Goal:
  
  A : Type
  P : list A → A → Type
  b0 : All_fold P []
  b' : list A
  b : All_fold P b'
  ============================
   ({| pr1 := []; pr2 := b0 |} = {| pr1 := b'; pr2 := b |}
    → let H := CoreTactics.block in
      NoConfusionHom_All_fold A P [] (All_fold_nil P) b0
      → let H0 := CoreTactics.block in All_fold_nil P = b0)


DEBUG:Going to execute:
match p with
           | _ => generalize dependent p; intros p
           end
Level 3: evaluation returns
first
[ match p with
  | _ => generalize dependent p; intros p
  end
| intros
until
p
| intros
until
1
| intros ]
where
p := b
of type
constr of type tacvalue

Level 3: evaluation returns
first
[ match p with
  | _ => generalize dependent p; intros p
  end
| intros
until
p
| intros
until
1
| intros ]
where
p := b
of type
constr of type tacvalue