Re: [PATCH v3 2/4] rust: add `const_assert!` macro

[Alice Ryhl]

On Thu, Mar 19, 2026 at 02:26:06PM +0000, Gary Guo wrote:
> On Thu Mar 19, 2026 at 2:12 PM GMT, Alice Ryhl wrote:
> > On Thu, Mar 19, 2026 at 12:16:46PM +0000, Gary Guo wrote:
> >> From: Gary Guo <gary@xxxxxxxxxxx>
> >> 
> >> The macro is a more powerful version of `static_assert!` for use inside
> >> function contexts. This is powered by inline consts, so enable the feature
> >> for old compiler versions that does not have it stably.
> >> 
> >> While it is possible already to write `const { assert!(...) }`, this
> >> provides a short hand that is more uniform with other assertions. It also
> >> formats nicer with rustfmt where it will not be formatted into multiple
> >> lines.
> >> 
> >> Two users that would route via the Rust tree are converted.
> >> 
> >> Reviewed-by: Yury Norov <ynorov@xxxxxxxxxx>
> >> Signed-off-by: Gary Guo <gary@xxxxxxxxxxx>
> >
> > Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> >
> > It may be worth to mention in docs that const_assert! may only be
> > checked if the function it appears in has a caller. Whereas
> > static_assert! is always checked no matter what.
> >
> > Alice
> 
> I explained this in patch 3 on why `static_assert!` is preferred over
> `const_assert!`. Given that we recommend `const_assert!` only when it refers to
> generics, the check is inherently tied to a specific instance anyway, so I don't
> think it needs to be mentioned in the item doc.

Ok.