31f09da88a
This PR modifies the error message that is returned when more than one synthetic metavariable can't be resolved. The two heuristics used for prioritization are: - prefer typeclass problems associated with small ranges over typeclass problems associated with large ranges (I'm pretty confident in this heuristic) - do not prefer typeclass problems over other kinds of errors (not as confident in this heuristic)
7 lines
666 B
Text
7 lines
666 B
Text
353.lean:13:27-13:35: error: typeclass instance problem is stuck
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Arr.{1, ?u} Bool (@?m a₁ a₂)
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Note: Lean will not try to resolve this typeclass instance problem because the second type argument to `Arr.{u1,
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u2}` contains metavariables. This argument must be fully determined before Lean will try to resolve the typeclass.
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Hint: Adding type annotations and supplying implicit arguments to functions can give Lean more information for typeclass resolution. For example, if you have a variable `x` that you intend to be a `Nat`, but Lean reports it as having an unresolved type like `?m`, replacing `x` with `(x : Nat)` can get typeclass resolution un-stuck.
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