error: Undefined Behavior: pointer not dereferenceable: pointer must be dereferenceable for 4 bytes, but got 0x4[noalloc] which is a dangling pointer (it has no provenance)
  --> RUSTLIB/alloc/src/boxed.rs:LL:CC
   |
LL |         Box(unsafe { Unique::new_unchecked(raw) }, alloc)
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here
   |
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: BACKTRACE:
   = note: inside `std::boxed::Box::<i32>::from_raw_in` at RUSTLIB/alloc/src/boxed.rs:LL:CC
   = note: inside `std::boxed::Box::<i32>::from_raw` at RUSTLIB/alloc/src/boxed.rs:LL:CC
note: inside `main`
  --> tests/fail/both_borrows/issue-miri-1050-2.rs:LL:CC
   |
LL |         drop(Box::from_raw(ptr.as_ptr()));
   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^

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

error: aborting due to 1 previous error