Class definition scope using walrus assignment operator raises [name-defined] error

Bug Report

When using the assignment operator (aka "walrus") inside the class definition scope, I get a [name-defined] error.

To Reproduce
https://mypy-play.net/?mypy=latest&python=3.11&gist=367470bba328790329e68ce08bd7eb59

class TestTuple:
    t = (a := 1, a)


class TestExpression:
    (b := 2, b)


def add(x: int, y: int):
    return x + y


class TestAdd:
    result = add(c := 3, c)


class TestOverride:
    d = add(d := 4, d)


TestTuple.a      # output: 1
TestTuple.t      # output: (1, 1)
TestExpression.b # output: 2
TestAdd.c        # output: 3
TestAdd.result   # output: 6
TestOverride.d   # output: 8

Expected Behavior
I expected mypy to not raise any error as these all execute in python.

Actual Behavior

main.py:2: error: Name "a" is not defined  [name-defined]
main.py:6: error: Name "b" is not defined  [name-defined]
main.py:14: error: Name "c" is not defined  [name-defined]
main.py:18: error: Name "d" is not defined  [name-defined]
Found 4 errors in 1 file (checked 1 source file)

Your Environment

• Mypy version used: 1.6.1
• Mypy command-line flags:
• Mypy configuration options from mypy.ini (and other config files):
• Python version used: 3.11

Comienza con la reproducción enlazada de mypy-play y los ejemplos de Python 3.11 incluidos en el issue; después, sigue cómo se analizan las asignaciones con operador walrus en el ámbito de clase. Se considera terminado cuando los ejemplos indicados pasan la comprobación de tipos sin los cuatro errores name-defined, conservando los valores inferidos mostrados.