rust/tests/fail/provenance/provenance_transmute.rs

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2022-06-15 14:55:21 -05:00
// compile-flags: -Zmiri-permissive-provenance
2022-06-03 07:46:22 -05:00
#![feature(strict_provenance)]
use std::mem;
// This is the example from
// <https://github.com/rust-lang/unsafe-code-guidelines/issues/286#issuecomment-1085144431>.
unsafe fn deref(left: *const u8, right: *const u8) {
let left_int: usize = mem::transmute(left);
let right_int: usize = mem::transmute(right);
if left_int == right_int {
// The compiler is allowed to replace `left_int` by `right_int` here...
let left_ptr: *const u8 = mem::transmute(left_int);
// ...which however means here it could be dereferencing the wrong pointer.
let _val = *left_ptr; //~ERROR dereferencing pointer failed
}
}
fn main() {
let ptr1 = &0u8 as *const u8;
let ptr2 = &1u8 as *const u8;
unsafe {
// Two pointers with the same address but different provenance.
deref(ptr1, ptr2.with_addr(ptr1.addr()));
}
}