error: `[u8; _]` is forbidden as the type of a const generic parameter
  --> $DIR/nested-type.rs:6:21
   |
LL |   struct Foo<const N: [u8; {
   |  _____________________^
LL | |     struct Foo<const N: usize>;
LL | |
LL | |     impl<const N: usize> Foo<N> {
...  |
LL | |
LL | | }]>;
   | |__^
   |
   = note: the only supported types are integers, `bool` and `char`
   = help: more complex types are supported with `#![feature(adt_const_params)]`

error: aborting due to previous error