef std::true_type propagate_on_container_swap;
 };
 
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -53,7 +70,21 @@ int main()
     {
         typedef std::vector<bool, some_alloc<bool>> C;
         C c1, c2;
+#if TEST_STD_VER >= 14
+    //  In c++14, if POCS is set, swapping the allocator is required not to throw
+        static_assert( noexcept(swap(c1, c2)), "");
+#else
         static_assert(!noexcept(swap(c1, c2)), "");
+#endif
+    }
+#if TEST_STD_VER >= 14
+    {
+        typedef std::vector<bool, some_alloc2<bool>> C;
+        C c1, c2;
+    //  if the allocators are always equal, then the swap can be noexcept
+        static_assert( noexcept(swap(c1, c2)), "");
     }
 #endif
+
+#endif
 }

test/std/containers/sequences/vector/vector.special/swap_noexcept.pass.cpp

@@ -12,6 +12,10 @@
 // void swap(vector& c)
 //     noexcept(!allocator_type::propagate_on_container_swap::value ||
 //              __is_nothrow_swappable<allocator_type>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value ||
+//              allocator_traits<Allocator>::is_always_equal::value);
 
 // This tests a conforming extension
 
@@ -33,6 +37,19 @@ struct some_alloc
     typedef std::true_type propagate_on_container_swap;
 };
 
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -54,7 +71,21 @@ int main()
     {
         typedef std::vector<MoveOnly, some_alloc<MoveOnly>> C;
         C c1, c2;
+#if TEST_STD_VER >= 14
+    //  In c++14, if POCS is set, swapping the allocator is required not to throw
+        static_assert( noexcept(swap(c1, c2)), "");
+#else
         static_assert(!noexcept(swap(c1, c2)), "");
+#endif
+    }
+#if TEST_STD_VER >= 14
+    {
+        typedef std::vector<MoveOnly, some_alloc2<MoveOnly>> C;
+        C c1, c2;
+    //  if the allocators are always equal, then the swap can be noexcept
+        static_assert( noexcept(swap(c1, c2)), "");
     }
 #endif
+
+#endif
 }

test/std/containers/unord/unord.map/unord.map.swap/swap_noexcept.pass.cpp

@@ -10,8 +10,16 @@
 // <unordered_map>
 
 // void swap(unordered_map& c)
-//     noexcept(!allocator_type::propagate_on_container_swap::value ||
-//              __is_nothrow_swappable<allocator_type>::value);
+//      noexcept(
+//          (!allocator_type::propagate_on_container_swap::value ||
+//           __is_nothrow_swappable<allocator_type>::value) &&
+//           __is_nothrow_swappable<hasher>::value &&
+//           __is_nothrow_swappable<key_equal>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::is_always_equal::value &&
+//               noexcept(swap(declval<Hash&>(), declval<Hash&>())) &&
+//               noexcept(swap(declval<Pred&>(), declval<Pred&>())));
 
 // This tests a conforming extension
 
@@ -30,6 +38,22 @@ struct some_comp
     some_comp(const some_comp&) {}
 };
 
+template <class T>
+struct some_comp2
+{
+    typedef T value_type;
+    
+    some_comp2() {}
+    some_comp2(const some_comp2&) {}
+    void deallocate(void*, unsigned) {}
+    typedef std::true_type propagate_on_container_swap;
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_comp2<T>&, some_comp2<T>&) noexcept {}
+#endif
+
 template <class T>
 struct some_hash
 {
@@ -38,9 +62,62 @@ struct some_hash
     some_hash(const some_hash&);
 };
 
+template <class T>
+struct some_hash2
+{
+    typedef T value_type;
+    some_hash2() {}
+    some_hash2(const some_hash2&);
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_hash2<T>&, some_hash2<T>&) noexcept {}
+#endif
+
+template <class T>
+struct some_alloc
+{
+    typedef T value_type;
+    
+    some_alloc() {}
+    some_alloc(const some_alloc&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::true_type propagate_on_container_swap;
+};
+
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
+template <class T>
+struct some_alloc3
+{
+    typedef T value_type;
+    
+    some_alloc3() {}
+    some_alloc3(const some_alloc3&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::false_type is_always_equal;
+};
+
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
+	typedef std::pair<const MoveOnly, MoveOnly> MapType;
     {
         typedef std::unordered_map<MoveOnly, MoveOnly> C;
         C c1, c2;
@@ -48,13 +125,13 @@ int main()
     }
     {
         typedef std::unordered_map<MoveOnly, MoveOnly, std::hash<MoveOnly>,
-                           std::equal_to<MoveOnly>, test_allocator<std::pair<const MoveOnly, MoveOnly>>> C;
+                           std::equal_to<MoveOnly>, test_allocator<MapType>> C;
         C c1, c2;
         static_assert(noexcept(swap(c1, c2)), "");
     }
     {
         typedef std::unordered_map<MoveOnly, MoveOnly, std::hash<MoveOnly>,
-                          std::equal_to<MoveOnly>, other_allocator<std::pair<const MoveOnly, MoveOnly>>> C;
+                          std::equal_to<MoveOnly>, other_allocator<MapType>> C;
         C c1, c2;
         static_assert(noexcept(swap(c1, c2)), "");
     }
@@ -69,5 +146,54 @@ int main()
         C c1, c2;
         static_assert(!noexcept(swap(c1, c2)), "");
     }
+
+#if TEST_STD_VER >= 14
+    { // POCS allocator, throwable swap for hash, throwable swap for comp
+    typedef std::unordered_map<MoveOnly, MoveOnly, some_hash<MoveOnly>, some_comp <MoveOnly>, some_alloc <MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for hash, throwable swap for comp
+    typedef std::unordered_map<MoveOnly, MoveOnly, some_hash<MoveOnly>, some_comp <MoveOnly>, some_alloc2<MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, throwable swap for hash, nothrow swap for comp
+    typedef std::unordered_map<MoveOnly, MoveOnly, some_hash<MoveOnly>, some_comp2<MoveOnly>, some_alloc <MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for hash, nothrow swap for comp
+    typedef std::unordered_map<MoveOnly, MoveOnly, some_hash<MoveOnly>, some_comp2<MoveOnly>, some_alloc2<MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for hash, throwable swap for comp
+    typedef std::unordered_map<MoveOnly, MoveOnly, some_hash2<MoveOnly>, some_comp <MoveOnly>, some_alloc <MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for hash, throwable swap for comp
+    typedef std::unordered_map<MoveOnly, MoveOnly, some_hash2<MoveOnly>, some_comp <MoveOnly>, some_alloc2<MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_map<MoveOnly, MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc <MapType>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_map<MoveOnly, MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc2<MapType>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+
+    { // NOT always equal allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_map<MoveOnly, MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc3<MapType>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+#endif
 #endif
 }

test/std/containers/unord/unord.multimap/unord.multimap.swap/swap_noexcept.pass.cpp

@@ -10,8 +10,16 @@
 // <unordered_map>
 
 // void swap(unordered_multimap& c)
-//     noexcept(!allocator_type::propagate_on_container_swap::value ||
-//              __is_nothrow_swappable<allocator_type>::value);
+//      noexcept(
+//          (!allocator_type::propagate_on_container_swap::value ||
+//                __is_nothrow_swappable<allocator_type>::value) &&
+//           __is_nothrow_swappable<hasher>::value &&
+//           __is_nothrow_swappable<key_equal>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<allocator_type>::is_always_equal::value &&
+//               __is_nothrow_swappable<hasher>::value &&
+//               __is_nothrow_swappable<key_equal>::value);
 
 // This tests a conforming extension
 
@@ -30,6 +38,22 @@ struct some_comp
     some_comp(const some_comp&) {}
 };
 
+template <class T>
+struct some_comp2
+{
+    typedef T value_type;
+    
+    some_comp2() {}
+    some_comp2(const some_comp2&) {}
+    void deallocate(void*, unsigned) {}
+    typedef std::true_type propagate_on_container_swap;
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_comp2<T>&, some_comp2<T>&) noexcept {}
+#endif
+
 template <class T>
 struct some_hash
 {
@@ -38,9 +62,61 @@ struct some_hash
     some_hash(const some_hash&);
 };
 
+template <class T>
+struct some_hash2
+{
+    typedef T value_type;
+    some_hash2() {}
+    some_hash2(const some_hash2&);
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_hash2<T>&, some_hash2<T>&) noexcept {}
+#endif
+
+template <class T>
+struct some_alloc
+{
+    typedef T value_type;
+    
+    some_alloc() {}
+    some_alloc(const some_alloc&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::true_type propagate_on_container_swap;
+};
+
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
+template <class T>
+struct some_alloc3
+{
+    typedef T value_type;
+    
+    some_alloc3() {}
+    some_alloc3(const some_alloc3&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::false_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
+	typedef std::pair<const MoveOnly, MoveOnly> MapType;
     {
         typedef std::unordered_multimap<MoveOnly, MoveOnly> C;
         C c1, c2;
@@ -48,13 +124,13 @@ int main()
     }
     {
         typedef std::unordered_multimap<MoveOnly, MoveOnly, std::hash<MoveOnly>,
-                           std::equal_to<MoveOnly>, test_allocator<std::pair<const MoveOnly, MoveOnly>>> C;
+                           std::equal_to<MoveOnly>, test_allocator<MapType>> C;
         C c1, c2;
         static_assert(noexcept(swap(c1, c2)), "");
     }
     {
         typedef std::unordered_multimap<MoveOnly, MoveOnly, std::hash<MoveOnly>,
-                          std::equal_to<MoveOnly>, other_allocator<std::pair<const MoveOnly, MoveOnly>>> C;
+                          std::equal_to<MoveOnly>, other_allocator<MapType>> C;
         C c1, c2;
         static_assert(noexcept(swap(c1, c2)), "");
     }
@@ -69,5 +145,54 @@ int main()
         C c1, c2;
         static_assert(!noexcept(swap(c1, c2)), "");
     }
+
+#if TEST_STD_VER >= 14
+    { // POCS allocator, throwable swap for hash, throwable swap for comp
+    typedef std::unordered_multimap<MoveOnly, MoveOnly, some_hash<MoveOnly>, some_comp <MoveOnly>, some_alloc <MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for hash, throwable swap for comp
+    typedef std::unordered_multimap<MoveOnly, MoveOnly, some_hash<MoveOnly>, some_comp <MoveOnly>, some_alloc2<MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, throwable swap for hash, nothrow swap for comp
+    typedef std::unordered_multimap<MoveOnly, MoveOnly, some_hash<MoveOnly>, some_comp2<MoveOnly>, some_alloc <MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for hash, nothrow swap for comp
+    typedef std::unordered_multimap<MoveOnly, MoveOnly, some_hash<MoveOnly>, some_comp2<MoveOnly>, some_alloc2<MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for hash, throwable swap for comp
+    typedef std::unordered_multimap<MoveOnly, MoveOnly, some_hash2<MoveOnly>, some_comp <MoveOnly>, some_alloc <MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for hash, throwable swap for comp
+    typedef std::unordered_multimap<MoveOnly, MoveOnly, some_hash2<MoveOnly>, some_comp <MoveOnly>, some_alloc2<MapType>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_multimap<MoveOnly, MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc <MapType>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_multimap<MoveOnly, MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc2<MapType>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+    { // NOT always equal allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_multimap<MoveOnly, MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc3<MapType>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+#endif
+
 #endif
 }

test/std/containers/unord/unord.multiset/unord.multiset.swap/swap_noexcept.pass.cpp

@@ -10,8 +10,16 @@
 // <unordered_set>
 
 // void swap(unordered_multiset& c)
-//     noexcept(!allocator_type::propagate_on_container_swap::value ||
-//              __is_nothrow_swappable<allocator_type>::value);
+//      noexcept(
+//          (!allocator_type::propagate_on_container_swap::value ||
+//           __is_nothrow_swappable<allocator_type>::value) &&
+//           __is_nothrow_swappable<hasher>::value &&
+//           __is_nothrow_swappable<key_equal>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::is_always_equal::value &&
+//               noexcept(swap(declval<Hash&>(), declval<Hash&>())) &&
+//               noexcept(swap(declval<Pred&>(), declval<Pred&>())));
 
 // This tests a conforming extension
 
@@ -30,6 +38,22 @@ struct some_comp
     some_comp(const some_comp&) {}
 };
 
+template <class T>
+struct some_comp2
+{
+    typedef T value_type;
+    
+    some_comp2() {}
+    some_comp2(const some_comp2&) {}
+    void deallocate(void*, unsigned) {}
+    typedef std::true_type propagate_on_container_swap;
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_comp2<T>&, some_comp2<T>&) noexcept {}
+#endif
+
 template <class T>
 struct some_hash
 {
@@ -38,6 +62,57 @@ struct some_hash
     some_hash(const some_hash&);
 };
 
+template <class T>
+struct some_hash2
+{
+    typedef T value_type;
+    some_hash2() {}
+    some_hash2(const some_hash2&);
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_hash2<T>&, some_hash2<T>&) noexcept {}
+#endif
+
+template <class T>
+struct some_alloc
+{
+    typedef T value_type;
+    
+    some_alloc() {}
+    some_alloc(const some_alloc&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::true_type propagate_on_container_swap;
+};
+
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
+template <class T>
+struct some_alloc3
+{
+    typedef T value_type;
+    
+    some_alloc3() {}
+    some_alloc3(const some_alloc3&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::false_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -69,5 +144,55 @@ int main()
         C c1, c2;
         static_assert(!noexcept(swap(c1, c2)), "");
     }
+
+#if TEST_STD_VER >= 14
+    { // POCS allocator, throwable swap for hash, throwable swap for comp
+    typedef std::unordered_multiset<MoveOnly, some_hash<MoveOnly>, some_comp <MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for hash, throwable swap for comp
+    typedef std::unordered_multiset<MoveOnly, some_hash<MoveOnly>, some_comp <MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, throwable swap for hash, nothrow swap for comp
+    typedef std::unordered_multiset<MoveOnly, some_hash<MoveOnly>, some_comp2<MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for hash, nothrow swap for comp
+    typedef std::unordered_multiset<MoveOnly, some_hash<MoveOnly>, some_comp2<MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for hash, throwable swap for comp
+    typedef std::unordered_multiset<MoveOnly, some_hash2<MoveOnly>, some_comp <MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for hash, throwable swap for comp
+    typedef std::unordered_multiset<MoveOnly, some_hash2<MoveOnly>, some_comp <MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_multiset<MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_multiset<MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+
+    { // NOT always equal allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_multiset<MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc3<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+#endif
+
 #endif
 }

test/std/containers/unord/unord.set/unord.set.swap/swap_noexcept.pass.cpp

@@ -10,8 +10,16 @@
 // <unordered_set>
 
 // void swap(unordered_set& c)
-//     noexcept(!allocator_type::propagate_on_container_swap::value ||
-//              __is_nothrow_swappable<allocator_type>::value);
+//      noexcept(
+//          (!allocator_type::propagate_on_container_swap::value ||
+//           __is_nothrow_swappable<allocator_type>::value) &&
+//           __is_nothrow_swappable<hasher>::value &&
+//           __is_nothrow_swappable<key_equal>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::is_always_equal::value &&
+//               noexcept(swap(declval<Hash&>(), declval<Hash&>())) &&
+//               noexcept(swap(declval<Pred&>(), declval<Pred&>())));
 
 // This tests a conforming extension
 
@@ -30,6 +38,22 @@ struct some_comp
     some_comp(const some_comp&) {}
 };
 
+template <class T>
+struct some_comp2
+{
+    typedef T value_type;
+    
+    some_comp2() {}
+    some_comp2(const some_comp2&) {}
+    void deallocate(void*, unsigned) {}
+    typedef std::true_type propagate_on_container_swap;
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_comp2<T>&, some_comp2<T>&) noexcept {}
+#endif
+
 template <class T>
 struct some_hash
 {
@@ -38,6 +62,57 @@ struct some_hash
     some_hash(const some_hash&);
 };
 
+template <class T>
+struct some_hash2
+{
+    typedef T value_type;
+    some_hash2() {}
+    some_hash2(const some_hash2&);
+};
+
+#if TEST_STD_VER >= 14
+template <typename T>
+void swap(some_hash2<T>&, some_hash2<T>&) noexcept {}
+#endif
+
+template <class T>
+struct some_alloc
+{
+    typedef T value_type;
+    
+    some_alloc() {}
+    some_alloc(const some_alloc&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::true_type propagate_on_container_swap;
+};
+
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
+template <class T>
+struct some_alloc3
+{
+    typedef T value_type;
+    
+    some_alloc3() {}
+    some_alloc3(const some_alloc3&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::false_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -69,5 +144,55 @@ int main()
         C c1, c2;
         static_assert(!noexcept(swap(c1, c2)), "");
     }
+
+#if TEST_STD_VER >= 14
+    { // POCS allocator, throwable swap for hash, throwable swap for comp
+    typedef std::unordered_set<MoveOnly, some_hash<MoveOnly>, some_comp <MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for hash, throwable swap for comp
+    typedef std::unordered_set<MoveOnly, some_hash<MoveOnly>, some_comp <MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, throwable swap for hash, nothrow swap for comp
+    typedef std::unordered_set<MoveOnly, some_hash<MoveOnly>, some_comp2<MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, throwable swap for hash, nothrow swap for comp
+    typedef std::unordered_set<MoveOnly, some_hash<MoveOnly>, some_comp2<MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for hash, throwable swap for comp
+    typedef std::unordered_set<MoveOnly, some_hash2<MoveOnly>, some_comp <MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for hash, throwable swap for comp
+    typedef std::unordered_set<MoveOnly, some_hash2<MoveOnly>, some_comp <MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert(!noexcept(swap(c1, c2)), "");
+    }
+    { // POCS allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_set<MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc <MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+    { // always equal allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_set<MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc2<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+
+    { // NOT always equal allocator, nothrow swap for hash, nothrow swap for comp
+    typedef std::unordered_set<MoveOnly, some_hash2<MoveOnly>, some_comp2<MoveOnly>, some_alloc3<MoveOnly>> C;
+    C c1, c2;
+    static_assert( noexcept(swap(c1, c2)), "");
+    }
+#endif
+
 #endif
 }

test/std/strings/basic.string/string.nonmembers/string.special/swap_noexcept.pass.cpp

@@ -12,6 +12,10 @@
 // void swap(basic_string& c)
 //     noexcept(!allocator_type::propagate_on_container_swap::value ||
 //              __is_nothrow_swappable<allocator_type>::value);
+//
+//  In C++17, the standard says that swap shall have:
+//     noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value ||
+//              allocator_traits<Allocator>::is_always_equal::value);
 
 // This tests a conforming extension
 
@@ -32,6 +36,19 @@ struct some_alloc
     typedef std::true_type propagate_on_container_swap;
 };
 
+template <class T>
+struct some_alloc2
+{
+    typedef T value_type;
+    
+    some_alloc2() {}
+    some_alloc2(const some_alloc2&);
+    void deallocate(void*, unsigned) {}
+
+    typedef std::false_type propagate_on_container_swap;
+    typedef std::true_type is_always_equal;
+};
+
 int main()
 {
 #if __has_feature(cxx_noexcept)
@@ -48,7 +65,21 @@ int main()
     {
         typedef std::basic_string<char, std::char_traits<char>, some_alloc<char>> C;
         C c1, c2;
+#if TEST_STD_VER >= 14
+    //  In c++14, if POCS is set, swapping the allocator is required not to throw
+        static_assert( noexcept(swap(c1, c2)), "");
+#else
         static_assert(!noexcept(swap(c1, c2)), "");
+#endif
+    }
+#if TEST_STD_VER >= 14
+    {
+        typedef std::basic_string<char, std::char_traits<char>, some_alloc2<char>> C;
+        C c1, c2;
+    //  if the allocators are always equal, then the swap can be noexcept
+        static_assert( noexcept(swap(c1, c2)), "");
     }
 #endif
+
+#endif
 }