From: Paolo Bonzini <pbonzini@redhat.com>

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>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 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);
+    };
+}
-- 
2.43.0

On Thu, Mar 20, 2025 at 01:32:46PM +0000, Peter Maydell wrote:
> Date: Thu, 20 Mar 2025 13:32:46 +0000
> From: Peter Maydell <peter.maydell@linaro.org>
> Subject: [PATCH 1/3] rust: assertions: add static_assert
> X-Mailer: git-send-email 2.43.0
> 
> From: Paolo Bonzini <pbonzini@redhat.com>
> 
> 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>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  rust/qemu-api/src/assertions.rs | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>

On 20/3/25 14:32, Peter Maydell wrote:
> From: Paolo Bonzini <pbonzini@redhat.com>
> 
> 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>

^ extraneous tag

> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   rust/qemu-api/src/assertions.rs | 22 ++++++++++++++++++++++
>   1 file changed, 22 insertions(+)