lean4-htt/tests/elab/multiTargetCasesInductionIssue.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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def Vec (α : Type u) (n : Nat) : Type u := { a : List α // a.length = n }
def Vec.nil : Vec α 0 := ⟨[], rfl⟩
def Vec.cons (a : α) (as : Vec α n) : Vec α (n+1) := ⟨a :: as.val, by simp [as.property]⟩
set_option pp.analyze false
set_option linter.unusedVariables false
set_option pp.mvars false
def Vec.casesOn
(motive : (n : Nat) → Vec α n → Sort v)
(n : Nat)
(as : Vec α n)
(nil : motive 0 Vec.nil)
(cons : (n : Nat) → (a : α) → (as : Vec α n) → (ih : motive n as) → motive (n+1) (Vec.cons a as))
: motive n as :=
let rec go (n : Nat) (as : List α) (h : as.length = n) : motive n ⟨as, h⟩ :=
match n, as, h with
| 0, [], _ => nil
| n+1, a::as, h =>
have : as.length = n := by injection h
have ih : motive n ⟨as, this⟩ := go n as this
cons n a ⟨as, this⟩ ih
match as with
| ⟨as, h⟩ => go n as h
/--
trace: α : Type u_1
n✝ : Nat
a✝ : α
as✝ : Vec α n✝
x✝ n : Nat
a : α
as : Vec α n
ih : as = as
⊢ Vec.cons a as = Vec.cons a as
-/
#guard_msgs in
example (n : Nat) (a : α) (as : Vec α n) : Vec.cons a (Vec.cons a as) = Vec.cons a (Vec.cons a as) := by
induction n+2, Vec.cons a (Vec.cons a as) using Vec.casesOn
case nil => constructor
case cons n a as ih =>
trace_state
constructor
/--
trace: α : Type u_1
n✝ : Nat
a✝ : α
as✝ : Vec α n✝
n : Nat
a : α
as : Vec α n
ih : n + 1 = n → Vec.cons a as ≍ as → Vec.cons a as = Vec.cons a as
⊢ Vec.cons a as = Vec.cons a as
-/
#guard_msgs in
example (n : Nat) (a : α) (as : Vec α n) : Vec.cons a (Vec.cons a as) = Vec.cons a (Vec.cons a as) := by
cases n+2, Vec.cons a (Vec.cons a as) using Vec.casesOn
case nil => constructor
case cons n a as ih =>
trace_state
constructor
/--
trace: α : Type u_1
n : Nat
a : α
as : Vec α n
n' : Nat
a' : α
as' : Vec α n'
h₁ : n + 2 = n' + 1
h₂ : Vec.cons a (Vec.cons a as) ≍ Vec.cons a' as'
ih : n' + 1 = n' → Vec.cons a' as' ≍ as' → Vec.cons a' as' = Vec.cons a' as'
⊢ Vec.cons a' as' = Vec.cons a' as'
-/
#guard_msgs in
example (n : Nat) (a : α) (as : Vec α n) : Vec.cons a (Vec.cons a as) = Vec.cons a (Vec.cons a as) := by
cases h₁ : n+2, h₂ : Vec.cons a (Vec.cons a as) using Vec.casesOn
case nil => constructor
case cons n' a' as' ih =>
trace_state
constructor