Re: [PATCH v2] rust: assertions: add static_assert

[Pierrick Bouvier <pierrick.bouvier@linaro.org>]

On 3/20/25 04:55, Paolo Bonzini wrote:
> Add a new assertion that is similar to "const { assert!(...) }" but can be used
> outside functions and with older versions of Rust.  A similar macro is found in
> Linux, whereas the "static_assertions" crate has a const_assert macro that
> produces worse error messages.
> 
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Supersedes: <20250320113356.799412-1-pbonzini@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   rust/qemu-api/src/assertions.rs | 22 ++++++++++++++++++++++
>   1 file changed, 22 insertions(+)
> 
> diff --git a/rust/qemu-api/src/assertions.rs b/rust/qemu-api/src/assertions.rs
> index 104dec39774..bba38cfda11 100644
> --- a/rust/qemu-api/src/assertions.rs
> +++ b/rust/qemu-api/src/assertions.rs
> @@ -120,3 +120,25 @@ macro_rules! assert_match {
>           );
>       };
>   }
> +
> +/// Assert at compile time that an expression is true.  This is similar
> +/// to `const { assert!(...); }` but it works outside functions, as well as
> +/// on versions of Rust before 1.79.
> +///
> +/// # Examples
> +///
> +/// ```
> +/// # use qemu_api::static_assert;
> +/// static_assert!("abc".len() == 3);
> +/// ```
> +///
> +/// ```compile_fail
> +/// # use qemu_api::static_assert;
> +/// static_assert!("abc".len() == 2); // does not compile
> +/// ```
> +#[macro_export]
> +macro_rules! static_assert {
> +    ($x:expr) => {
> +        const _: () = assert!($x);
> +    };
> +}

How about using something already done, and exhaustive for this?
https://docs.rs/static_assertions/latest/static_assertions/

It provides a lot of convenient asserts related to types, traits, and 
configs, which will probably end up being introduced in QEMU Rust at 
some point.