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|
// Test how overloaded deref interacts with borrows when DerefMut
// is implemented.
use std::ops::{Deref, DerefMut};
struct Own<T> {
value: *mut T
}
impl<T> Deref for Own<T> {
type Target = T;
fn deref(&self) -> &T {
unsafe { &*self.value }
}
}
impl<T> DerefMut for Own<T> {
fn deref_mut(&mut self) -> &mut T {
unsafe { &mut *self.value }
}
}
struct Point {
x: isize,
y: isize
}
impl Point {
fn get(&self) -> (isize, isize) {
(self.x, self.y)
}
fn set(&mut self, x: isize, y: isize) {
self.x = x;
self.y = y;
}
fn x_ref(&self) -> &isize {
&self.x
}
fn y_mut(&mut self) -> &mut isize {
&mut self.y
}
}
fn deref_imm_field(x: Own<Point>) {
let __isize = &x.y;
}
fn deref_mut_field1(x: Own<Point>) {
let __isize = &mut x.y; //~ ERROR cannot borrow
}
fn deref_mut_field2(mut x: Own<Point>) {
let __isize = &mut x.y;
}
fn deref_extend_field(x: &Own<Point>) -> &isize {
&x.y
}
fn deref_extend_mut_field1(x: &Own<Point>) -> &mut isize {
&mut x.y //~ ERROR cannot borrow
}
fn deref_extend_mut_field2(x: &mut Own<Point>) -> &mut isize {
&mut x.y
}
fn deref_extend_mut_field3(x: &mut Own<Point>) {
// Hmm, this is unfortunate, because with box it would work,
// but it's presently the expected outcome. See `deref_extend_mut_field4`
// for the workaround.
let _x = &mut x.x;
let _y = &mut x.y; //~ ERROR cannot borrow
use_mut(_x);
}
fn deref_extend_mut_field4<'a>(x: &'a mut Own<Point>) {
let p = &mut **x;
let _x = &mut p.x;
let _y = &mut p.y;
}
fn assign_field1<'a>(x: Own<Point>) {
x.y = 3; //~ ERROR cannot borrow
}
fn assign_field2<'a>(x: &'a Own<Point>) {
x.y = 3; //~ ERROR cannot borrow
}
fn assign_field3<'a>(x: &'a mut Own<Point>) {
x.y = 3;
}
fn assign_field4<'a>(x: &'a mut Own<Point>) {
let _p: &mut Point = &mut **x;
x.y = 3; //~ ERROR cannot borrow
use_mut(_p);
}
fn deref_imm_method(x: Own<Point>) {
let __isize = x.get();
}
fn deref_mut_method1(x: Own<Point>) {
x.set(0, 0); //~ ERROR cannot borrow
}
fn deref_mut_method2(mut x: Own<Point>) {
x.set(0, 0);
}
fn deref_extend_method(x: &Own<Point>) -> &isize {
x.x_ref()
}
fn deref_extend_mut_method1(x: &Own<Point>) -> &mut isize {
x.y_mut() //~ ERROR cannot borrow
}
fn deref_extend_mut_method2(x: &mut Own<Point>) -> &mut isize {
x.y_mut()
}
fn assign_method1<'a>(x: Own<Point>) {
*x.y_mut() = 3; //~ ERROR cannot borrow
}
fn assign_method2<'a>(x: &'a Own<Point>) {
*x.y_mut() = 3; //~ ERROR cannot borrow
}
fn assign_method3<'a>(x: &'a mut Own<Point>) {
*x.y_mut() = 3;
}
pub fn main() {}
fn use_mut<T>(_: &mut T) {}
|
