From 3d650b7f92fbb30d8e247d387cef44e130807ad3 Mon Sep 17 00:00:00 2001
From: Eric Niebler <eric@boostpro.com>
Date: Sun, 23 Sep 2012 02:08:32 +0000
Subject: [PATCH] nicer work-around for gcc warnings

[SVN r80656]
---
 .../boost/utility/detail/result_of_iterate.hpp    |  8 +-------
 include/boost/utility/result_of.hpp               | 15 ++++++++-------
 test/result_of_test.cpp                           | 12 ++++++++++++
 3 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/include/boost/utility/detail/result_of_iterate.hpp b/include/boost/utility/detail/result_of_iterate.hpp
index 7dccf17..23aa650 100644
--- a/include/boost/utility/detail/result_of_iterate.hpp
+++ b/include/boost/utility/detail/result_of_iterate.hpp
@@ -15,12 +15,6 @@
 # error Boost result_of - do not include this file!
 #endif
 
-// This header generate spurious warnings on gcc, which we supress by
-// treating it as a system header.
-#if defined(__GNUC__) && (__GNUC__ >= 4) 
-#pragma GCC system_header 
-#endif
-
 // CWPro8 requires an argument in a function type specialization
 #if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3002)) && BOOST_PP_ITERATION() == 0
 # define BOOST_RESULT_OF_ARGS void
@@ -101,7 +95,7 @@ struct BOOST_PP_CAT(result_of_is_callable_, BOOST_PP_ITERATION()) {
     typedef typename BOOST_PP_CAT(result_of_select_call_wrapper_type_, BOOST_PP_ITERATION())<F>::type wrapper_t;
     static const bool value = (
         sizeof(result_of_no_type) == sizeof(detail::result_of_is_private_type(
-            (boost::declval<wrapper_t>()(BOOST_PP_ENUM_BINARY_PARAMS(BOOST_PP_ITERATION(), boost::declval<T, >() BOOST_PP_INTERCEPT)), 0)
+            (boost::declval<wrapper_t>()(BOOST_PP_ENUM_BINARY_PARAMS(BOOST_PP_ITERATION(), boost::declval<T, >() BOOST_PP_INTERCEPT)), result_of_weird_type())
         ))
     );
     typedef mpl::bool_<value> type;
diff --git a/include/boost/utility/result_of.hpp b/include/boost/utility/result_of.hpp
index f6add2f..4695fa4 100644
--- a/include/boost/utility/result_of.hpp
+++ b/include/boost/utility/result_of.hpp
@@ -74,18 +74,19 @@ template<typename F, typename FArgs, bool HasResultType> struct tr1_result_of_im
 
 template<typename T> T result_of_decay(T);
 
-struct result_of_private_type
-{
-  result_of_private_type const &operator,(int) const;
+struct result_of_private_type {};
+
+struct result_of_weird_type {
+  template<typename T>
+  friend result_of_weird_type operator,(T const &, result_of_weird_type);
+  friend result_of_private_type operator,(result_of_private_type, result_of_weird_type);
 };
 
 typedef char result_of_yes_type;      // sizeof(result_of_yes_type) == 1
 typedef char (&result_of_no_type)[2]; // sizeof(result_of_no_type)  == 2
 
-template<typename T>
-result_of_no_type result_of_is_private_type(T const &);
-
-result_of_yes_type result_of_is_private_type(result_of_private_type const &);
+result_of_no_type result_of_is_private_type(result_of_weird_type);
+result_of_yes_type result_of_is_private_type(result_of_private_type);
 
 template<typename C>
 struct result_of_callable_class : C {
diff --git a/test/result_of_test.cpp b/test/result_of_test.cpp
index 0c2834f..61592f5 100644
--- a/test/result_of_test.cpp
+++ b/test/result_of_test.cpp
@@ -160,6 +160,10 @@ int main()
   typedef int (&func_ref)(float, double);
   typedef int (*func_ptr_0)();
   typedef int (&func_ref_0)();
+  typedef void (*func_ptr_void)(float, double);
+  typedef void (&func_ref_void)(float, double);
+  typedef void (*func_ptr_void_0)();
+  typedef void (&func_ref_void_0)();
   typedef int (X::*mem_func_ptr)(float);
   typedef int (X::*mem_func_ptr_c)(float) const;
   typedef int (X::*mem_func_ptr_v)(float) volatile;
@@ -218,6 +222,10 @@ int main()
   BOOST_STATIC_ASSERT((is_same<result_of<func_ref(char, float)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<result_of<func_ptr_0()>::type, int>::value)); 
   BOOST_STATIC_ASSERT((is_same<result_of<func_ref_0()>::type, int>::value)); 
+  BOOST_STATIC_ASSERT((is_same<result_of<func_ptr_void(char, float)>::type, void>::value));
+  BOOST_STATIC_ASSERT((is_same<result_of<func_ref_void(char, float)>::type, void>::value));
+  BOOST_STATIC_ASSERT((is_same<result_of<func_ptr_void_0()>::type, void>::value)); 
+  BOOST_STATIC_ASSERT((is_same<result_of<func_ref_void_0()>::type, void>::value)); 
   BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr(X,char)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr_c(X,char)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr_v(X,char)>::type, int>::value));
@@ -228,6 +236,10 @@ int main()
   BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ref(char, float)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ptr_0()>::type, int>::value)); 
   BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ref_0()>::type, int>::value)); 
+  BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ptr_void(char, float)>::type, void>::value));
+  BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ref_void(char, float)>::type, void>::value));
+  BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ptr_void_0()>::type, void>::value)); 
+  BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ref_void_0()>::type, void>::value)); 
   BOOST_STATIC_ASSERT((is_same<tr1_result_of<mem_func_ptr(X,char)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<tr1_result_of<mem_func_ptr_c(X,char)>::type, int>::value));
   BOOST_STATIC_ASSERT((is_same<tr1_result_of<mem_func_ptr_v(X,char)>::type, int>::value));