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Date: Mon, 08 Sep 2025 10:57:36 +0200
Message-Id: <DCNALVTE4DIN.1K0U4BGN35CHI@kernel.org>
Subject: Re: [PATCH] rust: pin-init: add references to previously
 initialized fields
Cc: "Boqun Feng" <boqun.feng@gmail.com>, "Miguel Ojeda" <ojeda@kernel.org>,
 "Alex Gaynor" <alex.gaynor@gmail.com>, "Gary Guo" <gary@garyguo.net>,
 =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>, "Andreas
 Hindborg" <a.hindborg@kernel.org>, "Alice Ryhl" <aliceryhl@google.com>,
 "Trevor Gross" <tmgross@umich.edu>, "Fiona Behrens" <me@kloenk.dev>, "Alban
 Kurti" <kurti@invicto.ai>, "Greg Kroah-Hartman"
 <gregkh@linuxfoundation.org>, "Rafael J. Wysocki" <rafael@kernel.org>,
 "Bjorn Helgaas" <bhelgaas@google.com>,
 =?utf-8?q?Krzysztof_Wilczy=C2=B4nski?= <kwilczynski@kernel.org>,
 <rust-for-linux@vger.kernel.org>, <linux-kernel@vger.kernel.org>
To: "Benno Lossin" <lossin@kernel.org>
From: "Danilo Krummrich" <dakr@kernel.org>
References: <aLshd0_C-1rh3FAg@tardis-2.local>
 <DCLNSNWA7AT7.19OWOXUMJ5ZRJ@kernel.org> <aLzmcK2UM53I2Tbn@tardis-2.local>
 <aLzoyWpOr6eg-3yB@tardis-2.local> <DCMFN8UGD7QN.27HTYEXL87Z8@kernel.org>
 <DCMQVH09L1Y5.3A842FC1NGG5H@kernel.org>
 <DCMVHB8P7Z2G.PCOWPQXBSBT6@kernel.org>
 <DCMW6H0VJ9AP.1XWI1RI9YWO9H@kernel.org>
 <DCMXPGXDXHYT.D9VJ5QBMAVPN@kernel.org>
 <DCMYLXICOGM7.2G4JBQAE7805B@kernel.org> <aL46nRkYj2SlOhl8@tardis-2.local>
 <DCN9YYV750Q4.3K9X2EAA3RKJ8@kernel.org>
In-Reply-To: <DCN9YYV750Q4.3K9X2EAA3RKJ8@kernel.org>

On Mon Sep 8, 2025 at 10:27 AM CEST, Benno Lossin wrote:
> On Mon Sep 8, 2025 at 4:08 AM CEST, Boqun Feng wrote:
>> On Mon, Sep 08, 2025 at 01:33:26AM +0200, Danilo Krummrich wrote:
>>> On Mon Sep 8, 2025 at 12:51 AM CEST, Benno Lossin wrote:
>>> > I actually came up with a third option that looks best IMO:
>>> >
>>> >     init!(MyStruct {
>>> >         x: 42,
>>> >         #[with_binding]
>>> >         y: 24,
>>> >         z: *y,
>>> >     })
>>> >
>>> > The `#[with_binding]` attribute makes the macro generate a variable `=
y`.
>>> > `x` & `z` don't give access to their value. (we of course should come=
 up
>>> > with a better name).
>>> >
>>> > Any thoughts?
>>>=20
>>> It may be a bit verbose is some cases, but it makes things pretty obvio=
us, so
>>> LGTM.
>>>=20
>>> How about just #[bind] or #[access]?
>
> I like `#[bind]`.
>
>> #[shadow] or #[maybe_rebind] ? Or #[pin_ref], the last one is clear
>> about the purpose.
>
> Hmm in `init!` it's never pinned.

I thought about #[shadow] as well, but it is not really accurate I think, a=
s we
might not shadow anything. #[maybe_rebind] sounds a bit like it conditional=
ly
rebinds, as in "it may not do anything", but it always binds.

So, I think it should one clear instruction, i.e. #[bind], #[access], #[ref=
],
#[use], #[let], etc.