rust: make `build_assert` module the home of related macros

Given the macro scoping rules, all macros are rendered twice, in the
module and in the top-level of kernel crate.

Add `#[doc(hidden)]` to the macro definition and `#[doc(inline)]` to the
re-export inside `build_assert` module so the top-level items are hidden.

[ Sadly, because the definition is hidden, `rustdoc` decides to not list
  them as re-exports in the `prelude` page anymore, even if we refer to
  the not-actually-hidden item.

    - Miguel ]

Acked-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Acked-by: Boqun Feng <boqun@kernel.org>
Signed-off-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260609142637.373347-1-gary@kernel.org
[ Kept a single declaration in the prelude, and reworded since they
  already had `no_inline`. Removed other imports from `predefine` since
  we now use the prelude. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

4 files changed, 13 insertions, 10 deletions

diff --git a/rust/kernel/sync/atomic/internal.rs b/rust/kernel/sync/atomic/internal.rs
index ad810c2172ec..9c8a7a203abd 100644
--- a/rust/kernel/sync/atomic/internal.rs
+++ b/rust/kernel/sync/atomic/internal.rs
@@ -4,8 +4,11 @@
 //!
 //! Provides 1:1 mapping to the C atomic operations.
 
-use crate::bindings;
-use crate::macros::paste;
+use crate::{
+    bindings,
+    build_assert::static_assert,
+    macros::paste, //
+};
 use core::cell::UnsafeCell;
 use ffi::c_void;
 
@@ -46,7 +49,7 @@ pub trait AtomicImpl: Sized + Copy + private::Sealed {
 // In the future when a CONFIG_ARCH_SUPPORTS_ATOMIC_RMW=n architecture plans to support Rust, the
 // load/store helpers that guarantee atomicity against RmW operations (usually via a lock) need to
 // be added.
-crate::static_assert!(
+static_assert!(
     cfg!(CONFIG_ARCH_SUPPORTS_ATOMIC_RMW),
     "The current implementation of atomic i8/i16/ptr relies on the architecure being \
     ARCH_SUPPORTS_ATOMIC_RMW"
diff --git a/rust/kernel/sync/atomic/predefine.rs b/rust/kernel/sync/atomic/predefine.rs
index 7468153429e1..3d63f40791fa 100644
--- a/rust/kernel/sync/atomic/predefine.rs
+++ b/rust/kernel/sync/atomic/predefine.rs
@@ -2,9 +2,7 @@
 
 //! Pre-defined atomic types
 
-use crate::static_assert;
-use core::mem::{align_of, size_of};
-use ffi::c_void;
+use crate::prelude::*;
 
 // Ensure size and alignment requirements are checked.
 static_assert!(size_of::<bool>() == size_of::<i8>());
diff --git a/rust/kernel/sync/locked_by.rs b/rust/kernel/sync/locked_by.rs
index 61f100a45b35..fb4a1430b3b4 100644
--- a/rust/kernel/sync/locked_by.rs
+++ b/rust/kernel/sync/locked_by.rs
@@ -3,7 +3,7 @@
 //! A wrapper for data protected by a lock that does not wrap it.
 
 use super::{lock::Backend, lock::Lock};
-use crate::build_assert;
+use crate::build_assert::build_assert;
 use core::{cell::UnsafeCell, mem::size_of, ptr};
 
 /// Allows access to some data to be serialised by a lock that does not wrap it.
diff --git a/rust/kernel/sync/refcount.rs b/rust/kernel/sync/refcount.rs
index 6c7ae8b05a0b..23a5d201f343 100644
--- a/rust/kernel/sync/refcount.rs
+++ b/rust/kernel/sync/refcount.rs
@@ -4,9 +4,11 @@
 //!
 //! C header: [`include/linux/refcount.h`](srctree/include/linux/refcount.h)
 
-use crate::build_assert;
-use crate::sync::atomic::Atomic;
-use crate::types::Opaque;
+use crate::{
+    build_assert::build_assert,
+    sync::atomic::Atomic,
+    types::Opaque, //
+};
 
 /// Atomic reference counter.
 ///