Fix inference cycle in getattr when a base is an astroid.Attribute #934
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Ref pylint-dev#904. `getattr` attempts to find values on `self.ancestors`, which infers each node listed in `self.bases`. Removing or resetting the context passed to ancestors allows it to infer the nodes, but opens up the possibility of cycles through recursive definitions. We should be able to infer the value of the base node correctly as a `ClassDef`. The root of this issue stems from the fact that `infer_attribute` attempts to temporarily set `context.boundnode`, but when unwrapping its changes it sets the `boundnode` to `None` instead of its previous value, which loses state and causes the inference of the `Attribute` node to have a duplicate key: once when looking up the class definition (which should have `boundnode = None`), and once when inferring the (other) attribute value (which should not have `boundnode = None`)
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Steps
Description
Ref #904.
getattrattempts to find values onself.ancestors, whichinfers each node listed in
self.bases. Removing or resetting thecontext passed to ancestors allows it to infer the nodes, but opens up
the possibility of cycles through recursive definitions. We should be
able to infer the value of the base node correctly as a
ClassDef. Theroot of this issue stems from the fact that
infer_attributeattemptsto temporarily set
context.boundnode, but when unwrapping its changesit sets the
boundnodetoNoneinstead of its previous value, whichloses state and causes the inference of the
Attributenode to have aduplicate key: once when looking up the class definition (which should
have
boundnode = None), and once when inferring the (other) attributevalue (which should not have
boundnode = None)Type of Changes
Related Issue
Closes #904