Messages in this thread | | | Date | Mon, 14 Nov 2022 14:30:10 +0000 | From | Wei Liu <> | Subject | Re: [PATCH v1 25/28] rust: add `build_error` crate |
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On Thu, Nov 10, 2022 at 05:41:37PM +0100, Miguel Ojeda wrote: > From: Gary Guo <gary@garyguo.net> [...] > diff --git a/rust/build_error.rs b/rust/build_error.rs > new file mode 100644 > index 000000000000..0ff6b33059aa > --- /dev/null > +++ b/rust/build_error.rs > @@ -0,0 +1,24 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +//! Build-time error. > +//! > +//! This crate provides a function `build_error`, which will panic in
a const function `build_error`
Without this I read it as a "normal non-const function".
> +//! compile-time if executed in const context, and will cause a build error > +//! if not executed at compile time and the optimizer does not optimise away the > +//! call. > +//!
I can work out what the code does, but I also happen to know what Rust's const means and its behaviour in non-const context. Other kernel developers may not. Even so the description is a bit difficult for me to parse.
Maybe a few sentences about const and its behaviours can help?
Thanks, Wei.
> +//! It is used by `build_assert!` in the kernel crate, allowing checking of > +//! conditions that could be checked statically, but could not be enforced in > +//! Rust yet (e.g. perform some checks in const functions, but those > +//! functions could still be called in the runtime). > + > +#![no_std] > + > +/// Panics if executed in const context, or triggers a build error if not. > +#[inline(never)] > +#[cold] > +#[export_name = "rust_build_error"] > +#[track_caller] > +pub const fn build_error(msg: &'static str) -> ! { > + panic!("{}", msg); > +}
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