error: Undefined Behavior: trying to retag from <TAG> for Unique permission at ALLOC[0x0], but that tag only grants SharedReadOnly permission for this location
  --> RUSTLIB/core/src/ptr/mod.rs:LL:CC
   |
LL | pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   | |
   | trying to retag from <TAG> for Unique permission at ALLOC[0x0], but that tag only grants SharedReadOnly permission for this location
   | this error occurs as part of retag at ALLOC[0x0..0x1]
   |
   = help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
   = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information
help: <TAG> was created by a SharedReadOnly retag at offsets [0x0..0x1]
  --> $DIR/drop_in_place_retag.rs:LL:CC
   |
LL |         let x = core::ptr::addr_of!(x);
   |                 ^^^^^^^^^^^^^^^^^^^^^^
   = note: BACKTRACE:
   = note: inside `std::ptr::drop_in_place::<u8> - shim(None)` at RUSTLIB/core/src/ptr/mod.rs:LL:CC
note: inside `main`
  --> $DIR/drop_in_place_retag.rs:LL:CC
   |
LL |         core::ptr::drop_in_place(x.cast_mut());
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   = note: this error originates in the macro `core::ptr::addr_of` (in Nightly builds, run with -Z macro-backtrace for more info)

note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace

error: aborting due to previous error