False positive for `undefined-variable` and `unused-variable` when using the walrus operator in a decorator

[akosthekiss]

Bug description

"""Example to show incorrect diagnostics for the walrus operator"""

def f(a, b):
    """A simple function. When called, we will use the walrus operator."""
    print("f", a, b)

f(l := [1, 2, 3], [x * 2 for x in l])  # THIS PASSES


class Decor:  # pylint: disable=too-few-public-methods
    """A simple decorator with arguments. When called, we will use the walrus operator."""
    def __init__(self, a, b):
        self.a = a
        self.b = b

    def __call__(self, fn):
        print("decor", self.a, self.b)
        return fn

@Decor(k := [-1, -2, -3], [x * 2 for x in k])  # THIS FAILS
def g():
    """A simple function with the only purpose to be decorated."""
    print("g")

g()

Configuration

Command used

pylint walrus.py

Pylint output

************* Module walrus
walrus.py:20:42: E0602: Undefined variable 'k' (undefined-variable)
walrus.py:20:7: W0612: Unused variable 'k' (unused-variable)

Expected behavior

Not to report the error or the warning.

Pylint version

pylint 4.0.4
astroid 4.0.2
Python 3.13.7 (main, Aug 14 2025, 11:12:11) [Clang 17.0.0 (clang-1700.0.13.3)]

OS / Environment

macOS 15.6.1, Darwin 24.6.0 arm64

Additional dependencies