rust/src/test/run-pass/regions-fn-subtyping.rs
2017-01-31 21:27:13 -05:00

40 lines
1.3 KiB
Rust

// 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.
// Issue #2263.
// pretty-expanded FIXME #23616
#![allow(dead_assignment)]
#![allow(unused_variables)]
#![allow(unknown_features)]
// Should pass region checking.
fn ok(f: Box<FnMut(&usize)>) {
// Here, g is a function that can accept a usize pointer with
// lifetime r, and f is a function that can accept a usize pointer
// with any lifetime. The assignment g = f should be OK (i.e.,
// f's type should be a subtype of g's type), because f can be
// used in any context that expects g's type. But this currently
// fails.
let mut g: Box<for<'r> FnMut(&'r usize)> = Box::new(|x| { });
g = f;
}
// This version is the same as above, except that here, g's type is
// inferred.
fn ok_inferred(f: Box<FnMut(&usize)>) {
let mut g: Box<for<'r> FnMut(&'r usize)> = Box::new(|_| {});
g = f;
}
pub fn main() {
}