--- a/libinterp/parse-tree/oct-parse.in.yy	Wed Nov 08 16:32:48 2017 -0500
+++ b/libinterp/parse-tree/oct-parse.in.yy	Wed Nov 08 16:30:07 2017 -0500
@@ -3962,17 +3962,8 @@
     int l = tok_val->line ();
     int c = tok_val->column ();
 
-    std::list<std::string> names;
-    for (tree_decl_init_list::iterator p = lst->begin ();
-         p != lst->end (); p++)
-      {
-        tree_decl_elt *elt = *p;
-
-        std::string nm = elt->name ();
-        if (! nm.empty ())
-          names.push_back (nm);
-      }
-    m_lexer.mark_as_variables (names);
+    if (lst)
+      m_lexer.mark_as_variables (lst->variable_names ());
 
     switch (tok)
       {

--- a/libinterp/parse-tree/pt-decl.h	Wed Nov 08 16:32:48 2017 -0500
+++ b/libinterp/parse-tree/pt-decl.h	Wed Nov 08 16:30:07 2017 -0500
@@ -25,6 +25,7 @@
 
 #include "octave-config.h"
 
+#include <list>
 #include <string>
 
 #include "base-list.h"
@@ -89,7 +90,7 @@
 
     tree_identifier * ident (void) { return id; }
 
-    std::string name (void) { return id ? id->name () : ""; }
+    std::string name (void) const { return id ? id->name () : ""; }
 
     tree_expression * expression (void) { return expr; }
 
@@ -147,6 +148,21 @@
         elt->mark_persistent ();
     }
 
+    std::list<std::string> variable_names (void) const
+    {
+      std::list<std::string> retval;
+
+      for (const tree_decl_elt *elt : *this)
+      {
+        std::string nm = elt->name ();
+
+        if (! nm.empty ())
+          retval.push_back (nm);
+      }
+
+      return retval;
+    }
+
     void accept (tree_walker& tw)
     {
       tw.visit_decl_init_list (*this);