rust/tests/ui/span/borrowck-borrow-overloaded-deref-mut.rs
2023-01-11 09:32:08 +00:00

61 lines
1.1 KiB
Rust

// 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<'a>(&'a self) -> &'a T {
unsafe { &*self.value }
}
}
impl<T> DerefMut for Own<T> {
fn deref_mut<'a>(&'a mut self) -> &'a mut T {
unsafe { &mut *self.value }
}
}
fn deref_imm(x: Own<isize>) {
let __isize = &*x;
}
fn deref_mut1(x: Own<isize>) {
let __isize = &mut *x; //~ ERROR cannot borrow
}
fn deref_mut2(mut x: Own<isize>) {
let __isize = &mut *x;
}
fn deref_extend<'a>(x: &'a Own<isize>) -> &'a isize {
&**x
}
fn deref_extend_mut1<'a>(x: &'a Own<isize>) -> &'a mut isize {
&mut **x //~ ERROR cannot borrow
}
fn deref_extend_mut2<'a>(x: &'a mut Own<isize>) -> &'a mut isize {
&mut **x
}
fn assign1<'a>(x: Own<isize>) {
*x = 3; //~ ERROR cannot borrow
}
fn assign2<'a>(x: &'a Own<isize>) {
**x = 3; //~ ERROR cannot borrow
}
fn assign3<'a>(x: &'a mut Own<isize>) {
**x = 3;
}
pub fn main() {}