Re: [PATCH] rust: enable bindgen's `--enable-function-attribute-detection` flag

From: Gary Guo
Date: Thu Aug 15 2024 - 14:24:58 EST


On Wed, 14 Aug 2024 18:37:22 +0200
Miguel Ojeda <ojeda@xxxxxxxxxx> wrote:

> `bindgen` is able to detect certain function attributes and annotate
> functions correspondingly in its output for the Rust side, when the
> `--enable-function-attribute-detection` is passed.
>
> In particular, it is currently able to use `__must_check` in C
> (`#[must_use]` in Rust), which give us a bunch of annotations that are
> nice to have to prevent possible issues in Rust abstractions, e.g.:
>
> extern "C" {
> + #[must_use]
> pub fn kobject_add(
> kobj: *mut kobject,
> parent: *mut kobject,
> fmt: *const core::ffi::c_char,
> ...
> ) -> core::ffi::c_int;
> }
>
> Apparently, there are edge cases where this can make generation very slow,
> which is why it is behind a flag [1], but it does not seem to affect us
> in any major way at the moment.
>
> Link: https://github.com/rust-lang/rust-bindgen/issues/1465 [1]
> Link: https://lore.kernel.org/rust-for-linux/CANiq72=u5Nrz_NW3U3_VqywJkD8pECA07q2pFDd1wjtXOWdkAQ@xxxxxxxxxxxxxx/
> Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx>

Reviewed-by: Gary Guo <gary@xxxxxxxxxxx>

> ---
> If someone notices a major performance difference, please let me know!
>
> rust/Makefile | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/rust/Makefile b/rust/Makefile
> index 1f10f92737f2..c28b81e2a5fa 100644
> --- a/rust/Makefile
> +++ b/rust/Makefile
> @@ -270,7 +270,7 @@ quiet_cmd_bindgen = BINDGEN $@
> cmd_bindgen = \
> $(BINDGEN) $< $(bindgen_target_flags) \
> --use-core --with-derive-default --ctypes-prefix core::ffi --no-layout-tests \
> - --no-debug '.*' \
> + --no-debug '.*' --enable-function-attribute-detection \
> -o $@ -- $(bindgen_c_flags_final) -DMODULE \
> $(bindgen_target_cflags) $(bindgen_target_extra)
>
>
> base-commit: de9c2c66ad8e787abec7c9d7eff4f8c3cdd28aed
> --
> 2.46.0