Comparing pointers into different allocations

[kpp]

MRE:

use std::ffi::CStr;

fn main() {
    let cstr = CStr::from_bytes_with_nul(b"hello\0");
    assert!(cstr.is_ok());
    let ptr = cstr.unwrap().as_ptr();
    dbg!(ptr); // << here
}

https://play.rust-lang.org/?version=stable&mode=debug&edition=2015&gist=9a0295250c20f63f16a5895438502d8a

Error:

[src/main.rs:7] ptr = error[E0080]: Miri evaluation error: attempted to do invalid arithmetic on pointers that would leak base addresses, e.g., comparing pointers into different allocations
   --> /root/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/cmp.rs:978:52
    |
978 |                 fn ge(&self, other: &$t) -> bool { (*self) >= (*other) }
    |                                                    ^^^^^^^^^^^^^^^^^^^ Miri evaluation error: attempted to do invalid arithmetic on pointers that would leak base addresses, e.g., comparing pointers into different allocations
    |

Discovered in rust-lang/rust#60606

[oli-obk]

This is expected. Even just dbg!(&1 as *const i32); by itself will fail in miri.

The issue tracking a solution to this is #224

[kpp]

Thanks