f7031c7aa9
This PR adds a `Unit` assumption to alternatives of the splitter that would otherwise not have arguments. This fixes #11211. In practice these argument-less alternatives did not cause wrong behavior, as the motive when used with `split` is always a function type. But it is better to be safe here (maybe someone uses splitters in other ways), it may increase the effectiveness of #10184 and simplifies #11220. The perf impact is insignificant in the grand scheme of things on stdlib, but the change is effective: ``` ~/lean4 $ build/release/stage1/bin/lean tests/lean/run/matchSplitStats.lean 969 splitters found 455 splitters are const defs ~/lean4 $ build/release/stage2/bin/lean tests/lean/run/matchSplitStats.lean 969 splitters found 829 splitters are const defs ```
99 lines
2.7 KiB
Text
99 lines
2.7 KiB
Text
/-!
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Checks that splitters have `Unit →` thunks and that nothing is confused because of that.
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-/
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set_option linter.unusedVariables false
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-- set_option trace.Meta.Match.matchEqs true
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def f (xs : List Nat) : Nat :=
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match xs with
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| [] => 1
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| _ => 2
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/--
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info: def f.match_1.{u_1} : (motive : List Nat → Sort u_1) →
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(xs : List Nat) → (Unit → motive []) → ((x : List Nat) → motive x) → motive xs
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-/
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#guard_msgs in
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#print sig f.match_1
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/--
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info: private def f.match_1.splitter.{u_1} : (motive : List Nat → Sort u_1) →
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(xs : List Nat) → (Unit → motive []) → ((x : List Nat) → (x = [] → False) → motive x) → motive xs
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-/
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#guard_msgs(pass trace, all) in
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#print sig f.match_1.splitter
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/--
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info: private theorem f.match_1.congr_eq_1.{u_1} : ∀ (motive : List Nat → Sort u_1) (xs : List Nat) (h_1 : Unit → motive [])
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(h_2 : (x : List Nat) → motive x),
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xs = [] →
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(match xs with
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| [] => h_1 ()
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| x => h_2 x) ≍
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h_1 ()
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-/
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#guard_msgs(pass trace, all) in
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#print sig f.match_1.congr_eq_1
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-- set_option trace.split.debug true
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theorem test1: f n ≤ 2 := by
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unfold f
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split <;> grind
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theorem test2 : f n ≤ 2 := by
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unfold f
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grind
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/--
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info: theorem f.fun_cases : ∀ (motive : List Nat → Prop),
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motive [] → (∀ (xs : List Nat), (xs = [] → False) → motive xs) → ∀ (xs : List Nat), motive xs
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-/
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#guard_msgs(pass trace, all) in
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#print sig f.fun_cases
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def Option_map (f : α → β) : Option α → Option β
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| some x => some (f x)
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| none => none
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/--
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info: def Option_map.match_1.{u_1, u_2} : {α : Type u_1} →
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(motive : Option α → Sort u_2) → (x : Option α) → ((x : α) → motive (some x)) → (Unit → motive none) → motive x
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-/
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#guard_msgs in
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#print sig Option_map.match_1
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/--
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info: private def Option_map.match_1.splitter.{u_1, u_2} : {α : Type u_1} →
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(motive : Option α → Sort u_2) → (x : Option α) → ((x : α) → motive (some x)) → (Unit → motive none) → motive x :=
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@Option_map.match_1
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-/
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#guard_msgs in
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#print Option_map.match_1.splitter
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/--
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info: theorem Option_map.fun_cases.{u_1} : ∀ {α : Type u_1} (motive : Option α → Prop),
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(∀ (x : α), motive (some x)) → motive none → ∀ (x : Option α), motive x
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-/
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#guard_msgs(pass trace, all) in
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#print sig Option_map.fun_cases
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def List_map (f : α → β) (l : List α) : List β := match _ : l with
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| x::xs => f x :: List_map f xs
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| [] => []
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termination_by l
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def foo₁ (a : Nat) (ha : a = 37) :=
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(match h : a with | 42 => 23 | n => n) = 37
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/--
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info: private def foo₁.match_1.splitter.{u_1} : (motive : Nat → Sort u_1) →
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(a : Nat) → (a = 42 → motive 42) → ((n : Nat) → (n = 42 → False) → a = n → motive n) → motive a
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-/
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#guard_msgs in
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#print sig foo₁.match_1.splitter
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