From e049cc5f7558b15d673c565dfb21cae7d99cadc5 Mon Sep 17 00:00:00 2001
From: Howard Hinnant <hhinnant@apple.com>
Date: Mon, 27 Sep 2010 17:54:17 +0000
Subject: [PATCH] Cleaning up some tuple code.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@114848 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/__tuple | 52 +++++++++++++++++++++----------------------------
 include/tuple   | 16 +++++++++++----
 2 files changed, 34 insertions(+), 34 deletions(-)

diff --git a/include/__tuple b/include/__tuple
index 7fa74148f..e10f8d78b 100644
--- a/include/__tuple
+++ b/include/__tuple
@@ -127,6 +127,11 @@ template <class... _Tp> struct __tuple_like<__tuple_types<_Tp...>> : true_type {
 
 // __make_tuple_types
 
+// __make_tuple_types<_Tuple<_Types...>, _Ep, _Sp>::type is a
+// __tuple_types<_Types...> using only those _Types in the range [_Sp, _Ep).
+// _Sp defaults to 0 and _Ep defaults to tuple_size<_Tuple>.  If _Tuple is a
+// lvalue_reference type, then __tuple_types<_Types&...> is the result.
+
 template <class _TupleTypes, class _Tp, size_t _Sp, size_t _Ep>
 struct __make_tuple_types_imp;
 
@@ -135,7 +140,7 @@ struct __make_tuple_types_imp<__tuple_types<_Types...>, _Tp, _Sp, _Ep>
 {
     typedef typename remove_reference<_Tp>::type _Tpr;
     typedef typename __make_tuple_types_imp<__tuple_types<_Types...,
-                                            typename conditional<is_reference<_Tp>::value,
+                                            typename conditional<is_lvalue_reference<_Tp>::value,
                                                 typename tuple_element<_Sp, _Tpr>::type&,
                                                 typename tuple_element<_Sp, _Tpr>::type>::type>,
                                             _Tp, _Sp+1, _Ep>::type type;
@@ -154,32 +159,6 @@ struct __make_tuple_types
     typedef typename __make_tuple_types_imp<__tuple_types<>, _Tp, _Sp, _Ep>::type type;
 };
 
-// __make_assignable_types
-
-template <class _Tuple, class _Tp, size_t _Sp, size_t _Ep>
-struct __make_assignable_types_imp;
-
-template <class ..._Types, class _Tp, size_t _Sp, size_t _Ep>
-struct __make_assignable_types_imp<__tuple_types<_Types...>, _Tp, _Sp, _Ep>
-{
-    typedef typename __make_assignable_types_imp<__tuple_types<_Types...,
-                                      typename remove_reference<typename tuple_element<_Sp, _Tp>::type>::type>,
-                                      _Tp, _Sp+1, _Ep>::type type;
-};
-
-template <class ..._Types, class _Tp, size_t _Ep>
-struct __make_assignable_types_imp<__tuple_types<_Types...>, _Tp, _Ep, _Ep>
-{
-    typedef __tuple_types<_Types...> type;
-};
-
-template <class _Tp, size_t _Ep = tuple_size<typename remove_reference<_Tp>::type>::value, size_t _Sp = 0>
-struct __make_assignable_types
-{
-    static_assert(_Sp <= _Ep, "__make_assignable_types input error");
-    typedef typename __make_assignable_types_imp<__tuple_types<>, typename remove_reference<_Tp>::type, _Sp, _Ep>::type type;
-};
-
 // __tuple_convertible
 
 template <bool, class _Tp, class _Up>
@@ -209,6 +188,19 @@ struct __tuple_convertible<_Tp, _Up, true, true>
 
 // __tuple_assignable
 
+template <bool, class _Tp, class _Up>
+struct __tuple_assignable_imp : public false_type {};
+
+template <class _Tp0, class ..._Tp, class _Up0, class ..._Up>
+struct __tuple_assignable_imp<true, __tuple_types<_Tp0, _Tp...>, __tuple_types<_Up0, _Up...>>
+    : public integral_constant<bool,
+                               __is_assignable<_Up0&, _Tp0>::value &&
+                               __tuple_assignable_imp<true, __tuple_types<_Tp...>, __tuple_types<_Up...>>::value> {};
+
+template <>
+struct __tuple_assignable_imp<true, __tuple_types<>, __tuple_types<>>
+    : public true_type {};
+
 template <class _Tp, class _Up, bool = __tuple_like<typename remove_reference<_Tp>::type>::value,
                                 bool = __tuple_like<_Up>::value>
 struct __tuple_assignable
@@ -216,9 +208,9 @@ struct __tuple_assignable
 
 template <class _Tp, class _Up>
 struct __tuple_assignable<_Tp, _Up, true, true>
-    : public __tuple_convertible_imp<tuple_size<typename remove_reference<_Tp>::type>::value ==
-                                     tuple_size<_Up>::value,
-             typename __make_tuple_types<_Tp>::type, typename __make_assignable_types<_Up>::type>
+    : public __tuple_assignable_imp<tuple_size<typename remove_reference<_Tp>::type>::value ==
+                                    tuple_size<_Up>::value,
+             typename __make_tuple_types<_Tp>::type, typename __make_tuple_types<_Up>::type>
 {};
 
 _LIBCPP_END_NAMESPACE_STD
diff --git a/include/tuple b/include/tuple
index 5ec0f819c..2c294953f 100644
--- a/include/tuple
+++ b/include/tuple
@@ -193,18 +193,21 @@ public:
         {static_assert(!is_reference<_Hp>::value,
               "Attempted to default construct a reference element in a tuple");}
 
-    template <class _Tp>
+    template <class _Tp,
+              class = typename enable_if<is_constructible<_Hp, _Tp>::value>::type>
         _LIBCPP_INLINE_VISIBILITY
         explicit __tuple_leaf(_Tp&& __t)
             : value(_STD::forward<_Tp>(__t))
-        {static_assert(!is_lvalue_reference<_Hp>::value ||
+        {static_assert(!is_reference<_Hp>::value ||
                         is_lvalue_reference<_Hp>::value &&
                         (is_lvalue_reference<_Tp>::value ||
                          is_same<typename remove_reference<_Tp>::type,
                                  reference_wrapper<
                                     typename remove_reference<_Hp>::type
                                  >
-                                >::value),
+                                >::value) ||
+                        (is_rvalue_reference<_Hp>::value &&
+                         !is_lvalue_reference<_Tp>::value),
        "Attempted to construct a reference element in a tuple with an rvalue");}
 
     template <class _Tp, class _Alloc>
@@ -249,6 +252,10 @@ public:
                                 >::value),
        "Attempted to construct a reference element in a tuple with an rvalue");}
 
+    __tuple_leaf(const __tuple_leaf& __t)
+        : value(__t.get())
+        {static_assert(!is_rvalue_reference<_Hp>::value, "Can not copy a tuple with rvalue reference member");}
+
     template <class _Tp>
         _LIBCPP_INLINE_VISIBILITY
         explicit __tuple_leaf(const __tuple_leaf<_Ip, _Tp>& __t)
@@ -297,7 +304,8 @@ public:
         __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a)
             : _Hp(__a) {}
 
-    template <class _Tp>
+    template <class _Tp,
+              class = typename enable_if<is_constructible<_Hp, _Tp>::value>::type>
         _LIBCPP_INLINE_VISIBILITY
         explicit __tuple_leaf(_Tp&& __t)
             : _Hp(_STD::forward<_Tp>(__t)) {}