Remove DropImports; add Java Enum test

Author: noti0na1

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

@@ -101,7 +101,6 @@ class Compiler {
          new TupleOptimizations,     // Optimize generic operations on tuples
          new LetOverApply,           // Lift blocks from receivers of applications
          new ArrayConstructors) ::   // Intercept creation of (non-generic) arrays and intrinsify.
-    List(new DropImports) ::         // Drop all (language-) imports
     List(new Erasure) ::             // Rewrite types to JVM model, erasing all type parameters, abstract types and refinements.
     List(new ElimErasedValueType,    // Expand erased value types to their underlying implmementation types
          new PureStats,              // Remove pure stats from blocks

compiler/src/dotty/tools/dotc/transform/DropImports.scala

@@ -43,7 +43,7 @@ class Erasure extends Phase with DenotTransformer {
   override def description: String = Erasure.description
 
   /** List of names of phases that should precede this phase */
-  override def runsAfter: Set[String] = Set(InterceptedMethods.name, ElimRepeated.name, DropImports.name)
+  override def runsAfter: Set[String] = Set(InterceptedMethods.name, ElimRepeated.name)
 
   override def changesMembers: Boolean = true // the phase adds bridges
   override def changesParents: Boolean = true // the phase drops Any
@@ -1043,6 +1043,12 @@ object Erasure {
       (stats2.filterConserve(!_.isEmpty), finalCtx)
     }
 
+    /** Finally drops all (language-) imports in erasure.
+     *  Since some of the language imports change the subtyping,
+     *  we cannot check the trees before erasure.
+     */
+    override def typedImport(tree: untpd.Import)(using Context) = EmptyTree
+
     override def adapt(tree: Tree, pt: Type, locked: TypeVars, tryGadtHealing: Boolean)(using Context): Tree =
       trace(i"adapting ${tree.showSummary()}: ${tree.tpe} to $pt", show = true) {
         if ctx.phase != erasurePhase && ctx.phase != erasurePhase.next then

compiler/src/dotty/tools/dotc/transform/Erasure.scala

@@ -122,7 +122,8 @@ class SyntheticMembers(thisPhase: DenotTransformer) {
 
       def nameRef: Tree =
         if isJavaEnumValue then
-          Select(This(clazz), nme.name).ensureApplied
+          val name = Select(This(clazz), nme.name).ensureApplied
+          if ctx.explicitNulls then name.cast(defn.StringType) else name
         else
           identifierRef
 

compiler/src/dotty/tools/dotc/transform/SyntheticMembers.scala

@@ -51,7 +51,7 @@ class ReTyper(nestingLevel: Int = 0) extends Typer(nestingLevel) with ReChecking
   override def typedSuper(tree: untpd.Super, pt: Type)(using Context): Tree =
     promote(tree)
 
-  override def typedImport(tree: untpd.Import, sym: Symbol)(using Context): Tree =
+  override def typedImport(tree: untpd.Import)(using Context): Tree =
     promote(tree)
 
   override def typedTyped(tree: untpd.Typed, pt: Type)(using Context): Tree = {

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

@@ -2613,7 +2613,8 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
                 |The selector is not a member of an object or package.""")
     else typd(imp.expr, AnySelectionProto)
 
-  def typedImport(imp: untpd.Import, sym: Symbol)(using Context): Tree =
+  def typedImport(imp: untpd.Import)(using Context): Tree =
+    val sym = retrieveSym(imp)
     val expr1 = typedImportQualifier(imp, typedExpr(_, _)(using ctx.withOwner(sym)))
     checkLegalImportPath(expr1)
     val selectors1 = typedSelectors(imp.selectors)
@@ -2879,7 +2880,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
           case tree: untpd.If => typedIf(tree, pt)
           case tree: untpd.Function => typedFunction(tree, pt)
           case tree: untpd.Closure => typedClosure(tree, pt)
-          case tree: untpd.Import => typedImport(tree, retrieveSym(tree))
+          case tree: untpd.Import => typedImport(tree)
           case tree: untpd.Export => typedExport(tree)
           case tree: untpd.Match => typedMatch(tree, pt)
           case tree: untpd.Return => typedReturn(tree)

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

@@ -0,0 +1,12 @@
+enum ErrorMessageID(val isActive: Boolean = true) extends java.lang.Enum[ErrorMessageID]:
+
+  case NoExplanationID // errorNumber: -1
+  case EmptyCatchOrFinallyBlockID extends ErrorMessageID(isActive = false) // errorNumber: 0
+
+  def errorNumber = ordinal - 1
+
+enum Color(val rgb: Int):
+  case Red   extends Color(0xFF0000)
+  case Green extends Color(0x00FF00)
+  case Blue  extends Color(0x0000FF)
+