From 4c951652988b51c6adcf8e95646792a750994829 Mon Sep 17 00:00:00 2001
From: Nehal J Wani <nehaljw.kkd1@gmail.com>
Date: Wed, 27 Nov 2019 14:12:55 -0500
Subject: [PATCH] Constrain make_zoned for icc16

Build fails with Intel Compiler v16:

<source>(1698): error: expression must have a constant value
  std::is_class<typename std::decay<decltype(*std::declval<TimeZonePtr&>())>::type>{}
                                                                                    ^
---
 include/date/tz.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/date/tz.h b/include/date/tz.h
index a342e3e..22eac55 100644
--- a/include/date/tz.h
+++ b/include/date/tz.h
@@ -1684,6 +1684,7 @@ make_zoned(const sys_time<Duration>& tp)
 
 template <class TimeZonePtr
 #if !defined(_MSC_VER) || (_MSC_VER > 1916)
+#if !defined(__INTEL_COMPILER) || (__INTEL_COMPILER > 1600)
           , class = typename std::enable_if
           <
             std::is_class
@@ -1694,6 +1695,7 @@ template <class TimeZonePtr
                 >::type
             >{}
           >::type
+#endif
 #endif
          >
 inline
@@ -1712,10 +1714,12 @@ make_zoned(const std::string& name)
 
 template <class Duration, class TimeZonePtr
 #if !defined(_MSC_VER) || (_MSC_VER > 1916)
+#if !defined(__INTEL_COMPILER) || (__INTEL_COMPILER > 1600)
           , class = typename std::enable_if
           <
             std::is_class<typename std::decay<decltype(*std::declval<TimeZonePtr&>())>::type>{}
           >::type
+#endif
 #endif
          >
 inline
@@ -1728,10 +1732,12 @@ make_zoned(TimeZonePtr zone, const local_time<Duration>& tp)
 
 template <class Duration, class TimeZonePtr
 #if !defined(_MSC_VER) || (_MSC_VER > 1916)
+#if !defined(__INTEL_COMPILER) || (__INTEL_COMPILER > 1600)
           , class = typename std::enable_if
           <
             std::is_class<typename std::decay<decltype(*std::declval<TimeZonePtr&>())>::type>{}
           >::type
+#endif
 #endif
          >
 inline
@@ -1794,10 +1800,12 @@ make_zoned(const std::string& name, const zoned_time<Duration, TimeZonePtr>& zt,
 
 template <class Duration, class TimeZonePtr
 #if !defined(_MSC_VER) || (_MSC_VER > 1916)
+#if !defined(__INTEL_COMPILER) || (__INTEL_COMPILER > 1600)
           , class = typename std::enable_if
           <
             std::is_class<typename std::decay<decltype(*std::declval<TimeZonePtr&>())>::type>{}
           >::type
+#endif
 #endif
          >
 inline