33 lines
1.0 KiB
Rust
33 lines
1.0 KiB
Rust
// compile-flags: -Zmiri-allow-ptr-int-transmute
|
|
// A callee may not read the destination of our `&mut` without us noticing.
|
|
// Thise code got carefully checked to not introduce any reborrows
|
|
// that are not explicit in the source. Let's hope the compiler does not break this later!
|
|
|
|
#![feature(untagged_unions)]
|
|
|
|
use std::mem;
|
|
|
|
fn main() {
|
|
let mut x: i32 = 15;
|
|
let xref1 = &mut x;
|
|
let xref1_sneaky: usize = unsafe { mem::transmute_copy(&xref1) };
|
|
// Derived from `xref1`, so using raw value is still ok, ...
|
|
let xref2 = &mut *xref1;
|
|
callee(xref1_sneaky);
|
|
// ... though any use of it will invalidate our ref.
|
|
let _val = *xref2;
|
|
//~^ ERROR: borrow stack
|
|
}
|
|
|
|
fn callee(xref1: usize) {
|
|
// Transmuting through a union to avoid retagging.
|
|
union UsizeToRef {
|
|
from: usize,
|
|
to: &'static mut i32,
|
|
}
|
|
let xref1 = UsizeToRef { from: xref1 };
|
|
// Doing the deref and the transmute (through the union) in the same place expression
|
|
// should avoid retagging.
|
|
let _val = unsafe { *xref1.to };
|
|
}
|