vello_cpu: Fix clippy::cast_possible_wrap in Gaussian blur#1364
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tomcur merged 2 commits intolinebender:mainfrom Jan 19, 2026
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vello_cpu: Fix clippy::cast_possible_wrap in Gaussian blur#1364tomcur merged 2 commits intolinebender:mainfrom
clippy::cast_possible_wrap in Gaussian blur#1364tomcur merged 2 commits intolinebender:mainfrom
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Fixed by adding a reasonable limitation on `MAX_KERNEL_SIZE` (checked at compile time), and storing the kernel size as a `u8` instead of `usize`. The lint itself checks for possible wrapping when going from an unsigned to signed integer, and is not currently in our lint set (hence not triggered on CI). It triggers when manually requested. It probably should be included in the lint set, along with `clippy::cast_sign_loss` (going from signed to unsigned), but that's for another time.
tomcur
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Jan 15, 2026
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| #[cfg(test)] | ||
| const _: () = const { | ||
| if MAX_KERNEL_SIZE.is_multiple_of(2) { | ||
| panic!("`MAX_KERNEL_SIZE` must be odd"); | ||
| } | ||
| if MAX_KERNEL_SIZE > u8::MAX as usize { | ||
| panic!("`MAX_KERNEL_SIZE` must be less than or equal to `u8::MAX`"); | ||
| } | ||
| }; | ||
|
|
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`clippy::cast_possible_wrap` checks for casting an unsigned integer to a signed integer of the same size. If the value is too large to fit in the signed integer, it will wrap around to negative numbers. Such casts will usually be used when doing some math, so scrutiny of the cast is probably welcome. It's similar to the already-enabled `clippy::cast_possible_truncation`. See linebender/vello#1364 for an example where the lint is useful. The similar lint `clippy::cast_sign_loss` more or less does the opposite, triggering for casts from signed to unsigned numeric types. Floats are included in this lint, as they do a saturating cast, making it more likely to have false positives: it triggers 65 times on `vello_common` currently. Perhaps this one should not be added to the canonical lint set.
tomcur
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`clippy::cast_possible_wrap` checks for casting an unsigned integer to a signed integer of the same size. If the value is too large to fit in the signed integer, it will wrap around to negative numbers. Such casts will usually be used when doing some math, so scrutiny of the cast is probably welcome. It's similar to the already-enabled `clippy::cast_possible_truncation`. See linebender/vello#1364 for an example where the lint is useful. The similar lint `clippy::cast_sign_loss` more or less does the opposite, triggering for casts from signed to unsigned numeric types. Floats are included in this lint, as they do a saturating cast, making it more likely to have false positives: it triggers 65 times on `vello_common` currently. Perhaps this one should not be added to the canonical lint set (and I have not proposed adding it here). For the interested reader, rust-lang/rust-clippy#9231 has some further discussion of these lints.
grebmeg
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Jan 18, 2026
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Fixed by adding a reasonable limitation on
MAX_KERNEL_SIZE, and storing the kernel size as au8instead ofusize.The lint itself checks for possible wrapping when going from an unsigned to signed integer, and is not currently in our lint set (hence not triggered on CI). It triggers when manually requested.
It probably should be included in the lint set, but that's for another time (linebender/linebender.github.io#135).