linux-kernel - [PATCH v2 6/6] docs: rust: include other expressions in conditional compilation section

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Message-ID: <20240902165535.1101978-7-ojeda@kernel.org>
Date: Mon,  2 Sep 2024 18:55:33 +0200
From: Miguel Ojeda <ojeda@...nel.org>
To: Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Wedson Almeida Filho <wedsonaf@...il.com>,
	Masahiro Yamada <masahiroy@...nel.org>
Cc: Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <benno.lossin@...ton.me>,
	Andreas Hindborg <a.hindborg@...sung.com>,
	Alice Ryhl <aliceryhl@...gle.com>,
	rust-for-linux@...r.kernel.org,
	Nathan Chancellor <nathan@...nel.org>,
	Nicolas Schier <nicolas@...sle.eu>,
	linux-kbuild@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev
Subject: [PATCH v2 6/6] docs: rust: include other expressions in conditional compilation section

Expand the conditional compilation section to explain how to support
other expressions, such as testing whether `RUSTC_VERSION` is at least
a given version, which requires a numerical comparison that Rust's `cfg`
predicates do not support (yet?).

Signed-off-by: Miguel Ojeda <ojeda@...nel.org>
---
 Documentation/rust/general-information.rst | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/rust/general-information.rst b/Documentation/rust/general-information.rst
index 2d76e09da121..6146b49b6a98 100644
--- a/Documentation/rust/general-information.rst
+++ b/Documentation/rust/general-information.rst
@@ -151,3 +151,11 @@ configuration:
 	#[cfg(CONFIG_X="y")]   // Enabled as a built-in (`y`)
 	#[cfg(CONFIG_X="m")]   // Enabled as a module   (`m`)
 	#[cfg(not(CONFIG_X))]  // Disabled
+
+For other predicates that Rust's ``cfg`` does not support, e.g. expressions with
+numerical comparisons, one may define a new Kconfig symbol:
+
+.. code-block:: kconfig
+
+	config RUSTC_VERSION_MIN_107900
+		def_bool y if RUSTC_VERSION >= 107900
-- 
2.46.0