3a309ba4eb
This PR improves the error message encountered in the case of a type class instance resolution failure, and adds an error explanation that discusses the common new-user case of binary operation overloading and points to the `trace.Meta.synthInstance` option for advanced debugging. ## Example ```lean4 def f (x : String) := x + x ``` Before: ``` failed to synthesize HAdd String String ?m.5 Hint: Additional diagnostic information may be available using the `set_option diagnostics true` command. ``` After: ``` failed to synthesize instance of type class HAdd String String ?m.5 Hint: Type class instance resolution failures can be inspected with the `set_option trace.Meta.synthInstance true` command. Error code: lean.failedToSynthesizeTypeclassInstance [View explanation](https://lean-lang.org/doc/reference/latest/find/?domain=Manual.errorExplanation&name=lean.failedToSynthesizeTypeclassInstance) ``` The error message is changed in three important ways: * Explains *what* failed to synthesize, using the "type class" terminology that's more likely to be recognized than the "instance" terminology * Points to the `trace.Meta.synthInstance` option which is otherwise nearly undiscoverable but is quite powerful (see also leanprover/reference-manual#663 which is adding commentary on this option) * Gives an error explanation link (which won't actually work until the next release after this is merged) which prioritizes the common-case explanation of using the wrong binary operation
20 lines
860 B
Text
20 lines
860 B
Text
/-
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Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Joseph Rotella
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-/
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module
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prelude
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public import Lean.ErrorExplanations.CtorResultingTypeMismatch
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public import Lean.ErrorExplanations.DependsOnNoncomputable
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public import Lean.ErrorExplanations.InductiveParamMismatch
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public import Lean.ErrorExplanations.InductiveParamMissing
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public import Lean.ErrorExplanations.InferBinderTypeFailed
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public import Lean.ErrorExplanations.InferDefTypeFailed
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public import Lean.ErrorExplanations.InvalidDottedIdent
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public import Lean.ErrorExplanations.ProjNonPropFromProp
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public import Lean.ErrorExplanations.PropRecLargeElim
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public import Lean.ErrorExplanations.RedundantMatchAlt
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public import Lean.ErrorExplanations.SynthInstanceFailed
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public import Lean.ErrorExplanations.UnknownIdentifier
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