[PATCH] PR libstdc++/82966 fix swapping of node handles

[Jonathan Wakely]

        PR libstdc++/82966
        * include/bits/node_handle.h (_Node_handle_common::_M_swap): Use value
        instead of type.
        * testsuite/23_containers/set/modifiers/node_swap.cc: New.

Tested powerpc64le-linux, committed to trunk.

Backports to gcc-7 and gcc-8 will follow.


commit b6848af169ab5e7d344b01fd124c1f07a92d951e
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Mon May 14 15:10:39 2018 +0100

    PR libstdc++/82966 fix swapping of node handles
    
            PR libstdc++/82966
            * include/bits/node_handle.h (_Node_handle_common::_M_swap): Use 
value
            instead of type.
            * testsuite/23_containers/set/modifiers/node_swap.cc: New.

diff --git a/libstdc++-v3/include/bits/node_handle.h 
b/libstdc++-v3/include/bits/node_handle.h
index c02aca024bd..8bb4f3c0abc 100644
--- a/libstdc++-v3/include/bits/node_handle.h
+++ b/libstdc++-v3/include/bits/node_handle.h
@@ -109,7 +109,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       {
        using std::swap;
        swap(_M_ptr, __nh._M_ptr);
-       if (_AllocTraits::propagate_on_container_swap
+       if (_AllocTraits::propagate_on_container_swap::value
            || !_M_alloc || !__nh._M_alloc)
          _M_alloc.swap(__nh._M_alloc);
        else
diff --git a/libstdc++-v3/testsuite/23_containers/set/modifiers/node_swap.cc 
b/libstdc++-v3/testsuite/23_containers/set/modifiers/node_swap.cc
new file mode 100644
index 00000000000..8957d6e125a
--- /dev/null
+++ b/libstdc++-v3/testsuite/23_containers/set/modifiers/node_swap.cc
@@ -0,0 +1,48 @@
+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do run { target c++17 } }
+
+#include <set>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  // PR libstdc++/82966
+  std::set<int>::node_type n1, n2;
+  n1.swap(n2);
+  VERIFY( n1.empty() );
+  VERIFY( n2.empty() );
+}
+
+void
+test02()
+{
+  std::set<int> s{1, 2};
+  std::set<int>::node_type n1 = s.extract(1), n2;
+  swap(n1, n2);
+  VERIFY( n1.empty() );
+  VERIFY( !n2.empty() );
+}
+
+int main()
+{
+  test01();
+  test02();
+}