Fix indentWidth calculation when rewriting to braces

Author: odersky

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

@@ -607,10 +607,7 @@ object Parsers {
     /** Parse indentation region `body` and rewrite it to be in braces instead */
     def indentedToBraces[T](body: => T): T = {
       val enclRegion = in.currentRegion.enclosing
-      def indentWidth = enclRegion match {
-        case Indented(w, _, _, _) => w
-        case _ => IndentWidth.Zero
-      }
+      def indentWidth = enclRegion.indentWidth
       val followsColon = testChar(in.lastOffset - 1, ':')
       val startOpening =
         if (followsColon)
@@ -1175,7 +1172,7 @@ object Parsers {
     }
 
     def indentRegion[T](tag: EndMarkerTag)(op: => T): T = {
-      val iw = in.currentIndentWidth
+      val iw = in.currentRegion.indentWidth
       val t = op
       in.consumeEndMarker(tag, iw)
       t

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

@@ -307,11 +307,6 @@ object Scanners {
      */
     var currentRegion: Region = Outermost
 
-    def currentIndentWidth: IndentWidth = currentRegion match {
-      case r: Indented => r.width
-      case _ => IndentWidth.Zero
-    }
-
     /** The end marker that was skipped last */
     val endMarkers = new mutable.ListBuffer[EndMarker]
 
@@ -416,7 +411,7 @@ object Scanners {
      *  value at the end of the endMarkers queue.
      */
     private def handleEndMarkers(width: IndentWidth): Unit = {
-      if (next.token == IDENTIFIER && next.name == nme.end && width == currentIndentWidth) {
+      if (next.token == IDENTIFIER && next.name == nme.end && width == currentRegion.indentWidth) {
         val lookahead = lookaheadScanner
         lookahead.nextToken() // skip the `end`
 
@@ -589,15 +584,14 @@ object Scanners {
         insert(if (pastBlankLine) NEWLINES else NEWLINE, lineOffset)
       else if (indentIsSignificant) {
         if (nextWidth < lastWidth
-            || nextWidth == lastWidth && (indentPrefix == MATCH || indentPrefix == CATCH) && token != CASE) {
+            || nextWidth == lastWidth && (indentPrefix == MATCH || indentPrefix == CATCH) && token != CASE)
           currentRegion match {
             case r: Indented if !r.isOutermost && !isLeadingInfixOperator() =>
               currentRegion = r.enclosing
               insert(OUTDENT, offset)
               handleEndMarkers(nextWidth)
             case _ =>
           }
-        }
         else if (lastWidth < nextWidth ||
                  lastWidth == nextWidth && (lastToken == MATCH || lastToken == CATCH) && token == CASE) {
           if (canStartIndentTokens.contains(lastToken)) {
@@ -1369,16 +1363,21 @@ object Scanners {
     def outer: Region | Null
     def isOutermost = outer == null
     def enclosing: Region = outer.asInstanceOf[Region]
+    def indentWidth = IndentWidth.Zero
   }
-  case class InParens(prefix: Token, outer: Region) extends Region
-  case class InBraces(var width: IndentWidth | Null, outer: Region) extends Region
   case class InString(multiLine: Boolean, outer: Region) extends Region
+  case class InParens(prefix: Token, outer: Region) extends Region
+  case class InBraces(var width: IndentWidth | Null, outer: Region) extends Region {
+    override def indentWidth = width
+  }
 
   /** A class describing an indentation region.
    *  @param width   The principal indendation width
    *  @param others  Other indendation widths > width of lines in the same region
    */
-  case class Indented(width: IndentWidth, others: Set[IndentWidth], prefix: Token, outer: Region | Null) extends Region
+  case class Indented(width: IndentWidth, others: Set[IndentWidth], prefix: Token, outer: Region | Null) extends Region {
+    override def indentWidth = width
+  }
 
   val Outermost = Indented(IndentWidth.Zero, Set(), EMPTY, null)