Ivar copy needs to happen _before_ setting the shape

When we copy instance variables, it is possible for the GC to be kicked
off.  The GC looks at the shape to determine what slots to mark inside
the object.  If the shape is set too soon, the GC could think that there
are more instance variables on the object than there actually are at
that moment.

1 files changed, 4 insertions, 4 deletions

diff --git a/object.c b/object.c
index 5f8568e3b4..aa337ea2ce 100644
--- a/object.c
+++ b/object.c
@@ -298,6 +298,10 @@ init_copy(VALUE dest, VALUE obj)
     rb_copy_generic_ivar(dest, obj);
     rb_gc_copy_finalizer(dest, obj);
 
+    if (RB_TYPE_P(obj, T_OBJECT)) {
+        rb_obj_copy_ivar(dest, obj);
+    }
+
     if (!RB_TYPE_P(obj, T_CLASS) && !RB_TYPE_P(obj, T_MODULE)) {
         rb_shape_t *shape_to_set = rb_shape_get_shape(obj);
 
@@ -310,10 +314,6 @@ init_copy(VALUE dest, VALUE obj)
         // shape ids are different
         rb_shape_set_shape(dest, shape_to_set);
     }
-
-    if (RB_TYPE_P(obj, T_OBJECT)) {
-        rb_obj_copy_ivar(dest, obj);
-    }
 }
 
 static VALUE immutable_obj_clone(VALUE obj, VALUE kwfreeze);