3acd77a154
Floris van Doorn [reported on Zulip](https://leanprover.zulipchat.com/#narrow/stream/270676-lean4/topic/have.20tactic.20error.20recovery/near/425283053) that it is confusing that the `have : T := e` tactic completely fails if the body `e` is not of type `T`. This is in contrast to `have : T := by exact e`, which does not completely fail when `e` is not of type `T`. This ends up being caused by `elabTermEnsuringType` throwing an error when it fails to insert a coercion. Now, it detects this case, and it checks the `errToSorry` flag to decide whether to throw the error or to log the error and insert a `sorry`. This is justified by `elabTermEnsuringType` being a frontend to `elabTerm`, which inserts `sorry` on error. An alternative would be to make `ensureType` respect `errToSorry`, but there exists code that expects being able to catch when `ensureType` fails. Making such code manipulate `errToSorry` seems error prone, and this function is not a main entry point to the term elaborator, unlike `elabTermEnsuringType`.
56 lines
986 B
Text
56 lines
986 B
Text
--
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structure A (α : Type) :=
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(x : α)
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structure B (α : Type) :=
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(x : α)
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structure S : Nat := -- error expected Type
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(x : Nat)
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structure S extends Nat → Nat := -- error expected structure
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(x : Nat)
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set_option structureDiamondWarning true in
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structure S' extends A Nat, A Bool := -- error field toA already declared
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(x : Nat)
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structure S extends A Nat, B Bool := -- error field `x` from `B` has already been declared
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(x : Nat)
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structure S1 :=
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(_x : Nat)
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structure S2 :=
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(x _y : Nat)
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structure S :=
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(x : Nat)
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(x : Nat) -- error
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structure S extends A Nat :=
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(x : Nat) -- error
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structure S' extends A Nat :=
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(x := true) -- error type mismatch
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structure S extends A Nat :=
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(x : Bool := true) -- error omit type
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structure S'' :=
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(x : Nat := true) -- error type mismatch
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private structure S :=
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private mk :: (x : Nat)
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private structure S :=
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protected mk :: (x : Nat)
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private structure S :=
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protected (x : Nat)
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private structure S :=
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mk2 :: (x : Nat)
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#check S
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#check S.mk2
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