Re: [PATCH 03/10] rust/irq: Add a helper to convert [InterruptSource] to [*mut IRQState]

[Paolo Bonzini <pbonzini@redhat.com>]

On Sat, Jan 25, 2025 at 1:32 PM Zhao Liu <zhao1.liu@intel.com> wrote:
>
> This is useful to hanlde InterruptSource slice and pass it to C
> bindings.
>
> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>

This may be a bad suggestion, after all. clippy complains that you're
casting &[*mut IRQState] to mutable (https://rust-lang.github.io/rust-
clippy/master/#as_ptr_cast_mut).

I can think of two solutions:

1) add #[allow(clippy::as_ptr_cast_mut)] and explain with a comment

     // Casting to *mut *mut IRQState is valid, because
     // the source slice `pins` uses interior mutability.

2) drop as_slice_of_qemu_irq() and replace it with something like

     pub(crate) const fn slice_as_ptr(slice: &[Self]) -> *mut *mut IRQState {
         slice[0].as_ptr()
     }

You choose.

Paolo