Index: include/std/tuple
===================================================================
--- include/std/tuple	(revision 172305)
+++ include/std/tuple	(working copy)
@@ -1,6 +1,6 @@
 // <tuple> -*- C++ -*-
 
-// Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+// Copyright (C) 2007, 2008, 2009, 2010, 2011 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
@@ -177,10 +177,10 @@
         _Tuple_impl(const _Tuple_impl<_Idx, _UElements...>& __in)
 	: _Inherited(__in._M_tail()), _Base(__in._M_head()) { }
 
-      template<typename... _UElements>
-        _Tuple_impl(_Tuple_impl<_Idx, _UElements...>&& __in)
+      template<typename _UHead, typename... _UTails>
+        _Tuple_impl(_Tuple_impl<_Idx, _UHead, _UTails...>&& __in)
 	: _Inherited(std::move(__in._M_tail())),
-	  _Base(std::move(__in._M_head())) { }
+	  _Base(std::forward<_UHead>(__in._M_head())) { }
 
       _Tuple_impl&
       operator=(const _Tuple_impl& __in)
@@ -193,7 +193,7 @@
       _Tuple_impl&
       operator=(_Tuple_impl&& __in)
       {
-	_M_head() = std::move(__in._M_head());
+	_M_head() = std::forward<_Head>(__in._M_head());
 	_M_tail() = std::move(__in._M_tail());
 	return *this;
       }
@@ -207,11 +207,11 @@
 	  return *this;
 	}
 
-      template<typename... _UElements>
+      template<typename _UHead, typename... _UTails>
         _Tuple_impl&
-        operator=(_Tuple_impl<_Idx, _UElements...>&& __in)
+        operator=(_Tuple_impl<_Idx, _UHead, _UTails...>&& __in)
         {
-	  _M_head() = std::move(__in._M_head());
+	  _M_head() = std::forward<_UHead>(__in._M_head());
 	  _M_tail() = std::move(__in._M_tail());
 	  return *this;
 	}
@@ -672,7 +672,7 @@
 		       const tuple<_UElements...>& __u,
 		       const __index_holder<_UIdx...>&)
     { return tuple<_TElements..., _UElements...>
-	(std::move(get<_TIdx>(__t))..., get<_UIdx>(__u)...); }
+	(std::forward<_TElements>(get<_TIdx>(__t))..., get<_UIdx>(__u)...); }
 
   template<typename... _TElements, std::size_t... _TIdx,
 	   typename... _UElements, std::size_t... _UIdx>
@@ -682,7 +682,7 @@
 		       tuple<_UElements...>&& __u,
 		       const __index_holder<_UIdx...>&)
     { return tuple<_TElements..., _UElements...>
-	(get<_TIdx>(__t)..., std::move(get<_UIdx>(__u))...); }
+	(get<_TIdx>(__t)..., std::forward<_UElements>(get<_UIdx>(__u))...); }
 
   template<typename... _TElements, std::size_t... _TIdx,
 	   typename... _UElements, std::size_t... _UIdx> 
@@ -692,7 +692,8 @@
 		       tuple<_UElements...>&& __u,
 		       const __index_holder<_UIdx...>&)
     { return tuple<_TElements..., _UElements...>
-	(std::move(get<_TIdx>(__t))..., std::move(get<_UIdx>(__u))...); }
+	(std::forward<_TElements>(get<_TIdx>(__t))...,
+	 std::forward<_UElements>(get<_UIdx>(__u))...); }
 
   template<typename... _TElements, typename... _UElements>
     inline tuple<_TElements..., _UElements...> 
Index: testsuite/20_util/tuple/48476.cc
===================================================================
--- testsuite/20_util/tuple/48476.cc	(revision 0)
+++ testsuite/20_util/tuple/48476.cc	(revision 0)
@@ -0,0 +1,51 @@
+// { dg-options "-std=gnu++0x" }
+
+// Copyright (C) 2011 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/>.
+
+#include <tuple>
+#include <type_traits>
+#include <memory>
+#include <testsuite_hooks.h>
+
+template<typename T>
+  typename std::decay<T>::type copy(T&& x)
+  { return std::forward<T>(x); }
+
+// libstdc++/48476
+void test01()
+{
+  bool test __attribute__((unused)) = true;
+
+  std::shared_ptr<int> p(new int()), q, r;
+  
+  std::tuple<std::shared_ptr<int>&, int>  t0(p, 23), t1(q, 0);
+  t1 = copy(t0);  // shall be equivalent to
+                  // q = p; std::get<1>(t1) = std::get<1>(t0);
+  VERIFY( q == p ); 
+
+  std::tuple<std::shared_ptr<int>&, char> t2(r, 0);
+  t2 = copy(t1);  // shall be equivalent to
+                  // r = q; std::get<1>(t2) = std::get<1>(t1);
+  VERIFY( r == q );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
Index: testsuite/20_util/tuple/cons/48476.cc
===================================================================
--- testsuite/20_util/tuple/cons/48476.cc	(revision 0)
+++ testsuite/20_util/tuple/cons/48476.cc	(revision 0)
@@ -0,0 +1,27 @@
+// { dg-options "-std=gnu++0x" }
+// { dg-do compile }
+
+// Copyright (C) 2011 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/>.
+
+#include <tuple>
+
+void f()
+{
+  int i = 0;
+  std::tuple<int&, int> t __attribute__((unused)) = std::forward_as_tuple(i, 0);
+}
Index: testsuite/20_util/tuple/creation_functions/48476.cc
===================================================================
--- testsuite/20_util/tuple/creation_functions/48476.cc	(revision 0)
+++ testsuite/20_util/tuple/creation_functions/48476.cc	(revision 0)
@@ -0,0 +1,85 @@
+// { dg-options "-std=gnu++0x" }
+
+// Copyright (C) 2011 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/>.
+
+#include <tuple>
+#include <type_traits>
+#include <testsuite_hooks.h>
+
+template<typename T>
+  typename std::decay<T>::type copy(T&& x)
+  { return std::forward<T>(x); }
+
+template<typename... Args1, typename... Args2>
+  void
+  check_tuple_cat(std::tuple<Args1...> t1, std::tuple<Args2...> t2)
+  {
+    bool test __attribute__((unused)) = true;
+
+    typedef std::tuple<Args1..., Args2...> concatenated;
+  
+    auto cat1 = std::tuple_cat(     t1,       t2 );
+    auto cat2 = std::tuple_cat(copy(t1),      t2 );
+    auto cat3 = std::tuple_cat(     t1,  copy(t2));
+    auto cat4 = std::tuple_cat(copy(t1), copy(t2));
+  
+    static_assert( std::is_same<decltype(cat1), concatenated>::value, "" );
+    static_assert( std::is_same<decltype(cat2), concatenated>::value, "" );
+    static_assert( std::is_same<decltype(cat3), concatenated>::value, "" );
+    static_assert( std::is_same<decltype(cat4), concatenated>::value, "" );
+  
+    VERIFY( cat1 == cat2 );
+    VERIFY( cat1 == cat3 );
+    VERIFY( cat1 == cat4 );
+  }
+
+// libstdc++/48476
+void test01()
+{
+  int i = 0;
+  std::tuple<> t0;
+  std::tuple<int&> t1(i);
+  std::tuple<int&, int> t2(i, 0);
+  std::tuple<int const&, int, double> t3(i, 0, 0);
+  
+  check_tuple_cat(t0, t0);
+  check_tuple_cat(t0, t1);
+  check_tuple_cat(t0, t2);
+  check_tuple_cat(t0, t3);
+  
+  check_tuple_cat(t1, t0);
+  check_tuple_cat(t1, t1);
+  check_tuple_cat(t1, t2);
+  check_tuple_cat(t1, t3);
+  
+  check_tuple_cat(t2, t0);
+  check_tuple_cat(t2, t1);
+  check_tuple_cat(t2, t2);
+  check_tuple_cat(t2, t3);
+  
+  check_tuple_cat(t3, t0);
+  check_tuple_cat(t3, t1);
+  check_tuple_cat(t3, t2);
+  check_tuple_cat(t3, t3);
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
