Closed
Description
minimized code
class X[A,B]
abstract class A[T]
class B[F <: X[_,_]] extends A[F]
def fn1[T](a : A[T]) = a match {
case aa : B[f] => fn2(aa)
}
def fn2[F <: X[_,_]](b : B[F]) = ???This blows up on the call to fn2 saying that type parameter T does not conform to upper bound X[_,_]. While this is true, we just matched a to aa which is of type B[f], where f should by construction have the correct bounds. Somehow Dotty is considering f === T, ignoring changes in bounds due to the match.
expectation
This code compiles without the error described above.
Note: this might be related to #6697, since that looks similar but on the type level