fa36fcd448
This PR adds an alternative implementation of `DerivingBEq` based on comparing `.ctorIdx` and using a dedicated matcher for comparing same constructors (added in #10152), to avoid the quadratic overhead of the default match implementation. The new option `deriving.beq.linear_construction_threshold` sets the constructor count threshold (10 by default) for using the new construction. Such instances also allow `deriving ReflBEq, LawfulBeq`, although these proofs for these properties are still quadratic.
50 lines
1.7 KiB
Text
50 lines
1.7 KiB
Text
/-!
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This test checks what deriving `DecidableEq` does when the inductive type has
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non-injective indices, and just how bad the error messages are.
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-/
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opaque f : Nat → Nat
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set_option deriving.decEq.linear_construction_threshold 0
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set_option deriving.beq.linear_construction_threshold 0
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/--
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error: Dependent elimination failed: Failed to solve equation
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f n✝ = f n
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-/
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#guard_msgs(pass trace, all) in
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inductive T : (n : Nat) → Type where
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| mk1 : Fin n → T (f n)
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| mk2 : Fin (2*n) → T (f n)
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deriving BEq, DecidableEq
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set_option deriving.decEq.linear_construction_threshold 10000
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set_option deriving.beq.linear_construction_threshold 10000
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/--
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error: Tactic `cases` failed with a nested error:
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Dependent elimination failed: Failed to solve equation
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f n✝¹ = f n✝
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at case `T'.mk1` after processing
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_, (T'.mk1 _ _), _
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the dependent pattern matcher can solve the following kinds of equations
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- <var> = <term> and <term> = <var>
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- <term> = <term> where the terms are definitionally equal
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- <constructor> = <constructor>, examples: List.cons x xs = List.cons y ys, and List.cons x xs = List.nil
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---
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error: Tactic `cases` failed with a nested error:
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Dependent elimination failed: Failed to solve equation
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f n✝¹ = f n✝
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at case `T'.mk1` after processing
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_, (T'.mk1 _ _), _
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the dependent pattern matcher can solve the following kinds of equations
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- <var> = <term> and <term> = <var>
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- <term> = <term> where the terms are definitionally equal
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- <constructor> = <constructor>, examples: List.cons x xs = List.cons y ys, and List.cons x xs = List.nil
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-/
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#guard_msgs(pass trace, all) in
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inductive T' : (n : Nat) → Type where
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| mk1 : Fin n → T' (f n)
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| mk2 : Fin (2*n) → T' (f n)
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deriving BEq, DecidableEq
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