[PATCH v4] rust: static_assert: add optional message

[PATCH v4] rust: static_assert: add optional message

[Altan Ozlu]

Add an optional panic message to the `static_assert!` macro.

The panic message doesn't support argument formatting, because the
`assert!` macro only supports formatting in non-const contexts.

Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/1149
Signed-off-by: Altan Ozlu <altan@ozlu.eu>

---
Link to v3: https://lore.kernel.org/rust-for-linux/20250325211011.1093374-2-altan@ozlu.eu/
---
 rust/kernel/static_assert.rs | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/rust/kernel/static_assert.rs b/rust/kernel/static_assert.rs
index 3115ee0ba8e9..d8120f838260 100644
--- a/rust/kernel/static_assert.rs
+++ b/rust/kernel/static_assert.rs
@@ -6,6 +6,10 @@
 ///
 /// Similar to C11 [`_Static_assert`] and C++11 [`static_assert`].
 ///
+/// An optional panic message can be supplied after the expression.
+/// Currently only a string literal without formatting is supported
+/// due to constness limitations of the [`assert!`] macro.
+///
 /// The feature may be added to Rust in the future: see [RFC 2790].
 ///
 /// [`_Static_assert`]: https://en.cppreference.com/w/c/language/_Static_assert
@@ -25,10 +29,11 @@
 ///     x + 2
 /// }
 /// static_assert!(f(40) == 42);
+/// static_assert!(f(40) == 42, "f(x) must add 2 to the given input.");
 /// ```
 #[macro_export]
 macro_rules! static_assert {
-    ($condition:expr) => {
-        const _: () = core::assert!($condition);
+    ($condition:expr $(,$arg:literal)?) => {
+        const _: () = core::assert!($condition $(,$arg)?);
     };
 }

base-commit: a0b539ad369fe434fe488faf92d4ae770a27a90f
-- 
2.48.1

Re: [PATCH v4] rust: static_assert: add optional message

[Benno Lossin]

On Wed Mar 26, 2025 at 9:25 PM CET, Altan Ozlu wrote:
> Add an optional panic message to the `static_assert!` macro.
>
> The panic message doesn't support argument formatting, because the
> `assert!` macro only supports formatting in non-const contexts.
>
> Suggested-by: Miguel Ojeda <ojeda@kernel.org>
> Link: https://github.com/Rust-for-Linux/linux/issues/1149
> Signed-off-by: Altan Ozlu <altan@ozlu.eu>

Reviewed-by: Benno Lossin <benno.lossin@proton.me>

---
Cheers,
Benno

> ---
> Link to v3: https://lore.kernel.org/rust-for-linux/20250325211011.1093374-2-altan@ozlu.eu/
> ---
>  rust/kernel/static_assert.rs | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)

Re: [PATCH v4] rust: static_assert: add optional message

[Altan Ozlu]

Hello Miguel,

Patch has been reviewed by Benno Lossin, can you check when you have time ?

-- 
Kind regards,
Altan

Re: [PATCH v4] rust: static_assert: add optional message

[Miguel Ojeda]

On Tue, Apr 15, 2025 at 9:26 PM Altan Ozlu <altan@ozlu.eu> wrote:
>
> Patch has been reviewed by Benno Lossin, can you check when you have time ?

If you mean applying it, I have not picked any patch for the next cycle yet.

Cheers,
Miguel

Re: [PATCH v4] rust: static_assert: add optional message

[Altan Ozlu]

> 
> If you mean applying it, I have not picked any patch for the next cycle yet.

Yes I meant applying, I didn't knew about it. Thanks, have a nice day!
-- 
Kind regards,
Altan

Re: [PATCH v4] rust: static_assert: add optional message

[Trevor Gross]

On Wed, Mar 26, 2025 at 3:25 PM Altan Ozlu <altan@ozlu.eu> wrote:
>
> Add an optional panic message to the `static_assert!` macro.
>
> The panic message doesn't support argument formatting, because the
> `assert!` macro only supports formatting in non-const contexts.
>
> Suggested-by: Miguel Ojeda <ojeda@kernel.org>
> Link: https://github.com/Rust-for-Linux/linux/issues/1149

I think this could be "Closes:"

> Signed-off-by: Altan Ozlu <altan@ozlu.eu>
>
> ---
> Link to v3: https://lore.kernel.org/rust-for-linux/20250325211011.1093374-2-altan@ozlu.eu/
> ---
>  rust/kernel/static_assert.rs | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)

Reviewed-by: Trevor Gross <tmgross@umich.edu>

Re: [PATCH v4] rust: static_assert: add optional message

[Miguel Ojeda]

On Thu, Apr 17, 2025 at 9:42 AM Trevor Gross <tmgross@umich.edu> wrote:
>
> I think this could be "Closes:"

The documentation isn't very clear about it -- my reading is that
Closes is meant for bugs, so I have always used Link for feature
suggestions, but it would be reasonable to use it for that too like in
other trackers.

Thanks for reviewing!

Cheers,
Miguel

Re: [PATCH v4] rust: static_assert: add optional message

[Miguel Ojeda]

On Wed, Mar 26, 2025 at 9:25 PM Altan Ozlu <altan@ozlu.eu> wrote:
>
> Add an optional panic message to the `static_assert!` macro.
>
> The panic message doesn't support argument formatting, because the
> `assert!` macro only supports formatting in non-const contexts.
>
> Suggested-by: Miguel Ojeda <ojeda@kernel.org>
> Link: https://github.com/Rust-for-Linux/linux/issues/1149
> Signed-off-by: Altan Ozlu <altan@ozlu.eu>

Applied to `rust-next` -- thanks everyone!

Cheers,
Miguel