Allow refining a frozen class

Doing so modifies the class's method table, but not in a way that should
be detectable from Ruby, so it may be safe to avoid checking if the
class is frozen.

Fixes [Bug #11669]

1 files changed, 3 insertions, 1 deletions

diff --git a/vm_method.c b/vm_method.c
index f1b71a181c..2b2e28e10c 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -714,7 +714,9 @@ rb_method_entry_make(VALUE klass, ID mid, VALUE defined_class, rb_method_visibil
 	}
     }
 
-    rb_class_modify_check(klass);
+    if (type != VM_METHOD_TYPE_REFINED) {
+       rb_class_modify_check(klass);
+    }
 
     if (FL_TEST(klass, RMODULE_IS_REFINEMENT)) {
 	VALUE refined_class = rb_refinement_module_get_refined_class(klass);