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lean4/tests/elab/rewrites.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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private axiom test_sorry : {α}, α
-- To see the (sorted) list of lemmas that `rw?` will try rewriting by, use:
-- set_option trace.Tactic.rewrites.lemmas true
/--
info: Try this:
[apply] rw [List.map_append]
-- no goals
-/
#guard_msgs in
example (f : α β) (L M : List α) : (L ++ M).map f = L.map f ++ M.map f := by
rw?
/--
info: Try this:
[apply] rw [Nat.one_mul]
-- no goals
-/
#guard_msgs in
example (h : Nat) : 1 * h = h := by
rw?
#guard_msgs(drop info) in
example (h : Int) (hyp : g * 1 = h) : g = h := by
rw? at hyp
assumption
#guard_msgs(drop info) in
example : (x y : Nat), x y := by
intro x y
rw? -- Used to be an error here https://leanprover.zulipchat.com/#narrow/stream/287929-mathlib4/topic/panic.20and.20error.20with.20rw.3F/near/370495531
exact test_sorry
example : (x y : Nat), x y := by
-- Used to be a panic here https://leanprover.zulipchat.com/#narrow/stream/287929-mathlib4/topic/panic.20and.20error.20with.20rw.3F/near/370495531
fail_if_success rw?
exact test_sorry
axiom K : Type
@[instance] axiom K.hasOne : OfNat K 1
@[instance] axiom K.hasIntCoe : Coe K Int
noncomputable def foo : K K := test_sorry
#guard_msgs(drop info) in
example : foo x = 1 k : Int, x = k := by
rw? -- Used to panic, see https://leanprover.zulipchat.com/#narrow/stream/287929-mathlib4/topic/panic.20and.20error.20with.20rw.3F/near/370598036
exact test_sorry
theorem six_eq_seven : 6 = 7 := test_sorry
-- This test also verifies that we are removing duplicate results;
-- it previously also reported `Nat.cast_ofNat`
#guard_msgs(drop info) in
example : (x : Nat), x 6 := by
rw?
guard_target = (x : Nat), x 7
exact test_sorry
#guard_msgs(drop info) in
example : (x : Nat) (_w : x 6), x 8 := by
rw?
guard_target = (x : Nat) (_w : x 7), x 8
exact test_sorry
-- check we can look inside let expressions
#guard_msgs(drop info) in
example (n : Nat) : let y := 3; n + y = 3 + n := by
rw?
axiom α : Type
axiom f : α α
axiom z : α
axiom f_eq (n) : f n = z
-- Check that the same lemma isn't used multiple times.
-- This used to report two redundant copies of `f_eq`.
-- It be lovely if `rw?` could produce two *different* rewrites by `f_eq` here!
#guard_msgs(drop info) in
theorem test : f n = f m := by
fail_if_success rw? [-f_eq] -- Check that we can forbid lemmas.
rw?
rw [f_eq]
-- Check that we can rewrite by local hypotheses.
#guard_msgs(drop info) in
example (h : 1 = 2) : 2 = 1 := by
rw?
def zero : Nat := 0
-- This used to (incorrectly!) succeed because `rw?` would try `rfl`,
-- rather than `withReducible` `rfl`.
#guard_msgs(drop info) in
example : zero = 0 := by
rw?
exact test_sorry
-- Discharge side conditions from local hypotheses.
/--
info: Try this:
[apply] rw [h p]
-- no goals
-/
#guard_msgs in
example {P : Prop} (p : P) (h : P 1 = 2) : 2 = 1 := by
rw?
-- Use `solve_by_elim` to discharge side conditions.
/--
info: Try this:
[apply] rw [h (f p)]
-- no goals
-/
#guard_msgs in
example {P Q : Prop} (p : P) (f : P Q) (h : Q 1 = 2) : 2 = 1 := by
rw?
-- Rewrite in reverse, discharging side conditions from local hypotheses.
/--
info: Try this:
[apply] rw [← h₁ p]
-- Q a
-/
#guard_msgs in
example {P : Prop} (p : P) (Q : α Prop) (a b : α) (h₁ : P a = b) (w : Q a) : Q b := by
rw?
exact w