re PR libstdc++/45228 ([C++0x] Can't copy-construct "tuple<int,int,int>" from "const tuple<int,int,int>" rvalue)

2010-08-10  Paolo Carlini  <paolo.carlini@oracle.com>

	PR libstdc++/45228
	* include/std/tuple (tuple<typename... _Elements>): Constrain
	converting constructors and assignment operators with
	sizeof...(_UElements) == sizeof...(_Elements).
	(tuple(tuple<_UElements...>&): Remove.
	(tuple<typename _T1>): Add.
	* testsuite/20_util/tuple/cons/45228.cc: New.
	* testsuite/20_util/tuple/cons/converting.cc: Likewise.
	* testsuite/20_util/weak_ptr/comparison/cmp_neg.cc: Adjust
	dg-error line number.

	* include/std/tuple (_Tuple_impl<>::_Tuple_impl(const _Tuple_impl&)):
	Defaulted.

	* include/std/tuple (tuple<typename _T1, typename _T2>
	::operator=(pair<_U1, _U2>&&)): Use forward.

From-SVN: r163049

1 files changed, 89 insertions, 19 deletions

diff --git a/libstdc++-v3/include/std/tuple b/libstdc++-v3/include/std/tuple
index 2e35241..67a6eb7 100644
--- a/libstdc++-v3/include/std/tuple
+++ b/libstdc++-v3/include/std/tuple
@@ -160,8 +160,7 @@ namespace std
 	: _Inherited(std::forward<_UTail>(__tail)...),
 	  _Base(std::forward<_UHead>(__head)) { }
 
-      _Tuple_impl(const _Tuple_impl& __in)
-      : _Inherited(__in._M_tail()), _Base(__in._M_head()) { }
+      _Tuple_impl(const _Tuple_impl&) = default;
 
       _Tuple_impl(_Tuple_impl&& __in)
       : _Inherited(std::move(__in._M_tail())),
@@ -233,7 +232,9 @@ namespace std
       tuple(const _Elements&... __elements)
       : _Inherited(__elements...) { }
 
-      template<typename... _UElements>
+      template<typename... _UElements, typename = typename
+	       std::enable_if<sizeof...(_UElements)
+			      == sizeof...(_Elements)>::type>
         explicit
         tuple(_UElements&&... __elements)
 	: _Inherited(std::forward<_UElements>(__elements)...) {	}
@@ -243,20 +244,18 @@ namespace std
       tuple(tuple&& __in)
       : _Inherited(static_cast<_Inherited&&>(__in)) { }
 
-      template<typename... _UElements>
+      template<typename... _UElements, typename = typename
+	       std::enable_if<sizeof...(_UElements)
+			      == sizeof...(_Elements)>::type>
         tuple(const tuple<_UElements...>& __in)
-	: _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
-	{ }
+        : _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
+        { }
 
-      template<typename... _UElements>
+      template<typename... _UElements, typename = typename
+	       std::enable_if<sizeof...(_UElements)
+			      == sizeof...(_Elements)>::type>
         tuple(tuple<_UElements...>&& __in)
-	: _Inherited(static_cast<_Tuple_impl<0, _UElements...>&&>(__in)) { }
-
-      // XXX http://gcc.gnu.org/ml/libstdc++/2008-02/msg00047.html
-      template<typename... _UElements>
-        tuple(tuple<_UElements...>& __in)
-	: _Inherited(static_cast<const _Tuple_impl<0, _UElements...>&>(__in))
-	{ }
+        : _Inherited(static_cast<_Tuple_impl<0, _UElements...>&&>(__in)) { }
 
       tuple&
       operator=(const tuple& __in)
@@ -272,7 +271,9 @@ namespace std
 	return *this;
       }
 
-      template<typename... _UElements>
+      template<typename... _UElements, typename = typename
+	       std::enable_if<sizeof...(_UElements)
+			      == sizeof...(_Elements)>::type>
         tuple&
         operator=(const tuple<_UElements...>& __in)
         {
@@ -280,7 +281,9 @@ namespace std
 	  return *this;
 	}
 
-      template<typename... _UElements>
+      template<typename... _UElements, typename = typename
+	       std::enable_if<sizeof...(_UElements)
+			      == sizeof...(_Elements)>::type>
         tuple&
         operator=(tuple<_UElements...>&& __in)
         {
@@ -293,7 +296,6 @@ namespace std
       { _Inherited::_M_swap_impl(__in); }
     };
 
-
   template<>  
     class tuple<>
     {
@@ -385,8 +387,8 @@ namespace std
         tuple&
         operator=(pair<_U1, _U2>&& __in)
         {
-	  this->_M_head() = std::move(__in.first);
-	  this->_M_tail()._M_head() = std::move(__in.second);
+	  this->_M_head() = std::forward<_U1>(__in.first);
+	  this->_M_tail()._M_head() = std::forward<_U2>(__in.second);
 	  return *this;
 	}
 
@@ -399,6 +401,74 @@ namespace std
       }
     };
 
+  /// tuple (1-element).
+  template<typename _T1>
+    class tuple<_T1> : public _Tuple_impl<0, _T1>
+    {
+      typedef _Tuple_impl<0, _T1> _Inherited;
+
+    public:
+      tuple()
+      : _Inherited() { }
+
+      explicit
+      tuple(const _T1& __a1)
+      : _Inherited(__a1) { }
+
+      template<typename _U1, typename = typename
+	       std::enable_if<std::is_convertible<_U1, _T1>::value>::type>
+        explicit
+        tuple(_U1&& __a1)
+	: _Inherited(std::forward<_U1>(__a1)) { }
+
+      tuple(const tuple&) = default;
+
+      tuple(tuple&& __in)
+      : _Inherited(static_cast<_Inherited&&>(__in)) { }
+
+      template<typename _U1>
+        tuple(const tuple<_U1>& __in)
+        : _Inherited(static_cast<const _Tuple_impl<0, _U1>&>(__in)) { }
+
+      template<typename _U1>
+        tuple(tuple<_U1>&& __in)
+	: _Inherited(static_cast<_Tuple_impl<0, _U1>&&>(__in)) { }
+
+      tuple&
+      operator=(const tuple& __in)
+      {
+	static_cast<_Inherited&>(*this) = __in;
+	return *this;
+      }
+
+      tuple&
+      operator=(tuple&& __in)
+      {
+	static_cast<_Inherited&>(*this) = std::move(__in);
+	return *this;
+      }
+
+      template<typename _U1>
+        tuple&
+        operator=(const tuple<_U1>& __in)
+        {
+	  static_cast<_Inherited&>(*this) = __in;
+	  return *this;
+	}
+
+      template<typename _U1>
+        tuple&
+        operator=(tuple<_U1>&& __in)
+        {
+	  static_cast<_Inherited&>(*this) = std::move(__in);
+	  return *this;
+	}
+
+      void
+      swap(tuple& __in)
+      { _Inherited::_M_swap_impl(__in); }
+    };
+
 
   /// Gives the type of the ith element of a given tuple type.
   template<std::size_t __i, typename _Tp>