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