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)
+