Clean code

Author: noti0na1

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

@@ -269,8 +269,6 @@ object Contexts {
     /** Either the current scope, or, if the current context owner is a class,
      *  the declarations of the current class.
      */
-    // TODO: Should we change its type to nullable?
-    // We can see its value can be null in nestingLevel below.
     def effectiveScope(using Context): Scope =
       val co: Symbol | Null = owner
       if co != null && co.isClass then co.asClass.unforcedDecls

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

@@ -105,7 +105,6 @@ final class ProperGadtConstraint private(
               params.indexOf(tp.symbol) match {
                 case -1 =>
                   mapping(tp.symbol) match {
-                    // TODO: Improve flow typing so that ascription becomes redundant, see #11967
                     case tv: TypeVar => tv.origin
                     case null => tp
                   }
@@ -183,6 +182,7 @@ final class ProperGadtConstraint private(
   override def fullBounds(sym: Symbol)(using Context): TypeBounds | Null =
     mapping(sym) match {
       case null => null
+      // TODO: Improve flow typing so that ascription becomes redundant
       case tv: TypeVar =>
         fullBounds(tv.origin)
           // .ensuring(containsNoInternalTypes(_))
@@ -191,6 +191,7 @@ final class ProperGadtConstraint private(
   override def bounds(sym: Symbol)(using Context): TypeBounds | Null =
     mapping(sym) match {
       case null => null
+      // TODO: Improve flow typing so that ascription becomes redundant
       case tv: TypeVar =>
         def retrieveBounds: TypeBounds =
           bounds(tv.origin) match {

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

@@ -780,7 +780,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
     }
     catch {
       case ex: FromDigitsException =>
-        report.error(ex.getMessage.uncheckedNN, tree.srcPos)
+        report.error(ex.getMessage.nn, tree.srcPos)
         tree.kind match {
           case Whole(_) => lit(0)
           case _ => lit(0.0)
@@ -1649,7 +1649,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
           if ctx.scope.lookup(b.name) == NoSymbol then ctx.enter(sym)
           else report.error(new DuplicateBind(b, cdef), b.srcPos)
           if (!ctx.isAfterTyper) {
-            val bounds: TypeBounds | Null = ctx.gadt.fullBounds(sym)
+            val bounds = ctx.gadt.fullBounds(sym)
             if (bounds != null) sym.info = bounds
           }
           b

compiler/src/dotty/tools/dotc/util/GenericHashMap.scala

@@ -151,8 +151,8 @@ abstract class GenericHashMap[Key, Value]
     else
       var idx = 0
       while idx < oldTable.length do
-        val key: Key | Null = oldTable(idx).asInstanceOf[Key | Null]
-        if key != null then addOld(key.uncheckedNN, oldTable(idx + 1).asInstanceOf[Value])
+        val key = oldTable(idx)
+        if key != null then addOld(key.asInstanceOf[Key], oldTable(idx + 1).asInstanceOf[Value])
         idx += 2
 
   protected def growTable(): Unit =

compiler/src/dotty/tools/dotc/util/WeakHashSet.scala

@@ -259,7 +259,7 @@ abstract class WeakHashSet[A <: AnyRef](initialCapacity: Int = 8, loadFactor: Do
         else {
           val result = lookaheadelement.nn
           lookaheadelement = null
-          entry = entry.nn.tail // TODO
+          entry = entry.nn.tail
           result
         }
     }