use exceptions for better invalid index error reporting (bug #45957) * lo-array-gripes.h, lo-array-gripes.cc (index_exception): New base class for indexing errors. (invalid_index, out_of_range): New classes. (gripe_index_out_of_range): New overloaded function. (gripe_invalid_index): New overloaded functions. Delete version with no arguments. (gripe_invalid_assignment_size, gripe_assignment_dimension_mismatch): Delete. Change uses of gripe functions as needed. * Cell.cc (Cell::index, Cell::assign, Cell::delete_elements): Use exceptions to collect error info about and handle indexing errors. * data.cc (Fnth_element, do_accumarray_sum, F__accumarray_sum__, do_accumarray_minmax, do_accumarray_minmax_fun, F__accumdim_sum__): Likewise. * oct-map.cc (octave_map::index, octave_map::assign, octave_map::delete_elements): Likewise. * sparse.cc (Fsparse): Likewise. * sub2ind.cc (Fsub2ind, Find2sub): Likewise. New tests. * utils.cc (dims_to_numel): Likewise. * ov-base-diag.cc (octave_base_diag<DMT, MT>::do_index_op, octave_base_diag<DMT, MT>::subsasgn): Likewise. * ov-base-mat.cc (octave_base_matrix<MT>::subsref, octave_base_matrix<MT>::assign): Likewise. * ov-base-sparse.cc (octave_base_sparse<T>::do_index_op, octave_base_sparse<T>::assign, octave_base_sparse<MT>::delete_elements): Likewise. * ov-classdef.cc (cdef_object_array::subsref, cdef_object_array::subsasgn): Likewise. * ov-java.cc (make_java_index): Likewise. * ov-perm.cc (octave_perm_matrix::do_index_op): Likewise. * ov-range.cc (octave_range::do_index_op): Likewise. * ov-re-diag.cc (octave_diag_matrix::do_index_op): Likewise. * ov-str-mat.cc (octave_char_matrix_str::do_index_op_internal): Likewise. * pt-assign.cc (tree_simple_assignment::rvalue1): Likewise. * pt-idx.cc (tree_index_expression::rvalue, tree_index_expression::lvalue): Likewise. * Array-util.cc (sub2ind): Likewise. * toplev.cc (main_loop): Also catch unhandled index_exception exceptions. * ov-base.cc (octave_base_value::index_vector): Improve error message. * ov-re-sparse.cc (octave_sparse_matrix::index_vector): Likewise. * ov-complex.cc (complex_index): New class. (gripe_complex_index): New function. (octave_complex::index_vector): Use it. * pt-id.h, pt-id.cc (tree_identifier::is_variable, tree_black_hole::is_variable): Now const. * pt-idx.cc (final_index_error): New static function. (tree_index_expression::rvalue, tree_index_expression::lvalue): Use it. * index.tst: New tests.

--- a/libinterp/octave-value/ov-classdef.cc	Fri Oct 02 12:25:39 2015 -0400
+++ b/libinterp/octave-value/ov-classdef.cc	Fri Oct 02 15:07:37 2015 -0400
@@ -1647,7 +1647,16 @@
 
         for (int i = 0; ! error_state && i < ival.length (); i++)
           {
-            iv(i) = ival(i).index_vector ();
+            try
+              {
+                iv(i) = ival(i).index_vector ();
+              }
+            catch (index_exception& e)
+              {
+                // Rethrow to allow more info to be reported later.
+                e.set_pos_if_unset (ival.length (), i+1);
+                throw;
+              }
             if (! error_state)
               is_scalar = is_scalar && iv(i).is_scalar ();
           }
@@ -1745,7 +1754,15 @@
 
                   for (int i = 0; ! error_state && i < ival.length (); i++)
                     {
-                      iv(i) = ival(i).index_vector ();
+                      try
+                        {
+                          iv(i) = ival(i).index_vector ();
+                        }
+                      catch (index_exception& e)
+                        {
+                          e.set_pos_if_unset (ival.length (), i+1);
+                          throw;   // var name set in pt-idx.cc / pt-assign.cc
+                        }
                       if (! error_state)
                         is_scalar = is_scalar && iv(i).is_scalar ();
                     }
@@ -1798,7 +1815,16 @@
 
           for (int i = 0; ! error_state && i < ival.length (); i++)
             {
-              iv(i) = ival(i).index_vector ();
+              try
+                {
+                  iv(i) = ival(i).index_vector ();
+                }
+              catch (index_exception& e)
+                {
+                  // Rethrow to allow more info to be reported later.
+                  e.set_pos_if_unset (ival.length (), i+1);
+                  throw;
+                }
 
               if (! error_state)
                 {