Re: [PATCH v8] rust: add new macro for common bitflag operations

[Andreas Hindborg <a.hindborg@kernel.org>]

Andreas Hindborg <a.hindborg@kernel.org> writes:

> "Filipe Xavier" <felipeaggger@gmail.com> writes:
>
>> We have seen a proliferation of mod_whatever::foo::Flags
>> being defined with essentially the same implementation
>> for BitAnd, BitOr, contains and etc.
>>
>> This macro aims to bring a solution for this,
>> allowing to generate these methods for user-defined structs.
>> With some use cases in KMS and upcoming GPU drivers.
>>
>> Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/We.20really.20need.20a.20common.20.60Flags.60.20type
>> Suggested-by: Daniel Almeida <daniel.almeida@collabora.com>
>> Suggested-by: Lyude Paul <lyude@redhat.com>
>> Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
>> Reviewed-by: Lyude Paul <lyude@redhat.com>
>> Signed-off-by: Filipe Xavier <felipeaggger@gmail.com>
>
> Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
>
>
> I think it would be useful to add:
>
> impl Flags {
>      unsafe from_raw(value: Repr) -> {
>      ...
>      }
> }
>
> impl TryFrom<Repr> for Flag {
>      // Succeed if `value` is a valid `Flag` enum bit pattern.
> }
>
> impl TryFrom<Repr> for Flags {
>      // Succeed if `value` is the logical OR of valid enum bit patterns.
> }

Also bitwise operations on the underlying type such as

  impl BitOrAssign<Flag> for u32 {
  ...
  }

Not sure if that is possible with the orphan rule, but it would be nice.
I was trying to

  lim.features |= request::Feature::Rotational;

where `lim: bindings::queue_limits`.


Best regards,
Andreas Hindborg