class.c: suppress wrong warning

* class.c (HAVE_METACLASS_P): should check FL_SINGLTON flag before get
  instance variable to get rid of wrong warning about __attached__.
  [ruby-core:53839] [Bug #8188]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40013 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 22 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 75a0a949c4..da550910b5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sun Mar 31 06:27:17 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* class.c (HAVE_METACLASS_P): should check FL_SINGLTON flag before get
+	  instance variable to get rid of wrong warning about __attached__.
+	  [ruby-core:53839] [Bug #8188]
+
 Sat Mar 30 14:11:28 2013  Kazuhiro NISHIYAMA  <zn@mbf.nifty.com>
 
 	* bcc32: removed. agreed at
diff --git a/class.c b/class.c
index c6af2c8d3a..0f54a80cd5 100644
--- a/class.c
+++ b/class.c
@@ -307,6 +307,14 @@ rb_singleton_class_attached(VALUE klass, VALUE obj)
  */
 #define META_CLASS_OF_CLASS_CLASS_P(k)  (METACLASS_OF(k) == (k))
 
+/*!
+ * whether k has a metaclass
+ * @retval 1 if \a k has a metaclass
+ * @retval 0 otherwise
+ */
+#define HAVE_METACLASS_P(k) \
+    (FL_TEST(METACLASS_OF(k), FL_SINGLETON) && \
+     rb_ivar_get(METACLASS_OF(k), id_attached) == (k))
 
 /*!
  * ensures \a klass belongs to its own eigenclass.
@@ -316,7 +324,7 @@ rb_singleton_class_attached(VALUE klass, VALUE obj)
  * @note this macro creates a new eigenclass if necessary.
  */
 #define ENSURE_EIGENCLASS(klass) \
- (rb_ivar_get(METACLASS_OF(klass), id_attached) == (klass) ? METACLASS_OF(klass) : make_metaclass(klass))
+    (HAVE_METACLASS_P(klass) ? METACLASS_OF(klass) : make_metaclass(klass))
 
 
 /*!
diff --git a/test/ruby/test_eval.rb b/test/ruby/test_eval.rb
index 580d3e88b1..a97b982246 100644
--- a/test/ruby/test_eval.rb
+++ b/test/ruby/test_eval.rb
@@ -215,6 +215,13 @@ class TestEval < Test::Unit::TestCase
     end
   end
 
+  def test_instance_eval_on_argf_singleton_class
+    bug8188 = '[ruby-core:53839] [Bug #8188]'
+    assert_warning('', bug8188) do
+      ARGF.singleton_class.instance_eval{}
+    end
+  end
+
   class Foo
     Bar = 2
   end