[Deque] Make the from-sequence constructor SFINAE friendly

test/sequence/deque_is_constructible.cpp

@@ -0,0 +1,17 @@
+/*=============================================================================
+    Copyright (c) 2015 Louis Dionne
+
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+
+#include <type_traits>
+#include <boost/fusion/include/deque.hpp>
+
+
+struct Dummy { };
+
+// Make sure deque's constructor is SFINAE-friendly.
+static_assert(!std::is_constructible<boost::fusion::deque<int>, Dummy const&>::value, "");
+
+int main() { }