rust/src/test/run-pass/unsafe-coercion.rs

// Copyright 2013-2014 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.

// Check that safe fns are not a subtype of unsafe fns.


fn foo(x: i32) -> i32 {
    x * 22
}

fn bar(x: fn(i32) -> i32) -> unsafe fn(i32) -> i32 {
    x // OK, coercion!
}

fn main() {
    let f = bar(foo);
    let x = unsafe { f(2) };
    assert_eq!(x, 44);
}