error: Undefined Behavior: reading memory at ALLOC[0x5..0x6], but memory is uninitialized at [0x5..0x6], and this operation requires initialized memory
  --> tests/fail/uninit/uninit_byte_read.rs:LL:CC
   |
LL |     let undef = unsafe { *v.as_ptr().add(5) };
   |                          ^^^^^^^^^^^^^^^^^^ 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 `main` at tests/fail/uninit/uninit_byte_read.rs:LL:CC

Uninitialized memory occurred at ALLOC[0x5..0x6], in this allocation:
ALLOC (Rust heap, size: 10, align: 1) {
    __ __ __ __ __ __ __ __ __ __                   │ ░░░░░░░░░░
}

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

error: aborting due to 1 previous error