rust should able to infer `Array<T>[CONST_START..CONST_END]` to type `[T; CONST_END - CONST_START]` at compile time

title

rust should able to infer Array<T>[CONST_START..CONST_END] to type [T; CONST_END - CONST_START] at compile time

code

const A: usize = 2;
const B: usize = 6;

fn main() {
    let buf: &[u8] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

    // OK as expected
    {
        let _: &[u8] = &buf[A..B];
    }

    {
        // // error[E0308]: mismatched types
        // // expected `&[u8; 4]`, found `&[u8]`
        // let _: &[u8; 4] = &buf[A..B];
    }

    // https://doc.rust-lang.org/src/core/array/mod.rs.html
    {
        let _ = <[u8; 4]>::try_from(&buf[A..B]).unwrap();
    }

    // https://docs.rs/crate/arrayref/latest/source/src/lib.rs
    {
        let _ = unsafe { &*((&buf[A..B]).as_ptr() as *const [u8; B - A]) };
    }
}

Start by reproducing the examples in the issue and reading the referenced core array module and arrayref implementation. Determine the language and compiler changes needed for a constant range slice to infer its array length, with the desired outcome being successful compile-time inference of [T; CONST_END - CONST_START].