Merge pull request #6097 from dotty-staging/fix-new-alias

Fix typing of new

Author: odersky

compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -331,7 +331,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
         if (tree.hasType && tree.symbol == defn.QuotedExpr_splice) keywordStr("${") ~ toTextLocal(qual) ~ keywordStr("}")
         else if (tree.hasType && tree.symbol == defn.QuotedType_splice) typeText("${") ~ toTextLocal(qual) ~ typeText("}")
         else if (qual.isType) toTextLocal(qual) ~ "#" ~ typeText(toText(name))
-        else toTextLocal(qual) ~ ("." ~ nameIdText(tree) provided name != nme.CONSTRUCTOR)
+        else toTextLocal(qual) ~ ("." ~ nameIdText(tree) provided (name != nme.CONSTRUCTOR || ctx.settings.YprintDebug.value))
       case tree: This =>
         optDotPrefix(tree) ~ keywordStr("this") ~ idText(tree)
       case Super(qual: This, mix) =>
@@ -356,11 +356,7 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
         keywordStr("new ") ~ {
           tpt match {
             case tpt: Template => toTextTemplate(tpt, ofNew = true)
-            case _ =>
-              if (tpt.hasType)
-                toTextLocal(tpt.typeOpt.underlyingClassRef(refinementOK = false))
-              else
-                toTextLocal(tpt)
+            case _ => toTextLocal(tpt)
           }
         }
       case Typed(expr, tpt) =>

compiler/src/dotty/tools/dotc/typer/TypeAssigner.scala

@@ -301,8 +301,16 @@ trait TypeAssigner {
     ConstFold(tree.withType(tp))
   }
 
+  /** Normalize type T appearing in a new T by following eta expansions to
+   *  avoid higher-kinded types.
+   */
+  def typeOfNew(tpt: Tree)(implicit ctx: Context): Type = tpt.tpe.dealias match {
+    case TypeApplications.EtaExpansion(tycon) => tycon
+    case t => tpt.tpe
+  }
+
   def assignType(tree: untpd.New, tpt: Tree)(implicit ctx: Context): New =
-    tree.withType(tpt.tpe)
+    tree.withType(typeOfNew(tpt))
 
   def assignType(tree: untpd.Literal)(implicit ctx: Context): Literal =
     tree.withType {

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -534,11 +534,8 @@ class Typer extends Namer
       case _ =>
         var tpt1 = typedType(tree.tpt)
         tpt1 = tpt1.withType(ensureAccessible(tpt1.tpe, superAccess = false, tpt1.sourcePos))
-        tpt1.tpe.dealias match {
-          case TypeApplications.EtaExpansion(tycon) => tpt1 = tpt1.withType(tycon)
-          case _ =>
-        }
-        if (checkClassType(tpt1.tpe, tpt1.sourcePos, traitReq = false, stablePrefixReq = true) eq defn.ObjectType)
+
+        if (checkClassType(typeOfNew(tpt1), tpt1.sourcePos, traitReq = false, stablePrefixReq = true) eq defn.ObjectType)
           tpt1 = TypeTree(defn.ObjectType).withSpan(tpt1.span)
 
         tpt1 match {
@@ -549,7 +546,6 @@ class Typer extends Namer
         }
 
         assignType(cpy.New(tree)(tpt1), tpt1)
-        // todo in a later phase: checkInstantiatable(cls, tpt1.pos)
     }
   }
 

library/src/scala/tasty/reflect/Printers.scala

@@ -593,8 +593,8 @@ trait Printers
               printParent(fun)
               if (!args.isEmpty || needEmptyParens)
                 inParens(printTrees(args, ", "))
-            case IsTerm(Term.Select(Term.New(tpt), _)) =>
-              printTypeTree(tpt)
+            case IsTerm(Term.Select(Term.IsNew(newTree), _)) =>
+              printType(newTree.tpe)
             case IsTerm(parent) =>
               throw new MatchError(parent.show)
           }
@@ -772,9 +772,9 @@ trait Printers
           }
           this += "this"
 
-        case Term.New(tpt) =>
+        case Term.IsNew(tree) =>
           this += "new "
-          printTypeTree(tpt)
+          printType(tree.tpe)
 
         case Term.NamedArg(name, arg) =>
           this += name += " = "

tests/pos/alias-new.scala

@@ -0,0 +1,9 @@
+object O {
+  class B[T]
+}
+object O2 {
+  type B[T] = O.B[T]
+}
+object Test {
+  val x: O2.B[String] = new O2.B()
+}

tests/run-with-compiler/i3847-b.check

@@ -1 +1 @@
-new scala.Array[scala.List[scala.Int]](1)
+new scala.Array[scala.collection.immutable.List[scala.Int]](1)