introduce infrastructure for 3.2 language features

Co-authored-by: Tom Grigg <[email protected]>

Author: bishabosha

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

@@ -88,8 +88,7 @@ object Feature:
   /** If current source migrates to `version`, issue given warning message
    *  and return `true`, otherwise return `false`.
    */
-  def warnOnMigration(msg: Message, pos: SrcPos,
-      version: SourceVersion)(using Context): Boolean =
+  def warnOnMigration(msg: Message, pos: SrcPos, version: SourceVersion)(using Context): Boolean =
     if sourceVersion.isMigrating && sourceVersion.stable == version
        || (version == `3.0` || version == `3.1` || version == `3.2`) && migrateTo3
     then

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

@@ -5,6 +5,7 @@ import scala.language.unsafeNulls
 
 import dotty.tools.dotc.config.PathResolver.Defaults
 import dotty.tools.dotc.config.Settings.{Setting, SettingGroup}
+import dotty.tools.dotc.config.SourceVersion
 import dotty.tools.dotc.core.Contexts._
 import dotty.tools.dotc.rewrites.Rewrites
 import dotty.tools.io.{AbstractFile, Directory, JDK9Reflectors, PlainDirectory}
@@ -31,6 +32,9 @@ object ScalaSettings:
   def supportedScalaReleaseVersions: List[String] =
     ScalaRelease.values.toList.map(_.show)
 
+  def supportedSourceVersions: List[String] =
+    SourceVersion.values.toList.map(_.toString)
+
   def defaultClasspath: String = sys.env.getOrElse("CLASSPATH", ".")
 
   def defaultPageWidth: Int = {
@@ -51,7 +55,7 @@ trait AllScalaSettings extends CommonScalaSettings, PluginSettings, VerboseSetti
   /* Path related settings */
   val semanticdbTarget: Setting[String] = PathSetting("-semanticdb-target", "Specify an alternative output directory for SemanticDB files.", "")
 
-  val source: Setting[String] = ChoiceSetting("-source", "source version", "source version", List("3.0", "3.1", "future", "3.0-migration", "future-migration"), "3.0", aliases = List("--source"))
+  val source: Setting[String] = ChoiceSetting("-source", "source version", "source version", ScalaSettings.supportedSourceVersions, SourceVersion.defaultSourceVersion.toString, aliases = List("--source"))
   val uniqid: Setting[Boolean] = BooleanSetting("-uniqid", "Uniquely tag all identifiers in debugging output.", aliases = List("--unique-id"))
   val rewrite: Setting[Option[Rewrites]] = OptionSetting[Rewrites]("-rewrite", "When used in conjunction with a `...-migration` source version, rewrites sources to migrate to new version.", aliases = List("--rewrite"))
   val fromTasty: Setting[Boolean] = BooleanSetting("-from-tasty", "Compile classes from tasty files. The arguments are .tasty or .jar files.", aliases = List("--from-tasty"))

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

@@ -6,7 +6,9 @@ import core.Decorators.*
 import util.Property
 
 enum SourceVersion:
-  case `3.0-migration`, `3.0`, `3.1`, `3.2`, `future-migration`, `future`
+  case `3.0-migration`, `3.0`, `3.1` // Note: do not add `3.1-migration` here, 3.1 is the same language as 3.0.
+  case `3.2-migration`, `3.2`
+  case `future-migration`, `future`
 
   val isMigrating: Boolean = toString.endsWith("-migration")
 
@@ -16,6 +18,7 @@ enum SourceVersion:
   def isAtLeast(v: SourceVersion) = stable.ordinal >= v.ordinal
 
 object SourceVersion extends Property.Key[SourceVersion]:
+  def defaultSourceVersion = `3.0`
 
   /** language versions that may appear in a language import, are deprecated, but not removed from the standard library. */
   val illegalSourceVersionNames = List("3.1-migration").map(_.toTermName)

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

@@ -67,8 +67,7 @@ object report:
     error(ex.toMessage, pos, sticky = true)
     if ctx.settings.YdebugTypeError.value then ex.printStackTrace()
 
-  def errorOrMigrationWarning(msg: Message, pos: SrcPos = NoSourcePosition,
-      from: SourceVersion)(using Context): Unit =
+  def errorOrMigrationWarning(msg: Message, pos: SrcPos = NoSourcePosition, from: SourceVersion)(using Context): Unit =
     if sourceVersion.isAtLeast(from) then
       if sourceVersion.isMigrating && sourceVersion.ordinal <= from.ordinal then migrationWarning(msg, pos)
       else error(msg, pos)

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

@@ -38,7 +38,7 @@ class CompilationTests {
       compileFilesInDir("tests/pos-special/spec-t5545", defaultOptions),
       compileFilesInDir("tests/pos-special/strawman-collections", allowDeepSubtypes),
       compileFilesInDir("tests/pos-special/isInstanceOf", allowDeepSubtypes.and("-Xfatal-warnings")),
-      compileFilesInDir("tests/new", defaultOptions.and("-source", "3.1")), // just to see whether 3.1 works
+      compileFilesInDir("tests/new", defaultOptions.and("-source", "3.2")), // just to see whether 3.2 works
       compileFilesInDir("tests/pos-scala2", scala2CompatMode),
       compileFilesInDir("tests/pos-custom-args/erased", defaultOptions.and("-language:experimental.erasedDefinitions")),
       compileFilesInDir("tests/pos", defaultOptions.and("-Ysafe-init")),

library/src/scala/runtime/stdLibPatches/language.scala

@@ -165,19 +165,33 @@ object language:
   @compileTimeOnly("`3.1` can only be used at compile time in import statements")
   object `3.1`
 
-/* This can be added when we go to 3.2
   /** Set source version to 3.2-migration.
     *
-    * @see [[https://scalacenter.github.io/scala-3-migration-guide/docs/scala-3-migration-mode]]
+    * @see [[https://docs.scala-lang.org/scala3/guides/migration/compatibility-intro.html]]
     */
   @compileTimeOnly("`3.2-migration` can only be used at compile time in import statements")
   object `3.2-migration`
 
   /** Set source version to 3.2
     *
-    * @see [[https://scalacenter.github.io/scala-3-migration-guide/docs/scala-3-migration-mode]]
+    * @see [[https://docs.scala-lang.org/scala3/guides/migration/compatibility-intro.html]]
     */
   @compileTimeOnly("`3.2` can only be used at compile time in import statements")
   object `3.2`
+
+/* This can be added when we go to 3.3
+  /** Set source version to 3.3-migration.
+    *
+    * @see [[https://docs.scala-lang.org/scala3/guides/migration/compatibility-intro.html]]
+    */
+  @compileTimeOnly("`3.3-migration` can only be used at compile time in import statements")
+  object `3.3-migration`
+
+  /** Set source version to 3.3
+    *
+    * @see [[https://docs.scala-lang.org/scala3/guides/migration/compatibility-intro.html]]
+    */
+  @compileTimeOnly("`3.3` can only be used at compile time in import statements")
+  object `3.3`
 */
 end language

tests/pos/source-import-3-2-migration.scala

@@ -0,0 +1 @@
+import language.`3.2-migration`

tests/pos/source-import-3-2.scala

@@ -0,0 +1 @@
+import language.`3.2`