--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libinterp/parse-tree/anon-fcn-validator.cc	Wed Nov 20 19:22:54 2019 -0600
@@ -0,0 +1,80 @@
+/*
+
+Copyright (C) 2019 John W. Eaton
+
+This file is part of Octave.
+
+Octave is free software: you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Octave is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with Octave; see the file COPYING.  If not, see
+<https://www.gnu.org/licenses/>.
+
+*/
+
+#if defined (HAVE_CONFIG_H)
+#  include "config.h"
+#endif
+
+#include <string>
+
+#include "anon-fcn-validator.h"
+#include "ov.h"
+#include "pt-all.h"
+
+namespace octave
+{
+  anon_fcn_validator::anon_fcn_validator (tree_parameter_list *,
+                                          tree_expression *expr)
+    : m_ok (true), m_line (-1), m_column (-1), m_message ()
+  {
+    expr->accept (*this);
+  }
+
+  void anon_fcn_validator::visit_postfix_expression (tree_postfix_expression& expr)
+  {
+    octave_value::unary_op op = expr.op_type ();
+
+    if (op == octave_value::op_incr || op == octave_value::op_decr)
+      error (expr);
+    else
+      tree_walker::visit_postfix_expression (expr);
+  }
+
+  void anon_fcn_validator::visit_prefix_expression (tree_prefix_expression& expr)
+  {
+    octave_value::unary_op op = expr.op_type ();
+
+    if (op == octave_value::op_incr || op == octave_value::op_decr)
+      error (expr);
+    else
+      tree_walker::visit_prefix_expression (expr);
+  }
+
+  void anon_fcn_validator::visit_multi_assignment (tree_multi_assignment& expr)
+  {
+    error (expr);
+  }
+
+  void anon_fcn_validator::visit_simple_assignment (tree_simple_assignment& expr)
+  {
+    error (expr);
+  }
+
+  void anon_fcn_validator::error (tree_expression& expr)
+  {
+    m_ok = false;
+    m_line = expr.line ();
+    m_column = expr.column ();
+    m_message
+      = "invalid use of operator " + expr.oper () + " in anonymous function";
+  }
+}