$ cat a.rs 
pub static A: fn() -> fn() = {
    #[inline(never)]
    fn f() {}
    #[inline(always)]
    || -> fn() { f }
};
$ cat b.rs
static A: fn() -> fn () = a::A;
fn main() { A()() }
$ rustc a.rs --crate-type=lib
$ rustc b.rs --extern a -L.
error: missing optimized MIR for an item in the crate `a`
  |
note: missing optimized MIR for this item (was the crate `a` compiled with `--emit=metadata`?)
 --> /.../a.rs:3:5
  |
3 |     fn f() {}
  |     ^^^^^^

error: aborting due to 1 previous error