From c381b35ee671a9175a70348199da55f2f782ef43 Mon Sep 17 00:00:00 2001
From: badair <badair@harding.edu>
Date: Tue, 29 Mar 2016 21:27:32 -0500
Subject: [PATCH] enabling older versions of libstdc++

---
 include/callable_traits/config.hpp         | 9 +++++++++
 include/callable_traits/detail/any_arg.hpp | 3 ++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/include/callable_traits/config.hpp b/include/callable_traits/config.hpp
index 65bfafd..b97d745 100644
--- a/include/callable_traits/config.hpp
+++ b/include/callable_traits/config.hpp
@@ -23,6 +23,15 @@ Distributed under the Boost Software License, Version 1.0.
 #endif //ifndef __clang__
 #endif //_MSC_VER
 
+//libstdc++ formerly used this non-conforming trait
+#if defined(__GLIBCXX__) && __GLIBCXX__ < 20150422
+#define CALLABLE_TRAITS_IS_TRIVIALLY_DEFAULT_CONSTRUCTIBLE(T) \
+    std::has_trivial_default_constructor<T>::value
+#else
+#define CALLABLE_TRAITS_IS_TRIVIALLY_DEFAULT_CONSTRUCTIBLE(T) \
+    std::is_trivially_default_constructible<T>::value
+#endif //if defined(__GLIBCXX__) && __GLIBCXX__ < 20150422
+
 #include <utility>
 
 namespace callable_traits {
diff --git a/include/callable_traits/detail/any_arg.hpp b/include/callable_traits/detail/any_arg.hpp
index d79c6b9..3fb2bd1 100644
--- a/include/callable_traits/detail/any_arg.hpp
+++ b/include/callable_traits/detail/any_arg.hpp
@@ -12,6 +12,7 @@ Distributed under the Boost Software License, Version 1.0.
 
 #include <utility>
 #include <callable_traits/detail/make_constexpr.hpp>
+#include <callable_traits/config.hpp>
 
 namespace callable_traits {
 
@@ -40,7 +41,7 @@ namespace callable_traits {
         template<typename T, typename U = shallow_decay<T>>
         using int_if_trivial = 
             typename std::enable_if<
-                std::is_trivially_default_constructible<U>::value,
+                CALLABLE_TRAITS_IS_TRIVIALLY_DEFAULT_CONSTRUCTIBLE(U),
                 T
             >::type;