Issue 4807: fix glissando in case of accidentals

lily/line-spanner.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 2000--2015 Jan Nieuwenhuizen <janneke@gnu.org>
 
   LilyPond 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.
 
@@ skipping 95 matching lines @@
           extract_grob_set (me, "note-columns", columns);
           if (columns.size ())
             bound_grob = (dir == LEFT)
                          ? columns[0] : columns.back ();
         }
 
       Real x_coord = (has_interface<Paper_column> (bound_grob)
                       ? Axis_group_interface::generic_bound_extent (bound_grob, commonx, X_AXIS)
                       : robust_relative_extent (bound_grob, commonx, X_AXIS)).linear_combination (attach);
 
-      Grob *acc = unsmob<Grob> (bound_grob->get_object ("accidental-grob"));
+      Grob *acc = Note_column::accidentals (bound_grob->get_parent (X_AXIS));
       if (acc && to_boolean (ly_assoc_get (ly_symbol2scm ("end-on-accidental"), details, SCM_BOOL_F)))
         x_coord = robust_relative_extent (acc, commonx, X_AXIS).linear_combination (attach);
 
       Grob *dot = unsmob<Grob> (bound_grob->get_object ("dot"));
       if (dot && to_boolean (ly_assoc_get (ly_symbol2scm ("start-at-dot"), details, SCM_BOOL_F)))
         x_coord = robust_relative_extent (dot, commonx, X_AXIS).linear_combination (attach);
 
       details = scm_acons (ly_symbol2scm ("X"),
                            scm_from_double (x_coord),
                            details);
@@ skipping 261 matching lines @@
                "bound-details "
                "extra-dy "
                "gap "
                "left-bound-info "
                "note-columns "
                "right-bound-info "
                "simple-Y "
                "thickness "
                "to-barline "
               );