Don't allow looking at the shape ID of immediates (#14266)

It only makes sense for heap objects.

1 files changed, 4 insertions, 1 deletions

diff --git a/shape.c b/shape.c
index b10b52d76f..d58f9f1d0c 100644
--- a/shape.c
+++ b/shape.c
@@ -369,7 +369,7 @@ RUBY_FUNC_EXPORTED shape_id_t
 rb_obj_shape_id(VALUE obj)
 {
     if (RB_SPECIAL_CONST_P(obj)) {
-        return SPECIAL_CONST_SHAPE_ID;
+        rb_bug("rb_obj_shape_id: called on a special constant");
     }
 
     if (BUILTIN_TYPE(obj) == T_CLASS || BUILTIN_TYPE(obj) == T_MODULE) {
@@ -1425,6 +1425,9 @@ rb_shape_parent(VALUE self)
 static VALUE
 rb_shape_debug_shape(VALUE self, VALUE obj)
 {
+    if (RB_SPECIAL_CONST_P(obj)) {
+        rb_raise(rb_eArgError, "Can't get shape of special constant");
+    }
     return shape_id_t_to_rb_cShape(rb_obj_shape_id(obj));
 }