d10d41bc07
When named arguments introduce eta arguments, the full application contains fvars for these eta arguments, so `MVarErrorKind.implicitArg` needs to keep a local context for its error messages. This is because the local context of the mvar associated to the `MVarErrorKind` is not sufficient, since when an eta argument come after an implicit argument, the implicit argument's mvar doesn't contain the eta argument's fvar in its local context. Closes #5475
23 lines
465 B
Text
23 lines
465 B
Text
/-!
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# Eta arguments had wrong context in "don't know how to synthesize implicit" errors
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https://github.com/leanprover/lean4/issues/5475
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-/
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set_option pp.mvars false
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/-!
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Formerly, argument `x` appeared as `_fvar.123`
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-/
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def f {α β : Type} (x: α) (y: β) : α := x
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/--
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error: don't know how to synthesize implicit argument 'α'
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@f ?_ Nat x Nat.zero
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context:
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⊢ Type
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---
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error: failed to infer definition type
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-/
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#guard_msgs in
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example :=
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f (y := Nat.zero)
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