Fix #8404: Use both scrutinee type and given type in pattern ascriptions #8413
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…riptions In a pattern ascription `x: T` type `x` to have the intersection of the given type `T` and the scrutinee type. This matches scalac's behavior. It now makes i5418.scala compile. The type intersection was enough to make that one compile, it did not need unsound covariant GADT matching (which was what I claimed before in the issue).
smarter
reviewed
Mar 1, 2020
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I believe this fixes #3208 as well. |
yes, indeed! |
smarter
requested changes
Mar 1, 2020
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In a pattern ascription
x: T, typexto have the intersection ofthe given type
Tand the scrutinee type. This matches scalac's behavior.It now makes i5418.scala compile. The type intersection was enough to make
that one compile, it did not need unsound covariant GADT matching (which was
what I claimed before in the issue).
Fixes #3208