use `SET_SHAREABLE`

to adopt strict shareable rule.

* (basically) shareable objects only refer shareable objects
* (exception) shareable objects can refere unshareable objects
  but should not leak reference to unshareable objects to Ruby world

1 files changed, 1 insertions, 1 deletions

diff --git a/class.c b/class.c
index 74dcbe5fa7..4dddf08c67 100644
--- a/class.c
+++ b/class.c
@@ -775,7 +775,7 @@ class_alloc0(enum ruby_value_type type, VALUE klass, bool namespaceable)
 
     RUBY_ASSERT(type == T_CLASS || type == T_ICLASS || type == T_MODULE);
 
-    VALUE flags = type;
+    VALUE flags = type | FL_SHAREABLE;
     if (RGENGC_WB_PROTECTED_CLASS) flags |= FL_WB_PROTECTED;
     if (namespaceable) flags |= RCLASS_NAMESPACEABLE;