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Date: Mon, 18 Dec 2023 09:55:52 -0700
From: Nathan Chancellor <nathan@kernel.org>
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>,
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	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,
	Jonathan Corbet <corbet@lwn.net>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Bill Wendling <morbo@google.com>,
	Justin Stitt <justinstitt@google.com>, linux-doc@vger.kernel.org,
	llvm@lists.linux.dev
Subject: Re: [PATCH] docs: rust: remove `CC=clang` mentions
Message-ID: <20231218165552.GA601326@dev-arch.thelio-3990X>
References: <20231215124751.175191-1-ojeda@kernel.org>
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In-Reply-To: <20231215124751.175191-1-ojeda@kernel.org>

On Fri, Dec 15, 2023 at 01:47:51PM +0100, Miguel Ojeda wrote:
> Nowadays all architectures except s390 recommend using `LLVM=1` instead of
> `CC=clang`, and since commit a3c6bfba4429 ("Documentation/llvm: refresh
> docs") the Kbuild LLVM documentation makes `LLVM=1` the way to go:
> 
>     We want to encourage the use of ``LLVM=1`` rather than just
>     ``CC=clang``. Make that suggestion "above the fold" and "front and
>     center" in our docs.
> 
> In particular, that commit removes the examples with `CC=clang`.
> 
> Thus do the same in the Rust Quick Start guide, i.e. remove the `CC=clang`
> mentions, especially since the architectures that have had their Rust
> support upstreamed (or soon to be upstreamed) are all `LLVM=1` ones
> anyway. And perhaps by the time Rust is supported for s390 (or new
> architectures), it may have moved to `LLVM=1` anyway. Otherwise,
> this can be added back if needed (or perhaps an extra link to
> Documentation/kbuild/llvm.rst).
> 
> This should also help avoiding potential confusion around `CC=clang` [1].
> 
> Link: https://lore.kernel.org/rust-for-linux/6df6e8e5-8d5b-4d3d-91b5-bc0e90c424ea@nvidia.com/ [1]
> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Yes, the fact that no architecture that CONFIG_RUST supports requires
CC=clang seems reason enough for this to be eliminated from the Rust
documentation.

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  Documentation/rust/quick-start.rst | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/Documentation/rust/quick-start.rst b/Documentation/rust/quick-start.rst
> index f382914f4191..75faa987079a 100644
> --- a/Documentation/rust/quick-start.rst
> +++ b/Documentation/rust/quick-start.rst
> @@ -76,7 +76,7 @@ libclang
>  
>  ``libclang`` (part of LLVM) is used by ``bindgen`` to understand the C code
>  in the kernel, which means LLVM needs to be installed; like when the kernel
> -is compiled with ``CC=clang`` or ``LLVM=1``.
> +is compiled with ``LLVM=1``.
>  
>  Linux distributions are likely to have a suitable one available, so it is
>  best to check that first.
> @@ -229,10 +229,6 @@ at the moment. That is::
>  
>  	make LLVM=1
>  
> -For architectures that do not support a full LLVM toolchain, use::
> -
> -	make CC=clang
> -
>  Using GCC also works for some configurations, but it is very experimental at
>  the moment.
>  
> 
> base-commit: a39b6ac3781d46ba18193c9dbb2110f31e9bffe9
> -- 
> 2.43.0
>