error: the constant `MAIN_SEPARATOR` is not of type `usize`
  --> $DIR/non-local-const.rs:9:14
   |
LL | impl Foo for [u8; std::path::MAIN_SEPARATOR] {}
   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `usize`, found `char`
   |
   = note: the length of array `[u8; MAIN_SEPARATOR]` must be type `usize`

error: aborting due to 1 previous error