From cccac1d631b5388f560c9b9e302d1f972c41422a Mon Sep 17 00:00:00 2001
From: Glen Fernandes <glen.fernandes@gmail.com>
Date: Sun, 11 Jun 2017 10:53:28 -0400
Subject: [PATCH] Revert "Slightly more succint sfinae expressions"

---
 include/boost/core/addressof.hpp | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/include/boost/core/addressof.hpp b/include/boost/core/addressof.hpp
index 733a606..b73ea56 100644
--- a/include/boost/core/addressof.hpp
+++ b/include/boost/core/addressof.hpp
@@ -172,14 +172,19 @@ namespace detail {
 template<class T>
 T addressof_declval() BOOST_NOEXCEPT;
 
+template<class>
+struct addressof_void {
+    typedef void type;
+};
+
 template<class T, class E = void>
 struct addressof_member_operator {
     static constexpr bool value = false;
 };
 
 template<class T>
-struct addressof_member_operator<T,
-    decltype(addressof_declval<T&>().operator&(), void())> {
+struct addressof_member_operator<T, typename
+    addressof_void<decltype(addressof_declval<T&>().operator&())>::type> {
     static constexpr bool value = true;
 };
 
@@ -196,8 +201,8 @@ struct addressof_non_member_operator {
 };
 
 template<class T>
-struct addressof_non_member_operator<T,
-    decltype(operator&(addressof_declval<T&>()), void())> {
+struct addressof_non_member_operator<T, typename
+    addressof_void<decltype(operator&(addressof_declval<T&>()))>::type> {
     static constexpr bool value = true;
 };
 
@@ -208,7 +213,7 @@ struct addressof_expression {
 
 template<class T>
 struct addressof_expression<T,
-    decltype(&addressof_declval<T&>(), void())> {
+    typename addressof_void<decltype(&addressof_declval<T&>())>::type> {
     static constexpr bool value = true;
 };