Rust中数组原始指针转切片原始指针的合法性与运行疑问

我正在深入理解Rust的原始指针，原本以为下面这段代码会报错（甚至可能存在未定义行为）：

fn main() {
    println!("size of * const u32 ->{}", std::mem::size_of::<* const u32>());
    println!("size of * const [u32;13] ->{}", std::mem::size_of::<* const [u32;13]>());
    println!("size of * const [u32] ->{}", std::mem::size_of::<* const [u32]>());
    let x = 1u32;
    let arr = [1,2,3,4,5,6,7,8, 9, 10, 11, 12, 13u32];
    let px: * const u32 = &x;
    let parr: * const [u32;13] = &arr;
    let slice: &[u32] = &arr;
    let pslice: * const [u32] = slice;
    unsafe { println!("px -> {:?}", px.as_ref()) };
    unsafe { println!("parr -> {:?}", parr.as_ref()) };
    unsafe { println!("pslice -> {:?}", pslice.as_ref()) };
    //
    println!("How could this work:");
    let pslice2: * const [u32] = parr; // How could this work ?
    unsafe { println!("pslice2 -> {:?}", pslice2.as_ref()) }; // How could this work ?
}

但它甚至在miri下都能正常运行，输出如下：

Standard Error

   Compiling playground v0.0.1 (/playground)
    Finished dev [unoptimized + debuginfo] target(s) in 1.16s
     Running `/playground/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/cargo-miri runner target/miri/x86_64-unknown-linux-gnu/debug/playground`

Standard Output

size of * const u32 ->8
size of * const [u32;13] ->8
size of * const [u32] ->16
px -> Some(1)
parr -> Some([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13])
pslice -> Some([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13])
How could this work:
pslice2 -> Some([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13])

我能理解切片指针大小为16、数组指针大小为8——毕竟切片类型本身不包含数据长度。但我搞不懂的是，let pslice2: * const [u32] = parr;（parr是*const [u32;13]类型）这行代码为什么能被编译器接受？而且调用as_ref()后还能正常输出数据？

内容的提问来源于stack exchange，提问作者FreD