lean4-htt/tests/lean/run/grind_try_trace.lean
jrr6 34bd6e8bfd
feat: improve split error messages (#9424)
This PR improves the error messages produced by the `split` tactic,
including suggesting syntax fixes and related tactics with which it
might be confused.

Note that, to avoid clashing with the new error message styling
conventions used in these messages, this PR also updates the formatting
of the message produced by `throwTacticEx`.

Closes #6224
2025-07-18 22:36:10 +00:00

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reset_grind_attrs%
/--
info: Try these:
• simp
• simp only [ne_eq, reduceCtorEq, not_false_eq_true]
• grind
• grind only
• simp_all
-/
#guard_msgs (info) in
example : [1, 2] ≠ [] := by
try?
/--
info: Try these:
• simp +arith
• simp +arith only [ge_iff_le]
• grind
• grind only
-/
#guard_msgs (info) in
example : 4 + x + y ≥ 1 + x := by
try?
/--
info: Try these:
• simp +arith
• grind
-/
#guard_msgs (info) in
example : 4 + x + y ≥ 1 + x := by
try? -only
/--
info: Try these:
• grind
• grind only
-/
#guard_msgs (info) in
example (f : Nat → Nat) : f a = b → a = c → f c = b := by
try?
def f : Nat → Nat
| 0 => 1
| _ => 2
/--
info: Try these:
• grind [= f]
• grind only [f]
-/
#guard_msgs (info) in
example : f (f 0) > 0 := by
try?
/--
info: Try these:
• grind [= f.eq_def]
• grind only [= f.eq_def]
-/
#guard_msgs (info) in
example : f x > 0 := by
try?
def app : List α → List α → List α
| [], bs => bs
| a::as, bs => a :: app as bs
/--
info: Try these:
• rfl
• grind [= app]
• grind only [app]
-/
#guard_msgs (info) in
example : app [a, b] [c] = [a, b, c] := by
try?
/--
info: Try these:
• (fun_induction app as bs) <;> grind [= app]
• (fun_induction app as bs) <;> grind only [app]
-/
#guard_msgs (info) in
example : app (app as bs) cs = app as (app bs cs) := by
try?
/-- info: Try this: (fun_induction app as bs) <;> grind [= app] -/
#guard_msgs (info) in
example : app (app as bs) cs = app as (app bs cs) := by
try? (max := 1)
/--
info: Try these:
• · expose_names; fun_induction app as bs_1 <;> grind [= app]
• · expose_names; fun_induction app as bs_1 <;> grind only [app]
-/
#guard_msgs (info) in
example : app (app as bs) cs = app as (app bs cs) := by
have bs := 20 -- shadow variable in the goal
try?
/--
info: Try these:
• · expose_names; fun_induction app as bs <;> grind [= app]
• · expose_names; fun_induction app as bs <;> grind only [app]
-/
#guard_msgs (info) in
example : app (app as bs) cs = app as (app bs cs) := by
revert as bs cs
intro _ _ _
-- `as`, `bs`, and `cs` now have inaccessible names.
try?
def concat : List αα → List α
| .nil, b => .cons b .nil
| .cons a as, b => .cons a (concat as b)
attribute [simp] concat
/--
info: Try these:
• (fun_induction concat) <;> simp_all
• (fun_induction concat) <;> simp [*]
-/
#guard_msgs (info) in
example (as : List α) (a : α) : concat as a = as ++ [a] := by
try? -only
/--
info: Try these:
• (fun_induction concat) <;> simp_all
• · fun_induction concat
· simp
· simp [*]
-/
#guard_msgs (info) in
example (as : List α) (a : α) : concat as a = as ++ [a] := by
try? -only -merge
def map (f : α → β) : List α → List β
| [] => []
| x::xs => f x :: map f xs
/--
info: Try these:
• (fun_induction map f xs) <;> grind [= map]
• (fun_induction map f xs) <;> grind only [map]
-/
#guard_msgs (info) in
theorem map_map (f : α → β) (g : β → γ) xs :
map g (map f xs) = map (fun x => g (f x)) xs := by
try?
def foo : Nat → Nat
| 0 => 1
| x+1 => foo x - 1
/--
info: Try these:
• · fun_induction foo
· simp
· sorry
• · fun_induction foo
· grind
· sorry
• · fun_induction foo
· simp_all
· sorry
-/
#guard_msgs (info) in
example : foo x > 0 := by
try? +missing -only -- `try?` does not solve all subgoals.
sorry
/--
error: Tactic `try?` failed: consider using `grind` manually, or `try? +missing` for partial proofs containing `sorry`
x : Nat
⊢ foo x > 0
-/
#guard_msgs (error) in
example : foo x > 0 := by
try?
@[simp] def bla : List Nat → List Nat → List Nat
| [], ys => ys.reverse
| _::xs, ys => bla xs ys
attribute [grind] List.length_reverse bla
/--
info: Try these:
• (fun_induction bla) <;> grind
• (fun_induction bla) <;> simp_all
• (fun_induction bla) <;> simp [*]
• (fun_induction bla) <;> simp only [List.length_reverse, *]
• (fun_induction bla) <;> grind only [List.length_reverse]
-/
#guard_msgs (info) in
example : (bla xs ys).length = ys.length := by
try?