Several fixes and refactorings for typechecking

1) Refactoring of package loaders that ensures that a package is always loaded before new members are entered. This led to a refactoring of sourceModule in completers into its own trait

2) Refactoring of optSelfType ot selfInfo. Class Infos may now have a reference to a symbol in their selfInfo field, instead of always a type, as it was before. This allows to introduce laziness for self type evaluation. Laziness is needed so that modules can be desugared and the desugared version be compiled without special tricks.

3) <init> and $init members are no longer inherited.

4) Refactoring of createSymbol and enterSym, so that creating symbols and entering them in a scope is decoupled.
    Renamed the driver operation form `enterSym(s)` to `index`.

1 files changed, 5 insertions, 2 deletions

diff --git a/src/dotty/tools/dotc/core/Definitions.scala b/src/dotty/tools/dotc/core/Definitions.scala
index ea2682516..4b167baad 100644
--- a/src/dotty/tools/dotc/core/Definitions.scala
+++ b/src/dotty/tools/dotc/core/Definitions.scala
@@ -55,8 +55,11 @@ class Definitions(implicit ctx: Context) {
   private def newMethod(cls: ClassSymbol, name: TermName, info: Type, flags: FlagSet = EmptyFlags): TermSymbol =
     newSymbol(cls, name.encode, flags | Method, info).entered.asTerm
 
-  private def newAliasType(name: TypeName, tpe: Type, flags: FlagSet = EmptyFlags): TypeSymbol =
-    newSymbol(ScalaPackageClass, name, flags, TypeAlias(tpe)).entered.asType
+  private def newAliasType(name: TypeName, tpe: Type, flags: FlagSet = EmptyFlags): TypeSymbol = {
+    val sym = newSymbol(ScalaPackageClass, name, flags, TypeAlias(tpe))
+    ScalaPackageClass.preDecls.enter(sym)
+    sym
+  }
 
   private def newPolyMethod(cls: ClassSymbol, name: TermName, typeParamCount: Int,
                     resultTypeFn: PolyType => Type, flags: FlagSet = EmptyFlags) = {