Re: [PATCH v8 4/9] rust: acpi: add `acpi::DeviceId` abstraction

[Igor Korotin]

On 6/26/25 16:25, Danilo Krummrich wrote:
> On 6/20/25 5:24 PM, Igor Korotin wrote:
>> +impl DeviceId {
>> +    const ACPI_ID_LEN: usize = 16;
>> +
>> +    /// Create a new device id from an ACPI 'id' string.
>> +    pub const fn new<const N: usize>(id: &[u8; N]) -> Self {
> 
> Didn't notice before, but why was this silently changed from &CStr to
> &[u8; N]
> from v6 to v7?
> 
>> +        build_assert!(N <= Self::ACPI_ID_LEN, "ID exceeds 16 bytes");
>> +        // Replace with `bindings::acpi_device_id::default()` once
>> stabilized for `const`.
>> +        // SAFETY: FFI type is valid to be zero-initialized.
>> +        let mut acpi: bindings::acpi_device_id = unsafe
>> { core::mem::zeroed() };
>> +        let mut i = 0;
>> +        while i < N {
>> +            acpi.id[i] = id[i];
>> +            i += 1;
>> +        }
>> +
>> +        Self(acpi)
>> +    }
>> +}

In v6 I was asked to change assert! (runtime) to build_assert! (build time)
It was as follows:

> +    pub const fn new(id: &'static CStr) -> Self {
> +        assert!(id.len() <= Self::ACPI_ID_LEN, "ID exceeds 16 bytes");

but id.len() breaks const context and so build_assert! triggers
assertion. If I needed to explicitly describe change from CStr to
[u8;20], then it's my bad.

Thanks,
Igor