[PATCH 6/6] docs: rust: include other expressions in conditional compilation section

[Miguel Ojeda <ojeda@kernel.org>]

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@kernel.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 e3f388ef4ee4..071c5bafd668 100644
--- a/Documentation/rust/general-information.rst
+++ b/Documentation/rust/general-information.rst
@@ -142,3 +142,11 @@ 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