[PATCH 1/4] rust: macros: Add support for 'imports_ns' to module!

[Alice Ryhl]

On Tue, Oct 28, 2025 at 01:22:32PM +0100, Michal Wilczynski wrote:
> Kernel modules that use C symbols exported via `EXPORT_SYMBOL_NS` must
> declare this dependency for `modpost` verification. C modules achieve
> this by using the `MODULE_IMPORT_NS(NAMESPACE)` macro, which embeds an
> `import_ns=<NAMESPACE>` tag into the `.modinfo` section.
> 
> The Rust `module!` macro lacked the ability to generate these tags,
> resulting in build warnings for Rust drivers (like the PWM driver) that
> call namespaced C functions.
> 
> Modify the `module!` macro's internal parser (`ModuleInfo`) to accept a
> new optional field `imports_ns`, which takes an array of namespace
> strings.  Update the code generator (`ModInfoBuilder::emit`) loop to
> iterate over these strings and emit the corresponding
> `import_ns=<NAMESPACE>` tags into the `.modinfo` section using the
> existing `#[link_section]` mechanism.
> 
> This provides the necessary infrastructure for Rust modules to correctly
> declare their C namespace dependencies.
> 
> Signed-off-by: Michal Wilczynski <m.wilczynski at samsung.com>

Reviewed-by: Alice Ryhl <aliceryhl at google.com>