Ltac not_a_prop := match goal with
  | |- not_a_prop  (prop _) => fail 1
  | |- _ => apply Coq.Init.Logic.I
end.Ltac cancel1 :=
 first [
   simple apply cancel1_here; [
    try match goal with H := _ : list mpred |- _ => clear H end; (*
      this line is to work around Coq 8.4 bug,
      Anomaly: undefined_evars_of_term *)
    solve [eauto with nocore cancel]
   | ]
 | simple apply cancel1_next; cancel1
 | simple apply cancel1_last; [
    try match goal with H := _ : list mpred |- _ => clear H end; (*
      this line is to work around Coq 8.4 bug,
      Anomaly: undefined_evars_of_term *)
    solve [eauto with nocore cancel] | ]
 ].Ltac cancel2 :=
  simple apply cancel1_start;
  cancel1;
  repeat simple apply cancel1_finish1;
  try simple apply cancel1_finish2.Ltac lift1 a e1 rho  :=
 match e1 with
 | lift0 rho => constr:(a)
 | lift0 ?a1 => constr: (lift0 (a a1))
 | _ => constr:(lift1 a e1)
 end.Ltac lift2 a e1 e2 rho :=
 match e1 with
 |  lift0 ?a1 => lift1 (a a1) e2 rho
 | _ => constr:(lift2 a e1 e2)
 end.Ltac lift3 a e1 e2 e3 rho :=
 match e1 with
 |  lift0 ?a1 => lift2 (a a1) e2 e3 rho
 | _ => constr:(lift3 a e1 e2 e3)
 end.Ltac lift4 a e1 e2 e3 e4 rho :=
 match e1 with
 |  lift0 ?a1 => lift3 (a a1) e2 e3 e4 rho
 | _ => constr:(lift4 a e1 e2 e3 e4)
 end.Ltac abstract_env rho P :=
  match P with
   | @emp mpred _ _ => constr:(@emp (environ->mpred) _ _)
   | @sepcon mpred _ _ ?e1 ?e2 =>
      let e1' := abstract_env rho e1 in let e2' := abstract_env rho e2
       in constr:(@sepcon (environ->mpred) _ _ e1' e2')
   | ?a0 ?a1 ?a2 ?e1 ?e2 ?e3 ?e4 =>
      let e1' := abstract_env rho e1  in let e2' := abstract_env rho e2 in let e3' := abstract_env rho e3 in let e4' := abstract_env rho e4
      in lift3 (a0 a1 a2) e1' e2' e3' e4' rho
   | ?a0 ?a1 ?e1 ?e2 ?e3 ?e4 =>
      let e1' := abstract_env rho e1 in let e2' := abstract_env rho e2 in let e3' := abstract_env rho e3 in let e4' := abstract_env rho e4
      in lift3 (a0 a1) e1' e2' e3' e4' rho
   | ?a0 ?e1 ?e2 ?e3 ?e4 =>
      let e1' := abstract_env rho e1 in let e2' := abstract_env rho e2 in let e3' := abstract_env rho e3 in let e4' := abstract_env rho e4
      in lift4 a0 e1' e2' e3' e4' rho
   | ?a0 ?e1 ?e2 ?e3 =>
      let e1' := abstract_env rho e1 in let e2' := abstract_env rho e2 in let e3' := abstract_env rho e3
      in lift3 a0 e1' e2' e3' rho
   | ?a0 ?e1 ?e2 =>
      let e1' := abstract_env rho e1 in let e2' := abstract_env rho e2
      in lift2 a0 e1' e2' rho
   | ?a0 ?e1 => let e1' := abstract_env rho e1 in lift1 a0 e1' rho
   | rho => constr: (lift1)
   | ?a => constr:(lift0 a)
   end.Ltac fixup_lifts :=
 repeat
 match goal with
 | |- context[@lift0 mpred] => change (@lift0 mpred) with (@liftx (LiftEnviron mpred))
 | |- context[@lift1 ?A] => change (@lift1 A mpred) with (@liftx (Tarrow A (LiftEnviron mpred)))
 | |- context[@lift2 ?A ?B] =>  change (@lift2 A B mpred) with (@liftx (Tarrow A (Tarrow B (LiftEnviron mpred))))
 | |- context[@lift3 ?A ?B ?C] => change (@lift3 A B C mpred) with (@liftx (Tarrow A (Tarrow B (Tarrow C (LiftEnviron mpred)))))
 | |- context[@lift4 ?A ?B ?C ?D] => change (@lift4 A B C D mpred) with (@liftx (Tarrow A (Tarrow B (Tarrow C (Tarrow D (LiftEnviron mpred))))))
 end.Fixpoint fold_right_sepconx (l: list mpred) : mpred :=
match l with
| nil => emp
| a::nil => a
| a::b => a * fold_right_sepconx b
end.Definition fold_left_sepconx (l: list mpred) : mpred :=
match l with
| nil => emp
| a::l => (fix fold_left_sepconx (a: mpred) (l: list mpred) {struct l}: mpred :=
          match l with
          | nil => a
          | b :: l => fold_left_sepconx (sepcon a b) l
          end) a l
end.

Lemma fold_left_sepconx_eq: forall l, fold_left_sepconx l = fold_right_sepcon l.