From fb2f110eb4913b5df19e55f950317143efe7c11f Mon Sep 17 00:00:00 2001
From: morinmorin <mimomorin@gmail.com>
Date: Wed, 20 Sep 2017 23:37:39 +0900
Subject: [PATCH] Fix result_of_is_callable to support references to function
 pointers.

On compilers without the support of expression SFINAE, decltype-based
result_of<FP&(...)> failed to compile (FP is a function pointer type).
---
 include/boost/utility/detail/result_of_iterate.hpp | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/include/boost/utility/detail/result_of_iterate.hpp b/include/boost/utility/detail/result_of_iterate.hpp
index 5192172..cd21ed6 100644
--- a/include/boost/utility/detail/result_of_iterate.hpp
+++ b/include/boost/utility/detail/result_of_iterate.hpp
@@ -82,15 +82,12 @@ struct BOOST_PP_CAT(result_of_callable_fun_2_, BOOST_PP_ITERATION())<R(BOOST_PP_
 };
 
 template<typename F>
-struct BOOST_PP_CAT(result_of_callable_fun_, BOOST_PP_ITERATION());
-
-template<typename F>
-struct BOOST_PP_CAT(result_of_callable_fun_, BOOST_PP_ITERATION())<F *>
+struct BOOST_PP_CAT(result_of_callable_fun_, BOOST_PP_ITERATION())
   : BOOST_PP_CAT(result_of_callable_fun_2_, BOOST_PP_ITERATION())<F>
 {};
 
 template<typename F>
-struct BOOST_PP_CAT(result_of_callable_fun_, BOOST_PP_ITERATION())<F &>
+struct BOOST_PP_CAT(result_of_callable_fun_, BOOST_PP_ITERATION())<F *>
   : BOOST_PP_CAT(result_of_callable_fun_2_, BOOST_PP_ITERATION())<F>
 {};
 
@@ -99,7 +96,7 @@ struct BOOST_PP_CAT(result_of_select_call_wrapper_type_, BOOST_PP_ITERATION())
   : mpl::eval_if<
         is_class<typename remove_reference<F>::type>,
         result_of_wrap_callable_class<F>,
-        mpl::identity<BOOST_PP_CAT(result_of_callable_fun_, BOOST_PP_ITERATION())<typename remove_cv<F>::type> >
+        mpl::identity<BOOST_PP_CAT(result_of_callable_fun_, BOOST_PP_ITERATION())<typename remove_cv<typename remove_reference<F>::type>::type> >
     >
 {};