5f4e6a86d5
This PR updates the formatting of, and adds explanations for, "unknown identifier" errors as well as "failed to infer type" errors for binders and definitions. It attempts to ameliorate some of the confusion encountered in #1592 by modifying the wording of the "header is elaborated before body is processed" note and adding further discussion and examples of this behavior in the corresponding error explanation.
65 lines
1.2 KiB
Text
65 lines
1.2 KiB
Text
import Lean
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/-!
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# Make sure generated instance names are unique if there are macro scopes
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-/
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open Lean Elab Command
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/-!
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Example adapted from #2044
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-/
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#eval (do
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let stx ← `(
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structure Foo where
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field : String
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instance : Nonempty Foo := ⟨⟨"hi"⟩⟩)
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elabCommand stx
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: CommandElabM Unit
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)
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/-- error: Unknown identifier `instNonemptyFoo` -/
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#guard_msgs in #check instNonemptyFoo
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-- Verify that `instNonemptyFoo` is the name it would generate if it weren't hygienic
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structure Foo where
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field : String
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instance : Nonempty Foo := ⟨⟨"hi"⟩⟩
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/-- info: instNonemptyFoo : Nonempty Foo -/
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#guard_msgs in #check instNonemptyFoo
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/-!
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Example directly from #2044, deriving ToJson
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-/
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open Lean Elab Command
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#eval (do
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let stx ← `(
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structure Foo where
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field : String
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deriving ToJson)
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elabCommand stx
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: CommandElabM Unit
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)
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/-- error: Unknown identifier `instToJsonFoo` -/
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#guard_msgs in #check instToJsonFoo
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deriving instance ToJson for Foo
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/-- info: instToJsonFoo : ToJson Foo -/
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#guard_msgs in #check instToJsonFoo
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/-!
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Can derive RpcEncodable multiple times in the same namespace.
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-/
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structure A1 where
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n : Nat
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deriving Lean.Server.RpcEncodable
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structure A2 where
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n : Nat
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deriving Lean.Server.RpcEncodable
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