Rollup merge of #97219 - RalfJung:ptr-invalid, r=thomcc

make ptr::invalid not the same as a regular int2ptr cast

In Miri, we would like to distinguish `ptr::invalid` from `ptr::from_exposed_provenance`, so that we can provide better diagnostics issues like https://github.com/rust-lang/miri/issues/2134, and so that we can detect the UB in programs like
```rust
fn main() {
    let x = 0u8;
    let original_ptr = &x as *const u8;
    let addr = original_ptr.expose_addr();
    let new_ptr: *const u8 = core::ptr::invalid(addr);
    unsafe {
        dbg!(*new_ptr);
    }
}
```

To achieve that, the two functions need to have different implementations. Currently, both are just `as` casts. We *could* add an intrinsic for this, but it turns out `transmute` already has the right behavior, at least as far as Miri is concerned. So I propose we just use that.

Cc `@Gankra`

0 files changed, 0 insertions, 0 deletions