Merge pull request #11852 from dotty-staging/fix-11774

Fix #11774: only enable experimental features for snapshot and nightly

Author: liufengyun

community-build/community-projects/stdLib213

@@ -10,6 +10,9 @@ lazy val compilerVersion: String =
   val file = communitybuildDir.resolve("scala3-bootstrapped.version")
   new String(Files.readAllBytes(file), UTF_8)
 
+lazy val compilerSupportExperimental: Boolean =
+  compilerVersion.contains("SNAPSHOT") || compilerVersion.contains("NIGHTLY")
+
 lazy val sbtPluginFilePath: String =
   // Workaround for https://github.com/sbt/sbt/issues/4395
   new File(sys.props("user.home") + "/.sbt/1.0/plugins").mkdirs()

community-build/src/scala/dotty/communitybuild/projects.scala

@@ -116,7 +116,7 @@ class CommunityBuildTestB extends CommunityBuildTest:
   @Test def disciplineSpecs2 = projects.disciplineSpecs2.run()
   @Test def munit = projects.munit.run()
   @Test def perspective = projects.perspective.run()
-  @Test def scodec = projects.scodec.run()
+  @Test def scodec = if (compilerSupportExperimental) projects.scodec.run()
   @Test def scodecBits = projects.scodecBits.run()
   @Test def simulacrumScalafixAnnotations = projects.simulacrumScalafixAnnotations.run()
 end CommunityBuildTestB

community-build/test/scala/dotty/communitybuild/CommunityBuildTest.scala

@@ -77,6 +77,7 @@ class Driver {
     val ictx = rootCtx.fresh
     val summary = command.distill(args, ictx.settings)(ictx.settingsState)(using ictx)
     ictx.setSettings(summary.sstate)
+    Feature.checkExperimentalFlags(using ictx)
     MacroClassLoader.init(ictx)
     Positioned.init(using ictx)
 

compiler/src/dotty/tools/dotc/Driver.scala

@@ -279,6 +279,11 @@ trait TreeInfo[T >: Untyped <: Type] { self: Trees.Instance[T] =>
 
   def isLanguageImport(path: Tree): Boolean = languageImport(path).isDefined
 
+  def isExperimentalImport(path: Tree): Boolean =
+    languageImport(path) match
+    case Some(nme.experimental) => true
+    case _ => false
+
   /** The underlying pattern ignoring any bindings */
   def unbind(x: Tree): Tree = unsplice(x) match {
     case Bind(_, y) => unbind(y)

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -28,7 +28,19 @@ object Feature:
   val symbolLiterals = deprecated("symbolLiterals")
   val fewerBraces = experimental("fewerBraces")
 
-/** Is `feature` enabled by by a command-line setting? The enabling setting is
+  val experimentalWarningMessage = "Experimental features may only be used with nightly or snapshot version of compiler."
+
+  /** Experimental features are only enabled for snapshot and nightly compiler versions
+   */
+  def experimentalEnabled(using Context): Boolean =
+    Properties.experimental && !ctx.settings.YnoExperimental.value
+
+  def isExperimental(feature: TermName): Boolean =
+    feature != scala2macros && feature.match
+    case QualifiedName(nme.experimental, _) => true
+    case _ => false
+
+  /** Is `feature` enabled by by a command-line setting? The enabling setting is
    *
    *       -language:<prefix>feature
    *
@@ -56,9 +68,12 @@ object Feature:
    *  @param  feature   The name of the feature
    *  @param  owner     The prefix symbol (nested in `scala.language`) where the
    *                    feature is defined.
+   *
+   *  Note: Experimental features are only enabled for snapshot and nightly version of compiler.
    */
   def enabled(feature: TermName)(using Context): Boolean =
-    enabledBySetting(feature) || enabledByImport(feature)
+    (experimentalEnabled || !isExperimental(feature))
+    && (enabledBySetting(feature) || enabledByImport(feature))
 
   /** Is auto-tupling enabled? */
   def autoTuplingEnabled(using Context): Boolean = !enabled(nme.noAutoTupling)
@@ -71,6 +86,8 @@ object Feature:
 
   def genericNumberLiteralsEnabled(using Context) = enabled(genericNumberLiterals)
 
+  def erasedEnabled(using Context) = enabled(Feature.erasedDefinitions)
+
   def scala2ExperimentalMacroEnabled(using Context) = enabled(scala2macros)
 
   def sourceVersionSetting(using Context): SourceVersion =
@@ -97,4 +114,16 @@ object Feature:
     else
       false
 
+  /** Check that experimental compiler options are only set for snapshot or nightly compiler versions. */
+  def checkExperimentalFlags(using Context): Unit =
+    if !experimentalEnabled then
+      val features = ctx.settings.language.value.filter { feature =>
+        feature.contains(nme.experimental.toString) && !feature.contains("macros")
+      }
+      if features.nonEmpty then
+        report.error(
+          experimentalWarningMessage +
+          "\nThe experimental language features are enabled via -language:" + features.mkString(",")
+        )
+
 end Feature

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

@@ -11,7 +11,7 @@ import java.nio.charset.StandardCharsets
 /** Loads `library.properties` from the jar. */
 object Properties extends PropertiesTrait {
   protected def propCategory: String = "compiler"
-  protected def pickJarBasedOn: Class[Option[?]] = classOf[Option[?]]
+  protected def pickJarBasedOn: Class[PropertiesTrait] = classOf[PropertiesTrait]
 
   /** Scala manifest attributes.
    */

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

@@ -215,6 +215,7 @@ class ScalaSettings extends Settings.SettingGroup with CommonScalaSettings {
   val YretainTrees: Setting[Boolean] = BooleanSetting("-Yretain-trees", "Retain trees for top-level classes, accessible from ClassSymbol#tree")
   val YshowTreeIds: Setting[Boolean] = BooleanSetting("-Yshow-tree-ids", "Uniquely tag all tree nodes in debugging output.")
   val YfromTastyIgnoreList: Setting[List[String]] = MultiStringSetting("-Yfrom-tasty-ignore-list", "file", "List of `tasty` files in jar files that will not be loaded when using -from-tasty")
+  val YnoExperimental: Setting[Boolean] = BooleanSetting("-Yno-experimental", "Disable experimental language features")
 
   val YprofileEnabled: Setting[Boolean] = BooleanSetting("-Yprofile-enabled", "Enable profiling.")
   val YprofileDestination: Setting[String] = StringSetting("-Yprofile-destination", "file", "Where to send profiling output - specify a file, default is to the console.", "")

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

@@ -520,6 +520,7 @@ object StdNames {
     val longHash: N             = "longHash"
     val macroThis : N           = "_this"
     val macroContext : N        = "c"
+    val macros: N               = "macros"
     val main: N                 = "main"
     val manifest: N             = "manifest"
     val ManifestFactory: N      = "ManifestFactory"

compiler/src/dotty/tools/dotc/core/StdNames.scala

@@ -32,6 +32,7 @@ import config.Feature
 import config.Feature.{sourceVersion, migrateTo3}
 import config.SourceVersion._
 import config.SourceVersion
+import config.Properties
 
 object Parsers {
 
@@ -3079,6 +3080,11 @@ object Parsers {
       val imp = Import(tree, selectors)
       if isLanguageImport(tree) then
         in.languageImportContext = in.languageImportContext.importContext(imp, NoSymbol)
+        if isExperimentalImport(tree)
+           && !Feature.experimentalEnabled
+           && selectors.exists(_.name != nme.macros)
+        then
+          report.error(Feature.experimentalWarningMessage, imp.srcPos)
         for
           case ImportSelector(id @ Ident(imported), EmptyTree, _) <- selectors
           if allSourceVersionNames.contains(imported)