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fix: process delayed assignment metavariables correctly in Lean.Meta.…
…Closure This PR fixes a bug in `Lean.Meta.Closure` that would introduce under-applied delayed assignment metavariables, which would keep them from ever getting instantiated. This bug affected `match` elaboration when the expected type contains postponed elaboration problems, for example tactic blocks. Closes #6354
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/-! | ||
# Proper handling of delayed assignment metavariables in `match` elaboration | ||
https://github.com/leanprover/lean4/issues/6354 | ||
-/ | ||
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namespace Test1 | ||
/-! | ||
Simplified version of example from issue 6354. | ||
Previously, had error `(kernel) declaration has metavariables '_example'` | ||
-/ | ||
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structure A where | ||
p: Prop | ||
q: True | ||
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example := (λ ⟨_,_⟩ ↦ True.intro : (A.mk (And True True) (by exact True.intro)).p → True) | ||
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end Test1 | ||
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namespace Test2 | ||
/-! | ||
Example from issue (by @roos-j) | ||
-/ | ||
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structure A where | ||
p: Prop | ||
q: True | ||
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structure B extends A where | ||
q': p → True | ||
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example: B where | ||
p := True ∧ True | ||
q := by exact True.intro | ||
q' := λ ⟨_,_⟩ ↦ True.intro | ||
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end Test2 | ||
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namespace Test3 | ||
/-! | ||
Example from issue comment (by @b-mehta) | ||
-/ | ||
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class Preorder (α : Type) extends LE α, LT α where | ||
le_refl : ∀ a : α, a ≤ a | ||
lt := fun a b => a ≤ b ∧ ¬b ≤ a | ||
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class PartialOrder (α : Type) extends Preorder α where | ||
le_antisymm : ∀ a b : α, a ≤ b → b ≤ a → a = b | ||
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inductive MyOrder : Nat × Nat → Nat × Nat → Prop | ||
| within {x u m : Nat} : x ≤ u → MyOrder (x, m) (u, m) | ||
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instance : PartialOrder (Nat × Nat) where | ||
le := MyOrder | ||
le_refl x := .within (Nat.le_refl _) | ||
le_antisymm | _, _, .within _, .within _ => Prod.ext (Nat.le_antisymm ‹_› ‹_›) rfl | ||
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end Test3 |