From 6153eebc42b07d80afb9d3f90b959361681cfe06 Mon Sep 17 00:00:00 2001
From: Glen Fernandes <glen.fernandes@gmail.com>
Date: Sun, 11 Jun 2017 10:17:35 -0400
Subject: [PATCH] Slightly more succint sfinae expressions

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

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