From 0c6b09ef6aa318b794dca2beafeeee3a6e77f239 Mon Sep 17 00:00:00 2001
From: Andrey Semashev <andrey.semashev@gmail.com>
Date: Sun, 27 Aug 2017 17:31:34 +0300
Subject: [PATCH] Workaround MSVC 14.1 problem with template specialization
 partial ordering that caused compilation failure when next/prior is used with
 pointers. Added a test.

---
 include/boost/next_prior.hpp | 12 +++++++++---
 test/next_prior_test.cpp     |  9 +++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/include/boost/next_prior.hpp b/include/boost/next_prior.hpp
index 178cf67..5de705f 100644
--- a/include/boost/next_prior.hpp
+++ b/include/boost/next_prior.hpp
@@ -46,13 +46,13 @@ namespace next_prior_detail {
 // Since C++17 we can test for iterator_traits<T>::iterator_category presence instead as it is
 // required to be only present for iterators.
 template< typename T, typename Void = void >
-struct is_iterator
+struct is_iterator_class
 {
     static BOOST_CONSTEXPR_OR_CONST bool value = false;
 };
 
 template< typename T >
-struct is_iterator<
+struct is_iterator_class<
     T,
     typename enable_if_has_type<
 #if !defined(BOOST_NO_CXX17_ITERATOR_TRAITS)
@@ -67,7 +67,13 @@ struct is_iterator<
 };
 
 template< typename T >
-struct is_iterator< T*, void >
+struct is_iterator :
+    public is_iterator_class< T >
+{
+};
+
+template< typename T >
+struct is_iterator< T* >
 {
     static BOOST_CONSTEXPR_OR_CONST bool value = true;
 };
diff --git a/test/next_prior_test.cpp b/test/next_prior_test.cpp
index 734a212..65e74b1 100644
--- a/test/next_prior_test.cpp
+++ b/test/next_prior_test.cpp
@@ -92,6 +92,15 @@ int main(int, char*[])
     BOOST_TEST(minus_n_unsigned_test(x.rbegin(), x.rend(), x.size()));
     BOOST_TEST(minus_n_unsigned_test(x.rbegin(), x.rend(), y.size()));
 
+    // Test with pointers
+    int arr[8] = {};
+    int* p = arr;
+    BOOST_TEST(plus_one_test(x.begin(), x.end(), p));
+    BOOST_TEST(plus_n_test(x.begin(), x.end(), p));
+    BOOST_TEST(minus_one_test(x.begin(), x.end(), p + sizeof(arr)));
+    BOOST_TEST(minus_n_test(x.begin(), x.end(), p + sizeof(arr)));
+    BOOST_TEST(minus_n_unsigned_test(p, p + sizeof(arr), sizeof(arr)));
+
     // Tests with integers
     BOOST_TEST(boost::next(5) == 6);
     BOOST_TEST(boost::next(5, 7) == 12);