False-positive unreachable case warning with opaque types and List

[Iltotore]

Compiler version

3.3.1

Minimized code

unreachable.sc

//> using scala "3.3.1"
//> using file "unreachable_opaque.scala"

//Works for Seq and Set, does not work for List and Vector
val optionList: Option[Test[List[Int]]] = ???

optionList match
  case Some(value) => ??? // Compile warning: Unreachable case
  case None        => ???

unreachable_opaque.scala

//Works without <: A
opaque type Test[A] <: A = A

Output

[warn] .\unreachable.sc:8:8
[warn] Unreachable case
[warn]   case Some(value) => ??? // Compile warning: Unreachable case
[warn]        ^^^^^^^^^^^

Note that this only happen in very specific situations. Removing <: A from Test definition or replacing List by Seq or Set also removes the warning.

Expectation

No "unreachable case" warning since the case is actually reachable.