1//! Unstable module containing the unstable contracts lang items and attribute macros.
2
3pub use crate::macros::builtin::{contracts_ensures as ensures, contracts_requires as requires};
4
5/// This is an identity function used as part of the desugaring of the `#[ensures]` attribute.
6///
7/// This is an existing hack to allow users to omit the type of the return value in their ensures
8/// attribute.
9///
10/// Ideally, rustc should be able to generate the type annotation.
11/// The existing lowering logic makes it rather hard to add the explicit type annotation,
12/// while the function call is fairly straight forward.
13#[unstable(feature = "contracts_internals", issue = "128044" /* compiler-team#759 */)]
14// Similar to `contract_check_requires`, we need to use the user-facing
15// `contracts` feature rather than the perma-unstable `contracts_internals`.
16// Const-checking doesn't honor allow_internal_unstable logic used by contract expansion.
17#[rustc_const_unstable(feature = "contracts", issue = "128044")]
18#[lang = "contract_build_check_ensures"]
19pub const fn build_check_ensures<Ret, C>(cond: C) -> C
20where
21 C: Fn(&Ret) -> bool + Copy + 'static,
22{
23 cond
24}
25

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