Re: [PATCH v2 1/4] rust: alloc: implement `Borrow` and `BorrowMut` for `Vec`

[Alexandre Courbot]

On Sun Jun 15, 2025 at 4:19 AM JST, Benno Lossin wrote:
> On Fri Jun 13, 2025 at 3:46 PM CEST, Alexandre Courbot wrote:
>> Implement `Borrow<[T]>` and `BorrowMut<[T]>` for `Vec<T>`. This allows
>> `Vec<T>` to be used in generic APIs asking for types implementing those
>> traits. `[T; N]` and `&mut [T]` also implement those traits allowing
>> users to use either owned, borrowed and heap-owned values.
>>
>> The implementation leverages `as_slice` and `as_mut_slice`.
>>
>> Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
>> Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
>
> One comment below, with that fixed:
>
> Reviewed-by: Benno Lossin <lossin@xxxxxxxxxx>
>
>> ---
>>  rust/kernel/alloc/kvec.rs | 57 +++++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 57 insertions(+)
>>
>> diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs
>> index 1a0dd852a468ccda6ea1b521bc1e7dbc8d7fc79c..3f368d4a67683ac5a0ff87d7df33a3bb640ced59 100644
>> --- a/rust/kernel/alloc/kvec.rs
>> +++ b/rust/kernel/alloc/kvec.rs
>> @@ -8,6 +8,7 @@
>>      AllocError, Allocator, Box, Flags,
>>  };
>>  use core::{
>> +    borrow::{Borrow, BorrowMut},
>>      fmt,
>>      marker::PhantomData,
>>      mem::{ManuallyDrop, MaybeUninit},
>> @@ -890,6 +891,62 @@ fn deref_mut(&mut self) -> &mut [T] {
>>      }
>>  }
>>  
>> +/// Allows `Vec<T>` to be used as a `Borrow<[T]>`.
>
> I personally would vote against this first line description here. I
> don't think that it will show up in a summary view of rust doc (since
> trait impls don't appear in searches or module overviews). Additionally,
> this first sentence seems like this kind of comment:
>
>     // call `foo`:
>     foo();
>
> So let's just remove it and directly start with the examples :)

That's fine by me, I was just a bit nervous to start a doccomment
directly with the examples, but in this context it appears to make
sense.

Thanks for the review!