Re: [PATCH v5 21/38] rust: ptr: add const_align_up() and enable inline_const feature

[Alexandre Courbot]

On Thu Mar 5, 2026 at 9:28 PM JST, Gary Guo wrote:
>>
>>   const TEST_ALIGN: usize = const_align_up::<256, 10>();
>>
>> This uses purely const asserts, but you have to work with two `usize`
>> arguments. The version below looks a bit nicer as it leverages the
>> power-of-two invariant of `Alignment`:
>>
>>   impl Alignment {
>>       const fn const_align_up(self, value: usize) -> usize {
>>           build_assert!(value <= usize::MAX - !self.mask());
>>
>>           (value + !self.mask()) & self.mask()
>>       }
>
> This is fine, too, although I think just returning an `Option` and ask user to
> unwrap it in const eval is better.

Why? Aren't unwraps something we want to avoid?

We already have fallible methods for non-const contexts, so why give
another method that essentially behaves the same when we want to use it
in scenarios where we know the result will be successful anyway?