| // 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) {} |