Merge branch 'fix_7730' into develop

ChangeLog

@@ -26,7 +26,7 @@ TODO (known issues):
 (all refer to phoenix though not all may be in fact phoenix bugs
 #9291, #9260, #8820, #8800
 #8564, #8558, #8504, #8298, #8187, #8156, #7996
-#7953, #7946, #7730, #7481, #7480, #7423
+#7953, #7946, #7481, #7480, #7423
 #7391, #7356, #6911, #6848,
 #6202, #6133, #6026, #5687
 - Feature requests
@@ -49,6 +49,9 @@ CHANGELOG
 - Fixed #8704 Using Phoenix lambdas on top of custom Proto expressions
     This works for C++11 only.
     Test cmath applies to this.
+- Fixed #7730 Generic specializations of is_nullary for custom terminals are not possible
+    Define BOOST_PHOENIX_SPECIALIZE_CUSTOM_TERMINAL to use this.
+    Test bug7730 tests this.
 - Fixed #7624 Deduction failure
     This works for C++11 and has a workaround for C++03
     Test bug7624 tests both versions.

include/boost/phoenix/core/is_nullary.hpp

@@ -137,12 +137,20 @@ namespace boost { namespace phoenix
         struct is_nullary<T const >
             : is_nullary<T>
         {};
-        
+
+#ifdef BOOST_PHOENIX_SPECIALIZE_CUSTOM_TERMINAL
+        template <typename T>
+        struct is_nullary<custom_terminal<T>,
+        typename custom_terminal<T>::_is_default_custom_terminal >
+            : mpl::true_
+        {};
+#else
         template <typename T>
         struct is_nullary<custom_terminal<T> >
             : mpl::true_
         {};
-        
+#endif
+
         template <typename T>
         struct is_nullary<custom_terminal<actor<T> > >
             : evaluator

include/boost/phoenix/core/terminal.hpp

@@ -48,7 +48,13 @@ namespace boost { namespace phoenix
         : mpl::false_ {};
 
     template <typename T, typename Dummy>
-    struct custom_terminal;
+    struct custom_terminal
+#ifdef BOOST_PHOENIX_SPECIALIZE_CUSTOM_TERMINAL
+    {
+      typedef void _is_default_custom_terminal; // suggested fix for #7730
+    }
+#endif
+      ;
  
     namespace expression
     {

test/Jamfile

@@ -166,6 +166,7 @@ test-suite phoenix_include :
     [ run include/core/nothing.cpp ]
     [ run include/core/reference.cpp ]
     [ run include/core/terminal.cpp ]
+    [ run include/core/bug7730.cpp ]
     [ run include/core/value.cpp ]
     [ run include/core/visit_each.cpp ]
     [ run include/function/function.cpp : : : : function_function ]

test/include/core/bug7730.cpp

@@ -0,0 +1,8 @@
+/*=============================================================================
+    Copyright (c) 2011 Thomas Heller
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+#define BOOST_PHOENIX_SPECIALIZE_CUSTOM_TERMINAL 
+#include <boost/phoenix/core/terminal.hpp>
+int main() {}