mutably borrowed Type Alias incorrectly marked as immutable

this is a weird one. When asserting the type of the length of an array with as usize a bug occurs where passing a variable that is &mut Alias into a function that take &Alias marks that variable as immutable.

This does not happen when the type alias is changed to type ArrayAlias = [u16; 8];

type ArrayAlias = [u16; 8 as usize];

fn main() {}

fn produce_error(array: &mut ArrayAlias) {
    mark_register_immutable(array);
    array[0] = 5; // cannot mutate immutable variable `array`
}

fn mark_register_immutable(_: &ArrayAlias){
}

Start by reproducing the provided Rust snippet and compare it with the version using type ArrayAlias = [u16; 8];. Trace how the type alias with 8 as usize is handled when passing &mut ArrayAlias to &ArrayAlias. Done means array[0] = 5 remains mutable in the reproducer, with coverage for both alias definitions.