linux-kernel - Re: [PATCH 1/3] rust: add Aliased type

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Message-ID: <Z5KCuct3QmgGUkIU@tardis.local>
Date: Thu, 23 Jan 2025 09:56:09 -0800
From: Boqun Feng <boqun.feng@...il.com>
To: Christian Schrefl <chrisi.schrefl@...il.com>
Cc: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Lee Jones <lee@...nel.org>, rust-for-linux@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Daniel Almeida <daniel.almeida@...labora.com>,
	Danilo Krummrich <dakr@...nel.org>
Subject: Re: [PATCH 1/3] rust: add Aliased type

On Thu, Jan 23, 2025 at 11:21:23AM +0100, Christian Schrefl wrote:
[...]
> >> +
> >> +/// Stores a value that may be aliased.
> >> +///
> >> +/// This is similar to `Opaque<T>` but is guaranteed to contain valid data and will
> >> +/// Call the Drop implementation of T when dropped.
> >> +#[repr(transparent)]
> >> +pub struct Aliased<T> {
> > 
> > As I already mentioned [1], the name `Aliased` is more reflecting the
> > fact that this wrapper will avoid generating the "noalias" attribute(?)
> > on the reference/pointer to the type rather than an intuitive idea about
> > "why or when do I need this". Moreover, I think the argument about the
> > naming of the counterpart in unstable Rust (UnsafePinned) makes sense to
> > me [2]: this type alone won't prevent `&mut Aliased` getting `swap`, and
> > it has to be used with `Pin`.
> > 
> > Therefore, I think we should use a different name, perhaps
> > `(Always)Shared`, or just use `UnsafePinned`, or, as always, looking
> > fowards to a better name from anybody ;-)
> > 
> > [1]: https://lore.kernel.org/rust-for-linux/Z407egxOy7oNLpq8@boqun-archlinux/
> > [2]: https://rust-lang.github.io/rfcs/3467-unsafe-pinned.html#naming
> 
> I don't particularly care about the name, I mostly used aliased, because that's
> the name that Alice originally used.
> 
> `(Always)Shared` seems confusing to me.
> 
> I guess we can use `UnsafePinned`, but most people won't know what that means,

Hmm.. but doesn't `Aliased` have the same effect, i.e. most people won't
know what that means? Moreover, people who already knows `UnsafePinned`
will still take some time to realize "`Aliased` is actually
`UnsafePinned`".

> also I'm not sure if it's a good Idea to use the same name as a (future) 
> language type.

The benefit is that we won't re-invent the wheel since `UnsafePinned`
already does what `Aliased` does here. If we don't have a good name, we
should use the one that most people are already using. Honestly, at this
point, I think we should just use the unstable feature unsafe_pinned.

Regards,
Boqun

> 
> If there is a consensus on a good name I'll use that for the next version.
> 
> > 
> > Regards,
> > Boqun
> > 
[...]