sip23 condition

this bootstraps

Author: adriaanm

src/compiler/scala/tools/nsc/Global.scala

@@ -78,6 +78,9 @@ class Global(var currentSettings: Settings, var reporter: Reporter)
 
   override def settings = currentSettings
 
+  // TODO: temporary flag to easily enable/disable SIP-23 (aka the type formerly known as 42.type)
+  override def sip23: Boolean = true //settings.Xexperimental.value
+
   /** Switch to turn on detailed type logs */
   var printTypings = settings.Ytyperdebug.value
 

src/compiler/scala/tools/nsc/ast/parser/Parsers.scala

@@ -339,8 +339,6 @@ self =>
     }
     private def inScalaRootPackage = inScalaPackage && currentPackage == "scala"
 
-    // 42.type aka SIP-23
-    private[this] lazy val parseLiteralSingletonTypes = settings.Xexperimental.value
 
     def parseStartRule: () => Tree
 
@@ -678,7 +676,7 @@ self =>
 
     def isExprIntro: Boolean = isExprIntroToken(in.token)
 
-    def isTypeIntroToken(token: Token): Boolean = (parseLiteralSingletonTypes && isLiteralToken(token)) || (token match {
+    def isTypeIntroToken(token: Token): Boolean = (sip23 && isLiteralToken(token)) || (token match {
       case IDENTIFIER | BACKQUOTED_IDENT | THIS |
            SUPER | USCORE | LPAREN | AT => true
       case _ => false
@@ -945,7 +943,7 @@ self =>
         simpleTypeRest(in.token match {
           case LPAREN   => atPos(start)(makeTupleType(inParens(types())))
           case USCORE   => wildcardType(in.skipToken())
-          case tok if parseLiteralSingletonTypes && isLiteralToken(tok) => atPos(start){SingletonTypeTree(literal())} // SIP-23
+          case tok if sip23 && isLiteralToken(tok) => atPos(start){SingletonTypeTree(literal())} // SIP-23
           case _ =>
             path(thisOK = false, typeOK = true) match {
               case r @ SingletonTypeTree(_) => r
@@ -1028,7 +1026,7 @@ self =>
             mkOp(infixType(InfixMode.RightOp))
         }
         // SIP-23
-        def isNegatedLiteralType = parseLiteralSingletonTypes && (
+        def isNegatedLiteralType = sip23 && (
           t match { // the token for `t` (Ident("-")) has already been read, thus `isLiteral` below is looking at next token (must be a literal)
             case Ident(name) if isLiteral => name == nme.MINUS.toTypeName // TODO: OPT? lift out nme.MINUS.toTypeName?
             case _ => false

src/compiler/scala/tools/nsc/typechecker/Namers.scala

@@ -845,8 +845,6 @@ trait Namers extends MethodSynthesis {
       loop(tp)
     }
 
-//    private[this] val sip23 = settings.Xexperimental.value
-
     /**
      * This method has a big impact on the eventual compiled code.
      *  At this point many values have the most specific possible
@@ -862,7 +860,7 @@ trait Namers extends MethodSynthesis {
      *  whether it is otherwise redundant (such as in a singleton.)
      */
     private def widenIfNecessary(sym: Symbol, tpe: Type, pt: Type): Type =
-      if (settings.Xexperimental) { // SIP-23
+      if (sip23) { // SIP-23
         // TODO: spec -- this is a crucial part of type inference
         // NOTES:
         //  - Can we widen less? (E.g., for local definitions.)

src/compiler/scala/tools/nsc/typechecker/Typers.scala

@@ -5094,7 +5094,7 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
 
       def typedSingletonTypeTree(tree: SingletonTypeTree) = {
         // SIP-23: don't require AnyRef for 1.type etc
-        val pt = if (settings.Xexperimental) WildcardType else AnyRefTpe
+        val pt = if (sip23) WildcardType else AnyRefTpe
         val refTyped =
           context.withImplicitsDisabled {
             typed(tree.ref, MonoQualifierModes | mode.onlyTypePat, pt)

src/reflect/scala/reflect/internal/SymbolTable.scala

@@ -52,6 +52,7 @@ abstract class SymbolTable extends macros.Universe
   val gen = new InternalTreeGen { val global: SymbolTable.this.type = SymbolTable.this }
 
   def log(msg: => AnyRef): Unit
+  def sip23: Boolean = false // temporary, overriden in Global
 
   protected def elapsedMessage(msg: String, start: Long) =
     msg + " in " + (TimeUnit.NANOSECONDS.toMillis(System.nanoTime()) - start) + "ms"

src/reflect/scala/reflect/internal/Types.scala

@@ -1841,7 +1841,7 @@ trait Types
   abstract case class ConstantType(value: Constant) extends SingletonType with ConstantTypeApi {
     assert(underlying.typeSymbol != UnitClass)
 
-    override def underlying: Type = if (settings.Xexperimental && value.isSuitableLiteralType) LiteralType(value) else value.tpe // SIP-23
+    override def underlying: Type = if (sip23 && value.isSuitableLiteralType) LiteralType(value) else value.tpe // SIP-23
     override def isTrivial: Boolean = true
     override def deconst: Type = underlying.deconst
     override def safeToString: String =