Goal:
  
  A : Type
  P : A → Prop
  Q : A → Prop
  p : A → bool
  x : A
  l : list A
  H : Q x
  HQ : Forall Q l
  Hp : ∀ x : A, Q x → reflect (P x) (p x)
  IHHQ : Forall P l → forallb p l = true
  H0 : P x
  HP : Forall P l
  ============================
   (p x && true = true)


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

In environment
A : Type
P, Q : A → Prop
p : A → bool
x : A
l : list A
H : Q x
HQ : Forall Q l
Hp : ∀ x : A, Q x → reflect (P x) (p x)
IHHQ : Forall P l → forallb p l = true
H0 : P x
HP : Forall P l
Unable to unify "true" with "p x && true".
Level 0: Backtrace:

In environment
A : Type
P, Q : A → Prop
p : A → bool
x : A
l : list A
H : Q x
HQ : Forall Q l
Hp : ∀ x : A, Q x → reflect (P x) (p x)
IHHQ : Forall P l → forallb p l = true
H0 : P x
HP : Forall P l
Unable to unify "true" with "p x && true".
Level 0: Backtrace:

No applicable tactic.
Level 0: Backtrace:

No applicable tactic.