Goal:
  
  A : Type
  x : A
  xs : list A
  f : A → bool
  H0 : ∀ f0 : A → bool,
         (λ (x : A) (_ : In x xs), f x) = (λ (x : A) (_ : In x xs), f0 x)
         → forallb_InP xs (λ (x : A) (_ : In x xs), f x) = forallb f0 xs
  ============================
   (forallb_InP (x :: xs) (λ (x0 : A) (_ : In x0 (x :: xs)), f x0) =
    forallb f (x :: xs))


DEBUG:Going to execute:
case not_locked_false_eq_true; Ltac.assumption
Level 1: Backtrace:

In environment
A : Type
x : A
xs : list A
f : A → bool
H0 : ∀ f0 : A → bool,
       (λ (x : A) (_ : In x xs), f x) = (λ (x : A) (_ : In x xs), f0 x)
       → forallb_InP xs (λ (x : A) (_ : In x xs), f x) = forallb f0 xs
Unable to unify "forallb f (x :: xs)" with
 "forallb_InP (x :: xs) (λ (x0 : A) (_ : In x0 (x :: xs)), f x0)".
Level 0: Backtrace:

In environment
A : Type
x : A
xs : list A
f : A → bool
H0 : ∀ f0 : A → bool,
       (λ (x : A) (_ : In x xs), f x) = (λ (x : A) (_ : In x xs), f0 x)
       → forallb_InP xs (λ (x : A) (_ : In x xs), f x) = forallb f0 xs
Unable to unify "forallb f (x :: xs)" with
 "forallb_InP (x :: xs) (λ (x0 : A) (_ : In x0 (x :: xs)), f x0)".
Level 0: Backtrace:

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.