rust/src/test/compile-fail/borrowck-loan-blocks-mut-uniq.rs
Patrick Walton de70d76373 librustc: Remove cross-borrowing of Box<T> to &T from the language,
except where trait objects are involved.

Part of issue #15349, though I'm leaving it open for trait objects.
Cross borrowing for trait objects remains because it is needed until we
have DST.

This will break code like:

    fn foo(x: &int) { ... }

    let a = box 3i;
    foo(a);

Change this code to:

    fn foo(x: &int) { ... }

    let a = box 3i;
    foo(&*a);

[breaking-change]
2014-07-17 14:05:36 -07:00

27 lines
738 B
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.
fn borrow(v: &int, f: |x: &int|) {
f(v);
}
fn box_imm() {
let mut v = box 3;
borrow(&*v,
|w| { //~ ERROR cannot borrow `v` as mutable
v = box 4;
assert_eq!(*v, 3);
assert_eq!(*w, 4);
})
}
fn main() {
}