[PATCH] PR libstdc++/80504 qualify calls to avoid ADL

[Jonathan Wakely]

This has always been wrong, since 2004 when the overloads were added
to <tr1/functional>.

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

Tested powerpc64l4-linux, committed to trunk. I'll backport it too.

-------------- next part --------------
commit e284d7bff062e16b4e5b9c27f08e1e401840f867
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Apr 24 12:21:34 2017 +0100

    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.

diff --git a/libstdc++-v3/include/bits/refwrap.h b/libstdc++-v3/include/bits/refwrap.h
index 124ee97..786087e 100644
--- a/libstdc++-v3/include/bits/refwrap.h
+++ b/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
 
diff --git a/libstdc++-v3/testsuite/20_util/reference_wrapper/80504.cc b/libstdc++-v3/testsuite/20_util/reference_wrapper/80504.cc
new file mode 100644
index 0000000..727a560
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/reference_wrapper/80504.cc
@@ -0,0 +1,34 @@
+// 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);
+}