Fix #9206: Workaround missing type symbol in Scala2 constructors

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala

@@ -573,7 +573,13 @@ class Scala2Unpickler(bytes: Array[Byte], classRoot: ClassDenotation, moduleClas
 
         // println("reading type for " + denot) // !!! DEBUG
         val tp = at(inforef, () => readType()(ctx))
-        if denot.is(Method) then denot.rawParamss = paramssOfType(tp)
+        if denot.is(Method) &&
+           // FIXME: Compute symbols of Scala 2 constructors. Current issue is that `tp` does
+           //        not contain the type parameters.
+           //        reproduce with: dotty-bootstraped/testCompilation tests/run-macros/i9206
+           !(denot.isConstructor && denot.owner.is(Scala2x))
+        then
+          denot.rawParamss = paramssOfType(tp)
 
         denot match {
           case denot: ClassDenotation if !isRefinementClass(denot.symbol) =>

tests/run-macros/i9206/Macros_1.scala

@@ -0,0 +1,11 @@
+
+import scala.quoted.{Expr, QuoteContext}
+
+object Inspect {
+  inline def inspect[T <: AnyKind]: String = ${ inspectTpe[T] }
+
+  def inspectTpe[T <: AnyKind](using tpe: quoted.Type[T], qctx0: QuoteContext): Expr[String] = {
+    val tree = summon[quoted.Type[T]].unseal.tpe.typeSymbol.tree
+    Expr(tree.show)
+  }
+}

tests/run-macros/i9206/Test_2.scala

@@ -0,0 +1,10 @@
+import Inspect._
+
+object Test extends App {
+  inspect[scala.collection.immutable.List[Int]]
+  inspect[java.lang.String]
+  inspect[String]
+  inspect[List[Unit]]
+  inspect[Some[Unit]]
+  inspect[Tuple1[Unit]]
+}