lean4-htt/tests/elab/simpLoopProtection.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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set_option linter.unusedSimpArgs false
axiom testSorry : α
opaque a : Nat
opaque b : Nat
theorem ab : a = b := testSorry
theorem ba : b = a := testSorry
theorem aa : a = id a := testSorry
/--
warning: Possibly looping simp theorem: `aa`
Note: Possibly caused by: `id`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : id a = 23 := by simp -failIfUnchanged only [aa, id]
-- also simp_all
/--
warning: Possibly looping simp theorem: `aa`
Note: Possibly caused by: `id`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : id a = 23 := by simp_all -failIfUnchanged only [aa, id]
-- Other exceptions do not trigger the loop check
/--
error: unsolved goals
⊢ b = 23
-/
#guard_msgs in
example : id b = 23 := by simp -failIfUnchanged only [aa, id]
/--
warning: Possibly looping simp theorem: `aa`
Note: Possibly caused by: `id`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
Note: This linter can be disabled with `set_option linter.loopingSimpArgs false`
---
error: unsolved goals
⊢ b = 23
-/
#guard_msgs in
set_option linter.loopingSimpArgs true in
example : id b = 23 := by simp -failIfUnchanged only [aa, id]
/-- error: `simp` made no progress -/
#guard_msgs in
example : b = 23 := by simp only [aa, id]
/--
warning: Possibly looping simp theorem: `ab`
Note: Possibly caused by: `ba`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
warning: Possibly looping simp theorem: `ba`
Note: Possibly caused by: `ab`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : a = 23 := by simp -failIfUnchanged [ab, ba]
/--
warning: Possibly looping simp theorem: `ab`
Note: Possibly caused by: `ba`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
warning: Possibly looping simp theorem: `ba`
Note: Possibly caused by: `ab`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : a = 2*b := by simp -failIfUnchanged [ab, ba]
/--
warning: Possibly looping simp theorem: `← ab`
Note: Possibly caused by: `← ba`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
warning: Possibly looping simp theorem: `← ba`
Note: Possibly caused by: `← ab`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : a = 23 := by simp -failIfUnchanged [← ab, ← ba]
-- Local theorems are not checked for loops,
-- but are still applied when checking other rules
/--
warning: Possibly looping simp theorem: `ab`
Note: Possibly caused by: `h`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example (h : b = a) : a = 23 := by simp -failIfUnchanged [ab, h]
/-! Examples from the original RFC -/
variable (P : Nat → Prop)
/--
warning: Possibly looping simp theorem: `Nat.add_assoc`
Note: Possibly caused by: `(Nat.add_assoc _ _ _).symm`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
warning: Possibly looping simp theorem: `(Nat.add_assoc _ _ _).symm`
Note: Possibly caused by: `Nat.add_assoc`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example (a b c : Nat) : P (a + b + c) := by simp [Nat.add_assoc, (Nat.add_assoc _ _ _).symm]
inductive Tree (α : Type) where | node : α → List (Tree α) → Tree α
def Tree.children : Tree α → List (Tree α) | .node _ ts => ts
def Tree.size (t : Tree α) := 1 + List.sum (t.children.attach.map (fun ⟨c,_⟩ => c.size))
decreasing_by simp_wf; cases t; simp_all [Tree.children]; decreasing_trivial
/--
warning: Possibly looping simp theorem: `Tree.size.eq_1`
Note: Possibly caused by: `Tree.size`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example (t : Tree α) : 0 < t.size := by simp [Tree.size]
/--
Identifiyng looping theorems by their origin is not enough,
as the elements of conjunctions would clash, as shown by these:
(The error message isn't great yet, but it's a corner case)
-/
theorem b1ab : b = 1 ∧ a = b := testSorry
theorem baab : b = a ∧ a = b := testSorry
/--
error: unsolved goals
P : Nat → Prop
⊢ 1 > 0
-/
#guard_msgs in
example : a > 0 := by simp only [b1ab]
/--
warning: Possibly looping simp theorem: `baab`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
warning: Possibly looping simp theorem: `baab`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : a > 0 := by simp only [baab]
-- Same, with local theorems (should we ever support them):
/--
error: unsolved goals
P : Nat → Prop
a b : Nat
h1 : b = 1 ∧ a = b
h2 : 1 > 0
⊢ True
-/
#guard_msgs in
example
(a b : Nat)
(h1 : b = 1 ∧ a = b )
(h2 : a > 0) : True := by
simp only [h1] at h2
/-!
Unfolding should not confuse it.
(Error message is not optimal as it does not mention the unfolded definition.)
-/
def c := a
def ac : a = c := rfl
def ca : c = a := rfl
def d := c
def dc : d = c := rfl
/--
warning: Possibly looping simp theorem: `c.eq_1`
Note: Possibly caused by: `ac` and `c`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
warning: Possibly looping simp theorem: `ac`
Note: Possibly caused by: `c`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : c > 0 := by simp only [c, ac]
/--
warning: Possibly looping simp theorem: `dc`
Note: Possibly caused by: `c` and `ac`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
warning: Possibly looping simp theorem: `c.eq_1`
Note: Possibly caused by: `ac` and `c`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
warning: Possibly looping simp theorem: `ac`
Note: Possibly caused by: `c`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : d > 0 := by simp only [dc, c, ac]
/--
warning: Possibly looping simp theorem: `c.eq_1`
Note: Possibly caused by: `ac` and `c`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
warning: Possibly looping simp theorem: `ac`
Note: Possibly caused by: `c`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : a > 0 := by simp only [c, ac]
example (h : c = 1) : d > 0 := by simp only [dc, h, ca, ac, Nat.one_pos]
/-!
Simp? does not print the warnings for now. Lets see if users find that helpful or confusing.
-/
/--
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : d > 0 := by simp? only [dc, ca, ac]; exact testSorry
/-!
But we can turn it on:
-/
set_option linter.loopingSimpArgs true in
/--
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : d > 0 := by simp? only [dc, ca, ac]; exact testSorry
/--
info: Try this:
[apply] simp only [dc, h, Nat.one_pos]
-/
#guard_msgs in
example (h : c = 1) : d > 0 := by simp? only [dc, h, ca, ac, Nat.one_pos]
/-! An example where a second rewrite rules makes the looping rule looping,
without being itself looping.
-/
opaque f : Nat → Nat
theorem fbfa : f b = f a := testSorry
theorem fbffa : f b = f (f a) := testSorry
-- This one doesn't actually trigger because `simpLoop` does not recurse when
-- the expression is the same after `post`. Also see issue #8864
/--
error: unsolved goals
P : Nat → Prop
⊢ 0 < f a
-/
#guard_msgs in
example : 0 < f a := by simp -failIfUnchanged [fbfa, ab]
/--
warning: Possibly looping simp theorem: `fbffa`
Note: Possibly caused by: `ab`
Hint: You can disable a simp theorem from the default simp set by passing `- theoremName` to `simp`.
---
error: Tactic `simp` failed with a nested error:
maximum recursion depth has been reached
use `set_option maxRecDepth <num>` to increase limit
use `set_option diagnostics true` to get diagnostic information
-/
#guard_msgs in
example : 0 < f a := by simp -failIfUnchanged [fbffa, ab]