Update scope

Author: noti0na1

compiler/src/dotty/tools/dotc/core/Contexts.scala

@@ -274,9 +274,7 @@ object Contexts {
     def effectiveScope(using Context): Scope =
       val co: Symbol | Null = owner
       if co != null && co.isClass then co.asClass.unforcedDecls
-      else
-        val s: Scope | Null = scope
-        if s == null then EmptyScope else s
+      else scope
 
     def nestingLevel: Int = effectiveScope.nestingLevel
 
@@ -828,6 +826,7 @@ object Contexts {
     owner = NoSymbol
     tree = untpd.EmptyTree
     moreProperties = Map(MessageLimiter -> DefaultMessageLimiter())
+    scope = EmptyScope
     source = NoSource
     store = initialStore
       .updated(settingsStateLoc, settingsGroup.defaultState)

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -1237,7 +1237,7 @@ object SymDenotations {
           .map(tpd.definedSym)
           .find(_.name == name)
           .getOrElse(NoSymbol)
-      else if ((ctx.scope: Scope | Null) == null) // TODO
+      else if (ctx.scope eq EmptyScope)
         NoSymbol
       else if (ctx.scope.lookup(this.name) == symbol)
         ctx.scope.lookup(name)

compiler/src/dotty/tools/dotc/interactive/Completion.scala

@@ -11,6 +11,7 @@ import dotty.tools.dotc.core.Flags._
 import dotty.tools.dotc.core.Names.{Name, TermName}
 import dotty.tools.dotc.core.NameKinds.SimpleNameKind
 import dotty.tools.dotc.core.NameOps._
+import dotty.tools.dotc.core.Scopes._
 import dotty.tools.dotc.core.Symbols.{Symbol, defn}
 import dotty.tools.dotc.core.StdNames.nme
 import dotty.tools.dotc.core.SymDenotations.SymDenotation
@@ -185,7 +186,7 @@ object Completion {
             .groupByName.foreach { (name, denots) =>
               addMapping(name, ScopedDenotations(denots, ctx))
             }
-        else if ctx.scope != null then
+        else if ctx.scope ne EmptyScope then
           ctx.scope.toList.filter(symbol => include(symbol, symbol.name))
             .flatMap(_.alternatives)
             .groupByName.foreach { (name, denots) =>

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

@@ -324,8 +324,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
         (prevPrec.ordinal < prec.ordinal || prevPrec == prec && (prevCtx.scope eq ctx.scope))
 
       @tailrec def loop(lastCtx: Context)(using Context): Type =
-        // Can ctx.scope actually be null?
-        if ((ctx.scope: Scope | Null) == null) previous
+        if (ctx.scope eq EmptyScope) previous
         else {
           var result: Type = NoType