rust/src/test/compile-fail/never-fallback.rs
2016-08-13 21:37:09 +08:00

42 lines
1.1 KiB
Rust

// Copyright 2015 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.
// Test that diverging types default to ! when feature(never_type) is enabled. This test is the
// same as run-pass/unit-fallback.rs except that ! is enabled.
#![feature(never_type)]
trait Balls: Sized {
fn smeg() -> Result<Self, ()>;
}
impl Balls for () {
fn smeg() -> Result<(), ()> { Ok(()) }
}
struct Flah;
impl Flah {
fn flah<T: Balls>(&self) -> Result<T, ()> {
T::smeg()
}
}
fn doit() -> Result<(), ()> {
// The type of _ is unconstrained here and should default to !
let _ = try!(Flah.flah()); //~ ERROR the trait bound
Ok(())
}
fn main() {
let _ = doit();
}