Fix #8982: Insert colons when rewriting classes to indentation syntax

Allow `for {` under -new-syntax

Author: odersky

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

@@ -797,8 +797,7 @@ object Parsers {
       canRewrite &= (in.isAfterLineEnd || statCtdTokens.contains(in.token)) // test (5)
       if (canRewrite && (!colonRequired || in.colonSyntax)) {
         val openingPatchStr =
-          if (!colonRequired) ""
-          else if (testChar(startOpening - 1, Chars.isOperatorPart(_))) " :"
+          if (testChar(startOpening - 1, Chars.isOperatorPart(_))) " :"
           else ":"
         val (startClosing, endClosing) = closingElimRegion()
         patch(source, Span(startOpening, endOpening), openingPatchStr)
@@ -2469,11 +2468,10 @@ object Parsers {
                   val pos = t.sourcePos
                   pos.startLine < pos.endLine
                 }
-              if (rewriteToNewSyntax(Span(start)) && (leading == LBRACE || !hasMultiLineEnum)) {
+              if in.newSyntax && in.rewrite && (leading == LBRACE || !hasMultiLineEnum) then
                 // Don't rewrite if that could change meaning of newlines
                 newLinesOpt()
                 dropParensOrBraces(start, if (in.token == YIELD || in.token == DO) "" else "do")
-              }
             }
             in.observeIndented()
             res

tests/pos/i8982.scala

@@ -0,0 +1,14 @@
+
+object Foo {
+  def bar(x: Int): Unit = {
+    println(x)
+  }
+}
+
+class Baz(n: Int) {
+  def printRepeat(repeat: Int) = {
+    for {
+      x <- 1 to repeat
+    } println(s"$x - ${n * x}")
+  }
+}