Re: [PATCH v5 0/4] rust: add `TryFrom` and `Into` derive macros

["Alexandre Courbot" <acourbot@nvidia.com>]

Hi Jesung,

On Fri Mar 20, 2026 at 7:04 PM JST, Jesung Yang wrote:
> Apologies for the delay.

Same. :)

>
> On Sat Feb 28, 2026 at 2:31 PM KST, Alexandre Courbot wrote:
> [...]
>> FWIW I have converted nova-core to use this, and this results in -200LoC
>> delta. Obviously I like this very much. :)
>>
>> A few pieces of feedback for things I noticed while doing the
>> conversion:
>>
>> - Very often we need to convert a type from and into the same primitive.
>>   Not having to repeat the same thing in `#[try_from(foo)]` and
>>   `#[into(foo)]` for these cases would be nice.
>
> I think I can add a common attribute that works for both `TryFrom` and
> `Into`, e.g. `#[convert(foo)]`.
>
>> - In some rare cases, we want to convert an enum with 4 variants into
>>   e.g. a `Bounded<u8, 2>`. This can be done using a `From`
>>   implementation, and that's what the register macro expects. These
>>   cases are not covered by the current macro (they are few however).
>
> I think you can just do the following?:
>
>     #[derive(Into)]
>     #[into(Bounded<u8, 2>)]
>     enum Enum {
>         A,
>         B,
>         C,
>         D,
>     }
>
>     let a = Bounded::<u8, 2>::from(Enum::A);
>     // or let a: Bounded<u8, 2> = Enum::A.into();
>
> This works because `Into` actually generates the `From<Enum>`
> implementation for `Bounded<u8, 2>`.

Sorry, I said the opposite of what I meant - we want to convert a
`Bounded<u8, 2>` into an enum with 4 variants using a `From`
implementation.