Jocelyn Falempe
2025-Jun-18 17:40 UTC
[PATCH v12 5/6] rust: enable `clippy::cast_lossless` lint
On 15/06/2025 22:55, Tamir Duberstein wrote:> Before Rust 1.29.0, Clippy introduced the `cast_lossless` lint [1]: > >> Rust?s `as` keyword will perform many kinds of conversions, including >> silently lossy conversions. Conversion functions such as `i32::from` >> will only perform lossless conversions. Using the conversion functions >> prevents conversions from becoming silently lossy if the input types >> ever change, and makes it clear for people reading the code that the >> conversion is lossless. > > While this doesn't eliminate unchecked `as` conversions, it makes such > conversions easier to scrutinize. It also has the slight benefit of > removing a degree of freedom on which to bikeshed. Thus apply the > changes and enable the lint -- no functional change intended.Thanks, it looks good to me, for the drm_panic_qr.rs part. Acked-by: Jocelyn Falempe <jfalempe at redhat.com>> > Link: https://rust-lang.github.io/rust-clippy/master/index.html#cast_lossless [1] > Suggested-by: Benno Lossin <benno.lossin at proton.me> > Link: https://lore.kernel.org/all/D8ORTXSUTKGL.1KOJAGBM8F8TN at proton.me/ > Reviewed-by: Benno Lossin <benno.lossin at proton.me> > Reviewed-by: Boqun Feng <boqun.feng at gmail.com> > Signed-off-by: Tamir Duberstein <tamird at gmail.com> > --- > Makefile | 1 + > drivers/gpu/drm/drm_panic_qr.rs | 4 ++-- > drivers/gpu/nova-core/regs.rs | 2 +- > drivers/gpu/nova-core/regs/macros.rs | 2 +- > rust/bindings/lib.rs | 1 + > rust/kernel/net/phy.rs | 4 ++-- > rust/uapi/lib.rs | 1 + > 7 files changed, 9 insertions(+), 6 deletions(-) > > diff --git a/Makefile b/Makefile > index 0ba22c361de8..29cf39be14de 100644 > --- a/Makefile > +++ b/Makefile > @@ -481,6 +481,7 @@ export rust_common_flags := --edition=2021 \ > -Wclippy::all \ > -Wclippy::as_ptr_cast_mut \ > -Wclippy::as_underscore \ > + -Wclippy::cast_lossless \ > -Wclippy::ignored_unit_patterns \ > -Wclippy::mut_mut \ > -Wclippy::needless_bitwise_bool \ > diff --git a/drivers/gpu/drm/drm_panic_qr.rs b/drivers/gpu/drm/drm_panic_qr.rs > index dd55b1cb764d..6b59d19ab631 100644 > --- a/drivers/gpu/drm/drm_panic_qr.rs > +++ b/drivers/gpu/drm/drm_panic_qr.rs > @@ -404,7 +404,7 @@ fn pop3(&mut self) -> Option<(u16, usize)> { > let mut out = 0; > let mut exp = 1; > for i in 0..poplen { > - out += self.decimals[self.len + i] as u16 * exp; > + out += u16::from(self.decimals[self.len + i]) * exp; > exp *= 10; > } > Some((out, NUM_CHARS_BITS[poplen])) > @@ -425,7 +425,7 @@ fn next(&mut self) -> Option<Self::Item> { > match self.segment { > Segment::Binary(data) => { > if self.offset < data.len() { > - let byte = data[self.offset] as u16; > + let byte = u16::from(data[self.offset]); > self.offset += 1; > Some((byte, 8)) > } else { > diff --git a/drivers/gpu/nova-core/regs.rs b/drivers/gpu/nova-core/regs.rs > index 5a1273230306..c1cb6d4c49ee 100644 > --- a/drivers/gpu/nova-core/regs.rs > +++ b/drivers/gpu/nova-core/regs.rs > @@ -32,7 +32,7 @@ pub(crate) fn architecture(self) -> Result<Architecture> { > pub(crate) fn chipset(self) -> Result<Chipset> { > self.architecture() > .map(|arch| { > - ((arch as u32) << Self::IMPLEMENTATION.len()) | self.implementation() as u32 > + ((arch as u32) << Self::IMPLEMENTATION.len()) | u32::from(self.implementation()) > }) > .and_then(Chipset::try_from) > } > diff --git a/drivers/gpu/nova-core/regs/macros.rs b/drivers/gpu/nova-core/regs/macros.rs > index 7ecc70efb3cd..6851af8b5885 100644 > --- a/drivers/gpu/nova-core/regs/macros.rs > +++ b/drivers/gpu/nova-core/regs/macros.rs > @@ -264,7 +264,7 @@ pub(crate) fn $field(self) -> $res_type { > pub(crate) fn [<set_ $field>](mut self, value: $to_type) -> Self { > const MASK: u32 = $name::[<$field:upper _MASK>]; > const SHIFT: u32 = $name::[<$field:upper _SHIFT>]; > - let value = ((value as u32) << SHIFT) & MASK; > + let value = (u32::from(value) << SHIFT) & MASK; > self.0 = (self.0 & !MASK) | value; > > self > diff --git a/rust/bindings/lib.rs b/rust/bindings/lib.rs > index 81b6c7aa4916..7631c9f6708d 100644 > --- a/rust/bindings/lib.rs > +++ b/rust/bindings/lib.rs > @@ -25,6 +25,7 @@ > )] > > #[allow(dead_code)] > +#[allow(clippy::cast_lossless)] > #[allow(clippy::ptr_as_ptr)] > #[allow(clippy::undocumented_unsafe_blocks)] > #[cfg_attr(CONFIG_RUSTC_HAS_UNNECESSARY_TRANSMUTES, allow(unnecessary_transmutes))] > diff --git a/rust/kernel/net/phy.rs b/rust/kernel/net/phy.rs > index 32ea43ece646..65ac4d59ad77 100644 > --- a/rust/kernel/net/phy.rs > +++ b/rust/kernel/net/phy.rs > @@ -142,7 +142,7 @@ pub fn is_autoneg_enabled(&self) -> bool { > // SAFETY: The struct invariant ensures that we may access > // this field without additional synchronization. > let bit_field = unsafe { &(*self.0.get())._bitfield_1 }; > - bit_field.get(13, 1) == bindings::AUTONEG_ENABLE as u64 > + bit_field.get(13, 1) == u64::from(bindings::AUTONEG_ENABLE) > } > > /// Gets the current auto-negotiation state. > @@ -427,7 +427,7 @@ impl<T: Driver> Adapter<T> { > // where we hold `phy_device->lock`, so the accessors on > // `Device` are okay to call. > let dev = unsafe { Device::from_raw(phydev) }; > - T::match_phy_device(dev) as i32 > + T::match_phy_device(dev).into() > } > > /// # Safety > diff --git a/rust/uapi/lib.rs b/rust/uapi/lib.rs > index e79a1f49f055..08e68ebef606 100644 > --- a/rust/uapi/lib.rs > +++ b/rust/uapi/lib.rs > @@ -14,6 +14,7 @@ > #![cfg_attr(test, allow(unsafe_op_in_unsafe_fn))] > #![allow( > clippy::all, > + clippy::cast_lossless, > clippy::ptr_as_ptr, > clippy::undocumented_unsafe_blocks, > dead_code, >