| // 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. |
| |
| use error::Error; |
| #[cfg(target_arch = "wasm32")] |
| mod exit { |
| pub const SUCCESS: i32 = 0; |
| pub const FAILURE: i32 = 1; |
| } |
| #[cfg(not(target_arch = "wasm32"))] |
| mod exit { |
| use libc; |
| pub const SUCCESS: i32 = libc::EXIT_SUCCESS; |
| pub const FAILURE: i32 = libc::EXIT_FAILURE; |
| } |
| |
| /// A trait for implementing arbitrary return types in the `main` function. |
| /// |
| /// The c-main function only supports to return integers as return type. |
| /// So, every type implementing the `Termination` trait has to be converted |
| /// to an integer. |
| /// |
| /// The default implementations are returning `libc::EXIT_SUCCESS` to indicate |
| /// a successful execution. In case of a failure, `libc::EXIT_FAILURE` is returned. |
| #[cfg_attr(not(test), lang = "termination")] |
| #[unstable(feature = "termination_trait", issue = "43301")] |
| #[rustc_on_unimplemented = |
| "`main` can only return types that implement {Termination}, not `{Self}`"] |
| pub trait Termination { |
| /// Is called to get the representation of the value as status code. |
| /// This status code is returned to the operating system. |
| fn report(self) -> i32; |
| } |
| |
| #[unstable(feature = "termination_trait", issue = "43301")] |
| impl Termination for () { |
| fn report(self) -> i32 { exit::SUCCESS } |
| } |
| |
| #[unstable(feature = "termination_trait", issue = "43301")] |
| impl<T: Termination, E: Error> Termination for Result<T, E> { |
| fn report(self) -> i32 { |
| match self { |
| Ok(val) => val.report(), |
| Err(err) => { |
| print_error(err); |
| exit::FAILURE |
| } |
| } |
| } |
| } |
| |
| #[unstable(feature = "termination_trait", issue = "43301")] |
| fn print_error<E: Error>(err: E) { |
| eprintln!("Error: {}", err.description()); |
| |
| if let Some(ref err) = err.cause() { |
| eprintln!("Caused by: {}", err.description()); |
| } |
| } |
| |
| #[unstable(feature = "termination_trait", issue = "43301")] |
| impl Termination for ! { |
| fn report(self) -> i32 { unreachable!(); } |
| } |
| |
| #[unstable(feature = "termination_trait", issue = "43301")] |
| impl Termination for bool { |
| fn report(self) -> i32 { |
| if self { exit::SUCCESS } else { exit::FAILURE } |
| } |
| } |
| |
| #[unstable(feature = "termination_trait", issue = "43301")] |
| impl Termination for i32 { |
| fn report(self) -> i32 { |
| self |
| } |
| } |