Using type alias with dependent type produces error. Manual inlining makes the error go away.

[marcinzh]

Compiler version

3.0.0

Minimized code

trait Signature:
  type Impl[A, U]

type Operation[Z <: Signature, A, U] = (z: Z) => z.Impl[A, U]

// This produces error:
case class Perform[Z <: Signature, A, U](op: Operation[Z, A, U])

// However, if I manually inline the type alias, the error goes away:
case class Perform_fix[Z <: Signature, A, U](op: (z: Z) => z.Impl[A, U])

// Also, using the alias in other contexts does not produce errors:
def foo[Z <: Signature, A, U](op: Operation[Z, A, U]): Unit = ???

Above snippet in Scastie: https://scastie.scala-lang.org/h8VPuvAMS72F42Cb11RubA

Output

Found:    (Perform.this.op : Operation[Z, A, U])
Required: Operation[<? <: Signature>, <?>, <?>]

Expectation

Not having to manually inline the type alias.