X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fscheme-engraver.cc;h=1b1aad924ac1efd10e3bb2c19148646572ca70c2;hb=3ab72d07304757de5c1f92be0c4be7707b8649c4;hp=cde829a60788bec5b140942dad26a6fd75168184;hpb=08560a1b8076630c4fc6cb9b902614d8b74fd6fc;p=lilypond.git

diff --git a/lily/scheme-engraver.cc b/lily/scheme-engraver.cc
index cde829a607..1b1aad924a 100644
--- a/lily/scheme-engraver.cc
+++ b/lily/scheme-engraver.cc
@@ -186,10 +186,19 @@ void mark_listen_closure (void *target)
   scm_gc_mark ((SCM)target);
 }
 
+static
+bool equal_listen_closure (void *a, void *b)
+{
+  SCM target_a = (SCM) a;
+  SCM target_b = (SCM) b;
+
+  return ly_is_equal (target_a, target_b);
+}
+
 Listener_function_table listen_closure
 =
 {
-  call_listen_closure, mark_listen_closure
+  call_listen_closure, mark_listen_closure, equal_listen_closure
 };
 
 /* static */