PR libstdc++/80504 qualify calls to avoid ADL

	PR libstdc++/80504
	* include/bits/refwrap.h (ref, cref): Qualify calls.
	* testsuite/20_util/reference_wrapper/80504.cc: New test.

From-SVN: r247094

libstdc++-v3/ChangeLog

 2017-04-24  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/80504
+	* include/bits/refwrap.h (ref, cref): Qualify calls.
+	* testsuite/20_util/reference_wrapper/80504.cc: New test.
+
 	PR libstdc++/80493
 	* include/experimental/optional (optional::swap): Fix exception
 	specification.

libstdc++-v3/include/bits/refwrap.h

@@ -361,17 +361,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _Tp>
     void cref(const _Tp&&) = delete;
 
-  /// Partial specialization.
+  /// std::ref overload to prevent wrapping a reference_wrapper
   template<typename _Tp>
     inline reference_wrapper<_Tp>
     ref(reference_wrapper<_Tp> __t) noexcept
-    { return ref(__t.get()); }
+    { return __t; }
 
-  /// Partial specialization.
+  /// std::cref overload to prevent wrapping a reference_wrapper
   template<typename _Tp>
     inline reference_wrapper<const _Tp>
     cref(reference_wrapper<_Tp> __t) noexcept
-    { return cref(__t.get()); }
+    { return { __t.get() }; }
 
   // @} group functors
 

libstdc++-v3/testsuite/20_util/reference_wrapper/80504.cc

+// Copyright (C) 2017 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-do compile { target c++11 } }
+
+#include <functional>
+
+namespace X {
+  struct Y { };
+  template<typename T> void ref(T) { }
+  template<typename T> void cref(T) { }
+}
+
+int main()
+{
+  X::Y i;
+  std::reference_wrapper<X::Y> r(i);
+  ref(r);
+  cref(r);
+}