Replace Eigen type metaprogramming with corresponding std types and make use of alias templates
diff --git a/test/sparse_ref.cpp b/test/sparse_ref.cpp
index 8f33af8..098331e 100644
--- a/test/sparse_ref.cpp
+++ b/test/sparse_ref.cpp
@@ -34,7 +34,7 @@
 template<typename PlainObjectType> void check_const_correctness(const PlainObjectType&)
 {
   // verify that ref-to-const don't have LvalueBit
-  typedef typename internal::add_const<PlainObjectType>::type ConstPlainObjectType;
+  typedef std::add_const_t<PlainObjectType> ConstPlainObjectType;
   VERIFY( !(internal::traits<Ref<ConstPlainObjectType> >::Flags & LvalueBit) );
   VERIFY( !(internal::traits<Ref<ConstPlainObjectType, Aligned> >::Flags & LvalueBit) );
   VERIFY( !(Ref<ConstPlainObjectType>::Flags & LvalueBit) );