scala.MatchError: NoType when combining if and _*

[erikvanoosten]

Compiler version

Scala 3.2.1, but also with 3.1.2.
Note, this compiles fine with 2.11, 2.12 and 2.13.

Minimized code

import java.lang.reflect.Constructor

class MinimalScala3Bug {
  private val NO_ARG: Array[Class[_]] = Array.empty
  private val STRING_ARG: Array[Class[_]] = Array(classOf[String])

  def doesNotCompile(c: Class[_], useStringCTor: Boolean): Constructor[_] = {
    c.getDeclaredConstructor((if (useStringCTor) STRING_ARG else NO_ARG): _*)
  }

  def doesCompile(c: Class[_], useStringCTor: Boolean): Constructor[_] = {
    val array = if (useStringCTor) STRING_ARG else NO_ARG
    c.getDeclaredConstructor(array: _*)
  }
}

Output

First lines of the compiler output.

[warn] an unexpected type representation reached the compiler backend while compiling MinimalScala3Bug.scala: NoType. If possible, please file a bug on https://github.com/lampepfl/dotty/issues
Error while emitting MinimalScala3Bug.scala
scala.MatchError: NoType (of class dotty.tools.dotc.core.Types$NoType$) while running genBCode on MinimalScala3Bug.scala
[info] exception occurred while compiling MinimalScala3Bug.scala
scala.MatchError: NoType (of class dotty.tools.dotc.core.Types$NoType$) while compiling MinimalScala3Bug.scala

(Note: the output was slightly redacted to remove the full path to the scala file.)

[erikvanoosten]

Thanks! 🚀