[rustc.git] / src / test / run-pass / diverging-fallback-option.rs

// Copyright 2012 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.

#![allow(warnings)]

// Here the type of `c` is `Option<?T>`, where `?T` is unconstrained.
// Because there is data-flow from the `{ return; }` block, which
// diverges and hence has type `!`, into `c`, we will default `?T` to
// `!`, and hence this code compiles rather than failing and requiring
// a type annotation.

fn main() {
    let c = Some({ return; });
    c.unwrap();
}
Commit	Line	Data
223e47cc LB	1	// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
	2	// file at the top-level directory of this distribution and at
	3	// http://rust-lang.org/COPYRIGHT.
	4	//
	5	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	6	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	7	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	8	// option. This file may not be copied, modified, or distributed
	9	// except according to those terms.
	10
cc61c64b	11	#![allow(warnings)]
d9579d0f	12
cc61c64b XL	13	// Here the type of `c` is `Option<?T>`, where `?T` is unconstrained.
	14	// Because there is data-flow from the `{ return; }` block, which
	15	// diverges and hence has type `!`, into `c`, we will default `?T` to
	16	// `!`, and hence this code compiles rather than failing and requiring
	17	// a type annotation.
223e47cc LB	18
223e47cc LB	19	fn main() {
cc61c64b XL	20	let c = Some({ return; });
cc61c64b XL	21	c.unwrap();
223e47cc	22	}