Allow experimental features in Tests

... but not in TastyBootstrap tests

Author: odersky

compiler/src/dotty/tools/dotc/config/Config.scala

@@ -1,4 +1,5 @@
 package dotty.tools.dotc.config
+import annotation.internal.sharable
 
 object Config {
 
@@ -219,5 +220,5 @@ object Config {
    *  `Properties.experimental`. Can be re-assigned, e.g. to allow tests
    *  of experimental features.
    */
-  private[dotty] var allowExperimentalFeatures = Properties.experimental
+  @sharable private[dotty] var allowExperimentalFeatures = Properties.experimental
 }

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -240,7 +240,7 @@ class CompilationTests {
         Properties.compilerInterface, Properties.scalaLibrary, Properties.scalaAsm,
         Properties.dottyInterfaces, Properties.jlineTerminal, Properties.jlineReader,
       ).mkString(File.pathSeparator),
-      Array("-Ycheck-reentrant", "-language:postfixOps", "-Xsemanticdb")
+      Array("-Ycheck-reentrant", "-language:postfixOps", "-Xsemanticdb", "-Yno-experimental")
     )
 
     val libraryDirs = List(Paths.get("library/src"), Paths.get("library/src-bootstrapped"))

compiler/test/dotty/tools/vulpix/ParallelTesting.scala

@@ -25,6 +25,7 @@ import dotc.report
 import dotc.interfaces.Diagnostic.ERROR
 import dotc.reporting.{Reporter, TestReporter}
 import dotc.reporting.Diagnostic
+import dotc.config.Config
 import dotc.util.DiffUtil
 import io.AbstractFile
 import dotty.tools.vulpix.TestConfiguration.defaultOptions
@@ -36,9 +37,10 @@ import dotty.tools.vulpix.TestConfiguration.defaultOptions
  *  test suite itself runs with a high level of concurrency.
  */
 trait ParallelTesting extends RunnerOrchestration { self =>
-
   import ParallelTesting._
 
+  Config.allowExperimentalFeatures = true
+
   /** If the running environment supports an interactive terminal, each `Test`
    *  will be run with a progress bar and real time feedback
    */