Re: [PATCH v2 0/3] Inline helpers into Rust without full LTO

[Christian Schrefl]

On 3/26/26 6:30 PM, Miguel Ojeda wrote:
> On Thu, Mar 26, 2026 at 4:18 PM Russell King (Oracle)
> <linux@xxxxxxxxxxxxxxx> wrote:
>>
>> I'm not sure if this is still true, but I believe it used to be the case
>> that the -linux-gnueabi target has one behaviour for enums (fixed size)
>> whereas -none-eabi, the size of the type depends on the range of values
>> included in the enum.
>>
>> Certianly, when Arm Ltd were proposing EABI, EABI had the latter
>> behaviour, and I think there were cases where Linux used "enum" in
>> its UAPI.
> 
> Short enums? I see `c-enum-min-bits` in the armv7a-none-eabi built-in
> `rustc` target, and indeed:
> 
>     #![no_std]
> 
>     #[repr(C)]
>     enum T {
>         A,
>         B,
>     }
> 
>     pub static S: usize = core::mem::size_of::<T>();
> 
> is 1 for that one, and 4 for the other.

I guess we could use a custom target spec, but I'm not
sure if that is worth the hassle of adding another one.

Cheers,
Christian