rust: enable `clippy::cast_lossless` lint

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.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#cast_lossless [1]
Suggested-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/all/D8ORTXSUTKGL.1KOJAGBM8F8TN@proton.me/
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Acked-by: Jocelyn Falempe <jfalempe@redhat.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250615-ptr-as-ptr-v12-5-f43b024581e8@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 2 insertions, 2 deletions

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 @@ impl DecFifo {
             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 @@ impl Iterator for SegmentIterator<'_> {
         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 {