Ltac destruct_eqb_type :=
match goal with H: context [eqb_type ?t1 ?t2] |- _ =>
let J := fresh "J" in
destruct (eqb_type t1 t2) eqn:?J;
[apply eqb_type_true in J | apply eqb_type_false in J]
end.

Lemma classify_cast_eq:
forall t1 t2,
t1 <> int_or_ptr_type ->
t2 <> int_or_ptr_type ->
classify_cast t1 t2 = Cop.classify_cast t1 t2.