Re: [PATCH v6 4/9] rust: num: make Bounded::get const

[Gary Guo <gary@garyguo.net>]

On 2026-02-16 08:56, Alice Ryhl wrote:
> On Mon, Feb 16, 2026 at 05:04:40PM +0900, Alexandre Courbot wrote:
>> There is a need to access the inner value of a `Bounded` in const
>> context, notably for bitfields and registers. Remove the invariant 
>> check
>> of `Bounded::get`, which allows us to make it const.
>> 
>> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
>> ---
>>  rust/kernel/num/bounded.rs | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>> 
>> diff --git a/rust/kernel/num/bounded.rs b/rust/kernel/num/bounded.rs
>> index 8e4c08924d96..b09b93cd0c5c 100644
>> --- a/rust/kernel/num/bounded.rs
>> +++ b/rust/kernel/num/bounded.rs
>> @@ -379,6 +379,9 @@ pub fn from_expr(expr: T) -> Self {
>> 
>>      /// Returns the wrapped value as the backing type.
>>      ///
>> +    /// This is similar to the [`Deref`] implementation, but doesn't 
>> enforce the size invariant of
>> +    /// the [`Bounded`], which might produce slightly less optimal 
>> code.
> 
> The unreachable_unchecked() hint is const, so I see no reason you
> couldn't add the same call in `fn get`.

The issue is that trait impls are not const, so the if condition cannot 
be represented in const yet.

Best,
Gary