[PATCH] rust: bitfield: always inline test conversions

[Miguel Ojeda <ojeda@kernel.org>]

From: Antoni Boucher <bouanto@zoho.com>

When using the Rust GCC backend (i.e. `rustc_codegen_gcc`), GCC does not
inline enough these `Bounded::from_expr` calls:

    /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u16, 2> as core::convert::From<kernel::bitfield::tests::Priority>>::from':
    fake.c:(.text.unlikely+0x7be): undefined reference to `rust_build_error'

    /usr/bin/x86_64-linux-gnu-ld.bfd: rust/kernel.o: in function `<kernel::num::bounded::Bounded<u64, 4> as core::convert::From<kernel::bitfield::tests::MemoryType>>::from':
    fake.c:(.text.unlikely+0x90d): undefined reference to `rust_build_error'

Thus, similar to commit bc197e24a3ac ("rust: num: bounded: Always inline
fits_within and from_expr"), mark them as `#[inline(always)]`.

Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Antoni Boucher <bouanto@zoho.com>
[ Reworded to add the error and to follow our usual style and sent on
  behalf of Antoni, who found this during his work to support Rust for
  Linux with the GCC backend, i.e. with `rustc_codegen_gcc`.- Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/bitfield.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/rust/kernel/bitfield.rs b/rust/kernel/bitfield.rs
index 35ede53f2b8e..a0d089423f21 100644
--- a/rust/kernel/bitfield.rs
+++ b/rust/kernel/bitfield.rs
@@ -581,6 +581,7 @@ fn try_from(value: Bounded<u64, 4>) -> Result<Self, Self::Error> {
     }
 
     impl From<MemoryType> for Bounded<u64, 4> {
+        #[inline(always)]
         fn from(mt: MemoryType) -> Bounded<u64, 4> {
             Bounded::from_expr(mt as u64)
         }
@@ -606,6 +607,7 @@ fn from(value: Bounded<u16, 2>) -> Self {
     }
 
     impl From<Priority> for Bounded<u16, 2> {
+        #[inline(always)]
         fn from(p: Priority) -> Bounded<u16, 2> {
             Bounded::from_expr(p as u16)
         }

base-commit: dc01dfb37b34beeefcfe1c3055364d41a4070c7e
-- 
2.55.0