Fix and simplify typedTypeConstructor.

Investigating the useful output of devWarning (-Xdev people,
it's good for you) led back to this comment:

  "normalize to get rid of type aliases"

You may know that this is not all the normalizing does.
Normalizing also turns TypeRefs with unapplied arguments
(type constructors) into PolyTypes. That means that when
typedParentType would call typedTypeConstructor it would
find its parent had morphed into a PolyType. Not that it
noticed; it would blithely continue and unwittingly discard
the type arguments by way of appliedType (which smoothly
logged the incident, thank you appliedType.)

The simplification of typedTypeConstructor:

There was a whole complicated special treatment of AnyRef
here which appears to have become unnecessary. Removed special
treatment and lit a candle for regularity.

Updated lots of tests regarding newly not-so-special AnyRef.

1 files changed, 10 insertions, 21 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index a3688f249d..ad2ec7ff6c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -5307,29 +5307,18 @@ trait Typers extends Modes with Adaptations with Tags {
     def typedTypeConstructor(tree: Tree, mode: Int): Tree = {
       val result = typed(tree, forTypeMode(mode) | FUNmode, WildcardType)
 
-      val restpe = result.tpe.normalize // normalize to get rid of type aliases for the following check (#1241)
-      if (!phase.erasedTypes && restpe.isInstanceOf[TypeRef] && !restpe.prefix.isStable && !context.unit.isJava) {
-        // The isJava exception if OK only because the only type constructors scalac gets
-        // to see are those in the signatures. These do not need a unique object as a prefix.
-        // The situation is different for new's and super's, but scalac does not look deep
-        // enough to see those. See #3938
-        ConstructorPrefixError(tree, restpe)
-      } else {
-        //@M fix for #2208
-        // if there are no type arguments, normalization does not bypass any checks, so perform it to get rid of AnyRef
-        if (result.tpe.typeArgs.isEmpty) {
-          // minimal check: if(result.tpe.typeSymbolDirect eq AnyRefClass) {
-          // must expand the fake AnyRef type alias, because bootstrapping (init in Definitions) is not
-          // designed to deal with the cycles in the scala package (ScalaObject extends
-          // AnyRef, but the AnyRef type alias is entered after the scala package is
-          // loaded and completed, so that ScalaObject is unpickled while AnyRef is not
-          // yet defined )
-          // !!! TODO - revisit now that ScalaObject is gone.
-          result setType(restpe)
-        } else { // must not normalize: type application must be (bounds-)checked (during RefChecks), see #2208
+      // get rid of type aliases for the following check (#1241)
+      result.tpe.dealias match {
+        case restpe @ TypeRef(pre, _, _) if !phase.erasedTypes && !pre.isStable && !context.unit.isJava =>
+          // The isJava exception if OK only because the only type constructors scalac gets
+          // to see are those in the signatures. These do not need a unique object as a prefix.
+          // The situation is different for new's and super's, but scalac does not look deep
+          // enough to see those. See #3938
+          ConstructorPrefixError(tree, restpe)
+        case _ =>
+          // must not normalize: type application must be (bounds-)checked (during RefChecks), see #2208
           // during uncurry (after refchecks), all types are normalized
           result
-        }
       }
     }