Confusing syntax error for missing comma after import-as target

Bug report

Bug description:

Right now we have:

>>> import a as a  b
  File "<python-input-0>", line 1
    import a as a  b
                ^
SyntaxError: cannot use name as import target

>>> from x import a as a  b
  File "<python-input-1>", line 1
    from x import a as a  b
                       ^
SyntaxError: cannot use name as import target

This happens since these cases match these two rules.

One possible fix would be to add NAME to the list of not-matched tokens so that the current rules don't match this case.

However, I have an idea for a slightly nicer error. PR forthcoming.

cc @pablogsal @lysnikolaou @sobolevn

CPython versions tested on:

3.14, 3.15, CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-146493

在 Python REPL 中重現兩個 import-as 範例，然後檢查 Grammar/python.gram 中約在第 1435 行和第 1439 行的兩個相符規則。將產生的診斷與 issue 中描述的預期行為進行比較；缺少逗號的情況收到更清楚的語法錯誤，即表示完成。已註明一個相關的 PR。