Strange type inference failure for module types

[LPTK]

Compiler version

3.1.0

Minimized code

class Parent { class E }

object ChildA extends Parent

object ChildB extends Parent

class Printer[C <: Parent](val child: C):
  def print(e: child.E): String = ""

Printer(ChildA).print(new ChildA.E) // does not work

Printer[ChildA.type](ChildA).print(new ChildA.E) // works
val p = Printer(ChildA); p.print(new ChildA.E) // works

Output

Found:    Playground.ChildA.E
Required: Nothing

https://scastie.scala-lang.org/c1rQdb4BSgyv7ilyiiI0Zg

Expectation

This should compile. C should be inferred as ChildA.type, or a supertype of ChildA.type which is later constrained to be a subtype of it too.

It works in Scala 2: https://scastie.scala-lang.org/IEMNML09TryqcA48OqVq2A. Maybe Scala 2 was inferring an existential here? But this program should not need existentials to type check.

[bishabosha]

alternate version that also requires a Singleton bound to Printer:

class Parent { class E }

val ChildA: ChildAModule = new ChildAModule {}
trait ChildAModule extends Parent { self: ChildA.type => }

class Printer[C <: Parent & Singleton](val child: C):
  def print(e: child.E): String = ""

def test =
  Printer(ChildA).print(new ChildA.E) // does not work

  Printer[ChildA.type](ChildA).print(new ChildA.E) // works
  val p = Printer(ChildA); p.print(new ChildA.E) // works