Fix incorrect MRO being calculated for scoped multiple inheritance

If a class inherits from two bases and the classes are expressed as a
non-trivial expression such as qualified with a module name, classes
after the first could not be inferred due to reusing the context
object in _inferred_bases

3 files changed, 29 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index f4264935..86c6deee 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -53,6 +53,10 @@ Release Date: TBA
 
 * Fixed exception-chaining error messages.
 
+* Fix failure to infer base class type with multiple inheritance and qualified names
+
+  Fixes #843
+
 
 What's New in astroid 2.4.3?
 ============================
diff --git a/astroid/scoped_nodes.py b/astroid/scoped_nodes.py
index 5c941966..a44e6282 100644
--- a/astroid/scoped_nodes.py
+++ b/astroid/scoped_nodes.py
@@ -2858,7 +2858,7 @@ class ClassDef(mixins.FilterStmtsMixin, LocalsDictNodeNG, node_classes.Statement
 
         for stmt in self.bases:
             try:
-                baseobj = next(stmt.infer(context=context))
+                baseobj = next(stmt.infer(context=context.clone()))
             except exceptions.InferenceError:
                 continue
             if isinstance(baseobj, bases.Instance):
diff --git a/tests/unittest_scoped_nodes.py b/tests/unittest_scoped_nodes.py
index c4597fa6..2606fd47 100644
--- a/tests/unittest_scoped_nodes.py
+++ b/tests/unittest_scoped_nodes.py
@@ -1417,6 +1417,30 @@ class ClassNodeTest(ModuleLoader, unittest.TestCase):
             ],
         )
 
+    def test_mro_with_attribute_classes(self):
+        cls = builder.extract_node(
+            """
+        class A:
+            pass
+        class B:
+            pass
+        scope = object()
+        scope.A = A
+        scope.B = B
+        class C(scope.A, scope.B):
+            pass
+        """
+        )
+        self.assertEqualMro(
+            cls,
+            [
+                "C",
+                "A",
+                "B",
+                "object"
+            ]
+        )
+
     def test_generator_from_infer_call_result_parent(self):
         func = builder.extract_node(
             """