all of rust codebase: This codebase fails even the most basic miri checks, allows for UB in safe rust

error: Undefined Behavior: constructing invalid value of type &[u8]: encountered a dangling reference (0x20933[noalloc] has no provenance)
  --> src/main.rs:97:18
   |
97 |         unsafe { core::slice::from_raw_parts(ptr as *const u8, self.len()) }
   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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: stack backtrace:
           0: PathString::slice
               at src/main.rs:97:18: 97:75
           1: main
               at src/main.rs:130:22: 130:34

fn main() {
    let test = Box::new(*b"Hello World");
    let init = PathString::init(&*test);
    drop(test);

    println!("{:?}", init.slice());
}