Merge with default.

4 files changed, 110 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 7cc0ddc..68d0504 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,11 +1,14 @@
 Change log for the astroid package (used to be astng)
 =====================================================
 
+--
+    * `Class.metaclass()` looks in ancestors when the current class
+      does not define explicitly a metaclass.
+
     * Do not cache modules if a module with the same qname is already
       known, and only return cached modules if both name and filepath
       match. Fixes pylint Bitbucket issue #136.
 
-
 2014-04-18  --  1.1.0
     * All class nodes are marked as new style classes for Py3k.
 
diff --git a/scoped_nodes.py b/scoped_nodes.py
index 540e8a1..067f01f 100644
--- a/scoped_nodes.py
+++ b/scoped_nodes.py
@@ -1043,14 +1043,24 @@ class Class(Statement, LocalsDictNodeNG, FilterStmtsMixin):
             raise InferenceError()
 
     _metaclass = None
-    def metaclass(self):
-        """ Return the metaclass of this class """
+    def _explicit_metaclass(self):
+        """ Return the explicit defined metaclass
+        for the current class.
+
+        An explicit defined metaclass is defined
+        either by passing the ``metaclass`` keyword argument
+        in the class definition line (Python 3) or by
+        having a ``__metaclass__`` class attribute.
+        """
         if self._metaclass:
             # Expects this from Py3k TreeRebuilder
             try:
-                return next(self._metaclass.infer())
+                infered = next(self._metaclass.infer())
             except InferenceError:
-                return 
+                return
+            if infered is YES: # don't expose it
+                return None 
+            return infered
 
         try:
             meta = self.getattr('__metaclass__')[0]
@@ -1063,3 +1073,18 @@ class Class(Statement, LocalsDictNodeNG, FilterStmtsMixin):
         if infered is YES: # don't expose this
             return None
         return infered
+
+    def metaclass(self):
+        """ Return the metaclass of this class.
+
+        If this class does not define explicitly a metaclass,
+        then the first defined metaclass in ancestors will be used
+        instead.
+        """
+        klass = self._explicit_metaclass()
+        if klass is None:
+            for parent in self.ancestors():
+                klass = parent.metaclass()
+                if klass is not None:
+                    break
+        return klass
diff --git a/test/unittest_python3.py b/test/unittest_python3.py
index 96de632..9e80406 100644
--- a/test/unittest_python3.py
+++ b/test/unittest_python3.py
@@ -129,6 +129,44 @@ class Python3TC(TestCase):
         metaclass = klass.metaclass()
         self.assertIsInstance(metaclass, Class)
         self.assertEqual(metaclass.name, 'type')
+
+    @require_version('3.0')
+    def test_metaclass_yes_leak(self):
+        astroid = self.builder.string_build(dedent("""
+        from ab import ABCMeta
+
+        class Meta(metaclass=ABCMeta): pass
+        """))
+        klass = astroid['Meta']
+        self.assertIsNone(klass.metaclass())
+
+    @require_version('3.0')
+    def test_metaclass_ancestors(self):
+        astroid = self.builder.string_build(dedent("""
+        from abc import ABCMeta
+
+        class FirstMeta(metaclass=ABCMeta): pass
+        class SecondMeta(metaclass=type):
+            pass
+
+        class Simple:
+            pass
+
+        class FirstImpl(FirstMeta): pass
+        class SecondImpl(FirstImpl): pass
+        class ThirdImpl(Simple, SecondMeta):
+            pass
+        """))
+        classes = {
+            'ABCMeta': ('FirstImpl', 'SecondImpl'),
+            'type': ('ThirdImpl', )
+        }
+        for metaclass, names in classes.items():
+            for name in names:
+                impl = astroid[name]
+                meta = impl.metaclass()
+                self.assertIsInstance(meta, Class)
+                self.assertEqual(meta.name, metaclass)
                          
 if __name__ == '__main__':
     unittest_main()
diff --git a/test/unittest_scoped_nodes.py b/test/unittest_scoped_nodes.py
index f98d0ac..3d05318 100644
--- a/test/unittest_scoped_nodes.py
+++ b/test/unittest_scoped_nodes.py
@@ -716,6 +716,16 @@ def g2():
         self.assertIsInstance(metaclass, scoped_nodes.Class)
         self.assertEqual(metaclass.name, 'ABCMeta')
 
+    def test_metaclass_yes_leak(self):
+        astroid = abuilder.string_build(dedent("""
+        from ab import ABCMeta
+
+        class Meta(object):
+            __metaclass__ = ABCMeta
+        """))
+        klass = astroid['Meta']
+        self.assertIsNone(klass.metaclass())
+
     @require_version('2.7')
     def test_newstyle_and_metaclass_good(self):
         astroid = abuilder.string_build(dedent("""
@@ -751,6 +761,35 @@ def g2():
         self.assertIsInstance(metaclass, scoped_nodes.Class)
         self.assertEqual(metaclass.name, 'ABCMeta')
 
+    def test_metaclass_ancestors(self):
+        astroid = abuilder.string_build(dedent("""
+        from abc import ABCMeta
+
+        class FirstMeta(object):
+            __metaclass__ = ABCMeta
+
+        class SecondMeta(object):
+            __metaclass__ = type
+
+        class Simple(object):
+            pass
+
+        class FirstImpl(FirstMeta): pass
+        class SecondImpl(FirstImpl): pass
+        class ThirdImpl(Simple, SecondMeta):
+            pass
+        """))
+        classes = {
+            'ABCMeta': ('FirstImpl', 'SecondImpl'),
+            'type': ('ThirdImpl', )
+        }
+        for metaclass, names in classes.items():
+            for name in names:
+                impl = astroid[name]
+                meta = impl.metaclass()
+                self.assertIsInstance(meta, nodes.Class)
+                self.assertEqual(meta.name, metaclass)
+
     def test_nonregr_infer_callresult(self):
         astroid = abuilder.string_build(dedent("""
         class Delegate(object):