`__getattr__` in child class gets called when mixed with `cached_property`

[dalejung]

from functools import cached_property
from attrs import define

@define
class Bob:
    @cached_property
    def howdy(self):
        return 3

class Sup(Bob):
    def __getattr__(self, name):
        raise AttributeError(name)

b = Sup()

# reaches __getattr__ where I raise AttributeError
b.howdy

This previously did not error. I would expect __getattr__ to not be called since the attribute exists.

[hynek]

I believe his is fixed in #1253. I wanted to push a release before PyCon/travel but sadly #1267 blocked me. :(

[dalejung]

I just checked against latest master and it still exists. It looks like 23.2.0 is when the error started, 23.1.0 works.

[hynek]

@dlax any insights? 🤔 I can’t test anything for weeks to come.

[dlax]

The fix from #1253 does not cover this inheritance case, indeed. I'll see if this can be fixed.

[dlax]

#1289 fixes a slightly different version of the original problem, namely when the child class is also a (slotted) attr class, thus from the original example:

@define
class Sup(Bob):
    ...

I'm not sure if the original problem may be resolved. Or at least, not in the same manner as we have no mean to inspect the plain subclass.