lean4-htt/tests/lean/run/rewrites.lean
Marc Huisinga f180eee7bf
feat: use widget message for "try this" (#9966)
This PR adjusts the "try this" widget to be rendered as a widget message
under 'Messages', not a separate widget under a 'Suggestions' section.
The main benefit of this is that the message of the widget is not
duplicated between 'Messages' and 'Suggestions'.

Since widget message suggestions were already implemented by @jrr6 for
the new hint infrastructure, this PR replaces the old "try this"
implementation with the new hint infrastructure. In doing so, the
`style?` field of suggestions is deprecated, since the hint
infrastructure highlights hints using diff colors, and `style?` also
never saw much use downstream. Additionally, since the message and the
suggestion are now the same component, the `messageData?` field of
suggestions is deprecated as well. Notably, the "Try this:" message
string now also contains a newline and indentation to separate the
suggestion from the rest of the message more clearly and the `postInfo?`
field of the suggestion is now part of the message.

Finally, this PR changes the diff colors used by the hint infrastructure
to be more color-blindness-friendly (insertions are now blue, not green,
and text that remains unchanged is now using the editor foreground color
instead of blue).

### Breaking changes
Tests that use `#guard_msgs` to test the "Try this:" message may need to
be adjusted for the new formatting of the message.
2025-08-26 12:15:32 +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:
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:
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 : αα
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:
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:
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:
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