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>> +    (value + (ALIGN - 1)) & !(ALIGN - 1) >> +} > > So this is just like the issue I'm having with .next_multiple_of() in my patch #10. > > Shouldn't you have a check to make sure that value + (ALIGN - 1) doesn't overflow? Since I need to > align up to the nearest const power of two, I could use this function instead of align_up() and > avoid testing for an error condition. > Const items are special: they are evaluated at compile time, rather than at runtime. And so this will fail to compile, for values that would overflow. For example: error[E0080]: evaluation of constant value failed --> drivers/gpu/nova-core/num.rs:226:5 | 226 | (value + (ALIGN - 1)) & !(ALIGN - 1) | ^^^^^^^^^^^^^^^^^^^^^ attempt to compute `usize::MAX + 15_usize`, which would overflow | note: inside `const_align_up::<16>` --> drivers/gpu/nova-core/num.rs:226:5 | 226 | (value + (ALIGN - 1)) & !(ALIGN - 1) | ^^^^^^^^^^^^^^^^^^^^^ note: inside `_OVERFLOW_TEST` --> drivers/gpu/nova-core/num.rs:231:31 | 231 | const _OVERFLOW_TEST: usize = const_align_up::<16>(usize::MAX); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ thanks, -- John Hubbard