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From: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Date: Mon, 1 Apr 2024 23:52:11 +0200
Message-ID: <CANiq72=FM2+VWs1sJTc3i2u4Y4P-DBR8o_h4Gd7MYXfxULjR-A@mail.gmail.com>
Subject: Re: [PATCH 3/3] rust: upgrade to Rust 1.78.0
To: Miguel Ojeda <ojeda@kernel.org>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>, Alex Gaynor <alex.gaynor@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>, 
	Benno Lossin <benno.lossin@proton.me>, Andreas Hindborg <a.hindborg@samsung.com>, 
	Alice Ryhl <aliceryhl@google.com>, rust-for-linux@vger.kernel.org, 
	linux-kernel@vger.kernel.org, patches@lists.linux.dev
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On Mon, Apr 1, 2024 at 11:23=E2=80=AFPM Miguel Ojeda <ojeda@kernel.org> wro=
te:
>
> It also means that, ignoring non-language/library features, we are
> currently left with just the few language features needed to implement th=
e
> kernel `Arc`, the `new_uninit` library feature, the `compiler_builtins`
> marker and the few `no_*` `cfg`s we pass when compiling `core`/`alloc`.

To be clear, by "currently" I meant in mainline, i.e. it does not mean
that we will not need/add a few more language/library features in the
future.

> Rust 1.78.0 introduced support for mutable pointers to Rust statics,
> including a test case for the Linux kernel's `VTABLE` use case [13].

I should have mentioned constants so that it makes sense. I will link
to `const_refs_to_static`, i.e.
https://github.com/rust-lang/rust/issues/119618.

> Rust 1.78.0 with debug assertions enabled (i.e. `-Cdebug-assertions=3Dy`,
> kernel's `CONFIG_RUST_DEBUG_ASSERTIONS=3Dy`) now always checks all unsafe
> preconditions, without a way to opt-out for particular cases [14].

It would be ideal to have a way to selectively disable certain checks
per-call site for this one (i.e. not just per check but for particular
instances of a check), even if the vast majority of the checks remain
in place. I discuss the details a bit more at
https://github.com/Rust-for-Linux/linux/issues/354.

> Please note that Rust 1.78.0 will be released in a month (2024-05-02).

By the way, I tested these with arm64, loongarch64 and x86_64.

Cheers,
Miguel