Goal:
    A : Type  HA : ReflectEq A  x : option A  y : option A
  ============================
   (reflectProp (x = y) (eq_option eqb x y))


DEBUG:Going to execute:
match H with
           | H' => fail 2
           | _ => unify X Y; clear H' || clear H
           end
Level 4: Backtrace:

x is used in conclusion.
Level 4: Backtrace:

x is used in conclusion.
Level 4: Backtrace:

x is used in conclusion.
Level 4: Backtrace:

x is used in conclusion.
Level 4: Backtrace:

x is used in conclusion.
Level 4: Backtrace:

x is used in conclusion.
Level 4: Backtrace:

x is used in conclusion.
Level 3: Backtrace:

x is used in conclusion.