Issue 5057/8: Stop SCM/int confusion in stencil head registration

diff --git a/lily/stencil-expression.cc b/lily/stencil-expression.cc
index 06aabb992f943494b09561e3aa039d1bfbae5843..8d804196202368c1eaf1043cac78de4e91253fb2 100644 (file)
--- a/lily/stencil-expression.cc
+++ b/lily/stencil-expression.cc
@@ -18,16 +18,14 @@
 */
 
 #include "stencil.hh"
+#include "protected-scm.hh"
 
-static SCM heads;
+static Protected_scm heads (SCM_EOL);
 
 void register_stencil_head (SCM symbol)
 {
-  if (!heads)
-    heads = scm_permanent_object (scm_cons (SCM_EOL, SCM_EOL));
-
   scm_set_object_property_x (symbol, ly_symbol2scm ("stencil-head?"), SCM_BOOL_T);
-  scm_set_cdr_x (heads, scm_cons (symbol, scm_cdr (heads)));
+  heads = scm_cons (symbol, heads);
 }
 
 bool
@@ -39,6 +37,5 @@ is_stencil_head (SCM symbol)
 SCM
 all_stencil_heads ()
 {
-  return scm_cdr (heads);
+  return heads;
 }
-