Do not fold jlr.Array.newInstance(classOf[Unit], ...).

sjrd · sjrd · commit a79ce3f94596 · 2024-08-25T11:27:41.000+02:00
If we do, we generate code that statically refers to the array type
`void[]`, which is not a valid type.

With the following commit, the optimizer will have enough knowledge
to enter in this case when optimizing `ClassTag`s, resulting in
ClassDef checking errors after the optimizer.
diff --git a/linker/shared/src/main/scala/org/scalajs/linker/frontend/optimizer/OptimizerCore.scala b/linker/shared/src/main/scala/org/scalajs/linker/frontend/optimizer/OptimizerCore.scala
@@ -3195,7 +3195,7 @@ private[optimizer] abstract class OptimizerCore(
       case ArrayNewInstance =>
         val List(tcomponentType, tlength) = targs
         tcomponentType match {
-          case PreTransTree(ClassOf(elementTypeRef), _) =>
+          case PreTransTree(ClassOf(elementTypeRef), _) if elementTypeRef != VoidRef =>
             val arrayTypeRef = ArrayTypeRef.of(elementTypeRef)
             contTree(NewArray(arrayTypeRef, List(finishTransformExpr(tlength))))
           case _ =>
