Doc: ensure all level 3 and 4 headings have nodes (2967)

[lilypond.git] / lily / slur-scoring.cc

diff --git a/lily/slur-scoring.cc b/lily/slur-scoring.cc
index e1025fa545c56c1c20ee0a476355b778229cf336..47bb40611c483018713bae43ec380b3ed1cd9461 100644 (file)
--- a/lily/slur-scoring.cc
+++ b/lily/slur-scoring.cc
@@ -459,11 +459,16 @@ Slur_score_state::get_y_attachment_range () const
     {
       if (extremes_[d].note_column_)
         {
-          end_ys[d] = dir_
-                      * max (max (dir_ * (base_attachments_[d][Y_AXIS]
-                                          + parameters_.region_size_ * dir_),
-                                  dir_ * (dir_ + extremes_[d].note_column_->extent (common_[Y_AXIS], Y_AXIS)[dir_])),
-                             dir_ * base_attachments_[-d][Y_AXIS]);
+          Interval nc_extent = extremes_[d].note_column_
+                               ->extent (common_[Y_AXIS], Y_AXIS);
+          if (nc_extent.is_empty ())
+            slur_->warning ("slur trying to encompass an empty note column.");
+          else
+            end_ys[d] = dir_
+                        * max (max (dir_ * (base_attachments_[d][Y_AXIS]
+                                            + parameters_.region_size_ * dir_),
+                                    dir_ * (dir_ + nc_extent[dir_])),
+                               dir_ * base_attachments_[-d][Y_AXIS]);
         }
       else
         end_ys[d] = base_attachments_[d][Y_AXIS] + parameters_.region_size_ * dir_;