Silence initialization checker

Author: adpi2

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -161,11 +161,14 @@ object Parsers:
           else if (in.token == RBRACE || in.token == OUTDENT) openBraces -= 1
           in.nextToken()
 
-  class Parser private[parsing] (source: SourceFile, allowRewrite: Boolean = true)(using Context) extends ParserCommon(source) {
+  class Parser private[Parsers] (source: SourceFile, allowRewrite: Boolean = true)(using Context) extends ParserCommon(source) {
 
-    val in: Scanner = new Scanner(source, profile = Profile.current, allowRewrite = allowRewrite)
+    val in: Scanner = createScanner()
     // in.debugTokenStream = true    // uncomment to see the token stream of the standard scanner, but not syntax highlighting
 
+    def createScanner() =
+      new Scanner(source, profile = Profile.current, allowRewrite = allowRewrite)
+
     /** This is the general parse entry point.
      */
     def parse(): Tree = {
@@ -4063,19 +4066,17 @@ object Parsers:
   }
 
   /** The Scala parser that can rewrite to indent */
-  class ToIndentParser(source: SourceFile)(using Context) extends Parser(source):
-    class ToIndentScanner(source: SourceFile)(using Context) extends Scanner(source):
-      /** A copy of the previous token */
-      var prev: TokenData = Scanners.newTokenData
+  private class ToIndentParser(source: SourceFile)(using Context) extends Parser(source):
 
+    override def createScanner(): Scanner = new Scanner(source):
       override def nextToken(): Unit =
         if token != EMPTY then patchIndent()
         prev = saveCopy
         super.nextToken()
-    end ToIndentScanner
 
-    override val in: ToIndentScanner = new ToIndentScanner(source)
     assert(in.rewriteToIndent)
+    
+    private var prev: TokenData = Scanners.newTokenData
 
     /** The last offset where a colon at the end of line would be required if a subsequent { ... }
      *  block would be converted to an indentation region. */
@@ -4120,7 +4121,7 @@ object Parsers:
      *   7. last token is not a leading operator
      */
     private def bracesToIndented[T](body: => T, rewriteWithColon: Boolean): T =
-      val prevSaved = in.prev.saveCopy
+      val prevSaved = prev.saveCopy
       val lastOffsetSaved = in.lastOffset
       val underColonSyntax = possibleColonOffset == in.lastOffset
       val colonRequired = rewriteWithColon || underColonSyntax

compiler/src/dotty/tools/dotc/parsing/Scanners.scala

@@ -1457,7 +1457,7 @@ object Scanners:
 
    /* Initialization: read first char, then first token */
     nextChar()
-    nextToken()
+    (this: @unchecked).nextToken()
     currentRegion = topLevelRegion(indentWidth(offset))
   end Scanner
 

compiler/test/dotty/tools/dotc/parsing/ModifiersParsingTest.scala

@@ -17,7 +17,7 @@ object ModifiersParsingTest {
   given Context = (new ContextBase).initialCtx
 
   def parse(code: String): Tree = {
-    val (_, stats) = new Parser(SourceFile.virtual("<meta>", code)).templateStatSeq()
+    val (_, stats) = Parsers.parser(SourceFile.virtual("<meta>", code)).templateStatSeq()
     stats match { case List(stat) => stat; case stats => Thicket(stats) }
   }
 

compiler/test/dotty/tools/dotc/parsing/ParserTest.scala

@@ -25,7 +25,7 @@ class ParserTest extends DottyTest {
 
   private def parseSource(source: SourceFile): Tree = {
     //println("***** parsing " + source.file)
-    val parser = new Parser(source)
+    val parser = Parsers.parser(source)
     val tree = parser.parse()
     parsed += 1
     parsedTrees += tree