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From: Alice Ryhl <aliceryhl@google.com>
Date: Fri, 3 May 2024 16:36:02 +0200
Message-ID: <CAH5fLgj49zs2=O-e3h=VqkRDDzhozvV6p=-5AKN_Q9-caT++cQ@mail.gmail.com>
Subject: Re: [PATCH 1/9] rust: list: add ListArc
To: Benno Lossin <benno.lossin@proton.me>
Cc: Miguel Ojeda <ojeda@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, 
	Alex Gaynor <alex.gaynor@gmail.com>, Wedson Almeida Filho <wedsonaf@gmail.com>, 
	Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>, 
	=?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>, 
	Andreas Hindborg <a.hindborg@samsung.com>, Marco Elver <elver@google.com>, 
	Kees Cook <keescook@chromium.org>, Coly Li <colyli@suse.de>, Paolo Abeni <pabeni@redhat.com>, 
	Pierre Gondois <pierre.gondois@arm.com>, Ingo Molnar <mingo@kernel.org>, 
	Jakub Kicinski <kuba@kernel.org>, Wei Yang <richard.weiyang@gmail.com>, 
	Matthew Wilcox <willy@infradead.org>, linux-kernel@vger.kernel.org, 
	rust-for-linux@vger.kernel.org
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On Thu, Apr 4, 2024 at 4:00=E2=80=AFPM Alice Ryhl <aliceryhl@google.com> wr=
ote:
>
> On Wed, Apr 3, 2024 at 5:51=E2=80=AFPM Benno Lossin <benno.lossin@proton.=
me> wrote:
> >
> > On 02.04.24 14:16, Alice Ryhl wrote:
> > > +impl<T: ListArcSafe<ID>, const ID: u64> ListArc<T, ID> {
> > > +    /// Constructs a new reference counted instance of `T`.
> > > +    pub fn try_new(contents: T) -> Result<Self, AllocError> {
> > > +        Ok(Self::from_unique(UniqueArc::try_new(contents)?))
> > > +    }
> > > +
> > > +    /// Use the given initializer to in-place initialize a `T`.
> > > +    ///
> > > +    /// If `T: !Unpin` it will not be able to move afterwards.
> > > +    pub fn pin_init<E>(init: impl PinInit<T, E>) -> error::Result<Se=
lf>
> > > +    where
> > > +        Error: From<E>,
> > > +    {
> > > +        Ok(Self::from_pin_unique(UniqueArc::pin_init(init)?))
> > > +    }
> >
> > pin-init has a general trait for this: InPlaceInit. I don't know if the
> > other functions that it provides would help you.
>
> I will use that.

Turns out it's not possible to use the trait in this case, for the
same reasons as why Arc isn't using them either.

Alice