Issue 5705: Avoid warning in Stem::get_beaming ()

lily/stem.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 1996--2020 Han-Wen Nienhuys <hanwen@xs4all.nl>
   Jan Nieuwenhuizen <janneke@gnu.org>
 
   TODO: This is way too hairy
 
   TODO: fix naming.
 
@@ skipping 75 matching lines @@
 
 int
 Stem::get_beaming (Grob *me, Direction d)
 {
   SCM pair = me->get_property ("beaming");
   if (!scm_is_pair (pair))
     return 0;
 
   SCM lst = index_get_cell (pair, d);
 
-  int len = scm_ilength (lst); // -1 for dotted lists!
-  return std::max (len, 0);
+  long len = scm_ilength (lst); // -1 for dotted lists!
+  // TODO: scm_ilength () is O(n), so we don't want to call it for long lists.
+  // If scm_ilength () is OK, this cast should be OK too.  The question is, are
+  // we confident that the list is short?

[hanwenn, 2020/02/03 22:11:10]

Yes, I'm confident about that.

// This list represents the vertical positions at which beams
// start/end at this stem, so the O(N) cost of scm_ilength is 
// fine.

+  return static_cast<int> (std::max (len, 0L));
 }
 
 Interval
 Stem::head_positions (Grob *me)
 {
   if (head_count (me))
     {
       Drul_array<Grob *> e (extremal_heads (me));
       return Interval (Staff_symbol_referencer::get_position (e[DOWN]),
                        Staff_symbol_referencer::get_position (e[UP]));
@@ skipping 1100 matching lines @@
   ideal_y_ = shortest_y_ = 0;
   dir_ = CENTER;
 }
 
 void
 Stem_info::scale (Real x)
 {
   ideal_y_ *= x;
   shortest_y_ *= x;
 }