82c71fcc75
This PR fixes an issue where `x.f.g` wouldn't work but `(x.f).g` would when `x.f` is generalized field notation. The problem was that `x.f.g` would assume `x : T` should be the first explicit argument to `T.f`. Now it uses consistent argument insertion rules. Closes #6400. This also improves the algorithm for finding a relevant argument. Before it would try looking at the type and the whnf of the type, but now it iteratively unfolds types, checking each intermediate expansion.
68 lines
1.4 KiB
Text
68 lines
1.4 KiB
Text
/-!
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# Tests for issue #6400
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https://github.com/leanprover/lean4/issues/6400
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Nested field notation was not resolving correctly if there was generalized field notation coming first
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and the target wasn't the first explicit argument.
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-/
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/-!
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Example from issue #6400
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-/
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namespace Ex1
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structure S where
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x : Nat
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class Class where
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s : S
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def Class.foo [c : Class] : S := c.s
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-- Always worked
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example [c : Class] : S := c.foo
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-- Parens made it work
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example [c : Class] : Nat := (c.foo).x
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-- Formerly, "function expected at Class.foo"
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example [c : Class] : Nat := c.foo.x
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end Ex1
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/-!
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Fixed recursive calls too, which had the same problem.
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-/
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def Nat.f {n : Nat} : Nat :=
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match n with
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| 0 => 0
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| n + 1 => n.f.succ
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/-!
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Now instances are unfolded when searching for a relevant argument.
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-/
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namespace Ex2
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class Friend (α : Type) where
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friend : Type
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instance : Friend Nat where
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friend := Bool
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def _root_.Bool.f (b : Friend.friend Nat) := !b
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variable (a : Bool)
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/-- info: Bool.f a : Bool -/
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#guard_msgs in #check a.f
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-- Semireducible definitions are not unfolded however.
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def semifriend (α : Type) [Friend α] := Friend.friend α
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def _root_.Bool.g (b : semifriend Nat) := !b
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/--
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error: invalid field notation, function 'Bool.g' does not have argument with type (Bool ...) that can be used, it must be explicit or implicit with a unique name
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-/
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#guard_msgs in #check a.g
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end Ex2
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