rust/src/test/run-pass/borrowck-uniq-via-ref.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

56 lines
1.0 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.
struct Rec {
f: Box<int>,
}
struct Outer {
f: Inner
}
struct Inner {
g: Innermost
}
struct Innermost {
h: Box<int>,
}
fn borrow(_v: &int) {}
fn box_mut(v: &mut Box<int>) {
borrow(&**v); // OK: &mut -> &imm
}
fn box_mut_rec(v: &mut Rec) {
borrow(&*v.f); // OK: &mut -> &imm
}
fn box_mut_recs(v: &mut Outer) {
borrow(&*v.f.g.h); // OK: &mut -> &imm
}
fn box_imm(v: &Box<int>) {
borrow(&**v); // OK
}
fn box_imm_rec(v: &Rec) {
borrow(&*v.f); // OK
}
fn box_imm_recs(v: &Outer) {
borrow(&*v.f.g.h); // OK
}
pub fn main() {
}