Message-ID: <20260206171253.2704684-1-gary@kernel.org>
Date: Fri,  6 Feb 2026 17:12:49 +0000
From: Gary Guo <gary@...nel.org>
To: Miguel Ojeda <ojeda@...nel.org>,
	Boqun Feng <boqun@...nel.org>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	rust-for-linux@...r.kernel.org
Subject: [PATCH 1/2] rust: move `static_assert` into `build_assert`

From: Gary Guo <gary@...yguo.net>

Conceptually, `static_assert` is also a build-time assertion that occurs
earlier in the pipeline. Conslidate the implementation so that we can use
this as the canonical place to add more useful build-time assertions.

Signed-off-by: Gary Guo <gary@...yguo.net>
---
 rust/kernel/build_assert.rs  | 40 +++++++++++++++++++++++++++++++++---
 rust/kernel/lib.rs           |  1 -
 rust/kernel/prelude.rs       |  4 +---
 rust/kernel/static_assert.rs | 39 -----------------------------------
 4 files changed, 38 insertions(+), 46 deletions(-)
 delete mode 100644 rust/kernel/static_assert.rs

diff --git a/rust/kernel/build_assert.rs b/rust/kernel/build_assert.rs
index f8124dbc663f..d464494d430a 100644
--- a/rust/kernel/build_assert.rs
+++ b/rust/kernel/build_assert.rs
@@ -1,10 +1,46 @@
 // SPDX-License-Identifier: GPL-2.0
 
-//! Build-time assert.
+//! Various assertions that happen during build-time.
 
 #[doc(hidden)]
 pub use build_error::build_error;
 
+/// Static assert (i.e. compile-time assert).
+///
+/// Similar to C11 [`_Static_assert`] and C++11 [`static_assert`].
+///
+/// An optional panic message can be supplied after the expression.
+/// Currently only a string literal without formatting is supported
+/// due to constness limitations of the [`assert!`] macro.
+///
+/// The feature may be added to Rust in the future: see [RFC 2790].
+///
+/// [`_Static_assert`]: https://en.cppreference.com/w/c/language/_Static_assert
+/// [`static_assert`]: https://en.cppreference.com/w/cpp/language/static_assert
+/// [RFC 2790]: https://github.com/rust-lang/rfcs/issues/2790
+///
+/// # Examples
+///
+/// ```
+/// static_assert!(42 > 24);
+/// static_assert!(core::mem::size_of::<u8>() == 1);
+///
+/// const X: &[u8] = b"bar";
+/// static_assert!(X[1] == b'a');
+///
+/// const fn f(x: i32) -> i32 {
+///     x + 2
+/// }
+/// static_assert!(f(40) == 42);
+/// static_assert!(f(40) == 42, "f(x) must add 2 to the given input.");
+/// ```
+#[macro_export]
+macro_rules! static_assert {
+    ($condition:expr $(,$arg:literal)?) => {
+        const _: () = ::core::assert!($condition $(,$arg)?);
+    };
+}
+
 /// Fails the build if the code path calling `build_error!` can possibly be executed.
 ///
 /// If the macro is executed in const context, `build_error!` will panic.
@@ -74,8 +110,6 @@ macro_rules! build_error {
 ///     assert!(n > 1); // Run-time check
 /// }
 /// ```
-///
-/// [`static_assert!`]: crate::static_assert!
 #[macro_export]
 macro_rules! build_assert {
     ($cond:expr $(,)?) => {{
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 42120b0b45da..0cbc91695f57 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -141,7 +141,6 @@
 pub mod slice;
 #[cfg(CONFIG_SOC_BUS)]
 pub mod soc;
-mod static_assert;
 #[doc(hidden)]
 pub mod std_vendor;
 pub mod str;
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index 2877e3f7b6d3..c7e91b80d301 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -29,7 +29,7 @@
 
 pub use pin_init::{init, pin_data, pin_init, pinned_drop, InPlaceWrite, Init, PinInit, Zeroable};
 
-pub use super::{build_assert, build_error};
+pub use super::{build_assert, build_error, static_assert};
 
 // `super::std_vendor` is hidden, which makes the macro inline for some reason.
 #[doc(no_inline)]
@@ -39,8 +39,6 @@
 
 pub use super::{try_init, try_pin_init};
 
-pub use super::static_assert;
-
 pub use super::error::{code::*, Error, Result};
 
 pub use super::{str::CStrExt as _, ThisModule};
diff --git a/rust/kernel/static_assert.rs b/rust/kernel/static_assert.rs
deleted file mode 100644
index a57ba14315a0..000000000000
--- a/rust/kernel/static_assert.rs
+++ /dev/null
@@ -1,39 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-//! Static assert.
-
-/// Static assert (i.e. compile-time assert).
-///
-/// Similar to C11 [`_Static_assert`] and C++11 [`static_assert`].
-///
-/// An optional panic message can be supplied after the expression.
-/// Currently only a string literal without formatting is supported
-/// due to constness limitations of the [`assert!`] macro.
-///
-/// The feature may be added to Rust in the future: see [RFC 2790].
-///
-/// [`_Static_assert`]: https://en.cppreference.com/w/c/language/_Static_assert
-/// [`static_assert`]: https://en.cppreference.com/w/cpp/language/static_assert
-/// [RFC 2790]: https://github.com/rust-lang/rfcs/issues/2790
-///
-/// # Examples
-///
-/// ```
-/// static_assert!(42 > 24);
-/// static_assert!(core::mem::size_of::<u8>() == 1);
-///
-/// const X: &[u8] = b"bar";
-/// static_assert!(X[1] == b'a');
-///
-/// const fn f(x: i32) -> i32 {
-///     x + 2
-/// }
-/// static_assert!(f(40) == 42);
-/// static_assert!(f(40) == 42, "f(x) must add 2 to the given input.");
-/// ```
-#[macro_export]
-macro_rules! static_assert {
-    ($condition:expr $(,$arg:literal)?) => {
-        const _: () = ::core::assert!($condition $(,$arg)?);
-    };
-}

base-commit: 4c87cdd0328495759f6e9f9f4e1e53ef8032a76f
-- 
2.51.2

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