1 // SPDX-License-Identifier: GPL-2.0 2 3 //! Build-time error. 4 //! 5 //! This crate provides a [const function][const-functions] `build_error`, which will panic in 6 //! compile-time if executed in [const context][const-context], and will cause a build error 7 //! if not executed at compile time and the optimizer does not optimise away the call. 8 //! 9 //! It is used by `build_assert!` in the kernel crate, allowing checking of 10 //! conditions that could be checked statically, but could not be enforced in 11 //! Rust yet (e.g. perform some checks in [const functions][const-functions], but those 12 //! functions could still be called in the runtime). 13 //! 14 //! For details on constant evaluation in Rust, please see the [Reference][const-eval]. 15 //! 16 //! [const-eval]: https://doc.rust-lang.org/reference/const_eval.html 17 //! [const-functions]: https://doc.rust-lang.org/reference/const_eval.html#const-functions 18 //! [const-context]: https://doc.rust-lang.org/reference/const_eval.html#const-context 19 20 #![no_std] 21 22 /// Panics if executed in [const context][const-context], or triggers a build error if not. 23 /// 24 /// [const-context]: https://doc.rust-lang.org/reference/const_eval.html#const-context 25 #[inline(never)] 26 #[cold] 27 #[export_name = "rust_build_error"] 28 #[track_caller] 29 pub const fn build_error(msg: &'static str) -> ! { 30 panic!("{}", msg); 31 } 32