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// 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 point { x: int, y: int }
fn a() {
let mut p = point {x: 3, y: 4};
let _q = &p; //~ NOTE loan of mutable local variable granted here
// This assignment is illegal because the field x is not
// inherently mutable; since `p` was made immutable, `p.x` is now
// immutable. Otherwise the type of &_q.x (&int) would be wrong.
p.x = 5; //~ ERROR assigning to mutable field prohibited due to outstanding loan
}
fn c() {
// this is sort of the opposite. We take a loan to the interior of `p`
// and then try to overwrite `p` as a whole.
let mut p = point {x: 3, y: 4};
let _q = &p.y; //~ NOTE loan of mutable local variable granted here
p = point {x: 5, y: 7};//~ ERROR assigning to mutable local variable prohibited due to outstanding loan
copy p;
}
fn d() {
// just for completeness's sake, the easy case, where we take the
// address of a subcomponent and then modify that subcomponent:
let mut p = point {x: 3, y: 4};
let _q = &p.y; //~ NOTE loan of mutable field granted here
p.y = 5; //~ ERROR assigning to mutable field prohibited due to outstanding loan
copy p;
}
fn main() {
}
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