Update dotty to 0.23.0-RC1

Author: Philippus

.travis.yml

@@ -5,7 +5,7 @@ import: scala/scala-dev:travis/default.yml
 language: scala
 
 scala:
-  - 0.22.0-RC1
+  - 0.23.0-RC1
   - 2.11.12
   - 2.12.10
   - 2.13.1
@@ -18,9 +18,9 @@ env:
 
 matrix:
   exclude:
-    - scala: 0.22.0-RC1
+    - scala: 0.23.0-RC1
       env: ADOPTOPENJDK=8     SCALAJS_VERSION=0.6.32
-    - scala: 0.22.0-RC1
+    - scala: 0.23.0-RC1
       env: ADOPTOPENJDK=8     SCALAJS_VERSION=1.0.1
   include:
     - scala: 2.11.12

build.sbt

@@ -43,7 +43,7 @@ lazy val parserCombinators = crossProject(JVMPlatform, JSPlatform, NativePlatfor
     libraryDependencies += "com.novocode" % "junit-interface" % "0.11" % Test
   )
   .jsSettings(
-    crossScalaVersions -= "0.22.0-RC1",
+    crossScalaVersions -= "0.23.0-RC1",
     // Scala.js cannot run forked tests
     fork in Test := false
   )

shared/src/main/scala/scala/util/parsing/combinator/PackratParsers.scala

@@ -107,7 +107,7 @@ trait PackratParsers extends Parsers {
     val q = super.phrase(p)
     new PackratParser[T] {
       def apply(in: Input) = in match {
-        case in if in.isInstanceOf[PackratReader[_]] => q(in) // TODO: try to change back to "case in: PackratReader[_]" after https://github.com/lampepfl/dotty/pull/8413
+        case in: PackratReader[_] => q(in)
         case in => q(new PackratReader(in))
       }
     }