| //@compile-flags: -Zmiri-permissive-provenance |
| #![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: dangling pointer |
| } |
| } |
| |
| 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())); |
| } |
| } |
