False-positive `Unreachable case` warning for mix-in type test

[ivan-klass]

Compiler version

3.5.2

https://scastie.scala-lang.org/7iPISGKwTfOBxOKWIRIiaw

Minimized code

trait Figure

sealed trait Corners {
  self: Figure =>
}

enum Shape extends Figure:
  case Triange extends Shape with Corners
  case Square extends Shape with Corners
  case Circle extends Shape
  case Ellipsis extends Shape


def hasCorners(s: Shape): Boolean = s match
  case hasCorners: Corners => true //  <--- reported as `Unreachable case`
  case _ => false

println(hasCorners(Shape.Circle))

Output

warning: Unreachable case

true

Expectation

true

[Gedochao]

Last good stable version: 3.3.4
First bad stable version: 3.4.0

It seems bisect is failing a lot, the cause could be in any of the following commits:
1b2a16e
f432d08
2dd9f45
ec097a9

cc @sjrd