Doug Gregor 51abd3d56f Prevent opening existentials when the corresponding parameter is variant ...

Ensure that we only open existentials in an argument when the corresponding
parameter's type is a generic parameter that is only used in covariant
positions, because either invariant or contravariant uses mean that we
won't be able to type-erase other uses of that parameter. This mirrors
the requirement placed when opening existentials as a member of protocol
type.

2022-02-18 11:22:57 -08:00

500 KiB

Raw Blame History

View Raw