From: shugo@...
Date: 2015-12-22T02:36:38+00:00
Subject: [ruby-core:72425] [Ruby trunk - Bug #11740] ObjectSpace.each_object exposes internal metaclasses

Issue #11740 has been updated by Shugo Maeda.


Koichi Sasada wrote:
> Maybe I missed some points.
> Any idea?

You shouldn't hide singleton classes of non-class objects.

```diff
diff --git a/gc.c b/gc.c
index 12be1ea..a574656 100644
--- a/gc.c
+++ b/gc.c
@@ -2400,6 +2400,14 @@ internal_object_p(VALUE obj)
 	  case T_NODE:
 	  case T_ZOMBIE:
 	    break;
+	  case T_CLASS:
+	    {
+		if (FL_TEST(obj, FL_SINGLETON)) {
+		    int rb_singleton_class_has_metaclass_p(VALUE sklass);
+		    return RB_TYPE_P(rb_attr_get(obj, id__attached__), T_CLASS) &&
+			rb_singleton_class_has_metaclass_p(obj) == 0;
+		}
+	    }
 	  default:
 	    if (!p->as.basic.klass) break;
 	    return 0;
```



----------------------------------------
Bug #11740: ObjectSpace.each_object exposes internal metaclasses
https://bugs.ruby-lang.org/issues/11740#change-55718

* Author: Benoit Daloze
* Status: Assigned
* Priority: Normal
* Assignee: Koichi Sasada
* ruby -v: ruby 2.3.0dev (2015-11-19 trunk 52672) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
ObjectSpace.each_object exposes internal metaclasses and
this might result in assumptions being violated since the metaclass structure is not well preserved.

See the attached script for an example.
The #bla method should always be defined on the metaclass of "klass".

See https://bugs.ruby-lang.org/issues/11360#note-2 as well in which I warned against this problem ;)

---Files--------------------------------
objspace_expose_intern_meta.rb (413 Bytes)


-- 
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