[libcxx] r192038 - Implement LWG issue 2275 'forward_as_tuple should be constexpr'

[Marshall Clow]

Author: marshall
Date: Sat Oct  5 13:46:37 2013
New Revision: 192038

URL: http://llvm.org/viewvc/llvm-project?rev=192038&view=rev
Log:
Implement LWG issue 2275 'forward_as_tuple should be constexpr'

Modified:
    libcxx/trunk/include/tuple
    libcxx/trunk/test/utilities/tuple/tuple.tuple/tuple.creation/forward_as_tuple.pass.cpp

Modified: libcxx/trunk/include/tuple
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/tuple?rev=192038&r1=192037&r2=192038&view=diff
==============================================================================
--- libcxx/trunk/include/tuple (original)
+++ libcxx/trunk/include/tuple Sat Oct  5 13:46:37 2013
@@ -73,7 +73,7 @@ public:
 const unspecified ignore;
 
 template <class... T> tuple<V...>  make_tuple(T&&...); // constexpr in C++14
-template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept;
+template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept; // constexpr in C++14
 template <class... T> tuple<T&...> tie(T&...) noexcept;
 template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls); // constexpr in C++14
   
@@ -833,14 +833,6 @@ make_tuple(_Tp&&... __t)
 template <class... _Tp>
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
 tuple<_Tp&&...>
-__forward_as_tuple(_Tp&&... __t) _NOEXCEPT
-{
-    return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
-}
-
-template <class... _Tp>
-inline _LIBCPP_INLINE_VISIBILITY
-tuple<_Tp&&...>
 forward_as_tuple(_Tp&&... __t) _NOEXCEPT
 {
     return tuple<_Tp&&...>(_VSTD::forward<_Tp>(__t)...);
@@ -1041,7 +1033,7 @@ struct __tuple_cat<tuple<_Types...>, __t
     typename __tuple_cat_return_ref<tuple<_Types...>&&, _Tuple0&&>::type
     operator()(tuple<_Types...> __t, _Tuple0&& __t0)
     {
-        return __forward_as_tuple(_VSTD::forward<_Types>(get<_I0>(__t))...,
+        return forward_as_tuple(_VSTD::forward<_Types>(get<_I0>(__t))...,
                                       get<_J0>(_VSTD::forward<_Tuple0>(__t0))...);
     }
 
@@ -1056,7 +1048,7 @@ struct __tuple_cat<tuple<_Types...>, __t
            tuple<_Types..., typename __apply_cv<_Tuple0, typename tuple_element<_J0, _T0>::type>::type&&...>,
            typename __make_tuple_indices<sizeof ...(_Types) + tuple_size<_T0>::value>::type,
            typename __make_tuple_indices<tuple_size<_T1>::value>::type>()
-                           (__forward_as_tuple(
+                           (forward_as_tuple(
                               _VSTD::forward<_Types>(get<_I0>(__t))...,
                               get<_J0>(_VSTD::forward<_Tuple0>(__t0))...
                             ),

Modified: libcxx/trunk/test/utilities/tuple/tuple.tuple/tuple.creation/forward_as_tuple.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/utilities/tuple/tuple.tuple/tuple.creation/forward_as_tuple.pass.cpp?rev=192038&r1=192037&r2=192038&view=diff
==============================================================================
--- libcxx/trunk/test/utilities/tuple/tuple.tuple/tuple.creation/forward_as_tuple.pass.cpp (original)
+++ libcxx/trunk/test/utilities/tuple/tuple.tuple/tuple.creation/forward_as_tuple.pass.cpp Sat Oct  5 13:46:37 2013
@@ -51,6 +51,15 @@ test2a(const Tuple& t)
     assert(std::get<1>(t) == 'a');
 }
 
+#if _LIBCPP_STD_VER > 11
+template <class Tuple>
+constexpr int 
+test3(const Tuple& t)
+{
+    return std::tuple_size<Tuple>::value;
+}
+#endif
+
 int main()
 {
     {
@@ -67,5 +76,8 @@ int main()
         double i = 2.5;
         char c = 'a';
         test2a(std::forward_as_tuple(i, c));
+#if _LIBCPP_STD_VER > 11
+        static_assert ( test3 (std::forward_as_tuple(i, c)) == 2, "" );
+#endif
     }
 }