Re: [PATCH v4 3/9] rust: doctest: add LocalModule fallback for #[vtable] ThisModule

["Gary Guo" <gary@garyguo.net>]

On Tue Jun 23, 2026 at 7:29 AM BST, Alvin Sun wrote:
> Add a `LocalModule` struct with a null-pointer `ModuleMetadata` impl
> in the doctest harness, so that `crate::LocalModule` (auto-inserted
> by `#[vtable]`) resolves correctly when there is no `module!` macro.
>
> Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
> Signed-off-by: Alvin Sun <alvin.sun@linux.dev>
> ---
>  scripts/rustdoc_test_gen.rs | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
>
> diff --git a/scripts/rustdoc_test_gen.rs b/scripts/rustdoc_test_gen.rs
> index ee76e96b41eea..198af4e446c8c 100644
> --- a/scripts/rustdoc_test_gen.rs
> +++ b/scripts/rustdoc_test_gen.rs
> @@ -239,6 +239,22 @@ macro_rules! assert_eq {{
>  
>  const __LOG_PREFIX: &[u8] = b"rust_doctests_kernel\0";
>  
> +/// Dummy module type for doctest context.
> +struct LocalModule;
> +
> +use kernel::{{
> +    str::CStr,
> +    ModuleMetadata,
> +    ThisModule, //
> +}};
> +use core::ptr::null_mut;
> +
> +impl ModuleMetadata for LocalModule {{
> +    const NAME: &'static CStr = c"rust_doctests_kernel";
> +    // SAFETY: `try_module_get`/`module_put` handle null module pointers gracefully.
> +    const THIS_MODULE: ThisModule = unsafe {{ ThisModule::from_ptr(null_mut()) }};
> +}}

We probably a macro for crates that are built-in or are not the main crate of a
multi-crate module, and this would be able to use that mechanism.

But this looks okay for now.

Reviewed-by: Gary Guo <gary@garyguo.net>

> +
>  {rust_tests}
>  "#
>      )