Misleading SyntaxError: cannot use assignment expressions with lambda

Bug report

Bug description:

Python 3.12.8 (tags/v3.12.8:2dc476b, Dec  3 2024, 19:30:04) [MSC v.1942 64 bit (AMD64)] on win32
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>>> lambda x: foo := 2
  File "<stdin>", line 1
    lambda x: foo := 2
    ^^^^^^^^^^^^^
SyntaxError: cannot use assignment expressions with lambda
>>> lambda x: (foo := 2)
<function <lambda> at 0x00000229CC40E0C0>

IIRC, until today I believed that you could never use an assignment expression in a lambda. I was disabused of this notion only by reading PEP 572 itself. I believe the SyntaxError should ideally read something along the lines of "cannot use unparenthesized assignment expressions with lambda".

I wasn't sure to what category to file this under exactly, sorry if I chose wrong.

CPython versions tested on:

3.12

Operating systems tested on:

Windows

Comece pesquisando no CPython o diagnóstico exato "cannot use assignment expressions with lambda" e revise o tratamento relacionado no parser ou compilador, usando o PEP 572 como contexto. Reproduza os dois exemplos de lambda do relatório; considera-se concluído quando a forma sem parênteses relata a restrição mais precisa, enquanto a forma entre parênteses continua funcionando.