Fixing optional::swap

STEllAR-GROUP · Feb 26, 2018 · 75d72b8 · 75d72b8
1 parent a3faea3
commit 75d72b8
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Showing 3 changed files with 33 additions and 3 deletions.
diff --git a/hpx/util/optional.hpp b/hpx/util/optional.hpp
@@ -42,6 +42,15 @@ namespace hpx { namespace util
         }
     };
 
+    namespace _optional_swap
+    {
+        using std::swap;
+
+        template <typename T>
+        void check_swap(T&, T&) noexcept(noexcept(
+            swap(std::declval<T&>(), std::declval<T&>())));
+    }
+
     template <typename T>
     class optional
     {
@@ -249,9 +258,11 @@ namespace hpx { namespace util
             empty_ = false;
         }
 
-        void swap(optional& other)
-            noexcept(std::is_nothrow_move_constructible<T>::value &&
-                noexcept(swap(std::declval<T&>(), std::declval<T&>())))
+        void swap(optional& other) noexcept(
+            std::is_nothrow_move_constructible<T>::value &&
+            noexcept(
+                _optional_swap::check_swap(std::declval<T&>(),
+                    std::declval<T&>())))
         {
             // do nothing if both are empty
             if (empty_ && other.empty_)
@@ -261,6 +272,7 @@ namespace hpx { namespace util
             // swap content if both are non-empty
             if (!empty_ && !other.empty_)
             {
+                using std::swap;
                 swap(**this, *other);
                 return;
             }

diff --git a/tests/regressions/util/CMakeLists.txt b/tests/regressions/util/CMakeLists.txt
@@ -11,6 +11,7 @@ set(tests
     function_argument
     function_serialization_728
     iarchive_1237
+    optional_swap_3200
     protect_with_nullary_pfo
     serialize_buffer_1069
     set_config_entry_deadlock

diff --git a/tests/regressions/util/optional_swap_3200.cpp b/tests/regressions/util/optional_swap_3200.cpp
@@ -0,0 +1,17 @@
+//  Copyright (c) 2018 Hartmut Kaiser
+//
+//  Distributed under the Boost Software License, Version 1.0. (See accompanying
+//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <hpx/hpx_main.hpp>
+#include <hpx/util/optional.hpp>
+#include <hpx/util/lightweight_test.hpp>
+
+int main()
+{
+    hpx::util::optional<int> x;
+    int y = 1;
+    x = y;
+
+    return hpx::util::report_errors();
+}