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Date:   Fri, 1 Dec 2023 12:05:29 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Boqun Feng <boqun.feng@gmail.com>
Cc:     Matthew Wilcox <willy@infradead.org>,
        Alice Ryhl <aliceryhl@google.com>,
        Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Gary Guo <gary@garyguo.net>,
        =?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Andreas Hindborg <a.hindborg@samsung.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arve =?iso-8859-1?B?SGr4bm5lduVn?= <arve@android.com>,
        Todd Kjos <tkjos@android.com>,
        Martijn Coenen <maco@android.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Carlos Llamas <cmllamas@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Kees Cook <keescook@chromium.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Daniel Xu <dxu@dxuuu.xyz>, linux-kernel@vger.kernel.org,
        rust-for-linux@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        Josh Triplett <josh@joshtriplett.org>
Subject: Re: [PATCH 1/7] rust: file: add Rust abstraction for `struct file`
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On Fri, Dec 01, 2023 at 02:36:40AM -0800, Boqun Feng wrote:

> I don't speak for the Rust langauge community, but I think this is
> something that they should improve. I understand it could be frustrating
> that we find out the new stuff doesn't support good old tools we use
> (trust me, I do!), but I believe you also understand that a higher level
> language can help in some places, for example, SBRM is naturally
> supported ;-) This answers half of the question: "Why are we even trying
> to use it again?".

C++ does that too (and a ton of other languages), and has a much less
craptastic syntax (not claiming C++ syntax doesn't have problems, but at
least its the same language family). Now I realize C++ isn't ideal, it
inherits much of the safety issues from C. But gah, rust is such a royal
pain.

> The other half is how languages are designed is different in these days:
> a language community may do a better job on listening to the users and
> the real use cases can affect the language design in return. While we
> are doing our own experiment, we might well give that a shot too.

Well, rust was clearly not designed to interact with C/C++ sanely. Given
the kernel is a giant C project, this is somewhat of an issue IMO.

IIRC the way Chrome makes it work with C++ is by defining the interface
in a *third* language which compiles into 'compatible' Rust and C++,
which is total idiocy if you ask me.

Some langauges (Zig IIUC) can consume regular C headers and are much
less painful to interact with (I know very little about Zig, no
endorsement beyond it integrating much better with C).

> And at least the document admits these are "future possibilities", so
> they should be more motivated to implement these.
> 
> It's never perfect, but we gotta start somewhere.

How about they start by using this LLVM goodness to implement the rust
equivalent of Zig's @cImport? Have it use clang to munge the C/C++
headers into IR and squash the lot into the rust thing.

The syntax is ofcourse unfixable :-(