Re: [boost] [result_of] msvc work-around -- TESTERS NEEDED

From: Eric Niebler (eric_at_[hidden])
Date: 2007-01-14 01:17:58

Eric Niebler wrote:
> Tobias Schwinger wrote:
>> Hi,
>>
>> here is how it breaks.
>>
>> Let's start with the new bug:
>>
>> 1.
>>
>>     typedef int (*func_ptr_0)();
>>
>>     BOOST_STATIC_ASSERT((is_same<
>>         result_of<func_ptr_0()>::type,
>>         int>::value));
>>
>> ==> Ambiguous template specialization, this one got introduced by 
>> Eric's workaround
> 
> Yep, you're right. I hope find a fix before I leave for vacation on 
> Monday. If I can't and this is a serious issue for you, feel free to 
> revert the change until I can patch this up.
> 
> 
>> 2.
>>
>> Although it seems to be the same problem, it's actually a different 
>> one (just a typo - see result_of_iterate.patch). This test fails with 
>> the RC 1.34 version, too:
>>
>>     typedef int (X::*mem_func_ptr_0)();
>>
>>     BOOST_STATIC_ASSERT((is_same<
>>         result_of<mem_func_ptr_0(X)>::type,
>>         int>::value));
> 
> 
> I'll let Doug comment on this one.

The attached patch fixes both problems. Doug, should I commit (to HEAD)? 
Also see the new test (attached).

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com

? boost/utility/result_of_patch.txt
Index: boost/utility/result_of.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/utility/result_of.hpp,v
retrieving revision 1.8
diff -b -d -u -r1.8 result_of.hpp
--- boost/utility/result_of.hpp	8 Jan 2007 20:38:51 -0000	1.8
+++ boost/utility/result_of.hpp	14 Jan 2007 06:13:50 -0000
@@ -31,6 +31,24 @@
 
 template<typename F, typename FArgs, bool HasResultType> struct result_of_impl;
 
+template<typename F>
+struct result_of_void_impl
+{
+  typedef void type;
+};
+
+template<typename R>
+struct result_of_void_impl<R (*)(void)>
+{
+  typedef R type;
+};
+
+template<typename R>
+struct result_of_void_impl<R (&)(void)>
+{
+  typedef R type;
+};
+
 template<typename F, typename FArgs>
 struct result_of_impl<F, FArgs, true>
 {
@@ -44,9 +62,8 @@
 
 template<typename F>
 struct result_of_impl<F, F(void), false>
-{
-  typedef void type;
-};
+  : result_of_void_impl<F>
+{};
 
 } // end namespace detail
 
Index: boost/utility/detail/result_of_iterate.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/utility/detail/result_of_iterate.hpp,v
retrieving revision 1.4
diff -b -d -u -r1.4 result_of_iterate.hpp
--- boost/utility/detail/result_of_iterate.hpp	8 Jan 2007 20:38:51 -0000	1.4
+++ boost/utility/detail/result_of_iterate.hpp	14 Jan 2007 06:13:50 -0000
@@ -24,25 +24,27 @@
     : detail::result_of_impl<F, F(BOOST_RESULT_OF_ARGS), (detail::has_result_type<F>::value)> {};
 #endif
 
+#undef BOOST_RESULT_OF_ARGS
+
+#if BOOST_PP_ITERATION() >= 1 
+
 namespace detail {
 
 template<typename R,  typename FArgs BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
          BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
-struct result_of_impl<R (*)(BOOST_RESULT_OF_ARGS), FArgs, false>
+struct result_of_impl<R (*)(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), FArgs, false>
 {
   typedef R type;
 };
 
 template<typename R,  typename FArgs BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
          BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
-struct result_of_impl<R (&)(BOOST_RESULT_OF_ARGS), FArgs, false>
+struct result_of_impl<R (&)(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), FArgs, false>
 {
   typedef R type;
 };
 
-#undef BOOST_RESULT_OF_ARGS
-
-#if BOOST_PP_ITERATION() > 1 && !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551))
+#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551))
 template<typename R, typename FArgs BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
          BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
 struct result_of_impl<R (T0::*)
@@ -84,3 +86,4 @@
 #endif
 
 }
+#endif


// Boost result_of library

//  Copyright Douglas Gregor 2003-2004. Use, modification and
//  distribution is subject to 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)

// For more information, see http://www.boost.org/libs/utility
#include <boost/utility/result_of.hpp>
#include <utility>
#include <boost/static_assert.hpp>
#include <boost/type_traits/is_same.hpp>

struct int_result_type { typedef int result_type; };

struct int_result_of
{
  template<typename F> struct result { typedef int type; };
};

struct int_result_type_and_float_result_of
{
  typedef int result_type;
  template<typename F> struct result { typedef float type; };
};

template<typename T>
struct int_result_type_template { typedef int result_type; };

template<typename T>
struct int_result_of_template
{
  template<typename F> struct result;
  template<typename This, typename That> struct result<This(That)> { typedef int type; };
};

template<typename T>
struct int_result_type_and_float_result_of_template
{
  typedef int result_type;
  template<typename F> struct result;
  template<typename This, typename That> struct result<This(That)> { typedef float type; };
};

struct X {};

int main()
{
  using namespace boost;

  typedef int (*func_ptr)(float, double);
  typedef int (&func_ref)(float, double);
  typedef int (*func_ptr_0)();
  typedef int (&func_ref_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;
  typedef int (X::*mem_func_ptr_cv)(float) const volatile;
  typedef int (X::*mem_func_ptr_0)();

  BOOST_STATIC_ASSERT((is_same<result_of<int_result_type(float)>::type, int>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<int_result_of(double)>::type, int>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<int_result_of(void)>::type, void>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<const int_result_of(double)>::type, int>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<volatile int_result_of(void)>::type, void>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<int_result_type_and_float_result_of(char)>::type, int>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<int_result_type_template<void>(float)>::type, int>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<int_result_of_template<void>(double)>::type, int>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<int_result_of_template<void>(void)>::type, void>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<const int_result_of_template<void>(double)>::type, int>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<volatile int_result_of_template<void>(void)>::type, void>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<int_result_type_and_float_result_of_template<void>(char)>::type, int>::value));
  BOOST_STATIC_ASSERT((is_same<result_of<func_ptr(char, float)>::type, int>::value));
  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<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));
  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)); 

  return 0;
}