| // Copyright 2017 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| #![feature(rustc_attrs)] |
| |
| struct MyStruct; |
| |
| impl MyStruct { |
| #[must_use] //~ WARN `#[must_use]` on methods is experimental |
| fn need_to_use_method() -> bool { true } |
| } |
| |
| #[must_use] //~ WARN `#[must_use]` on functions is experimental |
| fn need_to_use_it() -> bool { true } |
| |
| |
| // Feature gates are tidy-required to have a specially named (or |
| // comment-annotated) compile-fail test (which MUST fail), but for |
| // backwards-compatibility reasons, we want `#[must_use]` on functions to be |
| // compilable even if the `fn_must_use` feature is absent, thus necessitating |
| // the usage of `#[rustc_error]` here, pragmatically if awkwardly solving this |
| // dilemma until a superior solution can be devised. |
| #[rustc_error] |
| fn main() {} //~ ERROR compilation successful |
