Match type widens the resulting type

[peter-jerry-ye]

Compiler version

3.2.0

Minimized code

enum A {
  case AA
  case AB
}
enum B {
  case BA
  case BB
  case BC
}
type P[X <: A] = X match {
  case A.AA.type => B.BA.type | B.BB.type
  case A.AB.type => B.BC.type
}
def p[X <: A](x: X): P[X] = x match {
  case x: A.AA.type => B.BA
  case x: A.AB.type => B.BC
}
p[A.AA.type](A.AA) // widened, BA: B
p[A.AB.type](A.AB) // widened, BC: B

sealed trait C
object CA extends C
object CB extends C
object CC extends C
type P2[X <: A] = X match {
  case A.AA.type => CA.type | CB.type
  case A.AB.type => CC.type
}
def p2[X <: A](x: X): P2[X] = x match {
  case x: A.AA.type => CA
  case x: A.AB.type => CC
}
p2[A.AA.type](A.AA) // widened, CA: C
p2[A.AB.type](A.AB) // not widened, CC: CC

Output

Expectation

I expect them not to be widened.