Allow declaring type synonyms

gcc/elna-tree.cc

@@ -23,6 +23,12 @@ namespace gcc
             && TYPE_MAIN_VARIANT(TREE_TYPE(type)) == char_type_node;
     }
 
+    bool is_array_type(tree type)
+    {
+        gcc_assert(TYPE_P(type));
+        return TREE_CODE(type) == ARRAY_TYPE;
+    }
+
     tree tree_chain_base::head()
     {
         return first;