import Lean

inductive MyEmpty

def f (x : MyEmpty) : Nat :=
  MyEmpty.casesOn _ x

set_option trace.Compiler.result true
/--
info: [Compiler.result] size: 0
    def f._redArg : Nat :=
      ⊥
[Compiler.result] size: 0 def f x : Nat := ⊥
-/
#guard_msgs in
run_meta Lean.Compiler.compile #[``f]