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>

2 files changed, 13 insertions, 8 deletions

diff --git a/rust/kernel/io/register.rs b/rust/kernel/io/register.rs
index 388647f28292..f924c7c7c1db 100644
--- a/rust/kernel/io/register.rs
+++ b/rust/kernel/io/register.rs
@@ -108,9 +108,10 @@
 
 use core::marker::PhantomData;
 
-use crate::io::IoLoc;
-
-use kernel::build_assert;
+use crate::{
+    build_assert::build_assert,
+    io::IoLoc, //
+};
 
 /// Trait implemented by all registers.
 pub trait Register: Sized {
@@ -872,7 +873,7 @@ macro_rules! register {
         @reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty)
             [ $size:expr, stride = $stride:expr ] @ $offset:literal { $($fields:tt)* }
     ) => {
-        ::kernel::static_assert!(::core::mem::size_of::<$storage>() <= $stride);
+        $crate::build_assert::static_assert!(::core::mem::size_of::<$storage>() <= $stride);
 
         $crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
         $crate::register!(@io_base $name($storage) @ $offset);
@@ -895,7 +896,9 @@ macro_rules! register {
         @reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty) => $alias:ident [ $idx:expr ]
             { $($fields:tt)* }
     ) => {
-        ::kernel::static_assert!($idx < <$alias as $crate::io::register::RegisterArray>::SIZE);
+        $crate::build_assert::static_assert!(
+            $idx < <$alias as $crate::io::register::RegisterArray>::SIZE
+        );
 
         $crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
         $crate::register!(
@@ -912,7 +915,7 @@ macro_rules! register {
             [ $size:expr, stride = $stride:expr ]
             @ $base:ident + $offset:literal { $($fields:tt)* }
     ) => {
-        ::kernel::static_assert!(::core::mem::size_of::<$storage>() <= $stride);
+        $crate::build_assert::static_assert!(::core::mem::size_of::<$storage>() <= $stride);
 
         $crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
         $crate::register!(@io_base $name($storage) @ $offset);
@@ -938,7 +941,9 @@ macro_rules! register {
         @reg $(#[$attr:meta])* $vis:vis $name:ident ($storage:ty)
             => $base:ident + $alias:ident [ $idx:expr ] { $($fields:tt)* }
     ) => {
-        ::kernel::static_assert!($idx < <$alias as $crate::io::register::RegisterArray>::SIZE);
+        $crate::build_assert::static_assert!(
+            $idx < <$alias as $crate::io::register::RegisterArray>::SIZE
+        );
 
         $crate::register!(@bitfield $(#[$attr])* $vis struct $name($storage) { $($fields)* });
         $crate::register!(
diff --git a/rust/kernel/io/resource.rs b/rust/kernel/io/resource.rs
index b7ac9faf141d..17b0c174cfc5 100644
--- a/rust/kernel/io/resource.rs
+++ b/rust/kernel/io/resource.rs
@@ -229,7 +229,7 @@ impl Flags {
     // Always inline to optimize out error path of `build_assert`.
     #[inline(always)]
     const fn new(value: u32) -> Self {
-        crate::build_assert!(value as u64 <= c_ulong::MAX as u64);
+        build_assert!(value as u64 <= c_ulong::MAX as u64);
         Flags(value as c_ulong)
     }
 }