On Mon, Aug 4, 2025 at 1:45 PM Alexandre Courbot <[email protected]> wrote:
>
> +/// align down/up operations. The alignment operations are done using the
> [`align_up!`] and
> +/// [`align_down!`] macros.
These intra-doc links don't work (they are not macros in this version at least).
> + /// Returns the alignment of `T`.
> + #[inline(always)]
> + pub const fn of<T>() -> Self {
> + // INVARIANT: `align_of` always returns a power of 2.
> + Self(unsafe { NonZero::new_unchecked(align_of::<T>()) })
Missing safety comment (`CLIPPY=1` spots it).
Also, cannot we use `new()` here? i.e. the value will be known at compile-time.
> + if !self.0.is_power_of_two() {
> + // SAFETY: per the invariants, `self.0` is always a power of two
> so this block will
> + // never be reached.
> + unsafe { core::hint::unreachable_unchecked() }
> + }
I guess this one is here to help optimize users after they inline the
cal? Is there a particular case you noticed? i.e. it may be worth
mentioning it.
> + pub const fn mask(self) -> usize {
> + // INVARIANT: `self.as_usize()` is guaranteed to be a power of two
> (i.e. non-zero), thus
> + // `1` can safely be substracted from it.
> + self.as_usize() - 1
> + }
I am not sure why there is `// INVARIANT` here, since we are not
creating a new `Self`.
I guess by "safely" you are trying to say there is no overflow risk --
I would be explicit and avoid "safe", since it is safe to overflow.
Typo: subtracted
Cheers,
Miguel
