Re: [PATCH v4 6/9] rust: device: Add bindings for reading device properties

["Remo Senekowitsch" <remo@buenzli.dev>]

On Tue May 20, 2025 at 9:40 AM CEST, Benno Lossin wrote:
> On Tue May 20, 2025 at 9:21 AM CEST, Benno Lossin wrote:
>> On Mon May 19, 2025 at 9:51 PM CEST, Remo Senekowitsch wrote:
>>> On Mon May 19, 2025 at 6:55 PM CEST, Danilo Krummrich wrote:
>>>> Also, the PropertyInt trait itself has to be unsafe, given that it contains
>>>> unsafe functions.
>>>
>>> I don't think a trait necessarily has to be marked unsafe just because
>>> it has unsafe methods. Marking a trait as unsafe means that implementors
>>> of the trait must uphold some invariants. This is not the case here
>>> IIUC. Here's a good explanation of my understanding: [1]
>>
>> Yes this is correct, I don't think that the trait itself should be
>> unsafe.
>
> Ahh, I understood now why Danilo suggested this: if the trait should
> guarantee that `fwnode_property_read_*_array` is called, then the trait
> would have to be `unsafe`.

Oh yeah, that's true. Callers rely on the fact that if the function
returns zero, the requested number of elements have been initialized.
That's definitely a safety invariant implementors must uphold...
So I guess marking the trait unsafe is correct.

> But I don't think that's necessary, we don't have any other unsafe code
> that needs to rely on that.