error: using function pointers as const generic parameters is forbidden
  --> $DIR/fn-const-param-infer.rs:7:25
   |
LL | struct Checked<const F: fn(usize) -> bool>;
   |                         ^^^^^^^^^^^^^^^^^
   |
   = note: the only supported types are integers, `bool` and `char`
   = note: more complex types are supported with `#[feature(const_generics)]`

error: aborting due to previous error