From 6c2e37ffdd85823549634ab53931bc412b297bde Mon Sep 17 00:00:00 2001
From: Todd Lipcon <todd@cloudera.com>
Date: Fri, 24 Mar 2017 15:14:31 -0700
Subject: [PATCH] Add compatibily for gcc 4.x in traits

gcc 4.x doesn't implement std::is_trivially_copy_constructible<>. In
order to maintain compatibility with those versions, we switch to using
the equivalent trait in boost.

Tested by building a small test using gcc 4.8, gcc 5.4, and clang 3.9.

This was discussed upstream at https://github.com/sparsehash/sparsehash-c11/pull/19
but determined that it wasn't a good idea for the upstream project.
---
 sparsehash/traits | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/sparsehash/traits b/sparsehash/traits
index 65135a6..e1e5648 100644
--- a/sparsehash/traits
+++ b/sparsehash/traits
@@ -30,6 +30,12 @@
 #pragma once
 #include <type_traits>
 #include <utility>  // For pair
+#include <boost/move/detail/type_traits.hpp>
+
+// Work around lack of std::is_trivially_copy_constructible in gcc 4.x by
+// using the boost version.
+#define SPARSEHASH_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
+  ::boost::move_detail::is_trivially_copy_constructible<T>::value
 
 namespace google {
 
@@ -43,7 +49,7 @@ namespace google {
 template <class T>
 struct is_relocatable
     : std::integral_constant<bool,
-                             (std::is_trivially_copy_constructible<T>::value &&
+                             (SPARSEHASH_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) &&
                               std::is_trivially_destructible<T>::value)> {};
 template <class T, class U>
 struct is_relocatable<std::pair<T, U>>
@@ -52,4 +58,4 @@ struct is_relocatable<std::pair<T, U>>
 
 template <class T>
 struct is_relocatable<const T> : is_relocatable<T> {};
-}
\ No newline at end of file
+}
-- 
2.7.4