lean4-htt/tests/lean/run/decideTacticKernel.lean
Kyle Miller b1e0c1b594
chore: remove decide! tactic (#6016)
This PR removes the `decide!` tactic in favor of `decide +kernel`
(breaking change).
2024-11-15 17:49:33 +00:00

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/-!
# `decide +kernel` tests
-/
/-!
Very basic tests
-/
theorem foo1 : True := by decide
theorem foo2 : True := by decide +kernel
/-!
Tests of the error message when goal is false.
-/
/--
error: tactic 'decide' proved that the proposition
False
is false
-/
#guard_msgs in
theorem foo3 : False := by decide
/--
error: tactic 'decide' proved that the proposition
False
is false
-/
#guard_msgs in
theorem foo4 : False := by decide +kernel
/-!
The kernel sees through irreducible definitions
-/
@[irreducible] def irred {α : Type} (x : α) : α := x
/--
error: tactic 'decide' failed for proposition
irred 3 = 3
since its 'Decidable' instance
instDecidableEqNat (irred 3) 3
did not reduce to 'isTrue' or 'isFalse'.
After unfolding the instances 'instDecidableEqNat' and 'Nat.decEq', reduction got stuck at the 'Decidable' instance
match h : (irred 3).beq 3 with
| true => isTrue ⋯
| false => isFalse ⋯
-/
#guard_msgs in theorem gcd_eq1 : irred 3 = 3 := by decide
theorem gcd_eq2 : irred 3 = 3 := by decide +kernel
/-!
The proofs from `decide +kernel` are cached.
-/
theorem thm1 : ∀ x < 100, x * x ≤ 10000 := by decide +kernel
theorem thm1' : ∀ x < 100, x * x ≤ 10000 := by decide +kernel
-- (Note: when run within VS Code, these tests fail since the auxLemmas have a `lean.run` prefix.)
/--
info: theorem thm1 : ∀ (x : Nat), x < 100 → x * x ≤ 10000 :=
decideTacticKernel._auxLemma.3
-/
#guard_msgs in #print thm1
/--
info: theorem thm1' : ∀ (x : Nat), x < 100 → x * x ≤ 10000 :=
decideTacticKernel._auxLemma.3
-/
#guard_msgs in #print thm1'
/-!
Reverting free variables.
-/
/--
error: expected type must not contain free variables
x + 1 ≤ 5
Use the '+revert' option to automatically cleanup and revert free variables.
-/
#guard_msgs in
example (x : Nat) (h : x < 5) : x + 1 ≤ 5 := by decide +kernel
example (x : Nat) (h : x < 5) : x + 1 ≤ 5 := by decide +kernel +revert
/--
Can handle universe levels.
-/
instance (p : PUnit.{u} → Prop) [Decidable (p PUnit.unit)] : Decidable (∀ x : PUnit.{u}, p x) :=
decidable_of_iff (p PUnit.unit) (by constructor; rintro _ ⟨⟩; assumption; intro h; apply h)
example : ∀ (x : PUnit.{u}), x = PUnit.unit := by decide +kernel