Issue 461: LilyPond should accept a tie between notes which are enharmonically identical

This patch connects the respective notes in Tie_engraver and
Tie_performer as a fallback after exhausting regular tie associations.
It also keeps the accidental engraver from applying its special rules
for tied notes that don't have exactly matching pitches.

No attempt is made to adjust the visuals of the ties: they will remain
horizontal, focused on the left note head.

1 files changed, 24 insertions, 5 deletions

diff --git a/lily/tie-engraver.cc b/lily/tie-engraver.cc
index 73fd6bfc91..4f72920eff 100644
--- a/lily/tie-engraver.cc
+++ b/lily/tie-engraver.cc
@@ -23,6 +23,7 @@
 #include "international.hh"
 #include "item.hh"
 #include "note-head.hh"
+#include "pitch.hh"
 #include "protected-scm.hh"
 #include "spanner.hh"
 #include "staff-symbol-referencer.hh"
@@ -77,6 +78,7 @@ class Tie_engraver : public Engraver
   vector<Grob *> ties_;
 
   Spanner *tie_column_;
+  bool tie_notehead (Grob *h, bool enharmonic);
 
 protected:
   void process_acknowledged ();
@@ -145,12 +147,11 @@ Tie_engraver::process_music ()
     context ()->set_property ("tieMelismaBusy", SCM_BOOL_T);
 }
 
-void
-Tie_engraver::acknowledge_note_head (Grob_info i)
+bool
+Tie_engraver::tie_notehead (Grob *h, bool enharmonic)
 {
-  Grob *h = i.grob ();
+  bool found = false;
 
-  now_heads_.push_back (h);
   for (vsize i = 0; i < heads_to_tie_.size (); i++)
     {
       Grob *th = heads_to_tie_[i].head_;
@@ -167,7 +168,12 @@ Tie_engraver::acknowledge_note_head (Grob_info i)
         Make a tie only if pitches are equal or if event end was not generated by
         Completion_heads_engraver.
       */
-      if (ly_is_equal (right_ev->get_property ("pitch"), left_ev->get_property ("pitch"))
+      SCM p1 = left_ev->get_property ("pitch");
+      SCM p2 = right_ev->get_property ("pitch");
+      if ((enharmonic
+           ? (Pitch::is_smob (p1) && Pitch::is_smob (p2) &&
+              Pitch::unsmob (p1)->tone_pitch () == Pitch::unsmob (p2)->tone_pitch ())
+           : ly_is_equal (p1, p2))
           && (!Tie_engraver::has_autosplit_end (left_ev)))
         {
           Grob *p = heads_to_tie_[i].tie_;
@@ -191,6 +197,7 @@ Tie_engraver::acknowledge_note_head (Grob_info i)
           ties_.push_back (p);
           heads_to_tie_.erase (heads_to_tie_.begin () + i);
 
+          found = true;
           /*
             Prevent all other tied notes ending at the same moment (assume
             implicitly the notes have also started at the same moment!)
@@ -205,6 +212,18 @@ Tie_engraver::acknowledge_note_head (Grob_info i)
           break;
         }
     }
+  return found;
+}
+
+void
+Tie_engraver::acknowledge_note_head (Grob_info i)
+{
+  Grob *h = i.grob ();
+
+  now_heads_.push_back (h);
+
+  if (!tie_notehead (h, false))
+    tie_notehead (h, true);
 
   if (ties_.size () && ! tie_column_)
     tie_column_ = make_spanner ("TieColumn", ties_[0]->self_scm ());