1 files changed, 19 insertions, 0 deletions
diff --git a/checkers/utils.py b/checkers/utils.py
index 000aee7..b3ba51b 100644
--- a/checkers/utils.py
+++ b/checkers/utils.py
@@ -462,3 +462,22 @@ def is_import_error(handler):
                     return True
         except astroid.InferenceError:
             continue
+
+def has_known_bases(klass):
+    """Returns true if all base classes of a class could be inferred."""
+    try:
+        return klass._all_bases_known
+    except AttributeError:
+        pass
+    try:
+        for base in klass.bases:
+            result = base.infer().next()
+            # TODO: check for A->B->A->B pattern in class structure too?
+            if not isinstance(result, astroid.Class) or result is klass or not has_known_bases(result):
+                klass._all_bases_known = False
+                return False
+    except astroid.InferenceError:
+        klass._all_bases_known = False
+        return False
+    klass._all_bases_known = True
+    return True