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This PR fixes an issue where `grind` would fail after multiple `norm_cast` calls with the error "unexpected metadata found during internalization". The `norm_cast` tactic adds mdata nodes to expressions, and when called multiple times it creates nested mdata. The `eraseIrrelevantMData` preprocessing function was using `.continue e` when stripping mdata, which causes `Core.transform` to reconstruct the mdata node around the visited children. By changing to `.visit e`, the inner expression is passed back to `pre` for another round of processing, allowing all nested mdata layers to be stripped. Closes #11411 🤖 Prepared with Claude Code Co-authored-by: Claude <noreply@anthropic.com>
59 lines
1.8 KiB
Text
59 lines
1.8 KiB
Text
/-!
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# Test that `grind` handles nested mdata from multiple `norm_cast` calls
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This is a regression test for https://github.com/leanprover/lean4/issues/11411
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The issue was that `norm_cast` adds mdata nodes to expressions, and when called
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multiple times it creates nested mdata. The `grind` preprocessing step
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`eraseIrrelevantMData` was only stripping one layer of mdata instead of all layers.
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-/
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-- Minimal WithTop definition
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def WithTop (α : Type u) := Option α
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namespace WithTop
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variable {α : Type u}
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@[coe] def some : α → WithTop α := Option.some
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instance : Coe α (WithTop α) := ⟨some⟩
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instance : NatCast (WithTop Nat) where
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natCast n := some n
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end WithTop
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-- AtLeastTwo infrastructure (from Mathlib.Data.Nat.Init)
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class Nat.AtLeastTwo (n : Nat) : Prop where
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prop : n ≥ 2
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instance Nat.instAtLeastTwo : Nat.AtLeastTwo (n + 2) where
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prop := Nat.le_add_left 2 n
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-- OfNat instance for numeric literals ≥ 2 (from Mathlib.Data.Nat.Cast.Defs)
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instance instOfNatAtLeastTwo {R : Type u} [NatCast R] (n : Nat) [Nat.AtLeastTwo n] : OfNat R n where
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ofNat := n
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-- The key norm_cast lemma (from Mathlib.Data.Nat.Cast.Defs)
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@[simp, norm_cast]
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theorem Nat.cast_ofNat {R : Type u} {n : Nat} [NatCast R] [Nat.AtLeastTwo n] :
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(Nat.cast (no_index (OfNat.ofNat n)) : R) = no_index (OfNat.ofNat n) := rfl
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variable {Foo : WithTop Nat → Prop} {Bar : Prop}
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-- Works: grind without norm_cast
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example (foo_imp_bar : ∀ x, Foo x → Bar) (h : Foo 2) : Bar := by
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grind
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-- Works: grind after one norm_cast
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example (foo_imp_bar : ∀ x, Foo x → Bar) (h : Foo 2) : Bar := by
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norm_cast at h
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grind
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-- Previously failed: grind after two norm_casts
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-- This used to fail with "unexpected metadata found during internalization"
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example (foo_imp_bar : ∀ x, Foo x → Bar) (h : Foo 2) : Bar := by
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norm_cast at h
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norm_cast at h
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grind
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