codegen: Revert some bitfield codegen changes and silence unnecessary_transmutes instead. - #3455
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This one references For Linux, we can allow unknown lints, but is that intentional? i.e. should users of |
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Gah, that's my bad. We should've made this conditional on But ignoring |
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Yeah, no worries, for the kernel side, we can work around it -- I did it conditionally to the version to avoid losing the lint in all cases, here (I Cc'd you there, but in case others wonder about it): https://lore.kernel.org/rust-for-linux/20260908170539.345207-1-ojeda@kernel.org/ But, yeah, a "more local" Thanks for the quick reply! |
Starting with bindgen 0.73.2 [1], `#[allow(unnecessary_transmutes)]`
are used, even when `--rust-target 1.85` is passed.
However, the lint was introduced in Rust 1.88.0. Thus building with
older Rust versions warns like:
error: unknown lint: `unnecessary_transmutes`
--> rust/uapi/uapi_generated.rs:26294:13
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26294 | #[allow(unnecessary_transmutes)]
| ^^^^^^^^^^^^^^^^^^^^^^
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= note: `-D unknown-lints` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(unknown_lints)]`
Thus allow `unknown_lints` in the generated bindings -- only when building
with older Rust versions.
I have asked upstream if this is intentional [1], i.e. if we are supposed
to always allow unknown lints in case `bindgen` uses such attributes,
or whether it is an oversight.
[ Emilio said it wasn't intentional -- we will work around it for now
on the kernel side. - Miguel ]
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Cc: Emilio Cobos Álvarez <emilio@crisal.io>
Link: rust-lang/rust-bindgen#3455 (comment) [1]
Assisted-by: LLM
Link: https://patch.msgid.link/20260908170539.345207-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Starting with bindgen 0.73.2 [1], `#[allow(unnecessary_transmutes)]`
are used, even when `--rust-target 1.85` is passed.
However, the lint was introduced in Rust 1.88.0. Thus building with
older Rust versions warns like:
error: unknown lint: `unnecessary_transmutes`
--> rust/uapi/uapi_generated.rs:26294:13
|
26294 | #[allow(unnecessary_transmutes)]
| ^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D unknown-lints` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(unknown_lints)]`
Thus allow `unknown_lints` in the generated bindings -- only when building
with older Rust versions.
I have asked upstream if this is intentional [1], i.e. if we are supposed
to always allow unknown lints in case `bindgen` uses such attributes,
or whether it is an oversight.
[ Emilio said it wasn't intentional -- we will work around it for now
on the kernel side. - Miguel ]
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Cc: Emilio Cobos Álvarez <emilio@crisal.io>
Link: rust-lang/rust-bindgen#3455 (comment) [1]
Assisted-by: LLM
Link: https://patch.msgid.link/20260908170539.345207-1-ojeda@kernel.org
[ Removed the `cfg` for `allow(unnecessary_transmutes)` as suggested by
Gary. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2 participants
This reverts commits a502187 and 01d65d9, because it breaks when the bitfield is a newtype enum, and adds a test for that.
Fixes #3454.