Wrong not-an-iterable error when model objects is InheritanceManager

[nirsalon]

Repro steps:

from model_utils.managers import InheritanceManager

class Unit(models.Model):
    sim = models.CharField(max_length=64, null=True, blank=True)
    objects = InheritanceManager()

installed_units = Unit.objects.filter(sim__isnull=False)
ids = [u.sim for u in installed_units]

Run pylint and get:
[E1133(not-an-iterable), ] Non-iterable value installed_units is used in an iterating context

using pylint==1.8.4 and pylint-django==0.11

[dianedelallee]

+1
using pylint==1.9.1 and pylint-django==0.11

[atodorov]

Note for maintainers:

ids = [u.sim for u in installed_units]

the error message is generated by the line above. In this context installed_units is a Name node with the inferred type of None from what I can tell.

I've toyed around making this work but couldn't. What I did was use node.frame() to start from the function/class or module that defined the variable. Search through all Assign nodes and their AssignName targets to match node.name. By doing this we're trying to identify the last time this variable has been re-assigned some value so we can later infer the type of this value and try to disable the error message based on that.

I managed to reach a Call to the .filter() attribute of the manager and failed to proceed further.

On a side note I was examining only .frame().body which is only the 1st level of nodes defined in the outer scope. We can have variables being redefined inside loops and if conditions so maybe inspect all children in the AST tree ?!?

I will give this another try tomorrow using the transforms machinery and basically redefine InheritanceManager and friends as iterators. If it works fine, if it doesn't then I'm open to suggestions.