From 2d860e2574952dea7267537151e0eae92ca6a8a4 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <doug.gregor@gmail.com>
Date: Mon, 5 Mar 2007 15:25:16 +0000
Subject: [PATCH] Fix result_of's handling of F(void).

[SVN r37140]
---
 include/boost/utility/result_of.hpp | 21 +++++++++++++++------
 test/result_of_test.cpp             |  1 +
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/include/boost/utility/result_of.hpp b/include/boost/utility/result_of.hpp
index c2e6478..cdcac34 100644
--- a/include/boost/utility/result_of.hpp
+++ b/include/boost/utility/result_of.hpp
@@ -15,6 +15,8 @@
 #include <boost/preprocessor.hpp>
 #include <boost/detail/workaround.hpp>
 #include <boost/mpl/has_xxx.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/mpl/bool.hpp>
 
 #ifndef BOOST_RESULT_OF_NUM_ARGS
 #  define BOOST_RESULT_OF_NUM_ARGS 10
@@ -55,14 +57,21 @@ struct result_of_impl<F, FArgs, true>
   typedef typename F::result_type type;
 };
 
-template<typename F, typename FArgs>
-struct result_of_impl<F, FArgs, false>
-  : F::template result<FArgs>
-{};
+template<typename FArgs>
+struct is_function_with_no_args : mpl::false_ {};
 
 template<typename F>
-struct result_of_impl<F, F(void), false>
-  : result_of_void_impl<F>
+struct is_function_with_no_args<F(void)> : mpl::true_ {};
+
+template<typename F, typename FArgs>
+struct result_of_nested_result : F::template result<FArgs>
+{};
+
+template<typename F, typename FArgs>
+struct result_of_impl<F, FArgs, false>
+  : mpl::if_<is_function_with_no_args<FArgs>,
+	     result_of_void_impl<F>,
+	     result_of_nested_result<F, FArgs> >::type
 {};
 
 } // end namespace detail
diff --git a/test/result_of_test.cpp b/test/result_of_test.cpp
index ca1cfae..10f3410 100644
--- a/test/result_of_test.cpp
+++ b/test/result_of_test.cpp
@@ -79,6 +79,7 @@ int main()
   BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr_v(X,char)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr_cv(X,char)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr_0(X)>::type, int>::value)); 
+  BOOST_STATIC_ASSERT((is_same<result_of<func_ptr(void)>::type, int>::value));
 
   return 0;
 }