Dynamic `__getattr__` still leads to `no-member` if inference is ambiguous

Description

"""
The following code should lint without errors, but pylint shows:
test.py:28:6: E1101: Instance of 'A' has no 'any' member (no-member)
"""
# pylint: disable=too-few-public-methods


class A:
    """class without attributes"""


class B:
    """class with any attribute"""
    def __getattr__(self, name):
        return None
    # uncomment to remove the error
    # any = 1


def a_or_b(p) -> A | B:
    """function, which may return an instance of A or B"""
    if p == "a":
        return A()
    return B()


x: B = a_or_b("b")  # we have annotated that x is an instance of B
print(x.any)  # pylint shows E1101 (no-member)

# this does not cause an error in any case
y = B()
print(y.any)

pylint test.py

************* Module test
test.py:28:6: E1101: Instance of 'A' has no 'any' member (no-member)

pylint 3.2.6
astroid 3.2.4
Python 3.10.12

Contributor guide

Tech stack

python

Domain

tooling

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

5

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

3-5 days

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

blocked

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

Understanding of Python's getattr Familiarity with Pylint's type inferenceBasic knowledge of ASTPython type annotations

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

25

Research direction

Investigate how Pylint resolves member access on union types involving classes with getattr . The issue suggests that when a variable is annotated as a specific type (e.g., B) but the inferred type is a union (A | B), the getattr of B is not considered. Check the handling of types in pylint/checkers/typecheck.py and astroid's inference engine. Look at the logic for method resolution when getattr is defined. The existing test cases for getattr may need to be updated.