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