In #144081, pointer fragment support was enabled in consteval. Then, a bug was found in #146291, so this support was supposedly then disabled in #146324. However, it seems like this disabling was not done properly.

The below code is adapted from the previously-deleted test in https://github.com/rust-lang/rust/pull/144081/files#diff-7882729ad52694021ddccdd40fefa200d6d24ead1d586852eb4816bce32f2c6b

const PARTIAL_OVERWRITE: () = { let mut p = &42; unsafe { let ptr: *mut _ = &mut p; *(ptr as *mut u8) = 123; } };

This code compiles in beta, but gives the following error in stable:

error[E0080]: unable to overwrite parts of a pointer in memory at alloc4 --> src/lib.rs:5:9 | 5 | *(ptr as *mut u8) = 123; | ^^^^^^^^^^^^^^^^^^^^^^^ evaluation of `PARTIAL_OVERWRITE` failed here | = help: this code performed an operation that depends on the underlying bytes representing a pointer = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported For more information about this error, try `rustc --explain E0080`. 

I am unable to reproduce the bug in #146291, but I still find it worrisome that new code was newly allowed seemingly unintentionally.

Is this operation intended to be supported in consteval?

cc @RalfJung

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Tested on the playground with versions 1.91.0-beta.9 (2025-10-17 1f251978870710eb72e9) and 1.90.0