Improving various error messages

Feature or enhancement

Proposal:

I propose improving the error messages as follows:

Starred expression

In the return type type hint

In Python 3.13.5:

>>> def func() -> *list:
  File "<python-input-0>", line 1
    def func() -> *list:
               ^^
SyntaxError: expected ':'

Proposed:

>>> def func() -> *list:
  File "<python-input-0>", line 1
    def func() -> *list:
                  ^^^^^
SyntaxError: can't use starred expression in the return type type hint

When unpacking to a set

In Python 3.13.5:

>>> {*x, y} = 1, 2
  File "<python-input-0>", line 1
    {*x, y} = 1, 2
    ^^^^^^^
SyntaxError: cannot assign to set display here. Maybe you meant '==' instead of '='?

Proposed:

>>> {*x, y} = 1, 2
  File "<python-input-0>", line 1
    {*x, y} = 1, 2
    ^^^^^^^
SyntaxError: starred assignment target must be in a list or tuple, not a set. Maybe you meant '==' instead of '='?

In type statement

In Python 3.13.5:

>>> type *Z = int
  File "<python-input-0>", line 1
    type *Z = int
    ^^^^^^^
SyntaxError: cannot assign to expression here. Maybe you meant '==' instead of '='?
>>> type Z = *int
  File "<python-input-1>", line 1
    type Z = *int
             ^
SyntaxError: invalid syntax

Proposed:

>>> type *Z = int
  File "<python-input-0>", line 1
    type *Z = int
         ^^
SyntaxError: cannot use starred expression in a type statement
>>> type Z = *int
  File "<python-input-1>", line 1
    type Z = *int
             ^^^^
SyntaxError: cannot use starred expression in a type statement

Assign to None/True/False

In Python 3.13.5:

>>> *None, _ = (1, 2)
  File "<python-input-1>", line 1
    *None, _ = (1, 2)
           ^^^^^^^^^^
SyntaxError: invalid syntax. Maybe you meant '==' or ':=' instead of '='?

Proposed:

>>> *None, _ = (1, 2)
  File "<python-input-1>", line 1
    *None, _ = (1, 2)
    ^^^^^
SyntaxError: cannot assign to None

(Same for True/False)

import statement

In Python 3.13.5:

>>> from typing import *, Any
  File "<python-input-0>", line 1
    from typing import *, Any
                        ^
SyntaxError: invalid syntax

Proposed:

>>> from typing import *, Any
  File "<python-input-0>", line 1
    from typing import *, Any
                       ^^^^^^
SyntaxError: can't use wildcard and identifier at the same time

---

Open questions:

"You don't need to use a starred expression here"?

In Python 3.13.5:

>>> lst = [1, 2, 3]
>>> a, b, c = *lst
  File "<python-input-1>", line 1
    a, b, c = *lst
              ^^^^
SyntaxError: can't use starred expression here

This is a tricky one. In my experience, this exists in many beginner codes, but I don't know how we can improve the error message here. The word "here" is very unclear IMHO.

Inconsistency of error messages

In Python 3.13.5:

>>> for *x in [[0]]: print(x)
  File "<python-input-0>", line 1
    for *x in [[0]]: print(x)
        ^^
SyntaxError: starred assignment target must be in a list or tuple
>>> for (*x) in [[0]]: print(x)
  File "<python-input-1>", line 1
    for (*x) in [[0]]: print(x)
         ^^
SyntaxError: cannot use starred expression here

I find the above inconsistency a little bit surprising, but I don't have a strong feeling about this.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Issue không nêu tên tệp hay bài kiểm thử nào; hãy bắt đầu bằng cách tái hiện các ví dụ cú pháp được liệt kê trong Python 3.13.5 và lần theo nơi các thông báo SyntaxError của chúng được tạo ra. Hoàn thành có nghĩa là thống nhất về các trường hợp còn bỏ ngỏ và cập nhật nhất quán các thông báo được đề xuất trong các kịch bản starred-expression và import được liệt kê.