add bound syntax for type variable tuples and parameter specifications

Feature or enhancement

Proposal:

# typical forms
class A[T: int, *Ts: int, **P: [int]]: ...
A[
    str, # error
    int, # ok, matching Ts bound
    str, # error, not matching Ts bound
    [str], # error, not matching P bound
]

A[
    int, # ok
    int, # ok, matching Ts bound
    bool, # ok, matching Ts bound
    [int], # ok, matching P bound
]

# tvt unpacked form
class B[*Ts: *tuple[int, str]]: ...

B[
    int, # ok
    int, # error, not subtype of str
    int, # error, too many types
]

Has this already been discussed elsewhere?

I have already discussed this feature proposal on Discourse

Links to previous discussion of this feature:

https://discuss.python.org/t/parameter-specification-and-type-variable-tuple-should-support-bounds/107068/6

Linked PRs

• gh-148946

実装ファイルやテストは指定されていません。まずリンク先の Discourse ディスカッションと PR gh-148946 を読み、次に提案にある境界付き型変数タプルとパラメータ仕様の例がどのように動作すべきかを追ってください。完了の条件は、文書化された例が有効な引数を受け入れ、無効な境界とアリティを拒否することです。