lean4-htt/tests/elab/wf_preprocess_leak.lean
Garmelon 08eb78a5b2
chore: switch to new test/bench suite (#12590)
This PR sets up the new integrated test/bench suite. It then migrates
all benchmarks and some related tests to the new suite. There's also
some documentation and some linting.

For now, a lot of the old tests are left alone so this PR doesn't become
even larger than it already is. Eventually, all tests should be migrated
to the new suite though so there isn't a confusing mix of two systems.
2026-02-25 13:51:53 +00:00

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/-! This tests demonstrates where and how wf preprocessing leaks to the user -/
structure Tree (α : Type) where
cs : List (Tree α)
def Tree.isLeaf (t : Tree α) := t.cs.isEmpty
-- The `cs.map` in the outer call to `revrev` gets the `attach`-attaching treatment and shows up in
-- the proof state:
/--
trace: α : Type
n : Nat
cs : List (Tree α)
x✝ :
(y : (_ : Nat) ×' Tree α) →
(invImage (fun x => PSigma.casesOn x fun n t => (n, t)) Prod.instWellFoundedRelation).1 y ⟨n.succ, { cs := cs }⟩ →
Tree α
⊢ Prod.Lex (fun a₁ a₂ => a₁ < a₂) (fun a₁ a₂ => sizeOf a₁ < sizeOf a₂)
(n, { cs := List.map (fun x => x✝ ⟨n + 1, x.val⟩ ⋯) cs.attach }) (n.succ, { cs := cs })
-/
#guard_msgs(trace) in
def Tree.revrev : (n : Nat) → (t : Tree α) → Tree α
| 0, t => t
| n + 1, Tree.mk cs => revrev n (Tree.mk (cs.map (·.revrev (n + 1))))
termination_by n t => (n, t)
decreasing_by
· apply Prod.Lex.right
simp
have := List.sizeOf_lt_of_mem _ ∈ _
omega
· trace_state
apply Prod.Lex.left
decreasing_tactic
-- as well as in the induction principle:
-- set_option trace.Meta.FunInd true
/--
info: Tree.revrev.induct {α : Type} (motive : Nat → Tree α → Prop) (case1 : ∀ (t : Tree α), motive 0 t)
(case2 :
∀ (n : Nat) (cs : List (Tree α)),
(∀ (x : Tree α), x ∈ cs → motive (n + 1) x) →
(∀ (x : Subtype (Membership.mem cs)), motive (n + 1) x.val) →
motive n
{
cs :=
List.map
(fun x =>
match x with
| ⟨x, h⟩ => Tree.revrev (n + 1) x)
cs.attach } →
motive n.succ { cs := cs })
(n : Nat) (t : Tree α) : motive n t
-/
#guard_msgs in
#check Tree.revrev.induct
-- Tangent: Why three IHs here? Because in the termination proof, the `
-- match x with | ⟨x, h⟩ => Tree.revrev (n + 1) x)
-- was replaced by
-- Tree.revrev (n + 1) ↑x
-- (maybe due to split/simpMatch) and funind picks up that recursive call as a separate one.
-- See
-- set_option pp.proofs true in #print Tree.revrev._unary
-- set_option pp.proofs true in #print Tree.revrev._unary.proof_3
-- It does not show up in the equational theorems:
/--
info: equations:
theorem Tree.revrev.eq_1 : ∀ {α : Type} (x : Tree α), Tree.revrev 0 x = x
theorem Tree.revrev.eq_2 : ∀ {α : Type} (n : Nat) (cs : List (Tree α)),
Tree.revrev n.succ { cs := cs } = Tree.revrev n { cs := List.map (fun x => Tree.revrev (n + 1) x) cs }
-/
#guard_msgs in
#print equations Tree.revrev
theorem sizeOf_map {α β : Type} [SizeOf α] [SizeOf β]
(f : α → β) (xs : List α) (hf : ∀ x, x ∈ xs → sizeOf (f x) = sizeOf x) :
sizeOf (List.map f xs) = sizeOf xs := by
induction xs with
| nil =>
simp
| cons x xs ih =>
simp [List.map]
simp [hf]
apply ih
intro x hx
apply hf
apply List.mem_cons.2
exact Or.inr hx
-- Lets see how tedious it is to use the functional induction principle:
example (n : Nat) (t : Tree α) : sizeOf (Tree.revrev n t) = sizeOf t := by
induction n, t using Tree.revrev.induct with
| case1 =>
simp [Tree.revrev]
| case2 n cs ih1 ih2 ih3 =>
simp [Tree.revrev]
simp only [Subtype.forall, List.map_subtype, List.unattach_attach, Tree.mk.sizeOf_spec] at *
rw [ih3]; clear ih3
rw [sizeOf_map]
· assumption