Re: [PATCH 2/5] rust: use inline const expressions

[Zhao Liu]

On Mon, May 05, 2025 at 12:08:51PM +0200, Paolo Bonzini wrote:
> Date: Mon,  5 May 2025 12:08:51 +0200
> From: Paolo Bonzini <pbonzini@redhat.com>
> Subject: [PATCH 2/5] rust: use inline const expressions
> X-Mailer: git-send-email 2.49.0
> 
> They were stabilized in Rust 1.79.0.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  docs/devel/rust.rst            |  9 +++------
>  rust/qemu-api/src/callbacks.rs | 27 +--------------------------
>  rust/qemu-api/src/chardev.rs   |  2 +-
>  rust/qemu-api/src/qdev.rs      |  2 +-
>  rust/qemu-api/src/timer.rs     |  2 +-
>  rust/qemu-api/src/vmstate.rs   |  2 +-
>  6 files changed, 8 insertions(+), 36 deletions(-)

...

> diff --git a/rust/qemu-api/src/chardev.rs b/rust/qemu-api/src/chardev.rs
> index 6e0590d758e..cb27be52569 100644
> --- a/rust/qemu-api/src/chardev.rs
> +++ b/rust/qemu-api/src/chardev.rs
> @@ -138,7 +138,7 @@ pub fn enable_handlers<
>              F::call((owner, event))
>          }
>  
> -        let _: () = CanReceiveFn::ASSERT_IS_SOME;
> +        const { assert!(CanReceiveFn::IS_SOME) };

Do you think it's a good idea to warp this as a helper for easy
callback calls?

>          let receive_cb: Option<unsafe extern "C" fn(*mut c_void, *const u8, 
> c_int)> =
>              if ReceiveFn::is_some() {
>                  Some(rust_receive_cb::<T, ReceiveFn>)

Thanks,
Zhao