Ship SIP 68: Referenceable package objects

Author: odersky

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

@@ -37,7 +37,6 @@ object Feature:
   val into = experimental("into")
   val modularity = experimental("modularity")
   val quotedPatternsWithPolymorphicFunctions = experimental("quotedPatternsWithPolymorphicFunctions")
-  val packageObjectValues = experimental("packageObjectValues")
   val multiSpreads = experimental("multiSpreads")
   val subCases = experimental("subCases")
   val relaxedLambdaSyntax = experimental("relaxedLambdaSyntax")
@@ -69,7 +68,6 @@ object Feature:
     (separationChecking, "Enable experimental separation checking (requires captureChecking)"),
     (into, "Allow into modifier on parameter types"),
     (modularity, "Enable experimental modularity features"),
-    (packageObjectValues, "Enable experimental package objects as values"),
     (multiSpreads, "Enable experimental varargs with multi-spreads"),
     (subCases, "Enable experimental match expressions with sub-cases"),
     (relaxedLambdaSyntax, "Enable experimental relaxed lambda syntax"),

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -747,9 +747,10 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
     val sym = tree.tpe.termSymbol
     if sym.isNoValue && !ctx.isJava then
       if sym.is(Package)
-          && Feature.enabled(Feature.packageObjectValues)
           && tree.tpe.member(nme.PACKAGE).hasAltWith(_.symbol.isPackageObject)
       then
+      	// The feature is in preview for 3.10
+        Feature.checkPreviewFeature("package object values", tree.srcPos)
         typed(untpd.Select(untpd.TypedSplice(tree), nme.PACKAGE))
       else
         report.error(SymbolIsNotAValue(sym), tree.srcPos)

library/src/scala/language.scala

@@ -195,7 +195,7 @@ object language {
    *
    *  @group experimental
    */
-  object experimental {
+  object experimental:
 
     import languageFeature.experimental._
 
@@ -299,15 +299,15 @@ object language {
      *  @see [[https://dotty.epfl.ch/docs/reference/experimental/into-modifier]]
      */
     @compileTimeOnly("`into` can only be used at compile time in import statements")
-    @deprecated("The into language import is no longer needed since the feature is now in preview", since = "3.8")
+    @deprecated("The `into` language import is no longer needed since the feature is now in preview", since = "3.8")
     object into
 
     /** Experimental support for named tuples.
      *
      *  @see [[https://dotty.epfl.ch/docs/reference/experimental/named-tuples]]
      */
     @compileTimeOnly("`namedTuples` can only be used at compile time in import statements")
-    @deprecated("The experimental.namedTuples language import is no longer needed since the feature is now standard", since = "3.7")
+    @deprecated("`experimental.namedTuples` is now standard, no language import is needed", since = "3.7")
     object namedTuples
 
     /** Experimental support for new features for better modularity, including
@@ -327,15 +327,15 @@ object language {
       * @see [[http://dotty.epfl.ch/docs/reference/contextual/extension-methods]]
       */
     @compileTimeOnly("`relaxedExtensionImports` can only be used at compile time in import statements")
-    @deprecated("The experimental.relaxedExtensionImports language import is no longer needed since the feature is now standard", since = "3.4")
+    @deprecated("`experimental.relaxedExtensionImports` is now standard, no language import is needed", since = "3.4")
     object relaxedExtensionImports
 
     /** Enhance match type extractors to follow aliases and singletons.
      *
      *  @see [[https://github.com/scala/improvement-proposals/pull/84]]
      */
     @compileTimeOnly("`betterMatchTypeExtractors` can only be used at compile time in import statements")
-    @deprecated("The experimental.betterMatchTypeExtractors language import is no longer needed since the feature is now standard. It now has no effect, including when setting an older source version.", since = "3.6")
+    @deprecated("`experimental.betterMatchTypeExtractors` is now standard, no language import is needed", since = "3.6")
     object betterMatchTypeExtractors
 
     /** Experimental support for quote pattern matching with polymorphic functions
@@ -350,12 +350,13 @@ object language {
      * @see [[https://github.com/scala/improvement-proposals/pull/79]]
      */
     @compileTimeOnly("`betterFors` can only be used at compile time in import statements")
-    @deprecated("The `experimental.betterFors` language import no longer has any effect, the feature is being stabilised and can be enabled using `-preview` flag", since = "3.7")
+    @deprecated("`experimental.betterFors` is now standard, no language import is needed", since = "3.7")
     object betterFors
 
     /** Experimental support for package object values
      */
     @compileTimeOnly("`packageObjectValues` can only be used at compile time in import statements")
+    @deprecated("The `experimental.packageObjectValues` language import is no longer needed since the feature is now in preview", since = "3.10")
     object packageObjectValues
 
     /** Experimental support for multiple spread arguments.
@@ -368,13 +369,13 @@ object language {
     @compileTimeOnly("`subCases` can only be used at compile time in import statements")
     object subCases
 
-   /** Experimental support for single-line lambdas and case clause expressions after `:`
+    /** Experimental support for single-line lambdas and case clause expressions after `:`
      */
     @compileTimeOnly("`relaxedLambdaSyntax` can only be used at compile time in import statements")
     object relaxedLambdaSyntax
-  }
+  end experimental
 
-    /** The deprecated object contains features that are no longer officially suypported in Scala.
+  /** The deprecated object contains features that are no longer officially suypported in Scala.
    *  Features in this object are slated for removal. New code should not use them and
    *  old code should migrate away from them.
    */

tests/pos/packageObjectValues.scala

@@ -1,4 +1,4 @@
-//> using options -language:experimental.packageObjectValues
+//> using options -preview
 
 package object p { }
 

tests/run/pkgobjvals.scala

@@ -1,4 +1,4 @@
-import language.experimental.packageObjectValues
+//> using options -preview
 
 package a:
   package object b: