Don't consider a class abstract if its members can't be properly inferred.

This fixes a false positive related to abstract-class-instantiated.
Closes issue #648.

1 files changed, 6 insertions, 0 deletions

diff --git a/pylint/checkers/utils.py b/pylint/checkers/utils.py
index 767bba8..dda5f44 100644
--- a/pylint/checkers/utils.py
+++ b/pylint/checkers/utils.py
@@ -524,6 +524,12 @@ def unimplemented_abstract_methods(node, is_abstract_cb=None):
             if isinstance(obj, astroid.AssignName):
                 infered = safe_infer(obj)
                 if not infered:
+                    # Might be an abstract function,
+                    # but since we don't have enough information
+                    # in order to take this decision, we're taking
+                    # the *safe* decision instead.
+                    if obj.name in visited:
+                        del visited[obj.name]
                     continue
                 if not isinstance(infered, astroid.FunctionDef):
                     if obj.name in visited: