[Bug libstdc++/49058] [C++0x] Bind no-arguments functor failed using std::bind with -pedantic option.

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49058

--- Comment #16 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-05-22 
22:52:13 UTC ---
With enable_if becomes a tad more concise.

///////////////////

Index: include/std/functional
===================================================================
--- include/std/functional    (revision 174044)
+++ include/std/functional    (working copy)
@@ -1210,7 +1210,8 @@

       // Call as const
       template<typename... _Args, typename _Result
-    = decltype( std::declval<const _Functor>()(
+    = decltype( std::declval<typename enable_if<(sizeof...(_Args) >= 0),
+               typename add_const<_Functor>::type>::type>()(
           _Mu<_Bound_args>()( std::declval<const _Bound_args&>(),
                   std::declval<tuple<_Args...>&>() )... ) )>
     _Result
@@ -1223,7 +1224,8 @@

       // Call as volatile
       template<typename... _Args, typename _Result
-    = decltype( std::declval<volatile _Functor>()(
+    = decltype( std::declval<typename enable_if<(sizeof...(_Args) >= 0),
+                       typename add_volatile<_Functor>::type>::type>()(
           _Mu<_Bound_args>()( std::declval<volatile _Bound_args&>(),
                   std::declval<tuple<_Args...>&>() )... ) )>
     _Result
@@ -1236,7 +1238,8 @@

       // Call as const volatile
       template<typename... _Args, typename _Result
-    = decltype( std::declval<const volatile _Functor>()(
+    = decltype( std::declval<typename enable_if<(sizeof...(_Args) >= 0),
+                       typename add_cv<_Functor>::type>::type>()(
           _Mu<_Bound_args>()( std::declval<const volatile _Bound_args&>(),
                   std::declval<tuple<_Args...>&>() )... ) )>
     _Result