Re: [PATCH 10/13] rust: introduce `Task::current`

[Wedson Almeida Filho <wedsonaf@gmail.com>]

Gary, thanks for reviewing!

On Fri, Mar 31, 2023 at 03:47:01AM +0100, Gary Guo wrote:
> 
> I don't think this API is sound, as you can do `&*Task::current()` and
> get a `&'static Task`, which is very problematic.

One thing that isn't clear to me is: how do you get a 'static lifetime in the
example above?

Altough `TaskRef` does have an arbitrary lifetime param, that's not the lifetime
that the returned `Task` reference gets. For illustration, I've explicitly added
a lifetime 'a in the impl below:

impl Deref for TaskRef<'_> {
    type Target = Task;
    fn deref(&'a self) -> &'a Self::Target {
        self.task
    }
}

Which means that the borrow of the `TaskRef` you use to call `deref` must
outlive the returned `Task`.

So how do you get a `TaskRef` with a static lifetime to begin with? Or is there
another trick to get the `&'static Task` that I can't see?

Thanks,
-Wedson