Matching bounded type parameter

[prolativ]

Compiler version

3.3.0-RC1-bin-20221111-cc4c279-NIGHTLY and earlier

Minimized code

Macro.scala:

import scala.quoted.*

trait Container[A]
trait Box[A] extends Container[A]

class Wrapper[T <: Container[?]]

inline def qux0() = ${ qux0Impl }
def qux0Impl(using Quotes) =
  Type.of[Wrapper[Container[Int]]] match
    case '[Wrapper[x]] => '{}

inline def qux1() = ${ qux1Impl }
def qux1Impl(using Quotes) =
  Type.of[Wrapper[Box[Int]]] match
    case '[Wrapper[x]] => '{}

inline def qux2() = ${ qux2Impl }
def qux2Impl(using Quotes) =
  Type.of[Wrapper[Container[Int]]] match
    case '[Wrapper[Container[x]]] => '{}

Main.scala:

def q0 = qux0()
def q1 = qux1()
def q2 = qux2()

Output

The match in qux0Impl fails:

[error] Main.scala:1:10: Exception occurred while executing macro expansion.
[error] scala.MatchError: Type.of[...] (of class scala.quoted.runtime.impl.TypeImpl)
[error]         at Macro$package$.qux0Impl(Macro.scala:11)
[error] 
[error] def q0 = qux0()
[error]          ^^^^^^

If ? inside class Wrapper[T <: Container[?]] gets replaced with Int, then qux0Impl seems to work correctly but qux2Impl stops compiling, producing the error:

[error] Macro.scala:21:20: Type argument Container[x] does not conform to upper bound Container[Int]
[error]     case '[Wrapper[Container[x]]] => '{}
[error]                    ^

Expectation

All qux cases should compile in both variants (with class Wrapper[T <: Container[?]] or class Wrapper[T <: Container[Int]]), capturing the following types as x:

• qux0 -> Container[Int]
• qux1 -> Box[Int]
• qux2 -> Int