Scope the inference to the current bound node when inferring instances of classes

When inferring instances of classes from arguments, such as ``self``
in a bound method, we could use as a hint the context's ``boundnode``,
which indicates the instance from which the inference originated.
As an example, a subclass that uses a parent's method which returns
``self``, will override the ``self`` to point to it instead of pointing
to the parent class.

Close PyCQA/pylint#3157

1 files changed, 2 insertions, 0 deletions

diff --git a/astroid/protocols.py b/astroid/protocols.py
index 891af0f6..bd1fede1 100644
--- a/astroid/protocols.py
+++ b/astroid/protocols.py
@@ -324,6 +324,8 @@ def _arguments_infer_argname(self, name, context):
         is_metaclass = isinstance(cls, nodes.ClassDef) and cls.type == "metaclass"
         # If this is a metaclass, then the first argument will always
         # be the class, not an instance.
+        if context.boundnode and isinstance(context.boundnode, bases.Instance):
+            cls = context.boundnode._proxied
         if is_metaclass or functype == "classmethod":
             yield cls
             return