Bug report

Bug description:

The language reference defines lambda_expr: "lambda" [parameter_list] ":" expression, reusing parameter_list from the function definition. The grammar explicitly avoids this because:

So, it uses parameter: identifier [":" expression] which is incorrect since lambda parameters can't be annotated. A separate lambda_parameter_list family of productions is probably needed, although it's not ideal as it would largely be duplicated. @encukou, what do you think?

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response