Re: [PATCH RFC v2 2/3] rust: kernel: add bounded integer types

[Alice Ryhl <aliceryhl@google.com>]

On Thu, Oct 09, 2025 at 09:37:09PM +0900, Alexandre Courbot wrote:
> Add the BoundedInt type, which restricts the number of bits allowed to
> be used in a given integer value. This is useful to carry guarantees
> when setting bitfields.
> 
> Alongside this type, many `From` and `TryFrom` implementations are
> provided to reduce friction when using with regular integer types. Proxy
> implementations of common integer traits are also provided.
> 
> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>

> +    pub const fn enlarge<const NEW_NUM_BITS: u32>(self) -> BoundedInt<T, NEW_NUM_BITS>
> +    where
> +        T: Boundable<NEW_NUM_BITS>,
> +        T: Copy,
> +    {
> +        build_assert!(NEW_NUM_BITS >= NUM_BITS);

This assertion can be evaluated in const context.

const {
    assert!(NEW_NUM_BITS >= NUM_BITS);
}

Alice