995fa4766b
This PR refines the new wording of the "application type mismatch" error message to avoid ambiguity in references to the "final" argument in a subexpression that may be followed by additional arguments. It does so by replacing "final" with "last," rephrasing the message so that this adjective modifies the argument itself rather than the word "argument," and only displaying this wording when two arguments could be confused (determined by expression equality). These changes were motivated by a report that in cases where a function application `f a b c` fails to elaborate because `b` is incorrectly typed, the existing error message's reference to `b` being the "final" argument in the application `f a b` may create confusion because it is not the final argument in the full application expression.
56 lines
1.2 KiB
Text
56 lines
1.2 KiB
Text
import Lean.Elab.Command
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set_option pp.mvars false
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/--
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error: Application type mismatch: In the application
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⟨Nat.lt_irrefl (?_ n), Fin.is_lt ?_⟩
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the argument
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Fin.is_lt ?_
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has type
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↑?_ < ?_ : Prop
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but is expected to have type
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?_ n < ?_ n : Prop
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-/
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#guard_msgs in
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def foo := fun n => (not_and_self_iff _).mp ⟨Nat.lt_irrefl _, Fin.is_lt _⟩
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/--
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error: type mismatch
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Fin.is_lt ?_
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has type
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↑?_ < ?_ : Prop
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but is expected to have type
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?_ < ?_ : Prop
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---
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error: unsolved goals
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case a
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⊢ Nat
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this : ?_ < ?_
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⊢ True
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-/
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#guard_msgs in
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def test : True := by
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have : ((?a : Nat) < ?a : Prop) := by
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refine Fin.is_lt ?_
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done
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done
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open Lean Meta
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/--
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info: Defeq?: false
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---
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info: fun x_0 x_1 => x_1
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-/
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#guard_msgs in
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run_meta do
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let mvarIdNat ← mkFreshExprMVar (.some (.const ``Nat []))
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let mvarIdFin ← mkFreshExprMVar (.some (.app (.const `Fin []) mvarIdNat))
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-- mvarIdNat.assign (.app (.const ``Fin.val []) mvaridFin))
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let b ← isDefEq mvarIdNat (mkApp2 (.const ``Fin.val []) mvarIdNat mvarIdFin)
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logInfo m!"Defeq?: {b}" -- prints true
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-- Now mvaridNat occurs in its own type
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-- This will stack overflow
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let r ← abstractMVars mvarIdFin (levels := false)
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logInfo m!"{r.expr}"
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