无法使用与特征相关的常量作为数组长度？

Question

请考虑以下特征：

trait Test {
    const COUNT: usize = 12;
    fn test() {
        let arr: [f32; Self::COUNT]; // doesn't work
        dbg!(Self::COUNT); // works
    }
}

dbg!(Self::COUNT)可以正常工作，但是我无法使用[f32; Self::COUNT]声明数组：

error[E0599]: no associated item named `COUNT` found for type `Self` in the current scope
 --> src/lib.rs:4:24
  |
4 |         let arr: [f32; Self::COUNT];
  |                        ^^^^^^^^^^^ associated item not found in `Self`
  |
  = help: items from traits can only be used if the trait is implemented and in scope
  = note: the following trait defines an item `COUNT`, perhaps you need to implement it:
          candidate #1: `Test`

但这在全局常量中有效：

const G_COUNT: usize = 1;
const G_ARR: [i32; G_COUNT] = [1]; // works

有没有办法使用与特质相关的常数，例如全局常数？

playground