Starting with Rust 1.88.0 (expected 2025-06-26) [1][2], `rustc` may introduce a new lint that catches unnecessary transmutes, e.g.:

error: unnecessary transmute --> rust/uapi/uapi_generated.rs:23242:18 | 23242 | unsafe { ::core::mem::transmute(self._bitfield_1.get(0usize, 1u8) as u8) } | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace this with: `(self._bitfield_1.get(0usize, 1u8) as u8 == 1)` | = note: `-D unnecessary-transmutes` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(unnecessary_transmutes)]`

There are a lot of them (at least 300), but luckily they are all in `bindgen`-generated code.

Thus clean all up by allowing it there.

Since unknown lints trigger a lint itself in older compilers, do it conditionally so that we can keep the `unknown_lints` lint enabled.

Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: https://github.com/rust-lang/rust/pull/136083 [1] Link: https://github.com/rust-lang/rust/issues/136067 [2] Signed-off-by: Miguel Ojeda ojeda@kernel.org --- init/Kconfig | 3 +++ rust/bindings/lib.rs | 1 + rust/uapi/lib.rs | 1 + 3 files changed, 5 insertions(+)

diff --git a/init/Kconfig b/init/Kconfig index 63f5974b9fa6..4cdd1049283c 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -140,6 +140,9 @@ config LD_CAN_USE_KEEP_IN_OVERLAY config RUSTC_HAS_COERCE_POINTEE def_bool RUSTC_VERSION >= 108400

+config RUSTC_HAS_UNNECESSARY_TRANSMUTES + def_bool RUSTC_VERSION >= 108800 + config PAHOLE_VERSION int default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE)) diff --git a/rust/bindings/lib.rs b/rust/bindings/lib.rs index 014af0d1fc70..a08eb5518cac 100644 --- a/rust/bindings/lib.rs +++ b/rust/bindings/lib.rs @@ -26,6 +26,7 @@

#[allow(dead_code)] #[allow(clippy::undocumented_unsafe_blocks)] +#[cfg_attr(CONFIG_RUSTC_HAS_UNNECESSARY_TRANSMUTES, allow(unnecessary_transmutes))] mod bindings_raw { // Manual definition for blocklisted types. type __kernel_size_t = usize; diff --git a/rust/uapi/lib.rs b/rust/uapi/lib.rs index 13495910271f..c98d7a8cde77 100644 --- a/rust/uapi/lib.rs +++ b/rust/uapi/lib.rs @@ -24,6 +24,7 @@ unreachable_pub, unsafe_op_in_unsafe_fn )] +#![cfg_attr(CONFIG_RUSTC_HAS_UNNECESSARY_TRANSMUTES, allow(unnecessary_transmutes))]

// Manual definition of blocklisted types. type __kernel_size_t = usize;